Plasmodium falciparum CS protein - prime malaria vaccine candidate: definition of the human CTL domain and analysis of its variation

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Denise L. Doolan

1992-01-01

Full Text Available Studies in mice have shown that immunity to malaria sporozoites is mediated primarily by citotoxic T lymphocytes (CTL specific for epitopes within the circumsporozoite (CS protein. Humans, had never been shown to generate CTL against any malaria or other parasite protein. The design of a sub-unit vaccine for humans ralies on the epitopes recognized by CTL being identified and polymorphisms therein being defined. We have developed a novel technique using an entire series of overlapping synthetic peptides to define the epitopes of the Plasmodium falciparum CS protein recognized by human CTL and have analyzed the sequence variation of the protein with respect to the identified CTL epitopic domain. We have demonstrated that some humans can indeed generate CTL. against the P. falciparum CS protein. Furthermore, the extent of variation observed for the CTL recognition domain is finite and the combination of peptides necessary for inclusion in a polyvalent vaccine may be small. If ways can be found to increase immune responsiveness, then a vaccine designed to stimulate CS protein-specific CTL activity may prevent malaria.

The synthetic Plasmodium falciparum circumsporozoite peptide PfCS102 as a malaria vaccine candidate: a randomized controlled phase I trial.

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Régine Audran

Full Text Available BACKGROUND: Fully efficient vaccines against malaria pre-erythrocytic stage are still lacking. The objective of this dose/adjuvant-finding study was to evaluate the safety, reactogenicity and immunogenicity of a vaccine candidate based on a peptide spanning the C-terminal region of Plasmodium falciparum circumsporozoite protein (PfCS102 in malaria naive adults. METHODOLOGY AND PRINCIPAL FINDINGS: Thirty-six healthy malaria-naive adults were randomly distributed into three dose blocks (10, 30 and 100 microg and vaccinated with PfCS102 in combination with either Montanide ISA 720 or GSK proprietary Adjuvant System AS02A at days 0, 60, and 180. Primary end-point (safety and reactogenicity was based on the frequency of adverse events (AE and of abnormal biological safety tests; secondary-end point (immunogenicity on P. falciparum specific cell-mediated immunity and antibody response before and after immunization. The two adjuvant formulations were well tolerated and their safety profile was good. Most AEs were local and, when systemic, involved mainly fatigue and headache. Half the volunteers in AS02A groups experienced severe AEs (mainly erythema. After the third injection, 34 of 35 volunteers developed anti-PfCS102 and anti-sporozoite antibodies, and 28 of 35 demonstrated T-cell proliferative responses and IFN-gamma production. Five of 22 HLA-A2 and HLA-A3 volunteers displayed PfCS102 specific IFN-gamma secreting CD8(+ T cell responses. Responses were only marginally boosted after the 3(rd vaccination and remained stable for 6 months. For both adjuvants, the dose of 10 microg was less immunogenic in comparison to 30 and 100 microg that induced similar responses. AS02A formulations with 30 microg or 100 microg PfCS102 induced about 10-folds higher antibody and IFN-gamma responses than Montanide formulations. CONCLUSIONS/SIGNIFICANCE: PfCS102 peptide was safe and highly immunogenic, allowing the design of more advanced trials to test its potential

Conjugating recombinant proteins to Pseudomonas aeruginosa ExoProtein A: a strategy for enhancing immunogenicity of malaria vaccine candidates

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Qian, Feng; Wu, Yimin; Muratova, Olga; Zhou, Hong; Dobrescu, Gelu; Duggan, Peter; Lynn, Lambert; Song, Guanhong; Zhang, Yanling; Reiter, Karine; MacDonald, Nicholas; Narum, David L.; Long, Carole A.; Miller, Louis H.; Saul, Allan

2007-01-01

Conjugation of polysaccharides to carrier proteins has been a successful approach for producing safe and effective vaccines. In an attempt to increase the immunogenicity of two malarial vaccine candidate proteins of Plasmodium falciparum, apical membrane antigen 1 (AMA1) for blood stage vaccines and surface protein 25 (Pfs25) for mosquito stage vaccines, each was chemically conjugated to the mutant, nontoxic Pseudomonas aeruginosa ExoProtein A (rEPA). AMA1 is a large (66 kD) relatively good i...

Evidence for globally shared, cross-reacting polymorphic epitopes in the pregnancy-associated malaria vaccine candidate VAR2CSA

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Avril, Marion; Kulasekara, Bridget R; Gose, Severin O

2008-01-01

Pregnancy-associated malaria (PAM) is characterized by the placental sequestration of Plasmodium falciparum-infected erythrocytes (IEs) with the ability to bind to chondroitin sulfate A (CSA). VAR2CSA is a leading candidate for a pregnancy malaria vaccine, but its large size ( approximately 350 k...

Force Spectroscopy of the Plasmodium falciparum Vaccine Candidate Circumsporozoite Protein Suggests a Mechanically Pliable Repeat Region.

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Patra, Aditya Prasad; Sharma, Shobhona; Ainavarapu, Sri Rama Koti

2017-02-10

The most effective vaccine candidate of malaria is based on the Plasmodium falciparum circumsporozoite protein (CSP), a major surface protein implicated in the structural strength, motility, and immune evasion properties of the infective sporozoites. It is suspected that reversible conformational changes of CSP are required for infection of the mammalian host, but the detailed structure and dynamic properties of CSP remain incompletely understood, limiting our understanding of its function in the infection. Here, we report the structural and mechanical properties of the CSP studied using single-molecule force spectroscopy on several constructs, one including the central region of CSP, which is rich in NANP amino acid repeats (CSP rep ), and a second consisting of a near full-length sequence without the signal and anchor hydrophobic domains (CSP ΔHP ). Our results show that the CSP rep is heterogeneous, with 40% of molecules requiring virtually no mechanical force to unfold (<10 piconewtons (pN)), suggesting that these molecules are mechanically compliant and perhaps act as entropic springs, whereas the remaining 60% are partially structured with low mechanical resistance (∼70 pN). CSP ΔHP having multiple force peaks suggests specifically folded domains, with two major populations possibly indicating the open and collapsed forms. Our findings suggest that the overall low mechanical resistance of the repeat region, exposed on the outer surface of the sporozoites, combined with the flexible full-length conformations of CSP, may provide the sporozoites not only with immune evasion properties, but also with lubricating capacity required during its navigation through the mosquito and vertebrate host tissues. We anticipate that these findings would further assist in the design and development of future malarial vaccines. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Naturally acquired antibody responses to recombinant Pfs230 and Pfs48/45 transmission blocking vaccine candidates

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Jones, Sophie; Grignard, Lynn; Nebie, Issa

2015-01-01

for the future evaluation of vaccine immunogenicity and efficacy in populations naturally exposed to malaria. METHODS: We determined naturally acquired antibody responses to the recombinant proteins Pfs48/45-10C and Pfs230-230CMB in children from three malaria endemic settings in Ghana, Tanzania and Burkina Faso......OBJECTIVES: Pfs48/45 and Pfs230 are Plasmodium falciparum sexual stage proteins and promising malaria transmission-blocking vaccine candidates. Antibody responses against these proteins may be naturally acquired and target antigens may be under selective pressure. This has consequences....... We also examined genetic polymorphisms in the P. falciparum gene pfs48/45. RESULTS: Antibody prevalence was 1.1-18.2% for 10C and 6.7-18.9% for 230CMB. In Burkina Faso we observed evidence of an age-dependent acquisition pattern for both 10C (p assays...

Transgenic Parasites Stably Expressing Full-Length Plasmodium falciparum Circumsporozoite Protein as a Model for Vaccine Down-Selection in Mice Using Sterile Protection as an Endpoint

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Porter, Michael D.; Nicki, Jennifer; Pool, Christopher D.; DeBot, Margot; Illam, Ratish M.; Brando, Clara; Bozick, Brooke; De La Vega, Patricia; Angra, Divya; Spaccapelo, Roberta; Crisanti, Andrea; Murphy, Jittawadee R.; Bennett, Jason W.; Schwenk, Robert J.; Ockenhouse, Christian F.

2013-01-01

Circumsporozoite protein (CSP) of Plasmodium falciparum is a protective human malaria vaccine candidate. There is an urgent need for models that can rapidly down-select novel CSP-based vaccine candidates. In the present study, the mouse-mosquito transmission cycle of a transgenic Plasmodium berghei malaria parasite stably expressing a functional full-length P. falciparum CSP was optimized to consistently produce infective sporozoites for protection studies. A minimal sporozoite challenge dose was established, and protection was defined as the absence of blood-stage parasites 14 days after intravenous challenge. The specificity of protection was confirmed by vaccinating mice with multiple CSP constructs of differing lengths and compositions. Constructs that induced high NANP repeat-specific antibody titers in enzyme-linked immunosorbent assays were protective, and the degree of protection was dependent on the antigen dose. There was a positive correlation between antibody avidity and protection. The antibodies in the protected mice recognized the native CSP on the parasites and showed sporozoite invasion inhibitory activity. Passive transfer of anti-CSP antibodies into naive mice also induced protection. Thus, we have demonstrated the utility of a mouse efficacy model to down-select human CSP-based vaccine formulations. PMID:23536694

Differing patterns of selection and geospatial genetic diversity within two leading Plasmodium vivax candidate vaccine antigens.

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Christian M Parobek

2014-04-01

Full Text Available Although Plasmodium vivax is a leading cause of malaria around the world, only a handful of vivax antigens are being studied for vaccine development. Here, we investigated genetic signatures of selection and geospatial genetic diversity of two leading vivax vaccine antigens--Plasmodium vivax merozoite surface protein 1 (pvmsp-1 and Plasmodium vivax circumsporozoite protein (pvcsp. Using scalable next-generation sequencing, we deep-sequenced amplicons of the 42 kDa region of pvmsp-1 (n = 44 and the complete gene of pvcsp (n = 47 from Cambodian isolates. These sequences were then compared with global parasite populations obtained from GenBank. Using a combination of statistical and phylogenetic methods to assess for selection and population structure, we found strong evidence of balancing selection in the 42 kDa region of pvmsp-1, which varied significantly over the length of the gene, consistent with immune-mediated selection. In pvcsp, the highly variable central repeat region also showed patterns consistent with immune selection, which were lacking outside the repeat. The patterns of selection seen in both genes differed from their P. falciparum orthologs. In addition, we found that, similar to merozoite antigens from P. falciparum malaria, genetic diversity of pvmsp-1 sequences showed no geographic clustering, while the non-merozoite antigen, pvcsp, showed strong geographic clustering. These findings suggest that while immune selection may act on both vivax vaccine candidate antigens, the geographic distribution of genetic variability differs greatly between these two genes. The selective forces driving this diversification could lead to antigen escape and vaccine failure. Better understanding the geographic distribution of genetic variability in vaccine candidate antigens will be key to designing and implementing efficacious vaccines.

Safety and immunogenicity of the malaria vaccine candidate MSP3 long synthetic peptide in 12-24 months-old Burkinabe children.

NARCIS (Netherlands)

Sirima, S.B.; Tiono, A.B.; Diarra, A.; Ouedraogo, A.L.; Yaro, J.B.; Ouedraogo, E.; Gansane, A.; Bougouma, E.C.; Konate, A.T.; Kabore, Y.; Traore, A.; Roma, C.; Soulama, I.; Luty, A.J.F.; Cousens, S.; Nebie, I.

2009-01-01

BACKGROUND: A Phase Ia trial in European volunteers of the candidate vaccine merozoite surface protein 3 (MSP3), a Plasmodium falciparum blood stage membrane, showed that it induces biologically active antibodies able to achieve parasite killing in vitro, while a phase Ib trial in semi-immune adult

Improving the malaria transmission-blocking activity of a Plasmodium falciparum 48/45 based vaccine antigen by SpyTag/SpyCatcher mediated virus-like display

DEFF Research Database (Denmark)

Singh, Susheel K; Thrane, Susan; Janitzek, Christoph M

2017-01-01

Malaria is a devastating disease caused by Plasmodium parasites, resulting in almost 0.5 million deaths per year. The Pfs48/45 protein exposed on the P. falciparum sexual stages is one of the most advanced antigen candidates for a transmission-blocking (TB) vaccine in the clinical pipeline. However...

A multilateral effort to develop DNA vaccines against falciparum malaria.

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Kumar, Sanjai; Epstein, Judith E; Richie, Thomas L; Nkrumah, Francis K; Soisson, Lorraine; Carucci, Daniel J; Hoffman, Stephen L

2002-03-01

Scientists from several organizations worldwide are working together to develop a multistage, multigene DNA-based vaccine against Plasmodium falciparum malaria. This collaborative vaccine development effort is named Multi-Stage DNA-based Malaria Vaccine Operation. An advisory board of international experts in vaccinology, malariology and field trials provides the scientific oversight to support the operation. This article discusses the rationale for the approach, underlying concepts and the pre-clinical development process, and provides a brief outline of the plans for the clinical testing of a multistage, multiantigen malaria vaccine based on DNA plasmid immunization technology.

Satisfactory safety and immunogenicity of MSP3 malaria vaccine candidate in Tanzanian children aged 12–24 months

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Segeja Method D

2009-07-01

Full Text Available Abstract Background Development and deployment of an effective malaria vaccine would complement existing malaria control measures. A blood stage malaria vaccine candidate, Merozoite Surface Protein-3 (MSP3, produced as a long synthetic peptide, has been shown to be safe in non-immune and semi-immune adults. A phase Ib dose-escalating study was conducted to assess the vaccine's safety and immunogenicity in children aged 12 to 24 months in Korogwe, Tanzania (ClinicalTrials.gov number: NCT00469651. Methods This was a double-blind, randomized, controlled, dose escalation phase Ib trial, in which children were given one of two different doses of the MSP3 antigen (15 μg or 30 μg or a control vaccine (Engerix B. Children were randomly allocated either to the MSP3 candidate malaria vaccine or the control vaccine administered at a schedule of 0, 1, and 2 months. Immunization with lower and higher doses was staggered for safety reasons starting with the lower dose. The primary endpoint was safety and reactogenicity within 28 days post-vaccination. Blood samples were obtained at different time points to measure immunological responses. Results are presented up to 84 days post-vaccination. Results A total of 45 children were enrolled, 15 in each of the two MSP3 dose groups and 15 in the Engerix B group. There were no important differences in reactogenicity between the two MSP3 groups and Engerix B. Grade 3 adverse events were infrequent; only five were detected throughout the study, all of which were transient and resolved without sequelae. No serious adverse event reported was considered to be related to MSP3 vaccine. Both MSP3 dose regimens elicited strong cytophilic IgG responses (subclasses IgG1 and IgG3, the isotypes involved in the monocyte-dependant mechanism of Plasmodium falciparum parasite-killing. The titers reached are similar to those from African adults having reached a state of premunition. Furthermore, vaccination induced seroconversion in

Naturally acquired antibody responses to recombinant Pfs230 and Pfs48/45 transmission blocking vaccine candidates.

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Jones, Sophie; Grignard, Lynn; Nebie, Issa; Chilongola, Jaffu; Dodoo, Daniel; Sauerwein, Robert; Theisen, Michael; Roeffen, Will; Singh, Shrawan Kumar; Singh, Rajesh Kumar; Singh, Sanjay; Kyei-Baafour, Eric; Tetteh, Kevin; Drakeley, Chris; Bousema, Teun

2015-07-01

Pfs48/45 and Pfs230 are Plasmodium falciparum sexual stage proteins and promising malaria transmission-blocking vaccine candidates. Antibody responses against these proteins may be naturally acquired and target antigens may be under selective pressure. This has consequences for the future evaluation of vaccine immunogenicity and efficacy in populations naturally exposed to malaria. We determined naturally acquired antibody responses to the recombinant proteins Pfs48/45-10C and Pfs230-230CMB in children from three malaria endemic settings in Ghana, Tanzania and Burkina Faso. We also examined genetic polymorphisms in the P. falciparum gene pfs48/45. Antibody prevalence was 1.1-18.2% for 10C and 6.7-18.9% for 230CMB. In Burkina Faso we observed evidence of an age-dependent acquisition pattern for both 10C (p < 0.001) and 230CMB (p = 0.031). Membrane feeding assays on a separate dataset demonstrated an association between functional transmission reducing activity and antibody prevalence for both 10C (p = 0.017) and 230CMB (p = 0.049). 17 single nucleotide polymorphisms were found in pfs48/45 (from 126 samples), with 5 non-synonymous SNPs in the Pfs48/45 10C region. We conclude there are naturally acquired antibody responses to both vaccine candidates which have functional relevance by reducing the transmissibility of infected individuals. We identified genetic polymorphisms, in pfs48/45 which exhibited geographical specificity. Copyright © 2015 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Development of vaccines against Plasmodium falciparum malaria: taking lessons from naturally acquired protective immunity

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Hviid, Lars

2007-01-01

The acquisition of substantial anti-malarial protection in people naturally exposed to P. falciparum is often cited as evidence that malaria vaccines can be developed, but is rarely used to guide the development. We are pursuing the development of vaccines based on antigens and immune responses...

Construct design, production, and characterization of Plasmodium falciparum 48/45 R0.6C subunit protein produced in Lactococcus lactis as candidate vaccine.

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Singh, Susheel K; Roeffen, Will; Mistarz, Ulrik H; Chourasia, Bishwanath Kumar; Yang, Fen; Rand, Kasper D; Sauerwein, Robert W; Theisen, Michael

2017-05-31

The sexual stages of Plasmodium falciparum are responsible for the spread of the parasite in malaria endemic areas. The cysteine-rich Pfs48/45 protein, exposed on the surface of sexual stages, is one of the most advanced antigens for inclusion into a vaccine that will block transmission. However, clinical Pfs48/45 sub-unit vaccine development has been hampered by the inability to produce high yields of recombinant protein as the native structure is required for the induction of functional transmission-blocking (TB) antibodies. We have investigated a downstream purification process of a sub-unit (R0.6C) fragment representing the C-terminal 6-Cys domain of Pfs48/45 (6C) genetically fused to the R0 region (R0) of asexual stage Glutamate Rich Protein expressed in Lactococcus lactis. A series of R0.6C fusion proteins containing features, which aim to increase expression levels or to facilitate protein purification, were evaluated at small scale. None of these modifications affected the overall yield of recombinant protein. Consequently, R0.6C with a C-terminal his tag was used for upstream and downstream process development. A simple work-flow was developed consisting of batch fermentation followed by two purification steps. As such, the recombinant protein was purified to homogeneity. The composition of the final product was verified by HPLC, mass spectrometry, SDS-PAGE and Western blotting with conformation dependent antibodies against Pfs48/45. The recombinant protein induced high levels of functional TB antibodies in rats. The established production and purification process of the R0.6C fusion protein provide a strong basis for further clinical development of this candidate transmission blocking malaria vaccine.

A Large Size Chimeric Highly Immunogenic Peptide Presents Multistage Plasmodium Antigens as a Vaccine Candidate System against Malaria.

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Lozano, José Manuel; Varela, Yahson; Silva, Yolanda; Ardila, Karen; Forero, Martha; Guasca, Laura; Guerrero, Yuly; Bermudez, Adriana; Alba, Patricia; Vanegas, Magnolia; Patarroyo, Manuel Elkin

2017-11-01

Rational strategies for obtaining malaria vaccine candidates should include not only a proper selection of target antigens for antibody stimulation, but also a versatile molecular design based on ordering the right pieces from the complex pathogen molecular puzzle towards more active and functional immunogens. Classical Plasmodium falciparum antigens regarded as vaccine candidates have been selected as model targets in this study. Among all possibilities we have chosen epitopes of Pf CSP, STARP; MSA1 and Pf 155/RESA from pre- and erythrocyte stages respectively for designing a large 82-residue chimeric immunogen. A number of options aimed at diminishing steric hindrance for synthetic procedures were assessed based on standard Fmoc chemistry such as building block orthogonal ligation; pseudo-proline and microwave-assisted procedures, therefore the large-chimeric target was produced, characterized and immunologically tested. Antigenicity and functional in vivo efficacy tests of the large-chimera formulations administered alone or as antigen mixtures have proven the stimulation of high antibody titers, showing strong correlation with protection and parasite clearance of vaccinated BALB/c mice after being lethally challenged with both P. berghei -ANKA and P. yoelii 17XL malaria strains. Besides, 3D structure features shown by the large-chimera encouraged as to propose using these rational designed large synthetic molecules as reliable vaccine candidate-presenting systems.

A Large Size Chimeric Highly Immunogenic Peptide Presents Multistage Plasmodium Antigens as a Vaccine Candidate System against Malaria

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José Manuel Lozano

2017-11-01

Full Text Available Rational strategies for obtaining malaria vaccine candidates should include not only a proper selection of target antigens for antibody stimulation, but also a versatile molecular design based on ordering the right pieces from the complex pathogen molecular puzzle towards more active and functional immunogens. Classical Plasmodium falciparum antigens regarded as vaccine candidates have been selected as model targets in this study. Among all possibilities we have chosen epitopes of PfCSP, STARP; MSA1 and Pf155/RESA from pre- and erythrocyte stages respectively for designing a large 82-residue chimeric immunogen. A number of options aimed at diminishing steric hindrance for synthetic procedures were assessed based on standard Fmoc chemistry such as building block orthogonal ligation; pseudo-proline and microwave-assisted procedures, therefore the large-chimeric target was produced, characterized and immunologically tested. Antigenicity and functional in vivo efficacy tests of the large-chimera formulations administered alone or as antigen mixtures have proven the stimulation of high antibody titers, showing strong correlation with protection and parasite clearance of vaccinated BALB/c mice after being lethally challenged with both P. berghei-ANKA and P. yoelii 17XL malaria strains. Besides, 3D structure features shown by the large-chimera encouraged as to propose using these rational designed large synthetic molecules as reliable vaccine candidate-presenting systems.

Construct design, production, and characterization of Plasmodium falciparum 48/45 R0.6C subunit protein produced in Lactococcus lactis as candidate vaccine

DEFF Research Database (Denmark)

Singh, Susheel K; Roeffen, Will; Mistarz, Ulrik H

2017-01-01

BACKGROUND: The sexual stages of Plasmodium falciparum are responsible for the spread of the parasite in malaria endemic areas. The cysteine-rich Pfs48/45 protein, exposed on the surface of sexual stages, is one of the most advanced antigens for inclusion into a vaccine that will block transmissi...

Genetic diversity of the merozoite surface protein-3 gene in Plasmodium falciparum populations in Thailand.

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Pattaradilokrat, Sittiporn; Sawaswong, Vorthon; Simpalipan, Phumin; Kaewthamasorn, Morakot; Siripoon, Napaporn; Harnyuttanakorn, Pongchai

2016-10-21

An effective malaria vaccine is an urgently needed tool to fight against human malaria, the most deadly parasitic disease of humans. One promising candidate is the merozoite surface protein-3 (MSP-3) of Plasmodium falciparum. This antigenic protein, encoded by the merozoite surface protein (msp-3) gene, is polymorphic and classified according to size into the two allelic types of K1 and 3D7. A recent study revealed that both the K1 and 3D7 alleles co-circulated within P. falciparum populations in Thailand, but the extent of the sequence diversity and variation within each allelic type remains largely unknown. The msp-3 gene was sequenced from 59 P. falciparum samples collected from five endemic areas (Mae Hong Son, Kanchanaburi, Ranong, Trat and Ubon Ratchathani) in Thailand and analysed for nucleotide sequence diversity, haplotype diversity and deduced amino acid sequence diversity. The gene was also subject to population genetic analysis (F st ) and neutrality tests (Tajima's D, Fu and Li D* and Fu and Li' F* tests) to determine any signature of selection. The sequence analyses revealed eight unique DNA haplotypes and seven amino acid sequence variants, with a haplotype and nucleotide diversity of 0.828 and 0.049, respectively. Neutrality tests indicated that the polymorphism detected in the alanine heptad repeat region of MSP-3 was maintained by positive diversifying selection, suggesting its role as a potential target of protective immune responses and supporting its role as a vaccine candidate. Comparison of MSP-3 variants among parasite populations in Thailand, India and Nigeria also inferred a close genetic relationship between P. falciparum populations in Asia. This study revealed the extent of the msp-3 gene diversity in P. falciparum in Thailand, providing the fundamental basis for the better design of future blood stage malaria vaccines against P. falciparum.

Protective antibody and CD8+ T-cell responses to the Plasmodium falciparum circumsporozoite protein induced by a nanoparticle vaccine.

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Stephen A Kaba

Full Text Available The worldwide burden of malaria remains a major public health problem due, in part, to the lack of an effective vaccine against the Plasmodium falciparum parasite. An effective vaccine will most likely require the induction of antigen specific CD8(+ and CD4(+ T-cells as well as long-lasting antibody responses all working in concert to eliminate the infection. We report here the effective modification of a self-assembling protein nanoparticle (SAPN vaccine previously proven effective in control of a P. berghei infection in a rodent model to now present B- and T-cell epitopes of the human malaria parasite P. falciparum in a platform capable of being used in human subjects.To establish the basis for a SAPN-based vaccine, B- and CD8(+ T-cell epitopes from the P. falciparum circumsporozoite protein (PfCSP and the universal CD4 T-helper epitope PADRE were engineered into a versatile small protein (∼125 amino acids that self-assembles into a spherical nanoparticle repetitively displaying the selected epitopes. P. falciparum epitope specific immune responses were evaluated in mice using a transgenic P. berghei malaria parasite of mice expressing the human malaria full-length P. falciparum circumsporozoite protein (Tg-Pb/PfCSP. We show that SAPN constructs, delivered in saline, can induce high-titer, long-lasting (1 year protective antibody and poly-functional (IFNγ(+, IL-2(+ long-lived central memory CD8(+ T-cells. Furthermore, we demonstrated that these Ab or CD8(+ T-cells can independently provide sterile protection against a lethal challenge of the transgenic parasites.The SAPN construct induces long-lasting antibody and cellular immune responses to epitope specific sequences of the P. falciparum circumsporozoite protein (PfCSP and prevents infection in mice by a transgenic P. berghei parasite displaying the full length PfCSP.

Development of a metabolically active, non-replicating sporozoite vaccine to prevent Plasmodium falciparum malaria.

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Hoffman, Stephen L; Billingsley, Peter F; James, Eric; Richman, Adam; Loyevsky, Mark; Li, Tao; Chakravarty, Sumana; Gunasekera, Anusha; Chattopadhyay, Rana; Li, Minglin; Stafford, Richard; Ahumada, Adriana; Epstein, Judith E; Sedegah, Martha; Reyes, Sharina; Richie, Thomas L; Lyke, Kirsten E; Edelman, Robert; Laurens, Matthew B; Plowe, Christopher V; Sim, B Kim Lee

2010-01-01

Immunization of volunteers by the bite of mosquitoes carrying radiation-attenuated Plasmodium falciparum sporozoites protects greater than 90% of such volunteers against malaria, if adequate numbers of immunizing biting sessions and sporozoite-infected mosquitoes are used. Nonetheless, until recently it was considered impossible to develop, license and commercialize a live, whole parasite P. falciparum sporozoite (PfSPZ) vaccine. In 2003 Sanaria scientists reappraised the potential impact of a metabolically active, non-replicating PfSPZ vaccine, and outlined the challenges to producing such a vaccine. Six years later, significant progress has been made in overcoming these challenges. This progress has enabled the manufacture and release of multiple clinical lots of a 1(st) generation metabolically active, non-replicating PfSPZ vaccine, the Sanaria PfSPZ Vaccine, submission of a successful Investigational New Drug application to the US Food and Drug Administration, and initiation of safety, immunogenicity and protective efficacy studies in volunteers in MD, US. Efforts are now focused on how best to achieve submission of a successful Biologics License Application and introduce the vaccine to the primary target population of African children in the shortest possible period of time. This will require implementation of a systematic, efficient clinical development plan. Short term challenges include optimizing the (1) efficiency and scale up of the manufacturing process and quality control assays, (2) dosage regimen and method of administration, (3) potency of the vaccine, and (4) logistics of delivering the vaccine to those who need it most, and finalizing the methods for vaccine stabilization and attenuation. A medium term goal is to design and build a facility for manufacturing highly potent and stable vaccine for pivotal Phase 3 studies and commercial launch.

Impact of pre-existing MSP142-allele specific immunity on potency of an erythrocytic Plasmodium falciparum vaccine

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Bergmann-Leitner Elke S

2012-09-01

Full Text Available Abstract Background MSP1 is the major surface protein on merozoites and a prime candidate for a blood stage malaria vaccine. Preclinical and seroepidemiological studies have implicated antibodies to MSP1 in protection against blood stage parasitaemia and/or reduced parasite densities, respectively. Malaria endemic areas have multiple strains of Plasmodium falciparum circulating at any given time, giving rise to complex immune responses, an issue which is generally not addressed in clinical trials conducted in non-endemic areas. A lack of understanding of the effect of pre-existing immunity to heterologous parasite strains may significantly contribute to vaccine failure in the field. The purpose of this study was to model the effect of pre-existing immunity to MSP142 on the immunogenicity of blood-stage malaria vaccines based on alternative MSP1 alleles. Methods Inbred and outbred mice were immunized with various recombinant P. falciparum MSP142 proteins that represent the two major alleles of MSP142, MAD20 (3D7 and Wellcome (K1, FVO. Humoral immune responses were analysed by ELISA and LuminexTM, and functional activity of induced MSP142-specific antibodies was assessed by growth inhibition assays. T-cell responses were characterized using ex vivo ELISpot assays. Results Analysis of the immune responses induced by various immunization regimens demonstrated a strong allele-specific response at the T cell level in both inbred and outbred mice. The success of heterologous regimens depended on the degree of homology of the N-terminal p33 portion of the MSP142, likely due to the fact that most T cell epitopes reside in this part of the molecule. Analysis of humoral immune responses revealed a marked cross-reactivity between the alleles. Functional analyses showed that some of the heterologous regimens induced antibodies with improved growth inhibitory activities. Conclusion The development of a more broadly efficacious MSP1 based vaccine may be

Geographical and temporal conservation of antibody recognition of Plasmodium falciparum variant surface antigens

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Nielsen, Morten A; Vestergaard, Lasse S; Lusingu, John

2004-01-01

The slow acquisition of protection against Plasmodium falciparum malaria probably reflects the extensive diversity of important antigens. The variant surface antigens (VSA) that mediate parasite adhesion to a range of host molecules are regarded as important targets of acquired protective immunity......, but their diversity makes them questionable vaccine candidates. We determined levels of VSA-specific immunoglobulin G (IgG) in human plasma collected at four geographically distant and epidemiologically distinct localities with specificity for VSA expressed by P. falciparum isolates from three African countries...

Effect of the pre-erythrocytic candidate malaria vaccine RTS,S/AS01E on blood stage immunity in young children

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Bejon, Philip; Cook, Jackie; Bergmann-Leitner, Elke

2011-01-01

(See the article by Greenhouse et al, on pages 19-26.) Background. RTS,S/AS01(E) is the lead candidate malaria vaccine and confers pre-erythrocytic immunity. Vaccination may therefore impact acquired immunity to blood-stage malaria parasites after natural infection. Methods. We measured, by enzyme......, MSP-1(42), and MSP-3 antibody concentrations and no significant change in GIA. Increasing anti-merozoite antibody concentrations and GIA were prospectively associated with increased risk of clinical malaria. Conclusions. Vaccination with RTS,S/AS01E reduces exposure to blood-stage parasites and, thus......-linked immunosorbent assay, antibodies to 4 Plasmodium falciparum merozoite antigens (AMA-1, MSP-1(42), EBA-175, and MSP-3) and by growth inhibitory activity (GIA) using 2 parasite clones (FV0 and 3D7) at 4 times on 860 children who were randomized to receive with RTS,S/AS01(E) or a control vaccine. Results. Antibody...

The Malaria Vaccine Candidate GMZ2 Elicits Functional Antibodies in Individuals From Malaria Endemic and Non-Endemic Areas

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Jepsen, Micha Phill Grønholm; Jogdand, Prajakta S; Singh, Susheel K

2013-01-01

against Plasmodium falciparum. Results. We showed that the maximum level of immunoglobulin G (IgG) antibodies obtained by GMZ2 vaccination is independent of ethnicity, time under malaria-exposure, and vaccine dose and that GMZ2 elicits high levels of functionally active IgG antibodies. Both, malaria......-naive adults and malaria-exposed preschool children elicit vaccine-specific antibodies with broad inhibitory activity against geographically diverse P. falciparum isolates. Peptide-mapping studies of IgG subclass responses identified IgG3 against a peptide derived from MSP3 as the strongest predictor...

Plasmodium falciparum associated with severe childhood malaria preferentially expresses PfEMP1 encoded by group A var genes

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Jensen, Anja T R; Magistrado, Pamela; Sharp, Sarah

2004-01-01

Parasite-encoded variant surface antigens (VSAs) like the var gene-encoded Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family are responsible for antigenic variation and infected red blood cell (RBC) cytoadhesion in P. falciparum malaria. Parasites causing severe malaria in noni...... genes, such as PFD1235w/MAL7P1.1, appear to be involved in the pathogenesis of severe disease and are thus attractive candidates for a vaccine against life-threatening P. falciparum malaria....

Conjugating recombinant proteins to Pseudomonas aeruginosa ExoProtein A: a strategy for enhancing immunogenicity of malaria vaccine candidates.

Science.gov (United States)

Qian, Feng; Wu, Yimin; Muratova, Olga; Zhou, Hong; Dobrescu, Gelu; Duggan, Peter; Lynn, Lambert; Song, Guanhong; Zhang, Yanling; Reiter, Karine; MacDonald, Nicholas; Narum, David L; Long, Carole A; Miller, Louis H; Saul, Allan; Mullen, Gregory E D

2007-05-16

Conjugation of polysaccharides to carrier proteins has been a successful approach for producing safe and effective vaccines. In an attempt to increase the immunogenicity of two malarial vaccine candidate proteins of Plasmodium falciparum, apical membrane antigen 1 (AMA1) to a blood stage vaccine candidate and surface protein 25 (Pfs25) a mosquito stage vaccine candidate, were each independently chemically conjugated to the mutant, nontoxic Pseudomonas aeruginosa ExoProtein A (rEPA). AMA1 is a large (66kD) relatively good immunogen in mice; Pfs25 is a poorly immunogenic protein when presented on alum to mice. Mice were immunized on days 0 and 28 with AMA1- or Pfs25-rEPA conjugates or unconjugated AMA1 or Pfs25, all formulated on Alhydrogel. Remarkably, sera from mice 14 days after the second immunization with Pfs25-rEPA conjugates displayed over a 1000-fold higher antibody titers as compared to unconjugated Pfs25. In contrast, AMA1 conjugated under the same conditions induced only a three-fold increase in antibody titers. When tested for functional activity, antibodies elicited by the AMA1-rEPA inhibited invasion of erythrocytes by blood-stage parasites and antibodies elicited by the Pfs25-rEPA conjugates blocked the development of the sexual stage parasites in the mosquito midgut. These results demonstrate that conjugation to rEPA induces a marked improvement in the antibody titer in mice for the poor immunogen (Pfs25) and for the larger protein (AMA1). These conjugates now need to be tested in humans to determine if mice are predictive of the response in humans.

Advances and challenges in malaria vaccine development.

Science.gov (United States)

Crompton, Peter D; Pierce, Susan K; Miller, Louis H

2010-12-01

Malaria caused by Plasmodium falciparum remains a major public health threat, especially among children and pregnant women in Africa. An effective malaria vaccine would be a valuable tool to reduce the disease burden and could contribute to elimination of malaria in some regions of the world. Current malaria vaccine candidates are directed against human and mosquito stages of the parasite life cycle, but thus far, relatively few proteins have been studied for potential vaccine development. The most advanced vaccine candidate, RTS,S, conferred partial protection against malaria in phase II clinical trials and is currently being evaluated in a phase III trial in Africa. New vaccine targets need to be identified to improve the chances of developing a highly effective malaria vaccine. A better understanding of the mechanisms of naturally acquired immunity to malaria may lead to insights for vaccine development.

Advanced Vaccine Candidates for Lassa Fever

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Igor S. Lukashevich

2012-10-01

Full Text Available Lassa virus (LASV is the most prominent human pathogen of the Arenaviridae. The virus is transmitted to humans by a rodent reservoir, Mastomys natalensis, and is capable of causing lethal Lassa Fever (LF. LASV has the highest human impact of any of the viral hemorrhagic fevers (with the exception of Dengue Fever with an estimated several hundred thousand infections annually, resulting in thousands of deaths in Western Africa. The sizeable disease burden, numerous imported cases of LF in non-endemic countries, and the possibility that LASV can be used as an agent of biological warfare make a strong case for vaccine development. Presently there is no licensed vaccine against LF or approved treatment. Recently, several promising vaccine candidates have been developed which can potentially target different groups at risk. The purpose of this manuscript is to review the LASV pathogenesis and immune mechanisms involved in protection. The current status of pre-clinical development of the advanced vaccine candidates that have been tested in non-human primates will be discussed. Major scientific, manufacturing, and regulatory challenges will also be considered.

A Library of Plasmodium vivax Recombinant Merozoite Proteins Reveals New Vaccine Candidates and Protein-Protein Interactions

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Hostetler, Jessica B.; Sharma, Sumana; Bartholdson, S. Josefin; Wright, Gavin J.; Fairhurst, Rick M.; Rayner, Julian C.

2015-01-01

Background A vaccine targeting Plasmodium vivax will be an essential component of any comprehensive malaria elimination program, but major gaps in our understanding of P. vivax biology, including the protein-protein interactions that mediate merozoite invasion of reticulocytes, hinder the search for candidate antigens. Only one ligand-receptor interaction has been identified, that between P. vivax Duffy Binding Protein (PvDBP) and the erythrocyte Duffy Antigen Receptor for Chemokines (DARC), and strain-specific immune responses to PvDBP make it a complex vaccine target. To broaden the repertoire of potential P. vivax merozoite-stage vaccine targets, we exploited a recent breakthrough in expressing full-length ectodomains of Plasmodium proteins in a functionally-active form in mammalian cells and initiated a large-scale study of P. vivax merozoite proteins that are potentially involved in reticulocyte binding and invasion. Methodology/Principal Findings We selected 39 P. vivax proteins that are predicted to localize to the merozoite surface or invasive secretory organelles, some of which show homology to P. falciparum vaccine candidates. Of these, we were able to express 37 full-length protein ectodomains in a mammalian expression system, which has been previously used to express P. falciparum invasion ligands such as PfRH5. To establish whether the expressed proteins were correctly folded, we assessed whether they were recognized by antibodies from Cambodian patients with acute vivax malaria. IgG from these samples showed at least a two-fold change in reactivity over naïve controls in 27 of 34 antigens tested, and the majority showed heat-labile IgG immunoreactivity, suggesting the presence of conformation-sensitive epitopes and native tertiary protein structures. Using a method specifically designed to detect low-affinity, extracellular protein-protein interactions, we confirmed a predicted interaction between P. vivax 6-cysteine proteins P12 and P41, further

Genetic diversity in the block 2 region of the merozoite surface protein-1 of Plasmodium falciparum in central India

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Bharti Praveen K

2012-03-01

Full Text Available Abstract Background Malaria continues to be a significant health problem in India. Several of the intended Plasmodium falciparum vaccine candidate antigens are highly polymorphic. The genetic diversity of P. falciparum merozoite surface protein-1 (MSP-1 has been extensively studied from various parts of the world. However, limited data are available from India. The aim of the present study was a molecular characterization of block 2 region of MSP-1 gene from the tribal-dominated, forested region of Madhya Pradesh. Methods DNA sequencing analysis was carried out in 71 field isolates collected between July 2005 to November 2005 and in 98 field isolates collected from July 2009 to December 2009. Alleles identified by DNA sequencing were aligned with the strain 3D7 and polymorphism analysis was done by using Edit Sequence tool (DNASTAR. Results The malaria positivity was 26% in 2005, which rose to 29% in 2009 and P. falciparum prevalence was also increased from 72% in 2005 to 81% in 2009. The overall allelic prevalence was higher in K1 (51% followed by MAD20 (28% and RO33 (21% in 2005 while in 2009, RO33 was highest (40% followed by K1 (36% and MAD20 (24%. Conclusions The present study reports extensive genetic variations and dynamic evolution of block 2 region of MSP-1 in central India. Characterization of antigenic diversity in vaccine candidate antigens are valuable for future vaccine trials as well as understanding the population dynamics of P. falciparum parasites in this area.

Promising new vaccine candidates against Campylobacter in broilers.

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Marine Meunier

Full Text Available Campylobacter is the leading cause of human bacterial gastroenteritis in the European Union. Birds represent the main reservoir of the bacteria, and human campylobacteriosis mainly occurs after consuming and/or handling poultry meat. Reducing avian intestinal Campylobacter loads should impact the incidence of human diseases. At the primary production level, several measures have been identified to reach this goal, including vaccination of poultry. Despite many studies, however, no efficient vaccine is currently available. We have recently identified new vaccine candidates using the reverse vaccinology strategy. This study assessed the in vivo immune and protective potential of six newly-identified vaccine antigens. Among the candidates tested on Ross broiler chickens, four (YP_001000437.1, YP_001000562.1, YP_999817.1, and YP_999838.1 significantly reduced cecal Campylobacter loads by between 2 and 4.2 log10 CFU/g, with the concomitant development of a specific humoral immune response. In a second trial, cecal load reductions results were not statistically confirmed despite the induction of a strong immune response. These vaccine candidates need to be further investigated since they present promising features.

ION-EXCHANGE IMMUNOAFFINITY PURIFICATION OF A RECOMBINANT BACULOVIRUS PLASMODIUM-FALCIPARUM APICAL MEMBRANE ANTIGEN, PF83/AMA-1

NARCIS (Netherlands)

NARUM, DL; WELLING, GW; THOMAS, AW

1993-01-01

A two-step purification regime has been developed for a quantitatively minor, putatively transmembrane, M(r) 83 000, apical membrane blood stage vaccine candidate antigen of Plasmodium falciparum (PF83/AMA-1), that has been expressed as a full-length baculovirus recombinant protein, PF83-FG8-1. The

A novel live-attenuated vaccine candidate for mayaro Fever.

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William J Weise

2014-08-01

Full Text Available Mayaro virus (MAYV is an emerging, mosquito-borne alphavirus that causes a dengue-like illness in many regions of South America, and which has the potential to urbanize. Because no specific treatment or vaccine is available for MAYV infection, we capitalized on an IRES-based approach to develop a live-attenuated MAYV vaccine candidate. Testing in infant, immunocompetent as well as interferon receptor-deficient mice demonstrated a high degree of attenuation, strong induction of neutralizing antibodies, and efficacy against lethal challenge. This vaccine strain was also unable to infect mosquito cells, a major safety feature for a live vaccine derived from a mosquito-borne virus. Further preclinical development of this vaccine candidate is warranted to protect against this important emerging disease.

APPROACHING THE TARGET: THE PATH TOWARDS AN EFFECTIVE MALARIA VACCINE

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Alberto L. García-Basteiro

2012-01-01

Full Text Available Eliciting an effective malaria vaccine has been the goal of the scientific community for many years. A malaria vaccine, added to existing tools and strategies, would further prevent and decrease the unacceptable malaria morbidity and mortality burden. Great progress has been made over the last decade, with some vaccine candidates in the clinical phases of development. The RTS,S malaria vaccine candidate, based on a recombinant P. falciparum protein, is the most advanced of such candidates, currently undergoing a large phase III trial. RTS,S has consistently shown an efficacy of around 50% against the first clinical episode of malaria, with protection in some cases extending up to 4 years of duration. Thus, it is hoped that this candidate vaccine will eventually become the first licensed malaria vaccine. This first vaccine against a human parasite is a groundbreaking achievement, but improved malaria vaccines conferring higher protection will be needed if the aspiration of malaria eradication is to be achieved

Safety and immunogenicity of a malaria vaccine, Plasmodium falciparum AMA-1/MSP-1 chimeric protein formulated in montanide ISA 720 in healthy adults.

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Jinhong Hu

Full Text Available BACKGROUND: The P. falciparum chimeric protein 2.9 (PfCP-2.9 consisting of the sequences of MSP1-19 and AMA-1 (III is a malaria vaccine candidate that was found to induce inhibitory antibodies in rabbits and monkeys. This was a phase I randomized, single-blind, placebo-controlled, dose-escalation study to evaluate the safety and immunogenicity of the PfCP-2.9 formulated with a novel adjuvant Montanide ISA720. Fifty-two subjects were randomly assigned to 4 dose groups of 10 participants, each receiving the test vaccine of 20, 50, 100, or 200 microg respectively, and 1 placebo group of 12 participants receiving the adjuvant only. METHODS AND FINDINGS: The vaccine formulation was shown to be safe and well-tolerated, and none of the participants withdrew. The total incidence of local adverse events (AEs was 75%, distributed among 58% of the placebo group and 80% of those vaccinated. Among the vaccinated, 65% had events that were mild and 15% experienced moderate AEs. Almost all systemic adverse reactions observed in this study were graded as mild and required no therapy. The participants receiving the test vaccine developed detectable antibody responses which were boosted by the repeated vaccinations. Sixty percent of the vaccinated participants had high ELISA titers (>1:10,000 of antigen-specific antibodies which could also recognize native parasite proteins in an immunofluorescence assay (IFA. CONCLUSION: This study is the first clinical trial for this candidate and builds on previous investigations supporting PfCP-2.9/ISA720 as a promising blood-stage malaria vaccine. Results demonstrate safety, tolerability (particularly at the lower doses tested and immunogenicity of the formulation. Further clinical development is ongoing to explore optimizing the dose and schedule of the formulation to decrease reactogenicity without compromising immunogenicity. TRIAL REGISTRATION: Chinese State Food and Drug Administration (SFDA 2002SL0046; Controlled

Allelic Diversity and Geographical Distribution of the Gene Encoding Plasmodium falciparum Merozoite Surface Protein-3 in Thailand.

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Sawaswong, Vorthon; Simpalipan, Phumin; Siripoon, Napaporn; Harnyuttanakorn, Pongchai; Pattaradilokrat, Sittiporn

2015-04-01

Merozoite surface proteins (MSPs) of malaria parasites play critical roles during the erythrocyte invasion and so are potential candidates for malaria vaccine development. However, because MSPs are often under strong immune selection, they can exhibit extensive genetic diversity. The gene encoding the merozoite surface protein-3 (MSP-3) of Plasmodium falciparum displays 2 allelic types, K1 and 3D7. In Thailand, the allelic frequency of the P. falciparum msp-3 gene was evaluated in a single P. falciparum population in Tak at the Thailand and Myanmar border. However, no study has yet looked at the extent of genetic diversity of the msp-3 gene in P. falciparum populations in other localities. Here, we genotyped the msp-3 alleles of 63 P. falciparum samples collected from 5 geographical populations along the borders of Thailand with 3 neighboring countries (Myanmar, Laos, and Cambodia). Our study indicated that the K1 and 3D7 alleles coexisted, but at different proportions in different Thai P. falciparum populations. K1 was more prevalent in populations at the Thailand-Myanmar and Thailand-Cambodia borders, whilst 3D7 was more prevalent at the Thailand-Laos border. Global analysis of the msp-3 allele frequencies revealed that proportions of K1 and 3D7 alleles of msp-3 also varied in different continents, suggesting the divergence of malaria parasite populations. In conclusion, the variation in the msp-3 allelic patterns of P. falciparum in Thailand provides fundamental knowledge for inferring the P. falciparum population structure and for the best design of msp-3 based malaria vaccines.

Update on the Clinical Development of Candidate Malaria Vaccines

National Research Council Canada - National Science Library

Ballou, W. R; Arevalo-Herrera, Myriam; Carucci, Daniel; Richie, Thomas L; Corradin, Giampietro; Diggs, Carter; Druilhe, Pierre; Giersing, Birgitte K; Saul, Allan; Heppner, D. G

2004-01-01

... powerful driver for stimulating clinical development of candidate vaccines for malaria. This new way forward promises to greatly increase the likelihood of bringing a safe and effective vaccine to licensure...

Prospects and Pitfalls of Pregnancy-Associated Malaria Vaccination Based on the Natural Immune Response to Plasmodium falciparum VAR2CSA-Expressing Parasites

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Elizabeth G. Kane

2011-01-01

Full Text Available Pregnancy-associated malaria, a manifestation of severe malaria, is the cause of up to 200,000 infant deaths a year, through the effects of placental insufficiency leading to growth restriction and preterm delivery. Development of a vaccine is one strategy for control. Plasmodium falciparum-infected red blood cells accumulate in the placenta through specific binding of pregnancy-associated parasite variants that express the VAR2CSA antigen to chondroitin sulphate A on the surface of syncytiotrophoblast cells. Parasite accumulation, accompanied by an inflammatory infiltrate, disrupts the cytokine balance of pregnancy with the potential to cause placental damage and compromise foetal growth. Multigravid women develop immunity towards VAR2CSA-expressing parasites in a gravidity-dependent manner which prevents unfavourable pregnancy outcomes. Although current vaccine design, targeting VAR2CSA antigens, has succeeded in inducing antibodies artificially, this candidate may not provide protection during the first trimester and may only protect those women living in areas endemic for malaria. It is concluded that while insufficient information about placental-parasite interactions is presently available to produce an effective vaccine, incremental progress is being made towards achieving this goal.

Plasmodium falciparum ookinete expression of plasmepsin VII and plasmepsin X.

Science.gov (United States)

Li, Fengwu; Bounkeua, Viengngeun; Pettersen, Kenneth; Vinetz, Joseph M

2016-02-24

Plasmodium invasion of the mosquito midgut is a population bottleneck in the parasite lifecycle. Interference with molecular mechanisms by which the ookinete invades the mosquito midgut is one potential approach to developing malaria transmission-blocking strategies. Plasmodium aspartic proteases are one such class of potential targets: plasmepsin IV (known to be present in the asexual stage food vacuole) was previously shown to be involved in Plasmodium gallinaceum infection of the mosquito midgut, and plasmepsins VII and plasmepsin X (not known to be present in the asexual stage food vacuole) are upregulated in Plasmodium falciparum mosquito stages. These (and other) parasite-derived enzymes that play essential roles during ookinete midgut invasion are prime candidates for transmission-blocking vaccines. Reverse transcriptase PCR (RT-PCR) was used to determine timing of P. falciparum plasmepsin VII (PfPM VII) and plasmepsin X (PfPM X) mRNA transcripts in parasite mosquito midgut stages. Protein expression was confirmed by western immunoblot and immunofluorescence assays (IFA) using anti-peptide monoclonal antibodies (mAbs) against immunogenic regions of PfPM VII and PfPM X. These antibodies were also used in standard membrane feeding assays (SMFA) to determine whether inhibition of these proteases would affect parasite transmission to mosquitoes. The Mann-Whitney U test was used to analyse mosquito transmission assay results. RT-PCR, western immunoblot and immunofluorescence assay confirmed expression of PfPM VII and PfPM X in mosquito stages. Whereas PfPM VII was expressed in zygotes and ookinetes, PfPM X was expressed in gametes, zygotes, and ookinetes. Antibodies against PfPM VII and PfPM X decreased P. falciparum invasion of the mosquito midgut when used at high concentrations, indicating that these proteases play a role in Plasmodium mosquito midgut invasion. Failure to generate genetic knockouts of these genes limited determination of the precise role of

Strain-specific Plasmodium falciparum growth inhibition among Malian children immunized with a blood-stage malaria vaccine.

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Matthew B Laurens

Full Text Available The blood-stage malaria vaccine FMP2.1/AS02A, comprised of recombinant Plasmodium falciparum apical membrane antigen 1 (AMA1 and the adjuvant system AS02A, had strain-specific efficacy against clinical malaria caused by P. falciparum with the vaccine strain 3D7 AMA1 sequence. To evaluate a potential correlate of protection, we measured the ability of participant sera to inhibit growth of 3D7 and FVO strains in vitro using high-throughput growth inhibition assay (GIA testing. Sera from 400 children randomized to receive either malaria vaccine or a control rabies vaccine were assessed at baseline and over two annual malaria transmission seasons after immunization. Baseline GIA against vaccine strain 3D7 and FVO strain was similar in both groups, but more children in the malaria vaccine group than in the control group had 3D7 and FVO GIA activity ≥15% 30 days after the last vaccination (day 90 (49% vs. 16%, p<0.0001; and 71.8% vs. 60.4%, p = 0.02. From baseline to day 90, 3D7 GIA in the vaccine group was 7.4 times the mean increase in the control group (p<0.0001. In AMA1 vaccinees, 3D7 GIA activity subsequently returned to baseline one year after vaccination (day 364 and did not correlate with efficacy in the extended efficacy time period to day 730. In Cox proportional hazards regression models with time-varying covariates, there was a slight suggestion of an association between 3D7 GIA activity and increased risk of clinical malaria between day 90 and day 240. We conclude that vaccination with this AMA1-based malaria vaccine increased inhibition of parasite growth, but this increase was not associated with allele-specific efficacy in the first malaria season. These results provide a framework for testing functional immune correlates of protection against clinical malaria in field trials, and will help to guide similar analyses for next-generation malaria vaccines. Clinical trials registry: This clinical trial was registered on clinicaltrials

The case for PfEMP1-based vaccines to protect pregnant women against Plasmodium falciparum malaria

DEFF Research Database (Denmark)

Hviid, Lars

2011-01-01

, as well as knowledge regarding the protective immune response that is acquired in response to placental P. falciparum infection. Nevertheless, it remains controversial in some quarters whether such a vaccine would have the desired impact, or indeed whether the strategy is meaningful. This article......Vaccines are very cost-effective tools in combating infectious disease mortality and morbidity. Unfortunately, vaccines efficiently protecting against infection with malaria parasites are not available and are not likely to appear in the near future. An alternative strategy would be vaccines...... protecting against the disease and its consequences rather than against infection per se, by accelerating the development of the protective immunity that is normally acquired after years of exposure to malaria parasites in areas of stable transmission. This latter strategy is being energetically pursued...

Efficacy of chimeric Pestivirus vaccine candidates against classical swine fever: protection and DIVA characteristics.

Science.gov (United States)

Eblé, P L; Geurts, Y; Quak, S; Moonen-Leusen, H W; Blome, S; Hofmann, M A; Koenen, F; Beer, M; Loeffen, W L A

2013-03-23

Currently no live DIVA (Differentiating Infected from Vaccinated Animals) vaccines against classical swine fever (CSF) are available. The aim of this study was to investigate whether chimeric pestivirus vaccine candidates (CP7_E2alf, Flc11 and Flc9) are able to protect pigs against clinical signs, and to reduce virus shedding and virus transmission, after a challenge with CSF virus (CSFV), 7 or 14 days after a single intramuscular vaccination. In these vaccine candidates, either the E2 or the E(rns) encoding genome region of a bovine viral diarrhoea virus strain were combined with a cDNA copy of CSFV or vice versa. Furthermore, currently available serological DIVA tests were evaluated. The vaccine candidates were compared to the C-strain. All vaccine candidates protected against clinical signs. No transmission to contact pigs was detected in the groups vaccinated with C-strain, CP7_E2alf and Flc11. Limited transmission occurred in the groups vaccinated with Flc9. All vaccine candidates would be suitable to stop on-going transmission of CSFV. For Flc11, no reliable differentiation was possible with the current E(rns)-based DIVA test. For CP7_E2alf, the distribution of the inhibition percentages was such that up to 5% false positive results may be obtained in a large vaccinated population. For Flc9 vaccinated pigs, the E2 ELISA performed very well, with an expected 0.04% false positive results in a large vaccinated population. Both CP7_E2alf and Flc9 are promising candidates to be used as live attenuated marker vaccines against CSF, with protection the best feature of CP7_E2alf, and the DIVA principle the best feature of Flc9. Copyright © 2012 Elsevier B.V. All rights reserved.

A longitudinal study of type-specific antibody responses to Plasmodium falciparum merozoite surface protein-1 in an area of unstable malaria in Sudan

DEFF Research Database (Denmark)

Cavanagh, D R; Elhassan, I M; Roper, C

1998-01-01

Merozoite surface protein-1 (MSP-1) of Plasmodium falciparum is a malaria vaccine candidate Ag. Immunity to MSP-1 has been implicated in protection against infection in animal models. However, MSP-1 is a polymorphic protein and its immune recognition by humans following infection is not well unde...

The role of Plasmodium falciparum variant surface antigens in protective immunity and vaccine development

DEFF Research Database (Denmark)

Hviid, Lars

2010-01-01

There is substantial immuno-epidemiological evidence that the parasite-encoded, so-called variant surface antigens (VSAs) such as PfEMP1 on the surface of infected erythrocytes (IEs) are important-in some cases probably decisive-determinants of clinical outcome of P. falciparum malaria. The evide...... of VSAs, and how vaccines based on this type of antigens fit into the current global strategy to reduce, eliminate and eventually eradicate the burden of malaria....

Efficacy of RTS,S/AS01E malaria vaccine and exploratory analysis on anti-circumsporozoite antibody titres and protection in children aged 5-17 months in Kenya and Tanzania: a randomised controlled trial

DEFF Research Database (Denmark)

Olotu, Ally; Lusingu, John; Leach, Amanda

2011-01-01

RTS,S/AS01E is the lead candidate malaria vaccine. We recently showed efficacy against clinical falciparum malaria in 5-17 month old children, during an average of 8 months follow-up. We aimed to assess the efficacy of RTS,S/AS01E during 15 months of follow-up.......RTS,S/AS01E is the lead candidate malaria vaccine. We recently showed efficacy against clinical falciparum malaria in 5-17 month old children, during an average of 8 months follow-up. We aimed to assess the efficacy of RTS,S/AS01E during 15 months of follow-up....

Clinical development of a VAR2CSA-based placental malaria vaccine PAMVAC

DEFF Research Database (Denmark)

Gbédandé, Komi; Fievet, Nadine; Viwami, Firmine

2017-01-01

Background  The antigen VAR2CSA plays a pivotal role in the pathophysiology of pregnancy-associated malaria (PAM) caused by Plasmodium falciparum. A VAR2CSA-based vaccine candidate, PAMVAC, is under development by an EU-funded multi-country consortium (PlacMalVac project). As part of PAMVAC...

Solution structure of a Plasmodium falciparum AMA-1/MSP 1 chimeric protein vaccine candidate (PfCP-2.9 for malaria

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Jin Changwen

2010-03-01

Full Text Available Abstract Background The Plasmodium falciparum chimeric protein PfCP-2.9 is a promising asexual-stage malaria vaccine evaluated in clinical trials. This chimeric protein consists of two cysteine-rich domains: domain III of the apical membrane antigen 1 (AMA-1 [III] and the C-terminal region of the merozoite surface protein 1 (MSP1-19. It has been reported that the fusion of these two antigens enhanced their immunogenicity and antibody-mediated inhibition of parasite growth in vitro. Methods The 15N-labeled and 13C/15N-labeled PfCP-2.9 was produced in Pichia pastoris for nuclear magnetic resonance (NMR structure analysis. The chemical shift assignments of PfCP-2.9 were compared with those previously reported for the individual domains (i.e., PfAMA-1(III or PfMSP 1-19. The two-dimensional spectra and transverse relaxation rates (R2 of the PfMSP1-19 alone were compared with that of the PfCP-2.9. Results Confident backbone assignments were obtained for 122 out of 241 residues of PfCP-2.9. The assigned residues in PfCP-2.9 were very similar to those previously reported for the individual domains. The conformation of the PfMSP1-19 in different constructs is essentially the same. Comparison of transverse relaxation rates (R2 strongly suggests no weak interaction between the domains. Conclusions These data indicate that the fusion of AMA-1(III and MSP1-19 as chimeric protein did not change their structures, supporting the use of the chimeric protein as a potential malaria vaccine.

Whole-Genome Scans Provide Evidence of Adaptive Evolution in Malawian Plasmodium falciparum Isolates

DEFF Research Database (Denmark)

Ocholla, Harold; Preston, Mark D; Mipando, Mwapatsa

2014-01-01

BACKGROUND:  Selection by host immunity and antimalarial drugs has driven extensive adaptive evolution in Plasmodium falciparum and continues to produce ever-changing landscapes of genetic variation. METHODS:  We performed whole-genome sequencing of 69 P. falciparum isolates from Malawi and used......, an area of high malaria transmission. Allele frequency-based tests provided evidence of recent population growth in Malawi and detected potential targets of host immunity and candidate vaccine antigens. Comparison of the sequence variation between isolates from Malawi and those from 5 geographically...... dispersed countries (Kenya, Burkina Faso, Mali, Cambodia, and Thailand) detected population genetic differences between Africa and Asia, within Southeast Asia, and within Africa. Haplotype-based tests of selection to sequence data from all 6 populations identified signals of directional selection at known...

The transcriptome of the intraerythrocytic developmental cycle of Plasmodium falciparum.

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Zbynek Bozdech

2003-10-01

intraerythrocytic development of P. falciparum and provide a resource for the identification of new chemotherapeutic and vaccine candidates.

Recognition of Plasmodium falciparum mature gametocyte-infected erythrocytes by antibodies of semi-immune adults and malaria-exposed children from Gabon

DEFF Research Database (Denmark)

Gebru, Tamirat; Ajua, Anthony; Theisen, Michael

2017-01-01

BACKGROUND: Transmission of malaria from man to mosquito depends on the presence of gametocytes, the sexual stage of Plasmodium parasites in the infected host. Naturally acquired antibodies against gametocytes exist and may play a role in controlling transmission by limiting the gametocyte...... falciparum mature gametocytes were investigated in sera of semi-immune adults and malaria-exposed children. In addition, the effect of immunization with GMZ2, a blood stage malaria vaccine candidate, and the effect of intestinal helminth infection on the development of immunity to gametocytes of P...... was significantly higher after fixation and permeabilization of parasitized erythrocytes. Following vaccination with the malaria vaccine candidate GMZ2, anti-gametocyte Ab concentration decreased in adults compared to baseline. Ab response to whole asexual stage antigens had a significant but weak positive...

Sequence diversity of the C-terminal region of Plasmodium falciparum merozoite surface protein 1 in southern Iran.

Science.gov (United States)

Zamani, Zahra; Razavi, Mohammad Reza; Sadeghi, Sedigheh; Naddaf, Saeed; Pourfallah, Fatemeh; Mirkhani, Fatemeh; Arjmand, Mohammad; Feizhaddad, Hossein; Rad, Mina Ebrahimi; Ebrahimi Rad, Mina; Tameemi, Marzieh; Assmar, Mehdi

2009-01-01

The C-terminal region of the merozoite surface protein 1 (MSP-1) of Plasmodium falciparum is a strong vaccine candidate as it is associated with immunity to the parasite. This corresponds approximately to the conserved 17th block of the gene and is composed of two EGF- like domains. These domains exhibit only four single amino acid substitutions which show several potential variants in this region of the gene. As the variations might be important for a regional vaccine design, a study was carried out to determine the variations present in P. falciparum isolates from southern Iran. Besides the usual E-T-S-R-L and the Q-K-N-G-F types, we found Q-T-S-R-L, E-K-N-G-F, E-T-S-G-L, Z-T-S-G-L and Z-T-S-R-L types, where Z was E or Q signifying the presence of mixed clones in single isolates.

Effect of ingested human antibodies induced by RTS, S/AS01 malaria vaccination in children on Plasmodium falciparum oocyst formation and sporogony in mosquitoes

DEFF Research Database (Denmark)

Miura, Kazutoyo; Jongert, Erik; Deng, Bingbing

2014-01-01

falciparum CS protein, but the ability of serum from vaccinated individuals to inhibit sporogony in mosquitoes has not been evaluated. METHODS: Previously a double-blind, randomized trial of RTS,S/AS01 vaccine, as compared with rabies vaccine, in five- to 17-month old children in Tanzania was conducted....... In this study, polyclonal human antibodies were purified from the pools of sera taken one month after the third vaccination. IgGs were purified from four pools of sera from 25 RTS,S/AS01 vaccinated children each, and two pools of sera from 25 children vaccinated with rabies vaccine each. The ability...

Differential induction of functional IgG using the Plasmodium falciparum placental malaria vaccine candidate VAR2CSA

DEFF Research Database (Denmark)

Pinto, Vera V; Ditlev, Sisse B; Jensen, Kamilla E

2011-01-01

In Plasmodium falciparum malaria endemic areas placental malaria (PM) is an important complication of malaria. The recurrence of malaria in primigravidae women irrespective of acquired protection during childhood is caused by the interaction between the parasite-expressed VAR2CSA antigen and chon...

Synthetic TLR4 agonists enhance functional antibodies and CD4+ T-cell responses against the Plasmodium falciparum GMZ2.6C multi-stage vaccine antigen

NARCIS (Netherlands)

Baldwin, S.L.; Roeffen, W.; Singh, S.K; Tiendrebeogo, R.W.; Christiansen, M.; Beebe, E.; Carter, D.; Fox, C.B.; Howard, R.F.; Reed, S.G.; Sauerwein, R.; Theisen, M.

2016-01-01

A subunit vaccine targeting both transmission and pathogenic asexual blood stages of Plasmodium falciparum, i.e., a multi-stage vaccine, could be a powerful tool to combat malaria. Here, we report production and characterization of the recombinant protein GMZ2.6C, which contains a fragment of the

Transcript and protein expression profile of PF11_0394, a Plasmodium falciparum protein expressed in salivary gland sporozoites

Directory of Open Access Journals (Sweden)

Schlarman Maggie S

2012-03-01

Full Text Available Abstract Background Plasmodium falciparum malaria is a significant problem around the world today, thus there is still a need for new control methods to be developed. Because the sporozoite displays dual infectivity for both the mosquito salivary glands and vertebrate host tissue, it is a good target for vaccine development. Methods The P. falciparum gene, PF11_0394, was chosen as a candidate for study due to its potential role in the invasion of host tissues. This gene, which was selected using a data mining approach from PlasmoDB, is expressed both at the transcriptional and protein levels in sporozoites and likely encodes a putative surface protein. Using reverse transcription-polymerase chain reaction (RT-PCR and green fluorescent protein (GFP-trafficking studies, a transcript and protein expression profile of PF11_0394 was determined. Results The PF11_0394 protein has orthologs in other Plasmodium species and Apicomplexans, but none outside of the group Apicomplexa. PF11_0394 transcript was found to be present during both the sporozoite and erythrocytic stages of the parasite life cycle, but no transcript was detected during axenic exoerythrocytic stages. Despite the presence of transcript throughout several life cycle stages, the PF11_0394 protein was only detected in salivary gland sporozoites. Conclusions PF11_0394 appears to be a protein uniquely detected in salivary gland sporozoites. Even though a specific function of PF11_0394 has not been determined in P. falciparum biology, it could be another candidate for a new vaccine.

Meta-analysis of variables affecting mouse protection efficacy of whole organism Brucella vaccines and vaccine candidates

Science.gov (United States)

2013-01-01

Background Vaccine protection investigation includes three processes: vaccination, pathogen challenge, and vaccine protection efficacy assessment. Many variables can affect the results of vaccine protection. Brucella, a genus of facultative intracellular bacteria, is the etiologic agent of brucellosis in humans and multiple animal species. Extensive research has been conducted in developing effective live attenuated Brucella vaccines. We hypothesized that some variables play a more important role than others in determining vaccine protective efficacy. Using Brucella vaccines and vaccine candidates as study models, this hypothesis was tested by meta-analysis of Brucella vaccine studies reported in the literature. Results Nineteen variables related to vaccine-induced protection of mice against infection with virulent brucellae were selected based on modeling investigation of the vaccine protection processes. The variable "vaccine protection efficacy" was set as a dependent variable while the other eighteen were set as independent variables. Discrete or continuous values were collected from papers for each variable of each data set. In total, 401 experimental groups were manually annotated from 74 peer-reviewed publications containing mouse protection data for live attenuated Brucella vaccines or vaccine candidates. Our ANOVA analysis indicated that nine variables contributed significantly (P-value Brucella vaccine protection efficacy: vaccine strain, vaccination host (mouse) strain, vaccination dose, vaccination route, challenge pathogen strain, challenge route, challenge-killing interval, colony forming units (CFUs) in mouse spleen, and CFU reduction compared to control group. The other 10 variables (e.g., mouse age, vaccination-challenge interval, and challenge dose) were not found to be statistically significant (P-value > 0.05). The protection level of RB51 was sacrificed when the values of several variables (e.g., vaccination route, vaccine viability, and

Blood stage malaria vaccine eliciting high antigen-specific antibody concentrations confers no protection to young children in Western Kenya.

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Bernhards R Ogutu

Full Text Available The antigen, falciparum malaria protein 1 (FMP1, represents the 42-kDa C-terminal fragment of merozoite surface protein-1 (MSP-1 of the 3D7 clone of P. falciparum. Formulated with AS02 (a proprietary Adjuvant System, it constitutes the FMP1/AS02 candidate malaria vaccine. We evaluated this vaccine's safety, immunogenicity, and efficacy in African children.A randomised, double-blind, Phase IIb, comparator-controlled trial.The trial was conducted in 13 field stations of one mile radii within Kombewa Division, Nyanza Province, Western Kenya, an area of holoendemic transmission of P. falciparum. We enrolled 400 children aged 12-47 months in general good health.Children were randomised in a 1ratio1 fashion to receive either FMP1/AS02 (50 microg or Rabipur(R rabies vaccine. Vaccinations were administered on a 0, 1, and 2 month schedule. The primary study endpoint was time to first clinical episode of P. falciparum malaria (temperature >/=37.5 degrees C with asexual parasitaemia of >/=50,000 parasites/microL of blood occurring between 14 days and six months after a third dose. Case detection was both active and passive. Safety and immunogenicity were evaluated for eight months after first immunisations; vaccine efficacy (VE was measured over a six-month period following third vaccinations.374 of 400 children received all three doses and completed six months of follow-up. FMP1/AS02 had a good safety profile and was well-tolerated but more reactogenic than the comparator. Geometric mean anti-MSP-1(42 antibody concentrations increased from1.3 microg/mL to 27.3 microg/mL in the FMP1/AS02 recipients, but were unchanged in controls. 97 children in the FMP1/AS02 group and 98 controls had a primary endpoint episode. Overall VE was 5.1% (95% CI: -26% to +28%; p-value = 0.7.FMP1/AS02 is not a promising candidate for further development as a monovalent malaria vaccine. Future MSP-1(42 vaccine development should focus on other formulations and antigen constructs

Comparative Infectivity Determinations of Dengue Virus Vaccine Candidates in Rhesus Monkeys, Mosquitoes, and Cell Cultures

Science.gov (United States)

1993-01-28

34 are required for the evaluation of these vaccine candidates. RE: DAMDI7-89-C-9175 Page 16 REFERENCES 1. Sabin AB, Sclesinger RW, 1945. Production of...AD-A261 892 CONTRACT NO: DAMD17-89-C-9 175 \\II\\IllI\\I\\I1\\\\~il\\ TITLE: COMPARATIVE INFECTIVITY DETERMINATIONS OF DENGUE VIRUS VACCINE CANDIDATES IN... Vaccine Candidates in Rhesus Monkeys, 63002A Mosquitoes, and Cell Cultures 3M263002D870 AC 6. AUTHOR(S) DA335475 Edmundo Kraiselburd 7. PERFORMING

Plasmodium falciparum incidence relative to entomologic inoculation rates at a site proposed for testing malaria vaccines in western Kenya.

Science.gov (United States)

Beier, J C; Oster, C N; Onyango, F K; Bales, J D; Sherwood, J A; Perkins, P V; Chumo, D K; Koech, D V; Whitmire, R E; Roberts, C R

1994-05-01

Relationships between Plasmodium falciparum incidence and entomologic inoculation rates (EIRs) were determined for a 21-month period in Saradidi, western Kenya, in preparation for malaria vaccine field trials. Children, ranging in age from six months to six years and treated to clear malaria parasites, were monitored daily for up to 12 weeks to detect new malaria infections. Overall, new P. falciparum infections were detected in 77% of 809 children. The percentage of children that developed infections per two-week period averaged 34.7%, ranging from 7.3% to 90.9%. Transmission by vector populations was detected in 86.4% (38 of 44) of the two-week periods, with daily EIRs averaging 0.75 infective bites per person. Periods of intense transmission during April to August, and from November to January, coincided with seasonal rains. Relationships between daily malaria attack rates and EIRs indicated that an average of only 7.5% (1 in 13) of the sporozoite inoculations produced new infections in children. Regression analysis demonstrated that EIRs accounted for 74% of the variation in attack rates. One of the components of the EIR, the human-biting rate, alone accounted for 68% of the variation in attack rates. Thus, measurements of either the EIR or the human-biting rate can be used to predict corresponding attack rates in children. These baseline epidemiologic studies indicate that the intense transmission patterns of P. falciparum in Saradidi will provide excellent conditions for evaluating malaria vaccine efficacy.

Identification of Novel Potential Vaccine Candidates against Tuberculosis Based on Reverse Vaccinology

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Gloria P. Monterrubio-López

2015-01-01

Full Text Available Tuberculosis (TB is a chronic infectious disease, considered as the second leading cause of death worldwide, caused by Mycobacterium tuberculosis. The limited efficacy of the bacillus Calmette-Guérin (BCG vaccine against pulmonary TB and the emergence of multidrug-resistant TB warrants the need for more efficacious vaccines. Reverse vaccinology uses the entire proteome of a pathogen to select the best vaccine antigens by in silico approaches. M. tuberculosis H37Rv proteome was analyzed with NERVE (New Enhanced Reverse Vaccinology Environment prediction software to identify potential vaccine targets; these 331 proteins were further analyzed with VaxiJen for the determination of their antigenicity value. Only candidates with values ≥0.5 of antigenicity and 50% of adhesin probability and without homology with human proteins or transmembrane regions were selected, resulting in 73 antigens. These proteins were grouped by families in seven groups and analyzed by amino acid sequence alignments, selecting 16 representative proteins. For each candidate, a search of the literature and protein analysis with different bioinformatics tools, as well as a simulation of the immune response, was conducted. Finally, we selected six novel vaccine candidates, EsxL, PE26, PPE65, PE_PGRS49, PBP1, and Erp, from M. tuberculosis that can be used to improve or design new TB vaccines.

Development of an inactivated candidate vaccine against Chandipura virus (Rhabdoviridae: Vesiculovirus).

Science.gov (United States)

Jadi, R S; Sudeep, A B; Barde, P V; Arankalle, V A; Mishra, A C

2011-06-20

A Vero cell based vaccine candidate against Chandipura (CHP) virus (Rhabdoviridae: Vesiculovirus), was developed and evaluated for immunogenicity in mice. Virus was purified by ultracentrifugation on 30% glycerol cushion followed by differential centrifugation on 10-60% sucrose gradient and inactivated with β-propio lactone at a concentration of 1:3500. The inactivated product was blended with aluminium phosphate (3%) and immunized 4-week-old Swiss albino mice. Neutralizing antibodies in the range of 1:10 to 160 and 1:80 to 1:320 was detected with 85% and 100% sero-conversion after 2nd and 3rd dose, respectively. All the immunized mice with antibody titer above 1:20 survived live virus challenge. The vaccine candidate has potential to be an efficient vaccine against CHP virus. Copyright © 2011 Elsevier Ltd. All rights reserved.

Immunization with the Malaria Diversity-Covering Blood-Stage Vaccine Candidate Plasmodium falciparum Apical Membrane Antigen 1 DiCo in Complex with Its Natural Ligand PfRon2 Does Not Improve the In Vitro Efficacy

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Holger Spiegel

2017-06-01

Full Text Available The blood-stage malaria vaccine candidate Plasmodium falciparum apical membrane antigen 1 (PfAMA1 can induce strong parasite growth-inhibitory antibody responses in animals but has not achieved the anticipated efficacy in clinical trials. Possible explanations in humans are the insufficient potency of the elicited antibody responses, as well as the high degree of sequence polymorphisms found in the field. Several strategies have been developed to improve the cross-strain coverage of PfAMA1-based vaccines, whereas innovative concepts to increase the potency of PfAMA1-specific IgG responses have received little attention even though this may be an essential requirement for protective efficacy. A previous study has demonstrated that immunization with a complex of PyAMA1 and PyRON2, a ligand with an essential functional role in erythrocyte invasion, leads to protection from lethal Plasmodium yoelli challenge in an animal model and suggested to extend this strategy toward improved strain coverage by using multiple PfAMA1 alleles in combination with PfRon2L. As an alternative approach along this line, we decided to use PfRon2L in combination with three PfAMA1 diversity covering variants (DiCo to investigate the potential of this complex to induce more potent parasite growth inhibitory immune response in combination with better cross-strain-specific efficacy. Within the limits of the study design, the ability of the PfAMA1 DiCo-Mix to induce cross-strain-specific antibodies was not affected in all immunization groups, but the DiCo–PfRon2L complexes did not improve the potency of PfAMA1-specific IgG responses.

Discovery of Novel Leptospirosis Vaccine Candidates Using Reverse and Structural Vaccinology

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Alan John Alexander McBride

2017-04-01

Full Text Available Leptospira spp. are diderm (two membranes bacteria that infect mammals causing leptospirosis, a public health problem with global implications. Thousands of people die every year due to leptospirosis, especially in developing countries with tropical climates. Prophylaxis is difficult due to multiple factors, including the large number of asymptomatic hosts that transmit the bacteria, poor sanitation, increasing numbers of slum dwellers, and the lack of an effective vaccine. Several leptospiral recombinant antigens were evaluated as a replacement for the inactivated (bacterin vaccine; however, success has been limited. A prospective vaccine candidate is likely to be a surface-related protein that can stimulate the host immune response to clear leptospires from blood and organs. In this study, a comprehensive bioinformatics approach based on reverse and structural vaccinology was applied toward the discovery of novel leptospiral vaccine candidates. The Leptospira interrogans serovar Copenhageni strain L1-130 genome was mined in silico for the enhanced identification of conserved β-barrel (βb transmembrane proteins and outer membrane (OM lipoproteins. Orthologs of the prospective vaccine candidates were screened in the genomes of 20 additional Leptospira spp. Three-dimensional structural models, with a high degree of confidence, were created for each of the surface-exposed proteins. Major histocompatibility complex II (MHC-II epitopes were identified, and their locations were mapped on the structural models. A total of 18 βb transmembrane proteins and 8 OM lipoproteins were identified. These proteins were conserved among the pathogenic Leptospira spp. and were predicted to have epitopes for several variants of MHC-II receptors. A structural and functional analysis of the sequence of these surface proteins demonstrated that most βb transmembrane proteins seem to be TonB-dependent receptors associated with transportation. Other proteins

Identification Of Protein Vaccine Candidates Using Comprehensive Proteomic Analysis Strategies

National Research Council Canada - National Science Library

Rohrbough, James G

2007-01-01

Presented in this dissertation are proteomic analysis studies focused on identifying proteins to be used as vaccine candidates against Coccidioidomycosis, a potentially fatal human pulmonary disease...

Analysis of a Multi-component Multi-stage Malaria Vaccine Candidate--Tackling the Cocktail Challenge.

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Alexander Boes

Full Text Available Combining key antigens from the different stages of the P. falciparum life cycle in the context of a multi-stage-specific cocktail offers a promising approach towards the development of a malaria vaccine ideally capable of preventing initial infection, the clinical manifestation as well as the transmission of the disease. To investigate the potential of such an approach we combined proteins and domains (11 in total from the pre-erythrocytic, blood and sexual stages of P. falciparum into a cocktail of four different components recombinantly produced in plants. After immunization of rabbits we determined the domain-specific antibody titers as well as component-specific antibody concentrations and correlated them with stage specific in vitro efficacy. Using purified rabbit immune IgG we observed strong inhibition in functional in vitro assays addressing the pre-erythrocytic (up to 80%, blood (up to 90% and sexual parasite stages (100%. Based on the component-specific antibody concentrations we calculated the IC50 values for the pre-erythrocytic stage (17-25 μg/ml, the blood stage (40-60 μg/ml and the sexual stage (1.75 μg/ml. While the results underline the feasibility of a multi-stage vaccine cocktail, the analysis of component-specific efficacy indicates significant differences in IC50 requirements for stage-specific antibody concentrations providing valuable insights into this complex scenario and will thereby improve future approaches towards malaria vaccine cocktail development regarding the selection of suitable antigens and the ratios of components, to fine tune overall and stage-specific efficacy.

Comparative evaluation of phenol and thimerosal as preservatives for a candidate vaccine against American cutaneous leishmaniasis

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Wilson Mayrink

2010-02-01

Full Text Available For decades thimerosal has been used as a preservative in the candidate vaccine for cutaneous leishmaniasis, which was developed by Mayrink et al. The use of thimerosal in humans has been banned due to its mercury content. This study addresses the standardization of phenol as a new candidate vaccine preservative. We have found that the proteolytic activity was abolished when the test was conducted using the candidate vaccine added to merthiolate (MtVac as well as to phenol (PhVac. The Montenegro's skin test conversion rates induced by MtVac and by PhVac was 68.06% and 85.9%, respectively, and these values were statistically significant (p < 0.05. The proliferative response of peripheral mononuclear blood cells shows that the stimulation index of mice immunized with both candidate vaccines was higher than the one in control animals (p < 0.05. The ability of the candidate vaccines to induce protection in C57BL/10 mice against a challenge with infective Leishmania amazonensis promastigotes was tested and the mice immunized with PhVac developed smaller lesions than the mice immunized with MtVac. Electrophoresis of phenol-preserved antigen revealed a number of proteins, which were better preserved in PhVac. These results do in fact encourage the use of phenol for preserving the immunogenic and biochemical properties of the candidate vaccine for cutaneous leishmaniasis.

Clinical development of placental malaria vaccines and immunoassays harmonization

DEFF Research Database (Denmark)

Chêne, Arnaud; Houard, Sophie; Nielsen, Morten A

2016-01-01

Placental malaria caused by Plasmodium falciparum infection constitutes a major health problem manifesting as severe disease and anaemia in the mother, impaired fetal development, low birth weight or spontaneous abortion. Prevention of placental malaria currently relies on two key strategies...... that are losing efficacy due to spread of resistance: long-lasting insecticide-treated nets and intermittent preventive treatment during pregnancy. A placental malaria vaccine would be an attractive, cost-effective complement to the existing control tools. Two placental malaria vaccine candidates are currently...... in Phase Ia/b clinical trials. During two workshops hosted by the European Vaccine Initiative, one in Paris in April 2014 and the other in Brussels in November 2014, the main actors in placental malaria vaccine research discussed the harmonization of clinical development plans and of the immunoassays...

Population genomics diversity of Plasmodium falciparum in malaria ...

African Journals Online (AJOL)

Background: Plasmodium falciparum, the most dangerous malaria parasite species to ... tigen for subunit malaria vaccine.10 It comprises highly ... were also prepared for Giemsa staining as described by ... parasites with different alleles at a given locus and ranges ..... surface protein 1, immune evasion and vaccines against.

Biohazard Analysis of Select Biodefense Vaccine Candidates - Venezuelan Equine Encephalitis Virus Strain 3526 and Francisella Tularensis LVS

International Nuclear Information System (INIS)

Rao, V.

2007-01-01

Biohazard assessment of biodefense vaccine candidates forms the basis for a facility- and activity-specific risk assessment performed to determine the biosafety levels and general safety standards required for biological product development. As a part of our support to the US biodefense vaccine development program, we perform a systematic biohazard assessment of potential vaccine candidates with the primary objective to, (a) Identify and characterize hazard elements associated with the wild type and vaccine strains, (b) Provide biohazard information on the etiologic agent (vaccine candidate) to assess Phase 1 clinical trial facility sites, (c) Provide a baseline to conduct an agent and facility-specific risk assessment at clinical trial facilities interested in performing phase 1 clinical trial, (d) Provide comparative hazard profiles of the vaccine candidates wit MSDS for wild-type to identify and establish appropriate protective biosafety levels, and (e) Support determination of a hazard level to select personal protective equipment as required under the OSHA guidelines. This paper will describe the biohazard analysis of two vaccine candidates, Venezuelan Equine Encephalitis Virus Strain 3526 and Francisella tularensis LVS, a viral and bacterial agent, respectively. As part of the biohazard assessment we preformed a thorough review of published literature on medical pathology, epidemiology, pre-clinical investigational studies, and environmental data on the etiologic agent subtypes and the vaccine candidates. Using standard analytical procedures, the data were then analyzed relative to two intrinsic hazard parameters-health hazard and environmental hazard. Using a weight-of-evidence (WOE) approach, the potential hazards of etiologic agent wild subtypes and vaccine candidates were ranked under three main categories: Public Health Hazard, Environmental Hazard, and Overall Hazard. A WOE scoring system allows for both a determination of the intrinsic hazard of each

Biohazard Analysis of Select Biodefense Vaccine Candidates - Venezuelan Equine Encephalitis Virus Strain 3526 and Francisella Tularensis LVS

Energy Technology Data Exchange (ETDEWEB)

Rao, V [National Security Programs, Computer Science Corporation, Alexandria (United States)

2007-07-01

Biohazard assessment of biodefense vaccine candidates forms the basis for a facility- and activity-specific risk assessment performed to determine the biosafety levels and general safety standards required for biological product development. As a part of our support to the US biodefense vaccine development program, we perform a systematic biohazard assessment of potential vaccine candidates with the primary objective to, (a) Identify and characterize hazard elements associated with the wild type and vaccine strains, (b) Provide biohazard information on the etiologic agent (vaccine candidate) to assess Phase 1 clinical trial facility sites, (c) Provide a baseline to conduct an agent and facility-specific risk assessment at clinical trial facilities interested in performing phase 1 clinical trial, (d) Provide comparative hazard profiles of the vaccine candidates wit MSDS for wild-type to identify and establish appropriate protective biosafety levels, and (e) Support determination of a hazard level to select personal protective equipment as required under the OSHA guidelines. This paper will describe the biohazard analysis of two vaccine candidates, Venezuelan Equine Encephalitis Virus Strain 3526 and Francisella tularensis LVS, a viral and bacterial agent, respectively. As part of the biohazard assessment we preformed a thorough review of published literature on medical pathology, epidemiology, pre-clinical investigational studies, and environmental data on the etiologic agent subtypes and the vaccine candidates. Using standard analytical procedures, the data were then analyzed relative to two intrinsic hazard parameters-health hazard and environmental hazard. Using a weight-of-evidence (WOE) approach, the potential hazards of etiologic agent wild subtypes and vaccine candidates were ranked under three main categories: Public Health Hazard, Environmental Hazard, and Overall Hazard. A WOE scoring system allows for both a determination of the intrinsic hazard of each

A polyvalent hybrid protein elicits antibodies against the diverse allelic types of block 2 in Plasmodium falciparum merozoite surface protein 1.

Science.gov (United States)

Tetteh, Kevin K A; Conway, David J

2011-10-13

Merozoite surface protein 1 (MSP1) of Plasmodium falciparum has been implicated as an important target of acquired immunity, and candidate components for a vaccine include polymorphic epitopes in the N-terminal polymorphic block 2 region. We designed a polyvalent hybrid recombinant protein incorporating sequences of the three major allelic types of block 2 together with a composite repeat sequence of one of the types and N-terminal flanking T cell epitopes, and compared this with a series of recombinant proteins containing modular sub-components and similarly expressed in Escherichia coli. Immunogenicity of the full polyvalent hybrid protein was tested in both mice and rabbits, and comparative immunogenicity studies of the sub-component modules were performed in mice. The full hybrid protein induced high titre antibodies against each of the major block 2 allelic types expressed as separate recombinant proteins and against a wide range of allelic types naturally expressed by a panel of diverse P. falciparum isolates, while the sub-component modules had partial antigenic coverage as expected. This encourages further development and evaluation of the full MSP1 block 2 polyvalent hybrid protein as a candidate blood-stage component of a malaria vaccine. Copyright © 2011 Elsevier Ltd. All rights reserved.

Phase 1 trial of malaria transmission blocking vaccine candidates Pfs25 and Pvs25 formulated with montanide ISA 51.

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Yimin Wu

2008-07-01

Full Text Available Pfs25 and Pvs25, surface proteins of mosquito stage of the malaria parasites P. falciparum and P. vivax, respectively, are leading candidates for vaccines preventing malaria transmission by mosquitoes. This single blinded, dose escalating, controlled Phase 1 study assessed the safety and immunogenicity of recombinant Pfs25 and Pvs25 formulated with Montanide ISA 51, a water-in-oil emulsion.The trial was conducted at The Johns Hopkins Center for Immunization Research, Washington DC, USA, between May 16, 2005-April 30, 2007. The trial was designed to enroll 72 healthy male and non-pregnant female volunteers into 1 group to receive adjuvant control and 6 groups to receive escalating doses of the vaccines. Due to unexpected reactogenicity, the vaccination was halted and only 36 volunteers were enrolled into 4 groups: 3 groups of 10 volunteers each were immunized with 5 microg of Pfs25/ISA 51, 5 microg of Pvs25/ISA 51, or 20 microg of Pvs25/ISA 51, respectively. A fourth group of 6 volunteers received adjuvant control (PBS/ISA 51. Frequent local reactogenicity was observed. Systemic adverse events included two cases of erythema nodosum considered to be probably related to the combination of the antigen and the adjuvant. Significant antibody responses were detected in volunteers who completed the lowest scheduled doses of Pfs25/ISA 51. Serum anti-Pfs25 levels correlated with transmission blocking activity.It is feasible to induce transmission blocking immunity in humans using the Pfs25/ISA 51 vaccine, but these vaccines are unexpectedly reactogenic for further development. This is the first report that the formulation is associated with systemic adverse events including erythema nodosum.ClinicalTrials.gov NCT00295581.

Generation of a parvovirus B19 vaccine candidate.

Science.gov (United States)

Chandramouli, Sumana; Medina-Selby, Angelica; Coit, Doris; Schaefer, Mary; Spencer, Terika; Brito, Luis A; Zhang, Pu; Otten, Gillis; Mandl, Christian W; Mason, Peter W; Dormitzer, Philip R; Settembre, Ethan C

2013-08-20

Parvovirus B19 is the causative agent of fifth disease in children, aplastic crisis in those with blood dyscrasias, and hydrops fetalis. Previous parvovirus B19 virus-like-particle (VLP) vaccine candidates were produced by co-infection of insect cells with two baculoviruses, one expressing wild-type VP1 and the other expressing VP2. In humans, the VLPs were immunogenic but reactogenic. We have developed new VLP-based parvovirus B19 vaccine candidates, produced by co-expressing VP2 and either wild-type VP1 or phospholipase-negative VP1 in a regulated ratio from a single plasmid in Saccharomyces cerevisiae. These VLPs are expressed efficiently, are very homogeneous, and can be highly purified. Although VP2 alone can form VLPs, in mouse immunizations, VP1 and the adjuvant MF59 are required to elicit a neutralizing response. Wild-type VLPs and those with phospholipase-negative VP1 are equivalently potent. The purity, homogeneity, yeast origin, and lack of phospholipase activity of these VLPs address potential causes of previously observed reactogenicity. Copyright © 2013 Elsevier Ltd. All rights reserved.

Application of a scalable plant transient gene expression platform for malaria vaccine development

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Holger eSpiegel

2015-12-01

Full Text Available Despite decades of intensive research efforts there is currently no vaccine that provides sustained sterile immunity against malaria. In this context, a large number of targets from the different stages of the Plasmodium falciparum life cycle have been evaluated as vaccine candidates. None of these candidates has fulfilled expectations, and as long as we lack a single target that induces strain-transcending protective immune responses, combining key antigens from different life cycle stages seems to be the most promising route towards the development of efficacious malaria vaccines. After the identification of potential targets using approaches such as omics-based technology and reverse immunology, the rapid expression, purification and characterization of these proteins, as well as the generation and analysis of fusion constructs combining different promising antigens or antigen domains before committing to expensive and time consuming clinical development, represents one of the bottlenecks in the vaccine development pipeline. The production of recombinant proteins by transient gene expression in plants is a robust and versatile alternative to cell-based microbial and eukaryotic production platforms. The transfection of plant tissues and/or whole plants using Agrobacterium tumefaciens offers a low technical entry barrier, low costs and a high degree of flexibility embedded within a rapid and scalable workflow. Recombinant proteins can easily be targeted to different subcellular compartments according to their physicochemical requirements, including post-translational modifications, to ensure optimal yields of high quality product, and to support simple and economical downstream processing. Here we demonstrate the use of a plant transient expression platform based on transfection with A. tumefaciens as essential component of a malaria vaccine development workflow involving screens for expression, solubility and stability using fluorescent fusion

Immunogenicity of mumps virus vaccine candidates matching circulating genotypes in the United States and China.

Science.gov (United States)

Zengel, James; Phan, Shannon I; Pickar, Adrian; Xu, Pei; He, Biao

2017-07-13

Mumps virus (MuV) causes acute infection in humans with characteristic swelling of the parotid gland. While vaccination has greatly reduced the incidence of MuV infection, there have been multiple large outbreaks of mumps virus (MuV) in highly vaccinated populations. The most common vaccine strain, Jeryl Lynn, belongs to genotype A, which is no longer a circulating genotype. We have developed two vaccine candidates that match the circulating genotypes in the United States (genotype G) and China (genotype F). We found that there was a significant decrease in the ability of the Jeryl Lynn vaccine to produce neutralizing antibody responses to non-matched viruses, when compared to either of our vaccine candidates. Our data suggests that an updated vaccine may allow for better immunity against the circulating MuV genotypes G and F. Copyright © 2017 Elsevier Ltd. All rights reserved.

An Approach to Identify and Characterize a Subunit Candidate Shigella Vaccine Antigen.

Science.gov (United States)

Pore, Debasis; Chakrabarti, Manoj K

2016-01-01

Shigellosis remains a serious issue throughout the developing countries, particularly in children under the age of 5. Numerous strategies have been tested to develop vaccines targeting shigellosis; unfortunately despite several years of extensive research, no safe, effective, and inexpensive vaccine against shigellosis is available so far. Here, we illustrate in detail an approach to identify and establish immunogenic outer membrane proteins from Shigella flexneri 2a as subunit vaccine candidates.

Pilot scale production of highly efficacious and stable enterovirus 71 vaccine candidates.

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Ai-Hsiang Chou

Full Text Available BACKGROUND: Enterovirus 71 (EV71 has caused several epidemics of hand, foot and mouth diseases (HFMD in Asia and now is being recognized as an important neurotropic virus. Effective medications and prophylactic vaccine against EV71 infection are urgently needed. Based on the success of inactivated poliovirus vaccine, a prototype chemically inactivated EV71 vaccine candidate has been developed and currently in human phase 1 clinical trial. PRINCIPAL FINDING: In this report, we present the development of a serum-free cell-based EV71 vaccine. The optimization at each step of the manufacturing process was investigated, characterized and quantified. In the up-stream process development, different commercially available cell culture media either containing serum or serum-free was screened for cell growth and virus yield using the roller-bottle technology. VP-SFM serum-free medium was selected based on the Vero cell growth profile and EV71 virus production. After the up-stream processes (virus harvest, diafiltration and concentration, a combination of gel-filtration liquid chromatography and/or sucrose-gradient ultracentrifugation down-stream purification processes were investigated at a pilot scale of 40 liters each. Although the combination of chromatography and sucrose-gradient ultracentrifugation produced extremely pure EV71 infectious virus particles, the overall yield of vaccine was 7-10% as determined by a VP2-based quantitative ELISA. Using chromatography as the downstream purification, the virus yield was 30-43%. To retain the integrity of virus neutralization epitopes and the stability of the vaccine product, the best virus inactivation was found to be 0.025% formalin-treatment at 37 °C for 3 to 6 days. Furthermore, the formalin-inactivated virion vaccine candidate was found to be stable for >18 months at 4 °C and a microgram of viral proteins formulated with alum adjuvant could induce strong virus-neutralizing antibody responses in mice

Pilot scale production of highly efficacious and stable enterovirus 71 vaccine candidates.

Science.gov (United States)

Chou, Ai-Hsiang; Liu, Chia-Chyi; Chang, Cheng-Peng; Guo, Meng-Shin; Hsieh, Shih-Yang; Yang, Wen-Hsueh; Chao, Hsin-Ju; Wu, Chien-Long; Huang, Ju-Lan; Lee, Min-Shi; Hu, Alan Yung-Chi; Lin, Sue-Chen; Huang, Yu-Yun; Hu, Mei-Hua; Chow, Yen-Hung; Chiang, Jen-Ron; Chang, Jui-Yuan; Chong, Pele

2012-01-01

Enterovirus 71 (EV71) has caused several epidemics of hand, foot and mouth diseases (HFMD) in Asia and now is being recognized as an important neurotropic virus. Effective medications and prophylactic vaccine against EV71 infection are urgently needed. Based on the success of inactivated poliovirus vaccine, a prototype chemically inactivated EV71 vaccine candidate has been developed and currently in human phase 1 clinical trial. In this report, we present the development of a serum-free cell-based EV71 vaccine. The optimization at each step of the manufacturing process was investigated, characterized and quantified. In the up-stream process development, different commercially available cell culture media either containing serum or serum-free was screened for cell growth and virus yield using the roller-bottle technology. VP-SFM serum-free medium was selected based on the Vero cell growth profile and EV71 virus production. After the up-stream processes (virus harvest, diafiltration and concentration), a combination of gel-filtration liquid chromatography and/or sucrose-gradient ultracentrifugation down-stream purification processes were investigated at a pilot scale of 40 liters each. Although the combination of chromatography and sucrose-gradient ultracentrifugation produced extremely pure EV71 infectious virus particles, the overall yield of vaccine was 7-10% as determined by a VP2-based quantitative ELISA. Using chromatography as the downstream purification, the virus yield was 30-43%. To retain the integrity of virus neutralization epitopes and the stability of the vaccine product, the best virus inactivation was found to be 0.025% formalin-treatment at 37 °C for 3 to 6 days. Furthermore, the formalin-inactivated virion vaccine candidate was found to be stable for >18 months at 4 °C and a microgram of viral proteins formulated with alum adjuvant could induce strong virus-neutralizing antibody responses in mice, rats, rabbits, and non-human primates. These

PROTECTIVE ACTIVITY STUDY OF A CANDIDATE VACCINE AGAINST ROTAVIRUS INFECTION BASED ON RECOMBINANT PROTEIN FliCVP6VP8

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I. V. Dukhovlinov

2016-01-01

Full Text Available Rotavirus infection is among leading causes of severe diarrhea which often leads to severe dehydration, especially, in children under 5 years old. In Russia, the incidence of rotavirus infection is constantly increased, due to higher rates of actual rotavirus infection cases and improved diagnostics of the disease. Immunity to rotavirus is unstable, thus causing repeated infections intra vitam. Anti-infectious resistance in reconvalescents is explained by induction of specific IgM, IgG, and, notably, IgA antibodies. Due to absence of market drugs with direct action against rotavirus, a rational vaccination is considered the most effective way to control the disease. Currently available vaccines for prevention of rotavirus infection are based on live attenuated rotavirus strains, human and/or animal origin, which replicate in human gut. Their implementation may result into different complications. Meanwhile, usage of vaccines based on recombinant proteins is aimed to avoid risks associated with introduction of a complete virus into humans. In this paper, we studied protective activity of candidate vaccines against rotavirus.In this work we studied protective activity of a candidate vaccine against rotavirus infection based on recombinant FliCVP6VP8 protein which includes VP6 and VP8, as well as components of Salmonella typhimurium flagellin (FliC as an adjuvant. Different components are joined by flexible bridges. Efficiency of the candidate vaccine was studied in animal model using Balb/c mice. We have shown high level of protection which occurs when the candidate vaccine is administered twice intramuscularly. Complete protection of animals against mouse rotavirus EDC after intramuscular immunization with a candidate vaccine was associated with arising rotavirus-specific IgA and IgG antibodies in serum and intestine of immunized animals. The efficacy of candidate vaccine based on recombinant protein FliCVP6VP8 against rotavirus infection was

Immunogenicity of novel mumps vaccine candidates generated by genetic modification.

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Xu, Pei; Chen, Zhenhai; Phan, Shannon; Pickar, Adrian; He, Biao

2014-03-01

Mumps is a highly contagious human disease, characterized by lateral or bilateral nonsuppurative swelling of the parotid glands and neurological complications that can result in aseptic meningitis or encephalitis. A mumps vaccination program implemented since the 1960s reduced mumps incidence by more than 99% and kept the mumps case numbers as low as hundreds of cases per year in the United States before 2006. However, a large mumps outbreak occurred in vaccinated populations in 2006 and again in 2009 in the United States, raising concerns about the efficacy of the vaccination program. Previously, we have shown that clinical isolate-based recombinant mumps viruses lacking expression of either the V protein (rMuVΔV) or the SH protein (rMuVΔSH) are attenuated in a neurovirulence test using newborn rat brains (P. Xu et al., Virology 417:126-136, 2011, http://dx.doi.org/10.1016/j.virol.2011.05.003; P. Xu et al., J. Virol. 86:1768-1776, 2012, http://dx.doi.org/10.1128/JVI.06019-11) and may be good candidates for vaccine development. In this study, we examined immunity induced by rMuVΔSH and rMuVΔV in mice. Furthermore, we generated recombinant mumps viruses lacking expression of both the V protein and the SH protein (rMuVΔSHΔV). Analysis of rMuVΔSHΔV indicated that it was stable in tissue culture cell lines. Importantly, rMuVΔSHΔV was immunogenic in mice, indicating that it is a promising candidate for mumps vaccine development.

Identification of Novel Vaccine Candidates against Campylobacter through Reverse Vaccinology

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Marine Meunier

2016-01-01

Full Text Available Campylobacteriosis is the most prevalent bacterial foodborne gastroenteritis affecting humans in the European Union. Human cases are mainly due to Campylobacter jejuni or Campylobacter coli, and contamination is associated with the handling and/or consumption of poultry meat. In fact, poultry constitutes the bacteria’s main reservoir. A promising way of decreasing the incidence of campylobacteriosis in humans would be to decrease avian colonization. Poultry vaccination is of potential for this purpose. However, despite many studies, there is currently no vaccine available on the market to reduce the intestinal Campylobacter load in chickens. It is essential to identify and characterize new vaccine antigens. This study applied the reverse vaccinology approach to detect new vaccine candidates. The main criteria used to select immune proteins were localization, antigenicity, and number of B-epitopes. Fourteen proteins were identified as potential vaccine antigens. In vitro and in vivo experiments now need to be performed to validate the immune and protective power of these newly identified antigens.

Vaccination of dogs with six different candidate leishmaniasis vaccines composed of a chimerical recombinant protein containing ribosomal and histone protein epitopes in combination with different adjuvants.

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Poot, J; Janssen, L H M; van Kasteren-Westerneng, T J; van der Heijden-Liefkens, K H A; Schijns, V E J C; Heckeroth, A

2009-07-16

Chimerical protein "Q", composed of antigenic ribosomal and histone sequences, in combination with live BCG is a promising canine leishmaniasis vaccine candidate; one of the few vaccine candidates that have been tested successfully in dogs. Unfortunately, live BCG is not an appropriate adjuvant for commercial application due to safety problems in dogs. In order to find a safe adjuvant with similar efficacy to live BCG, muramyl dipeptide, aluminium hydroxide, Matrix C and killed Propionibacterium acnes in combination with either E. coli- or baculovirus-produced recombinant JPCM5_Q protein were tested. Groups of five or seven dogs were vaccinated with six different adjuvant-antigen combinations and challenged with a high dose intravenous injection of Leishmania infantum JPC strain promastigotes. All candidate vaccines proved to be safe, and both humoral and cellular responses to the recombinant proteins were detected at the end of the prime-boost vaccination scheme. However, clinical and parasitological data obtained during the 10 month follow-up period indicated that protection was not induced by either of the six candidate vaccines. Although no direct evidence was obtained, our data suggest that live BCG may have a significant protective effect against challenge with L. infantum in dogs.

SARS CTL vaccine candidates; HLA supertype-, genome-wide scanning and biochemical validation

DEFF Research Database (Denmark)

Sylvester-Hvid, C; Nielsen, M; Lamberth, K

2004-01-01

. Exact knowledge of how the immune system handles protein antigens would allow for the identification of such linear sequences directly from genomic/proteomic sequence information (Lauemoller et al., Rev Immunogenet 2001: 2: 477-91). The latter was recently established when a causative coronavirus (SARS...... of the HLA supertypes and identified almost 100 potential vaccine candidates. These should be further validated in SARS survivors and used for vaccine formulation. We suggest that immunobioinformatics may become a fast and valuable tool in rational vaccine design....

SARS CTL vaccine candidates; HLA supertype-, genome-wide scanning and biochemical validation

DEFF Research Database (Denmark)

Sylvester-Hvid, C.; Nielsen, Morten; Lamberth, K.

2004-01-01

. Exact knowledge of how the immune system handles protein antigens would allow for the identification of such linear sequences directly, from genomic/proteomic sequence information (Lauemoller et al., Rev Immunogenet 2001: 2: 477-91). The latter was recently established when a causative coronavirus (SARS...... of the HLA supertypes and identified almost 100 potential vaccine candidates. These should be further validated in SARS survivors and used for vaccine formulation. We suggest that immunobioinformatics may become a fast and valuable tool in rational vaccine design....

Characterization of sporozoite surface antigens of Plasmodium falciparum, using monoclonal antibodies. Part of a coordinated programme on the preparation of irradiated vaccines against some human diseases

International Nuclear Information System (INIS)

Groot, M.

1982-10-01

Sporozoites are considered as a source of potential vaccine. Characterization of their antigens is therefore important and can be achieved by monoclonal antibodies. The purpose of this project is to study the production of monoclonal antibodies against sporozoites of P. falciparum. Various infections of mosquitoes were carried out during the period 1981-1982 to obtain antigens for the production of hybridomas. Hybridomas were produced from mice immunized through the bites of infected mosquitoes and by intravenous inoculation. The anti-sporozoite activity of the hybridomas was tested by an immunofluorescent antibody test using P. falciparum sporozoites as antigens. Positive immunofluorescence was seen in hybridoma cell lines tested with P. falciparum, whereas negative results were obtained when the cell lines were cross-reacted with other human species (P. vivax) and with a rodent malaria parasite (P. berghei)

Sharing of antigens between Plasmodium falciparum and Anopheles albimanus Antígenos compartidos entre Plasmodium falciparum y Anopheles albimanus

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Albina Wide

2006-12-01

Full Text Available The presence of common antigens between Plasmodium falciparum and Anopheles albimanus was demonstrated. Different groups of rabbits were immunized with: crude extract from female An. albimanus (EAaF, red blood cells infected with Plasmodium falciparum (EPfs, and the SPf66 synthetic malaria vaccine. The rabbit's polyclonal antibodies were evaluated by ELISA, Multiple Antigen Blot Assay (MABA, and immunoblotting. All extracts were immunogenic in rabbits according to these three techniques, when they were evaluated against the homologous antigens. Ten molecules were identified in female mosquitoes and also in P. falciparum antigens by the autologous sera. The electrophoretic pattern by SDS-PAGE was different for the three antigens evaluated. Cross-reactions between An. albimanus and P. falciparum were found by ELISA, MABA, and immunoblotting. Anti-P. falciparum and anti-SPf66 antibodies recognized ten and five components in the EAaF crude extract, respectively. Likewise, immune sera against female An. albimanus identified four molecules in the P. falciparum extract antigen. As far as we know, this is the first work that demonstrates shared antigens between anophelines and malaria parasites. This finding could be useful for diagnosis, vaccines, and the study of physiology of the immune response to malaria.Epítopes de antígenos compartidos entre Plasmodium falciparum y Anopheles albimanus fueron identificados. Diferentes grupos de conejos fueron inmunizados con: extracto crudo de mosquito hembra de An. albimanus (EAaH, glóbulos rojos infectados con P. falciparum (EPfs y la vacuna antimalárica sintética SPf66. Los anticuerpos policlonales producidos en conejos fueron evaluados por ELISA, inmunoensayo simultáneo de múltiples antígenos (MABA e Immunoblotting. Todos los extractos resultaron inmunogénicos cuando se evaluaron por ELISA, MABA e Immunoblotting. Diez moléculas fueron identificadas en los mosquitos hembras y diez en los antígenos de

Safety and immunogenicity of a recombinant Plasmodium falciparum AMA1 malaria vaccine adjuvanted with Alhydrogel, Montanide ISA 720 or AS02.

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Meta Roestenberg

Full Text Available Plasmodium falciparum Apical Membrane Antigen 1 (PfAMA1 is a candidate vaccine antigen expressed by merozoites and sporozoites. It plays a key role in red blood cell and hepatocyte invasion that can be blocked by antibodies.We assessed the safety and immunogenicity of recombinant PfAMA1 in a dose-escalating, phase Ia trial. PfAMA1 FVO strain, produced in Pichia pastoris, was reconstituted at 10 microg and 50 microg doses with three different adjuvants, Alhydrogel, Montanide ISA720 and AS02 Adjuvant System. Six randomised groups of healthy male volunteers, 8-10 volunteers each, were scheduled to receive three immunisations at 4-week intervals. Safety and immunogenicity data were collected over one year. Transient pain was the predominant injection site reaction (80-100%. Induration occurred in the Montanide 50 microg group, resulting in a sterile abscess in two volunteers. Systemic adverse events occurred mainly in the AS02 groups lasting for 1-2 days. Erythema was observed in 22% of Montanide and 59% of AS02 group volunteers. After the second dose, six volunteers in the AS02 group and one in the Montanide group who reported grade 3 erythema (>50 mm were withdrawn as they met the stopping criteria. All adverse events resolved. There were no vaccine-related serious adverse events. Humoral responses were highest in the AS02 groups. Antibodies showed activity in an in vitro growth inhibition assay up to 80%. Upon stimulation with the vaccine, peripheral mononuclear cells from all groups proliferated and secreted IFNgamma and IL-5 cytokines.All formulations showed distinct reactogenicity profiles. All formulations with PfAMA1 were immunogenic and induced functional antibodies.(Clinicaltrials.gov NCT00730782.

Extended Preclinical Safety, Efficacy and Stability Testing of a Live-attenuated Chikungunya Vaccine Candidate.

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Kenneth S Plante

Full Text Available We recently described a new, live-attenuated vaccine candidate for chikungunya (CHIK fever, CHIKV/IRES. This vaccine was shown to be well attenuated, immunogenic and efficacious in protecting against CHIK virus (CHIKV challenge of mice and nonhuman primates. To further evaluate its preclinical safety, we compared CHIKV/IRES distribution and viral loads in interferon-α/β receptor-incompetent A129 mice to another CHIK vaccine candidate, 181/clone25, which proved highly immunogenic but mildly reactive in human Phase I/II clinical trials. Compared to wild-type CHIK virus, (wt-CHIKV, both vaccines generated lower viral loads in a wide variety of tissues and organs, including the brain and leg muscle, but CHIKV/IRES exhibited marked restrictions in dissemination and viral loads compared to 181/clone25, and was never found outside the blood, spleen and muscle. Unlike wt-CHIKV, which caused disrupted splenic architecture and hepatic lesions, histopathological lesions were not observed in animals infected with either vaccine strain. To examine the stability of attenuation, both vaccines were passaged 5 times intracranially in infant A129 mice, then assessed for changes in virulence by comparing parental and passaged viruses for footpad swelling, weight stability and survival after subcutaneous infection. Whereas strain 181/clone25 p5 underwent a significant increase in virulence as measured by weight loss (from 30% and mortality (from 0 to 100%, CHIKV/IRES underwent no detectible change in any measure of virulence (no significant weight loss and no mortality. These data indicate greater nonclinical safety of the CHIKV/IRES vaccine candidate compared to 181/clone25, further supporting its eligibility for human testing.

Newer Vaccines against Mosquito-borne Diseases.

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Aggarwal, Anju; Garg, Neha

2018-02-01

Mosquitos are responsible for a number of protozoal and viral diseases. Malaria, dengue, Japanese encephalitis (JE) and chikungunya epidemics occur commonly all over the world, leading to marked mortality and morbidity in children. Zika, Yellow fever and West Nile fever are others requiring prevention. Environmental control and mosquito bite prevention are useful in decreasing the burden of disease but vaccination has been found to be most cost-effective and is the need of the hour. RTS,S/AS01 vaccine is the first malaria vaccine being licensed for use against P. falciparum malaria. Dengvaxia (CYD-TDV) against dengue was licensed first in Mexico in 2015. A Vero-cell derived, inactivated and alum-adjuvanted JE vaccine based on the SA14-14-2 strain was approved in 2009 in North America, Australia and various European countries. It can be used from 2 mo of age. In India, immunization is carried out in endemic regions at 1 y of age. Another inactivated Vero-cell culture derived Kolar strain, 821564XY, JE vaccine is being used in India. Candidate vaccines against dengue, chikungunya and West Nile fever are been discussed. A continued research and development of new vaccines are required for controlling these mosquito-borne diseases.

Strategic evaluation of vaccine candidate antigens for the prevention of Visceral Leishmaniasis.

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Duthie, Malcolm S; Favila, Michelle; Hofmeyer, Kimberley A; Tutterrow, Yeung L; Reed, Steven J; Laurance, John D; Picone, Alessandro; Guderian, Jeffrey; Bailor, H Remy; Vallur, Aarthy C; Liang, Hong; Mohamath, Raodoh; Vergara, Julie; Howard, Randall F; Coler, Rhea N; Reed, Steven G

2016-05-27

Infection with Leishmania parasites results in a range of clinical manifestations and outcomes, the most severe of which is visceral leishmaniasis (VL). Vaccination will likely provide the most effective long-term control strategy, as the large number of vectors and potential infectious reservoirs renders sustained interruption of Leishmania parasite transmission extremely difficult. Selection of the best vaccine is complicated because, although several vaccine antigen candidates have been proposed, they have emerged following production in different platforms. To consolidate the information that has been generated into a single vaccine platform, we expressed seven candidates as recombinant proteins in E. coli. After verifying that each recombinant protein could be recognized by VL patients, we evaluated their protective efficacy against experimental L. donovani infection of mice. Administration in formulation with the Th1-potentiating adjuvant GLA-SE indicated that each antigen could elicit antigen-specific Th1 responses that were protective. Considering the ability to reduce parasite burden along with additional factors such as sequence identity across Leishmania species, we then generated a chimeric fusion protein comprising a combination of the 8E, p21 and SMT proteins. This E. coli -expressed fusion protein was also demonstrated to protect against L. donovani infection. These data indicate a novel recombinant vaccine antigen with the potential for use in VL control programs. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Interaction of an atypical Plasmodium falciparum ETRAMP with human apolipoproteins

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Sahasrabudhe Sudhir

2008-10-01

Full Text Available Abstract Background In order to establish a successful infection in the human host, the malaria parasite Plasmodium falciparum must establish interactions with a variety of human proteins on the surface of different cell types, as well as with proteins inside the host cells. To better understand this aspect of malaria pathogenesis, a study was conducted with the goal of identifying interactions between proteins of the parasite and those of its human host. Methods A modified yeast two-hybrid methodology that preferentially selects protein fragments that can be expressed in yeast was used to conduct high-throughput screens with P. falciparum protein fragments against human liver and cerebellum libraries. The resulting dataset was analyzed to exclude interactions that are not likely to occur in the human host during infection. Results An initial set of 2,200 interactions was curated to remove proteins that are unlikely to play a role in pathogenesis based on their annotation or localization, and proteins that behave promiscuously in the two-hybrid assay, resulting in a final dataset of 456 interactions. A cluster that implicates binding between P. falciparum PFE1590w/ETRAMP5, a putative parasitophorous vacuole membrane protein, and human apolipoproteins ApoA, ApoB and ApoE was selected for further analysis. Different isoforms of ApoE, which are associated with different outcomes of malaria infection, were shown to display differential interactions with PFE1590w. Conclusion A dataset of interactions between proteins of P. falciparum and those of its human host was generated. The preferential interaction of the P. falciparum PFE1590w protein with the human ApoE ε3 and ApoE ε4 isoforms, but not the ApoE ε2 isoform, supports the hypothesis that ApoE genotype affects risk of malaria infection. The dataset contains other interactions of potential relevance to disease that may identify possible vaccine candidates and drug targets.

Engineering and expression of a human rotavirus candidate vaccine in Nicotiana benthamiana.

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Pêra, Francisco F P G; Mutepfa, David L R; Khan, Ayesha M; Els, Johann H; Mbewana, Sandiswa; van Dijk, Alberdina A A; Rybicki, Edward P; Hitzeroth, Inga I

2015-12-02

Human rotaviruses are the main cause of severe gastroenteritis in children and are responsible for over 500 000 deaths annually. There are two live rotavirus vaccines currently available, one based on human rotavirus serotype G1P[8], and the other a G1-G4 P[8] pentavalent vaccine. However, the recent emergence of the G9 and other novel rotavirus serotypes in Africa and Asia has prompted fears that current vaccines might not be fully effective against these new varieties. We report an effort to develop an affordable candidate rotavirus vaccine against the new emerging G9P[6] (RVA/Human-wt/ZAF/GR10924/1999/G9P[6]) strain. The vaccine is based on virus-like particles which are both highly immunogenic and safe. The vaccine candidate was produced in Nicotiana benthamiana by transient expression, as plants allow rapid production of antigens at lower costs, without the risk of contamination by animal pathogens. Western blot analysis of plant extracts confirmed the successful expression of two rotavirus capsid proteins, VP2 and VP6. These proteins assembled into VLPs resembling native rotavirus particles when analysed by transmission electron microscopy (TEM). Expression of the rotavirus glycoprotein VP7 and the spike protein VP4 was also tried. However, VP7 expression caused plant wilting during the course of the time trial and expression could never be detected for either protein. We therefore created three fusion proteins adding the antigenic part of VP4 (VP8*) to VP6 in an attempt to produce more appropriately immunogenic particles. Fusion protein expression in tobacco plants was detected by western blot using anti-VP6 and anti-VP4 antibodies, but no regular particles were observed by TEM, even when co-expressed with VP2. Our results suggest that the rotavirus proteins produced in N. benthamiana are candidates for a subunit vaccine specifically for the G9P[6] rotavirus strain. This could be more effective in developing countries, thereby possibly providing a higher

Long-term clinical protection from falciparum malaria is strongly associated with IgG3 antibodies to merozoite surface protein 3.

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Christian Roussilhon

2007-11-01

Full Text Available BACKGROUND: Surrogate markers of protective immunity to malaria in humans are needed to rationalize malaria vaccine discovery and development. In an effort to identify such markers, and thereby provide a clue to the complex equation malaria vaccine development is facing, we investigated the relationship between protection acquired through exposure in the field with naturally occurring immune responses (i.e., induced by the parasite to molecules that are considered as valuable vaccine candidates. METHODS AND FINDINGS: We analyzed, under comparative conditions, the antibody responses of each of six isotypes to five leading malaria vaccine candidates in relation to protection acquired by exposure to natural challenges in 217 of the 247 inhabitants of the African village of Dielmo, Senegal (96 children and 121 older adolescents and adults. The status of susceptibility or resistance to malaria was determined by active case detection performed daily by medical doctors over 6 y from a unique follow-up study of this village. Of the 30 immune responses measured, only one, antibodies of the IgG3 isotype directed to merozoite surface protein 3 (MSP3, was strongly associated with clinical protection against malaria in all age groups, i.e., independently of age. This immunological parameter had a higher statistical significance than the sickle cell trait, the strongest factor of protection known against Plasmodium falciparum. A single determination of antibody was significantly associated with the clinical outcome over six consecutive years in children submitted to massive natural parasite challenges by mosquitoes (over three parasite inoculations per week. Finally, the target epitopes of these antibodies were found to be fully conserved. CONCLUSIONS: Since anti-MSP3 IgG3 antibodies can naturally develop along with protection against P. falciparum infection in young children, our results provide the encouraging indication that these antibodies should be

Identification and development of a promising novel mumps vaccine candidate strain.

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Liang, Yan; Ma, Shaohui; Liu, Longding; Zhao, Hongling; Wang, Lichun; Jiang, Li; Xie, Zhongping; Dong, Chenghong; Li, Qihan

2010-12-01

Mumps epidemics are usually caused by airborne transmission of mumps virus (MuV) and have high morbidity in non-immunized children. Epidemiological studies in many regions of China show that the genotype F viral strain is the most prevalent. However, the genotype A strain is currently used to prepare vaccines. Regional epidemiological MuV data suggest a significant application for the development of live attenuated mumps vaccines targeting specific genotypes. This article reports the isolation and culture of a genotype F MuV candidate strain that could be used to prepare a live attenuated mumps vaccine. This strain is shown to have good immunological efficacy and stability in neurovirulence evaluations. This work should facilitate the implementation of mumps vaccination in mainland China by targeting the most prevalent MuV genotype, genotype F. Copyright © 2010 Institut Pasteur. Published by Elsevier SAS. All rights reserved.

Bioinformatics analysis for structure and function of CPR of Plasmodium falciparum.

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Fan, Zhigang; Zhang, Lingmin; Yan, Guogang; Wu, Qiang; Gan, Xiufeng; Zhong, Saifeng; Lin, Guifen

2011-02-01

To analyse the structure and function of NADPH-cytochrome p450 reductase (CYPOR or CPR) from Plasmodium falciparum (Pf), and to predict its' drug target and vaccine target. The structure, function, drug target and vaccine target of CPR from Plasmodium falciparum were analyzed and predicted by bioinformatics methods. PfCPR, which was older CPR, had close relationship with the CPR from other Plasmodium species, but it was distant from its hosts, such as Homo sapiens and Anopheles. PfCPR was located in the cellular nucleus of Plasmodium falciparum. 335aa-352aa and 591aa - 608aa were inserted the interior side of the nuclear membrane, while 151aa-265aa was located in the nucleolus organizer regions. PfCPR had 40 function sites and 44 protein-protein binding sites in amino acid sequence. The teriary structure of 1aa-700aa was forcep-shaped with wings. 15 segments of PfCPR had no homology with Homo sapien CPR and most were exposed on the surface of the protein. These segments had 25 protein-protein binding sites. While 13 other segments all possessed function sites. The evolution or genesis of Plasmodium falciparum is earlier than those of Homo sapiens. PfCPR is a possible resistance site of antimalarial drug and may involve immune evasion, which is associated with parasite of sporozoite in hepatocytes. PfCPR is unsuitable as vaccine target, but it has at least 13 ideal drug targets. Copyright © 2011 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

Evaluation of novel oral vaccine candidates and validation of a caprine model of Johne's disease

Science.gov (United States)

Hines, Murray E.; Turnquist, Sue E.; Ilha, Marcia R. S.; Rajeev, Sreekumari; Jones, Arthur L.; Whittington, Lisa; Bannantine, John P.; Barletta, Raúl G.; Gröhn, Yrjö T.; Katani, Robab; Talaat, Adel M.; Li, Lingling; Kapur, Vivek

2014-01-01

Johne's disease (JD) caused by Mycobacterium avium subspecies paratuberculosis (MAP) is a major threat to the dairy industry and possibly some cases of Crohn's disease in humans. A MAP vaccine that reduced of clinical disease and/or reduced fecal shedding would aid in the control of JD. The objectives of this study were (1) to evaluate the efficacy of 5 attenuated strains of MAP as vaccine candidates compared to a commercial control vaccine using the protocol proposed by the Johne's Disease Integrated Program (JDIP) Animal Model Standardization Committee (AMSC), and (2) to validate the AMSC Johne's disease goat challenge model. Eighty goat kids were vaccinated orally twice at 8 and 10 weeks of age with an experimental vaccine or once subcutaneously at 8 weeks with Silirum® (Zoetis), or a sham control oral vaccine at 8 and 10 weeks. Kids were challenged orally with a total of approximately 1.44 × 109 CFU divided in two consecutive daily doses using MAP ATCC-700535 (K10-like bovine isolate). All kids were necropsied at 13 months post-challenge. Results indicated that the AMSC goat challenge model is a highly efficient and valid model for JD challenge studies. None of the experimental or control vaccines evaluated prevented MAP infection or eliminated fecal shedding, although the 329 vaccine lowered the incidence of infection, fecal shedding, tissue colonization and reduced lesion scores, but less than the control vaccine. Based on our results the relative performance ranking of the experimental live-attenuated vaccines evaluated, the 329 vaccine was the best performer, followed by the 318 vaccine, then 316 vaccine, 315 vaccine and finally the 319 vaccine was the worst performer. The subcutaneously injected control vaccine outperformed the orally-delivered mutant vaccine candidates. Two vaccines (329 and 318) do reduce presence of JD gross and microscopic lesions, slow progression of disease, and one vaccine (329) reduced fecal shedding and tissue colonization. PMID

Evaluation of Novel Oral Vaccine Candidates and Validation of a Caprine Model of Johne's Disease

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Murray E. Hines

2014-03-01

Full Text Available Johne’s disease (JD caused by Mycobacterium avium subspecies paratuberculosis (MAP is a major threat to the dairy industry and possibly some cases of Crohn’s disease in humans. A MAP vaccine that reduced of clinical disease and/or reduced fecal shedding would aid in the control of JD. The objectives of this study were 1 to evaluate the efficacy of 5 attenuated strains of MAP as vaccine candidates compared to a commercial control vaccine using the protocol proposed by the Johne’s Disease Integrated Program (JDIP Animal Model Standardization Committee (AMSC, and 2 to validate the AMSC Johne’s disease goat challenge model. Eighty goat kids were vaccinated orally twice at 8 and 10 weeks of age with an experimental vaccine or once subcutaneously at 8 weeks with Silirum® (Zoetis, or a sham control oral vaccine at 8 and 10 weeks. Kids were challenged orally with a total of approximately 1.44 X 10^9 CFU divided in 2 consecutive daily doses using MAP ATCC-700535 (K10-like bovine isolate. All kids were necropsied at 13 months post challenge. Results indicated that the AMSC goat challenge model is a highly efficient and valid model for JD challenge studies. None of the experimental or control vaccines evaluated prevented MAP infection or eliminated fecal shedding, although the 329 vaccine lowered the incidence of infection, fecal shedding, tissue colonization and reduced lesion scores, but less than the control vaccine. Based on our results the relative performance ranking of the experimental live-attenuated vaccines evaluated, the 329 vaccine was the best performer, followed by the 318 vaccine, then 316 vaccine, 315 vaccine and finally the 319 vaccine was the worst performer. The subcutaneously injected control vaccine outperformed the orally-delivered mutant vaccine candidates. Two vaccines (329 and 318 do reduce presence of JD gross and microscopic lesions, slow progression of disease, and one vaccine (329 reduced fecal shedding and tissue

Enhancing blockade of Plasmodium falciparum erythrocyte invasion: assessing combinations of antibodies against PfRH5 and other merozoite antigens.

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Andrew R Williams

Full Text Available No vaccine has yet proven effective against the blood-stages of Plasmodium falciparum, which cause the symptoms and severe manifestations of malaria. We recently found that PfRH5, a P. falciparum-specific protein expressed in merozoites, is efficiently targeted by broadly-neutralizing, vaccine-induced antibodies. Here we show that antibodies against PfRH5 efficiently inhibit the in vitro growth of short-term-adapted parasite isolates from Cambodia, and that the EC(50 values of antigen-specific antibodies against PfRH5 are lower than those against PfAMA1. Since antibody responses elicited by multiple antigens are speculated to improve the efficacy of blood-stage vaccines, we conducted detailed assessments of parasite growth inhibition by antibodies against PfRH5 in combination with antibodies against seven other merozoite antigens. We found that antibodies against PfRH5 act synergistically with antibodies against certain other merozoite antigens, most notably with antibodies against other erythrocyte-binding antigens such as PfRH4, to inhibit the growth of a homologous P. falciparum clone. A combination of antibodies against PfRH4 and basigin, the erythrocyte receptor for PfRH5, also potently inhibited parasite growth. This methodology provides the first quantitative evidence that polyclonal vaccine-induced antibodies can act synergistically against P. falciparum antigens and should help to guide the rational development of future multi-antigen vaccines.

A randomized controlled Phase Ib trial of the malaria vaccine candidate GMZ2 in African children

DEFF Research Database (Denmark)

Bélard, Sabine; Issifou, Saadou; Hounkpatin, Aurore B

2011-01-01

GMZ2 is a fusion protein of Plasmodium falciparum merozoite surface protein 3 (MSP3) and glutamate rich protein (GLURP) that mediates an immune response against the blood stage of the parasite. Two previous phase I clinical trials, one in naïve European adults and one in malaria-exposed Gabonese ...... adults showed that GMZ2 was well tolerated and immunogenic. Here, we present data on safety and immunogenicity of GMZ2 in one to five year old Gabonese children, a target population for future malaria vaccine efficacy trials....

Schistosomiasis coinfection in children influences acquired immune response against Plasmodium falciparum malaria antigens.

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Tamsir O Diallo

Full Text Available BACKGROUND: Malaria and schistosomiasis coinfection frequently occurs in tropical countries. This study evaluates the influence of Schistosoma haematobium infection on specific antibody responses and cytokine production to recombinant merozoite surface protein-1-19 (MSP1-(19 and schizont extract of Plasmodium falciparum in malaria-infected children. METHODOLOGY: Specific IgG1 to MSP1-(19, as well as IgG1 and IgG3 to schizont extract were significantly increased in coinfected children compared to P. falciparum mono-infected children. Stimulation with MSP1-(19 lead to a specific production of both interleukin-10 (IL-10 and interferon-γ (IFN-γ, whereas the stimulation with schizont extract produced an IL-10 response only in the coinfected group. CONCLUSIONS: Our study suggests that schistosomiasis coinfection favours anti-malarial protective antibody responses, which could be associated with the regulation of IL-10 and IFN-γ production and seems to be antigen-dependent. This study demonstrates the importance of infectious status of the population in the evaluation of acquired immunity against malaria and highlights the consequences of a multiple infection environment during clinical trials of anti-malaria vaccine candidates.

Genome-wide discovery and verification of novel structured RNAs in Plasmodium falciparum

DEFF Research Database (Denmark)

Mourier, Tobias; Carret, Celine; Kyes, Sue

2008-01-01

ncRNAs in P. falciparum and are not represented in any RNA databases. We provide supporting evidence for purifying selection acting on the experimentally verified ncRNAs by comparing the nucleotide substitutions in the predicted ncRNA candidate structures in P. falciparum with the closely related...

Egg-Independent Influenza Vaccines and Vaccine Candidates

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Ilaria Manini

2017-07-01

Full Text Available Vaccination remains the principal way to control seasonal infections and is the most effective method of reducing influenza-associated morbidity and mortality. Since the 1940s, the main method of producing influenza vaccines has been an egg-based production process. However, in the event of a pandemic, this method has a significant limitation, as the time lag from strain isolation to final dose formulation and validation is six months. Indeed, production in eggs is a relatively slow process and production yields are both unpredictable and highly variable from strain to strain. In particular, if the next influenza pandemic were to arise from an avian influenza virus, and thus reduce the egg-laying hen population, there would be a shortage of embryonated eggs available for vaccine manufacturing. Although the production of egg-derived vaccines will continue, new technological developments have generated a cell-culture-based influenza vaccine and other more recent platforms, such as synthetic influenza vaccines.

Ebola Virus Disease Candidate Vaccines Under Evaluation in Clinical Trials

Science.gov (United States)

2016-06-02

evidence that oral vaccines fail in populations with disturbed microbiota, poor nutrition , and high intestinal inflammation [102-104]. Additionally...countermeasure development against Ebola virus disease becoming a global public- health priority. This review summarizes the status quo of candidate...members of the mononegaviral family Filoviridae) cause two diseases recognized by the World Health Organization (WHO): Ebola virus disease (EVD) can be

Identification Of Protein Vaccine Candidates Using Comprehensive Proteomic Analysis Strategies

Science.gov (United States)

2007-12-01

that fascinating fungus known as Coccidioides. I also want to thank the UA Mass Spectrometry Facility and the UA Proteomics Consortium, especially...W. & N. N. Kav. 2006. The proteome of the phytopathogenic fungus Sclerotinia sclerotiorum. Proteomics 6: 5995-6007. 127. de Godoy, L. M., J. V...IDENTIFICATION OF PROTEIN VACCINE CANDIDATES USING COMPREHENSIVE PROTEOMIC ANALYSIS STRATEGIES by James G. Rohrbough

Rapid strategy for screening by pyrosequencing of influenza virus reassortants--candidates for live attenuated vaccines.

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Shcherbik, Svetlana V; Pearce, Nicholas C; Levine, Marnie L; Klimov, Alexander I; Villanueva, Julie M; Bousse, Tatiana L

2014-01-01

Live attenuated influenza vaccine viruses (LAIVs) can be generated by classical reassortment of gene segments between a cold adapted, temperature sensitive and attenuated Master Donor Virus (MDV) and a seasonal wild-type (wt) virus. The vaccine candidates contain hemagglutinin (HA) and neuraminidase (NA) genes derived from the circulating wt viruses and the remaining six genes derived from the MDV strains. Rapid, efficient selection of the viruses with 6∶2 genome compositions from the large number of genetically different viruses generated during reassortment is essential for the biannual production schedule of vaccine viruses. This manuscript describes a new approach for the genotypic analysis of LAIV reassortant virus clones based on pyrosequencing. LAIV candidate viruses were created by classical reassortment of seasonal influenza A (H3N2) (A/Victoria/361/2011, A/Ohio/02/2012, A/Texas/50/2012) or influenza A (H7N9) (A/Anhui/1/2013) wt viruses with the MDV A/Leningrad/134/17/57(H2N2). Using strain-specific pyrosequencing assays, mixed gene variations were detected in the allantoic progenies during the cloning procedure. The pyrosequencing analysis also allowed for estimation of the relative abundance of segment variants in mixed populations. This semi-quantitative approach was used for selecting specific clones for the subsequent cloning procedures. The present study demonstrates that pyrosequencing analysis is a useful technique for rapid and reliable genotyping of reassortants and intermediate clones during the preparation of LAIV candidates, and can expedite the selection of vaccine virus candidates.

Rapid strategy for screening by pyrosequencing of influenza virus reassortants--candidates for live attenuated vaccines.

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Svetlana V Shcherbik

Full Text Available BACKGROUND: Live attenuated influenza vaccine viruses (LAIVs can be generated by classical reassortment of gene segments between a cold adapted, temperature sensitive and attenuated Master Donor Virus (MDV and a seasonal wild-type (wt virus. The vaccine candidates contain hemagglutinin (HA and neuraminidase (NA genes derived from the circulating wt viruses and the remaining six genes derived from the MDV strains. Rapid, efficient selection of the viruses with 6∶2 genome compositions from the large number of genetically different viruses generated during reassortment is essential for the biannual production schedule of vaccine viruses. METHODOLOGY/PRINCIPAL FINDINGS: This manuscript describes a new approach for the genotypic analysis of LAIV reassortant virus clones based on pyrosequencing. LAIV candidate viruses were created by classical reassortment of seasonal influenza A (H3N2 (A/Victoria/361/2011, A/Ohio/02/2012, A/Texas/50/2012 or influenza A (H7N9 (A/Anhui/1/2013 wt viruses with the MDV A/Leningrad/134/17/57(H2N2. Using strain-specific pyrosequencing assays, mixed gene variations were detected in the allantoic progenies during the cloning procedure. The pyrosequencing analysis also allowed for estimation of the relative abundance of segment variants in mixed populations. This semi-quantitative approach was used for selecting specific clones for the subsequent cloning procedures. CONCLUSIONS/SIGNIFICANCE: The present study demonstrates that pyrosequencing analysis is a useful technique for rapid and reliable genotyping of reassortants and intermediate clones during the preparation of LAIV candidates, and can expedite the selection of vaccine virus candidates.

Plasmodium falciparum: genetic diversity and complexity of infections in an isolated village in western Thailand.

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Tanabe, Kazuyuki; Zollner, Gabriela; Vaughan, Jefferson A; Sattabongkot, Jetsumon; Khuntirat, Benjawan; Honma, Hajime; Mita, Toshihiro; Tsuboi, Takafumi; Coleman, Russell

2015-06-01

Genetic diversity of Plasmodium falciparum is intimately associated with morbidity, mortality and malaria control strategies. It is therefore imperative to study genetic makeup and population structure of this parasite in endemic areas. In Kong Mong Tha, an isolated village in western Thailand, the majority of P. falciparum infections are asymptomatic. In this study we investigated complexity of infections and single nucleotide polymorphisms (SNPs) in the P. falciparum population of Kong Mong Tha, and compared results with those previously obtained from Mae Sod, in northwestern Thailand, where the majority of infections were symptomatic. Using PCR-based determination of the 5' merozoite surface protein 1 gene (msp1) recombinant types, we found that 39% of 59 P. falciparum isolates from Kong Mong Tha had multiple 5' recombinant types with a mean number of 1.54. These values were much lower than those obtained from Mae Sod: 96% for multiple infections and with a mean number of 3.61. Analysis of full-length sequences of two housekeeping genes, the P-type Ca(2+)-transporting ATPase gene (n=33) plus adenylosuccinate lyase gene (n=33), and three vaccine candidate antigen genes, msp1 (n=26), the circumsporozoite protein gene, csp (n=30) and the apical membrane antigen 1 gene, ama 1 (n=32), revealed that in all of these genes within-population SNP diversity was at similar levels between Kong Mong Tha and Mae Sod, suggesting that the extent of MOI and clinical manifestations of malaria are not strongly associated with genetic diversity. Additionally, we did not detect significant genetic differentiation between the two parasite populations, as estimated by the Wright's fixation index of inter-population variance in allele frequencies, suggesting that gene flow prevented the formation of population structuring. Thus, this study highlights unique features of P. falciparum populations in Thailand. The implications of these finding are discussed. © 2013.

Population genetic structure and natural selection of Plasmodium falciparum apical membrane antigen-1 in Myanmar isolates.

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Kang, Jung-Mi; Lee, Jinyoung; Moe, Mya; Jun, Hojong; Lê, Hương Giang; Kim, Tae Im; Thái, Thị Lam; Sohn, Woon-Mok; Myint, Moe Kyaw; Lin, Khin; Shin, Ho-Joon; Kim, Tong-Soo; Na, Byoung-Kuk

2018-02-07

Plasmodium falciparum apical membrane antigen-1 (PfAMA-1) is one of leading blood stage malaria vaccine candidates. However, genetic variation and antigenic diversity identified in global PfAMA-1 are major hurdles in the development of an effective vaccine based on this antigen. In this study, genetic structure and the effect of natural selection of PfAMA-1 among Myanmar P. falciparum isolates were analysed. Blood samples were collected from 58 Myanmar patients with falciparum malaria. Full-length PfAMA-1 gene was amplified by polymerase chain reaction and cloned into a TA cloning vector. PfAMA-1 sequence of each isolate was sequenced. Polymorphic characteristics and effect of natural selection were analysed with using DNASTAR, MEGA4, and DnaSP programs. Polymorphic nature and natural selection in 459 global PfAMA-1 were also analysed. Thirty-seven different haplotypes of PfAMA-1 were identified in 58 Myanmar P. falciparum isolates. Most amino acid changes identified in Myanmar PfAMA-1 were found in domains I and III. Overall patterns of amino acid changes in Myanmar PfAMA-1 were similar to those in global PfAMA-1. However, frequencies of amino acid changes differed by country. Novel amino acid changes in Myanmar PfAMA-1 were also identified. Evidences for natural selection and recombination event were observed in global PfAMA-1. Among 51 commonly identified amino acid changes in global PfAMA-1 sequences, 43 were found in predicted RBC-binding sites, B-cell epitopes, or IUR regions. Myanmar PfAMA-1 showed similar patterns of nucleotide diversity and amino acid polymorphisms compared to those of global PfAMA-1. Balancing natural selection and intragenic recombination across PfAMA-1 are likely to play major roles in generating genetic diversity in global PfAMA-1. Most common amino acid changes in global PfAMA-1 were located in predicted B-cell epitopes where high levels of nucleotide diversity and balancing natural selection were found. These results highlight the

Levels of antibody to conserved parts of Plasmodium falciparum merozoite surface protein 1 in Ghanaian children are not associated with protection from clinical malaria

DEFF Research Database (Denmark)

Dodoo, D; Theander, T G; Kurtzhals, J A

1999-01-01

malaria season in April and after the season in November. Using enzyme-linked immunosorbent assay, we measured antibody responses to recombinant gluthathione S-transferase-PfMSP119 fusion proteins corresponding to the Wellcome and MAD20 allelic variants in these samples. Prevalence of antibodies......The 19-kDa conserved C-terminal part of the Plasmodium falciparum merozoite surface protein 1 (PfMSP119) is a malaria vaccine candidate antigen, and human antibody responses to PfMSP119 have been associated with protection against clinical malaria. In this longitudinal study carried out in an area...

Surface display of Clonorchis sinensis enolase on Bacillus subtilis spores potentializes an oral vaccine candidate.

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Wang, Xiaoyun; Chen, Wenjun; Tian, Yanli; Mao, Qiang; Lv, Xiaoli; Shang, Mei; Li, Xuerong; Yu, Xinbing; Huang, Yan

2014-03-10

Clonorchis sinensis (C. sinensis) infections remain the common public health problem in freshwater fish consumption areas. New effective prevention strategies are still the urgent challenges to control this kind of foodborne infectious disease. The biochemical importance and biological relevance render C. sinensis enolase (Csenolase) as a potential vaccine candidate. In the present study, we constructed Escherichia coli/Bacillus subtilis shuttle genetic engineering system and investigated the potential of Csenolase as an oral vaccine candidate for C. sinensis prevention in different immunization routes. Our results showed that, compared with control groups, both recombinant Csenolase protein and nucleic acid could induce a mixed IgG1/IgG2a immune response when administrated subcutaneously (Psinensis infection. Csenolase derived oral vaccine conferred worm reduction rate and egg reduction rate at 60.07% (Psinensis prevention. Copyright © 2014 Elsevier Ltd. All rights reserved.

Adenovirus Particles that Display the Plasmodium falciparum Circumsporozoite Protein NANP Repeat Induce Sporozoite-Neutralizing Antibodies in Mice

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Palma, Christopher; Overstreet, Michael G.; Guedon, Jean-Marc; Hoiczyk, Egbert; Ward, Cameron; Karen, Kasey A.; Zavala, Fidel; Ketner, Gary

2011-01-01

Adenovirus particles can be engineered to display exogenous peptides on their surfaces by modification of viral capsid proteins, and particles that display pathogen-derived peptides can induce protective immunity. We constructed viable recombinant adenoviruses that display B-cell epitopes from the Plasmodium falciparum circumsporozoite protein (PfCSP) in the major adenovirus capsid protein, hexon. Recombinants induced high-titer antibodies against CSP when injected intraperitoneally into mice. Serum obtained from immunized mice recognized both recombinant PfCSP protein and P. falciparum sporozoites, and neutralized P. falciparum sporozoites in vitro. Replicating adenovirus vaccines have provided economical protection against adenovirus disease for over three decades. The recombinants described here may provide a path to an affordable malaria vaccine in the developing world. PMID:21199707

Genetic polymorphisms in the glutamate-rich protein of Plasmodium falciparum field isolates from a malaria-endemic area of Brazil

DEFF Research Database (Denmark)

Pratt-Riccio, Lilian Rose; Perce-da-Silva, Daiana de Souza; Lima-Junior, Josué da Costa

2013-01-01

The genetic diversity displayed by Plasmodium falciparum, the most deadly Plasmodium species, is a significant obstacle for effective malaria vaccine development. In this study, we identified genetic polymorphisms in P. falciparum glutamate-rich protein (GLURP), which is currently being tested in...

Immune response profiles of calves following vaccination with live BCG and inactivated Mycobacterium bovis vaccine candidates.

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E M D L van der Heijden

Full Text Available Conventional control and eradication strategies for bovine tuberculosis (BTB face tremendous difficulties in developing countries; countries with wildlife reservoirs, a complex wildlife-livestock-human interface or a lack of veterinary and veterinary public health surveillance. Vaccination of cattle and other species might in some cases provide the only suitable control strategy for BTB, while in others it may supplement existing test-and-slaughter schemes. However, the use of live BCG has several limitations and the global rise of HIV/AIDS infections has furthermore warranted the exploration of inactivated vaccine preparations. The aim of this study was to compare the immune response profiles in response to parenteral vaccination with live BCG and two inactivated vaccine candidates in cattle. Twenty-four mixed breed calves (Bos taurus aged 4-6 months, were allocated to one of four groups and vaccinated sub-cutaneously with live M. bovis BCG (Danish 1331, formalin-inactivated M. bovis BCG, heat-killed M. bovis or PBS/Montanide™ (control. Interferon-γ responsiveness and antibody production were measured prior to vaccination and at weekly intervals thereafter for twelve weeks. At nine weeks post-priming, animals were skin tested using tuberculins and MTBC specific protein cocktails and subsequently challenged through intranodular injection of live M. bovis BCG. The animals in the heat-killed M. bovis group demonstrated strong and sustained cell-mediated and humoral immune responses, significantly higher than the control group in response to vaccination, which may indicate a protective immune profile. Animals in this group showed reactivity to the skin test reagents, confirming good vaccine take. Lastly, although not statistically significant, recovery of BCG after challenge was lowest in the heat-killed M. bovis group. In conclusion, the parenteral heat-killed M. bovis vaccine proved to be clearly immunogenic in cattle in the present study

Cell biological characterization of the malaria vaccine candidate trophozoite exported protein 1.

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Caroline Kulangara

Full Text Available In a genome-wide screen for alpha-helical coiled coil motifs aiming at structurally defined vaccine candidates we identified PFF0165c. This protein is exported in the trophozoite stage and was named accordingly Trophozoite exported protein 1 (Tex1. In an extensive preclinical evaluation of its coiled coil peptides Tex1 was identified as promising novel malaria vaccine candidate providing the rational for a comprehensive cell biological characterization of Tex1. Antibodies generated against an intrinsically unstructured N-terminal region of Tex1 and against a coiled coil domain were used to investigate cytological localization, solubility and expression profile. Co-localization experiments revealed that Tex1 is exported across the parasitophorous vacuole membrane and located to Maurer's clefts. Change in location is accompanied by a change in solubility: from a soluble state within the parasite to a membrane-associated state after export to Maurer's clefts. No classical export motifs such as PEXEL, signal sequence/anchor or transmembrane domain was identified for Tex1.

Construction of a trivalent candidate vaccine against Shigella species with DNA recombination

Institute of Scientific and Technical Information of China (English)

王恒樑; 冯尔玲; 林云; 廖翔; 金明; 黄留玉; 苏国富; 黄翠芬

2002-01-01

In this work asd gene of Shigella flexneri 2a strain T32 was replaced by Vibrio cholerae toxin B subunit (ctxB) gene with DNA recombination in vivo and in vitro. The resulting derivative of T32, designed as FWL01, could stably express CtxB, but its growth in LB medium depended on the presence of diaminopimelic acid (DAP). Then form I plasmid of Shigella sonnei strain S7 was labeled with strain T32 asd gene and mobilized into FWL01. Thus a trivalent candidate oral vaccine strain, designed as FSW01, was constructed. In this candidate strain, a balanced-lethal system was constituted between the host strain and the form I plasmid expressing S. sonnei O antigen. Therefore the candidate strain can express stably not only its own O antigen but also CtxB and O antigen of S. sonnei in the absence of any antibiotic. Experiments showed that FSW01 did not invade HeLa cells or cause keratoconjunctivitis in guinea pigs. However, rabbits immunized FSW01 can elicit significant immune responses. In mice and rhesus monkey models, vaccinated animals were protected against the challenges of wild S. flexneri 2a strain 2457T and S. sonnei strain S9.

Sequence diversity and natural selection at domain I of the apical membrane antigen 1 among Indian Plasmodium falciparum populations

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Kumar Ashwani

2007-11-01

Full Text Available Abstract Background The Plasmodium falciparum apical membrane antigen 1 (AMA1 is a leading malaria vaccine candidate antigen. The complete AMA1 protein is comprised of three domains where domain I exhibits high sequence polymorphism and is thus named as the hyper-variable region (HVR. The present study describes the extent of genetic polymorphism and natural selection at domain I of the ama1 gene among Indian P. falciparum isolates. Methods The part of the ama1 gene covering domain I was PCR amplified and sequenced from 157 P. falciparum isolates collected from five different geographical regions of India. Statistical and phylogenetic analyses of the sequences were done using DnaSP ver. 4. 10. 9 and MEGA version 3.0 packages. Results A total of 57 AMA1 haplotypes were observed among 157 isolates sequenced. Forty-six of these 57 haplotypes are being reported here for the first time. The parasites collected from the high malaria transmission areas (Assam, Orissa, and Andaman and Nicobar Islands showed more haplotypes (H and nucleotide diversity π as compared to low malaria transmission areas (Uttar Pradesh and Goa. The comparison of all five Indian P. falciparum subpopulations indicated moderate level of genetic differentiation and limited gene flow (Fixation index ranging from 0.048 to 0.13 between populations. The difference between rates of non-synonymous and synonymous mutations, Tajima's D and McDonald-Kreitman test statistics suggested that the diversity at domain I of the AMA1 antigen is due to positive natural selection. The minimum recombination events were also high indicating the possible role of recombination in generating AMA1 allelic diversity. Conclusion The level of genetic diversity and diversifying selection were higher in Assam, Orissa, and Andaman and Nicobar Islands populations as compared to Uttar Pradesh and Goa. The amounts of gene flow among these populations were moderate. The data reported here will be valuable for the

Identification and characterization of a novel Plasmodium falciparum adhesin involved in erythrocyte invasion.

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Nidhi Hans

Full Text Available Malaria remains a major health problem worldwide. All clinical symptoms of malaria are attributed to the asexual blood stages of the parasite life cycle. Proteins resident in apical organelles and present on the surface of P. falciparum merozoites are considered promising candidates for the development of blood stage malaria vaccines. In the present study, we have identified and characterized a microneme associated antigen, PfMA [PlasmoDB Gene ID: PF3D7_0316000, PFC0700c]. The gene was selected by applying a set of screening criteria such as transcriptional upregulation at late schizogony, inter-species conservation and the presence of signal sequence or transmembrane domains. The gene sequence of PfMA was found to be conserved amongst various Plasmodium species. We experimentally demonstrated that the transcript for PfMA was expressed only in the late blood stages of parasite consistent with a putative role in erythrocyte invasion. PfMA was localized by immunofluorescence and immuno-electron microscopy to be in the micronemes, an apical organelle of merozoites. The functional role of the PfMA protein in erythrocyte invasion was identified as a parasite adhesin involved in direct attachment with the target erythrocyte. PfMA was demonstrated to bind erythrocytes in a sialic acid independent, chymotrypsin and trypsin resistant manner and its antibodies inhibited P. falciparum erythrocyte invasion. Invasion of erythrocytes is a complex multistep process that involves a number of redundant ligand-receptor interactions many of which still remain unknown and even uncharacterized. Our work has identified and characterized a novel P. falciparum adhesin involved in erythrocyte invasion.

Computational identification of signalling pathways in Plasmodium falciparum.

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Oyelade, Jelili; Ewejobi, Itunu; Brors, Benedikt; Eils, Roland; Adebiyi, Ezekiel

2011-06-01

Malaria is one of the world's most common and serious diseases causing death of about 3 million people each year. Its most severe occurrence is caused by the protozoan Plasmodium falciparum. Reports have shown that the resistance of the parasite to existing drugs is increasing. Therefore, there is a huge and urgent need to discover and validate new drug or vaccine targets to enable the development of new treatments for malaria. The ability to discover these drug or vaccine targets can only be enhanced from our deep understanding of the detailed biology of the parasite, for example how cells function and how proteins organize into modules such as metabolic, regulatory and signal transduction pathways. It has been noted that the knowledge of signalling transduction pathways in Plasmodium is fundamental to aid the design of new strategies against malaria. This work uses a linear-time algorithm for finding paths in a network under modified biologically motivated constraints. We predicted several important signalling transduction pathways in Plasmodium falciparum. We have predicted a viable signalling pathway characterized in terms of the genes responsible that may be the PfPKB pathway recently elucidated in Plasmodium falciparum. We obtained from the FIKK family, a signal transduction pathway that ends up on a chloroquine resistance marker protein, which indicates that interference with FIKK proteins might reverse Plasmodium falciparum from resistant to sensitive phenotype. We also proposed a hypothesis that showed the FIKK proteins in this pathway as enabling the resistance parasite to have a mechanism for releasing chloroquine (via an efflux process). Furthermore, we also predicted a signalling pathway that may have been responsible for signalling the start of the invasion process of Red Blood Cell (RBC) by the merozoites. It has been noted that the understanding of this pathway will give insight into the parasite virulence and will facilitate rational vaccine design

A flow cytometry-based workflow for detection and quantification of anti-plasmodial antibodies in vaccinated and naturally exposed individuals

DEFF Research Database (Denmark)

Ajua, Anthony; Engleitner, Thomas; Esen, Meral

2012-01-01

information about natural exposure and vaccine immunogenicity. A novel, cytometry-based workflow for the quantitative detection of anti-plasmodial antibodies in human serum is presented. METHODS: Fixed red blood cells (RBCs), infected with late stages of P. falciparum were utilized to detect malaria...... vaccine trials in semiimmune adults and pre-school children residing in a malaria endemic area. RESULTS: Fixation, permeabilization, and staining of infected RBCs were adapted for best operation in flow cytometry. As asexual vaccine candidates are designed to induce antibody patterns similar to semi...... with those obtained by manual gating (r between 0.79 and 0.99) and outperformed other model-driven gating methods. Bland-Altman plots confirmed the agreement of manual gating and OSA derived results. A-1.33 fold increase (p=0.003) in the number of positive cells after vaccination in a subgroup of preschool...

DNA prime/Adenovirus boost malaria vaccine encoding P. falciparum CSP and AMA1 induces sterile protection associated with cell-mediated immunity.

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Ilin Chuang

Full Text Available BACKGROUND: Gene-based vaccination using prime/boost regimens protects animals and humans against malaria, inducing cell-mediated responses that in animal models target liver stage malaria parasites. We tested a DNA prime/adenovirus boost malaria vaccine in a Phase 1 clinical trial with controlled human malaria infection. METHODOLOGY/PRINCIPAL FINDINGS: The vaccine regimen was three monthly doses of two DNA plasmids (DNA followed four months later by a single boost with two non-replicating human serotype 5 adenovirus vectors (Ad. The constructs encoded genes expressing P. falciparum circumsporozoite protein (CSP and apical membrane antigen-1 (AMA1. The regimen was safe and well-tolerated, with mostly mild adverse events that occurred at the site of injection. Only one AE (diarrhea, possibly related to immunization, was severe (Grade 3, preventing daily activities. Four weeks after the Ad boost, 15 study subjects were challenged with P. falciparum sporozoites by mosquito bite, and four (27% were sterilely protected. Antibody responses by ELISA rose after Ad boost but were low (CSP geometric mean titer 210, range 44-817; AMA1 geometric mean micrograms/milliliter 11.9, range 1.5-102 and were not associated with protection. Ex vivo IFN-γ ELISpot responses after Ad boost were modest (CSP geometric mean spot forming cells/million peripheral blood mononuclear cells 86, range 13-408; AMA1 348, range 88-1270 and were highest in three protected subjects. ELISpot responses to AMA1 were significantly associated with protection (p = 0.019. Flow cytometry identified predominant IFN-γ mono-secreting CD8+ T cell responses in three protected subjects. No subjects with high pre-existing anti-Ad5 neutralizing antibodies were protected but the association was not statistically significant. SIGNIFICANCE: The DNA/Ad regimen provided the highest sterile immunity achieved against malaria following immunization with a gene-based subunit vaccine (27%. Protection

A multi-country study of dengue vaccination strategies with Dengvaxia and a future vaccine candidate in three dengue-endemic countries: Vietnam, Thailand, and Colombia.

Science.gov (United States)

Lee, Jung-Seok; Lourenço, José; Gupta, Sunetra; Farlow, Andrew

2018-04-19

The dengue vaccination era began when Dengvaxia (CYD-TDV) became available in 2016. In addition, several second-generation vaccine candidates are currently in phase 3 trials, suggesting that a broader availability of dengue vaccines may be possible in the near future. Advancing on the recent WHO-SAGE recommendations for the safe and effective use of CYD-TDV at the regional level on average, this study investigates the vaccination impacts and cost-effectiveness of CYD-TDV and of a hypothetical new vaccine candidate (NVC) in a country-specific manner for three endemic countries: Vietnam, Thailand, and Colombia. The vaccination impacts of CYD-TDV and NVC were derived by fitting the empirical seroprevalence rates of 9 year olds into an individual-based meta-population transmission model, previously used for the WHO-SAGE working group. The disability-adjusted life years were estimated by applying country-specific parametric values. The cost-effectiveness analyses of four intervention strategies in combination with routine and catch-up campaigns were compared for both vaccines to inform decision makers regarding the most suitable immunization program in each of the three countries. Both CYD-TDV and NVC could be cost-effective at the DALY threshold cost of $2000 depending upon vaccination costs. With CYD-TDV, targeting 9 year olds in routine vaccination programs and 10-29 year olds as a one-off catch-up campaign was the most cost-effective strategy in all three countries. With NVC, while the most cost-effective strategy was to vaccinate 9-29 and 9-18 year olds in Vietnam and Thailand respectively, vaccinating younger age cohorts between 1 and 5 years old in Colombia was more cost-effective than other strategies. Given that three countries will soon face decisions regarding whether and how to incorporate CYD-TDV or future dengue vaccines into their budget-constrained national immunization programs, the current study outcomes can be used to help decision makers

A research agenda for malaria eradication: vaccines.

NARCIS (Netherlands)

Abdulla, S.; Agre, P.; Alonso, P.L.; Arevalo-Herrera, M.; Bassat, Q.; Binka, F.; Chitnis, C.; Corradin, G.; Cowman, A. F.; Culpepper, J.; Portillo, H. del; Dinglasan, R.R.; Duffy, P.; Gargallo, D.; Greenwood, B.; Guinovart, C.; Hall, B.F.; Herrera, S.; Hoffman, S.; Lanzavecchia, A.; Leroy, O.; Levine, M.M.; Loucq, C.; Mendis, K.; Milman, J.; Moorthy, V.S.; Pleuschke, G.; Plowe, C.V.; Reed, S.; Sauerwein, R.W.; Saul, A.; Schofield, L.; Sinden, R.R.; Stubbs, J.; Villafana, T.; Wirth, D.; Yadav, P.; Ballou, R.; Brown, G.; Birkett, A.; Brandt, W.; Brooks, A.; Carter, T.; Golden, A.; Lee, C.; Nunes, J.; Puijalon, O.; Raphael, T.; Richards, H.; Warren, C.; Woods, C.

2011-01-01

Vaccines could be a crucial component of efforts to eradicate malaria. Current attempts to develop malaria vaccines are primarily focused on Plasmodium falciparum and are directed towards reducing morbidity and mortality. Continued support for these efforts is essential, but if

ChAd63-MVA-vectored blood-stage malaria vaccines targeting MSP1 and AMA1: assessment of efficacy against mosquito bite challenge in humans.

Science.gov (United States)

Sheehy, Susanne H; Duncan, Christopher J A; Elias, Sean C; Choudhary, Prateek; Biswas, Sumi; Halstead, Fenella D; Collins, Katharine A; Edwards, Nick J; Douglas, Alexander D; Anagnostou, Nicholas A; Ewer, Katie J; Havelock, Tom; Mahungu, Tabitha; Bliss, Carly M; Miura, Kazutoyo; Poulton, Ian D; Lillie, Patrick J; Antrobus, Richard D; Berrie, Eleanor; Moyle, Sarah; Gantlett, Katherine; Colloca, Stefano; Cortese, Riccardo; Long, Carole A; Sinden, Robert E; Gilbert, Sarah C; Lawrie, Alison M; Doherty, Tom; Faust, Saul N; Nicosia, Alfredo; Hill, Adrian V S; Draper, Simon J

2012-12-01

The induction of cellular immunity, in conjunction with antibodies, may be essential for vaccines to protect against blood-stage infection with the human malaria parasite Plasmodium falciparum. We have shown that prime-boost delivery of P. falciparum blood-stage antigens by chimpanzee adenovirus 63 (ChAd63) followed by the attenuated orthopoxvirus MVA is safe and immunogenic in healthy adults. Here, we report on vaccine efficacy against controlled human malaria infection delivered by mosquito bites. The blood-stage malaria vaccines were administered alone, or together (MSP1+AMA1), or with a pre-erythrocytic malaria vaccine candidate (MSP1+ME-TRAP). In this first human use of coadministered ChAd63-MVA regimes, we demonstrate immune interference whereby responses against merozoite surface protein 1 (MSP1) are dominant over apical membrane antigen 1 (AMA1) and ME-TRAP. We also show that induction of strong cellular immunity against MSP1 and AMA1 is safe, but does not impact on parasite growth rates in the blood. In a subset of vaccinated volunteers, a delay in time to diagnosis was observed and sterilizing protection was observed in one volunteer coimmunized with MSP1+AMA1-results consistent with vaccine-induced pre-erythrocytic, rather than blood-stage, immunity. These data call into question the utility of T cell-inducing blood-stage malaria vaccines and suggest that the focus should remain on high-titer antibody induction against susceptible antigen targets.

A Rapid and Improved Method to Generate Recombinant Dengue Virus Vaccine Candidates.

Science.gov (United States)

Govindarajan, Dhanasekaran; Guan, Liming; Meschino, Steven; Fridman, Arthur; Bagchi, Ansu; Pak, Irene; ter Meulen, Jan; Casimiro, Danilo R; Bett, Andrew J

2016-01-01

Dengue is one of the most important mosquito-borne infections accounting for severe morbidity and mortality worldwide. Recently, the tetravalent chimeric live attenuated Dengue vaccine Dengvaxia® was approved for use in several dengue endemic countries. In general, live attenuated vaccines (LAV) are very efficacious and offer long-lasting immunity against virus-induced disease. Rationally designed LAVs can be generated through reverse genetics technology, a method of generating infectious recombinant viruses from full length cDNA contained in bacterial plasmids. In vitro transcribed (IVT) viral RNA from these infectious clones is transfected into susceptible cells to generate recombinant virus. However, the generation of full-length dengue virus cDNA clones can be difficult due to the genetic instability of viral sequences in bacterial plasmids. To circumvent the need for a single plasmid containing a full length cDNA, in vitro ligation of two or three cDNA fragments contained in separate plasmids can be used to generate a full-length dengue viral cDNA template. However, in vitro ligation of multiple fragments often yields low quality template for IVT reactions, resulting in inconsistent low yield RNA. These technical difficulties make recombinant virus recovery less efficient. In this study, we describe a simple, rapid and efficient method of using LONG-PCR to recover recombinant chimeric Yellow fever dengue (CYD) viruses as potential dengue vaccine candidates. Using this method, we were able to efficiently generate several viable recombinant viruses without introducing any artificial mutations into the viral genomes. We believe that the techniques reported here will enable rapid and efficient recovery of recombinant flaviviruses for evaluation as vaccine candidates and, be applicable to the recovery of other RNA viruses.

Evaluation of Lethal Giant Larvae as a Schistosomiasis Vaccine Candidate

Directory of Open Access Journals (Sweden)

Yufan Cao

2016-01-01

Full Text Available Schistosomiasis is a neglected tropical disease of humans, and it is considered to be the second most devastating parasitic disease after malaria. Eggs produced by normally developed female worms are important in the transmission of the parasite, and they responsible for the pathogenesis of schistosomiasis. The tumor suppressor gene lethal giant larvae (lgl has an essential function in establishing apical-basal cell polarity, cell proliferation, differentiation, and tissue organization. In our earlier study, downregulation of the lgl gene induced a significant reduction in the egg hatching rate of Schistosoma japonicum (Sj eggs. In this study, the Sjlgl gene was used as a vaccine candidate against schistosomiasis, and vaccination achieved and maintained a stable reduction of the egg hatching rate, which is consistent with previous studies, in addition to reducing the worm burden and liver egg burden in some trials.

In vivo electroporation enhances the immunogenicity of an HIV-1 DNA vaccine candidate in healthy volunteers.

Directory of Open Access Journals (Sweden)

Sandhya Vasan

Full Text Available DNA-based vaccines have been safe but weakly immunogenic in humans to date.We sought to determine the safety, tolerability, and immunogenicity of ADVAX, a multigenic HIV-1 DNA vaccine candidate, injected intramuscularly by in vivo electroporation (EP in a Phase-1, double-blind, randomized placebo-controlled trial in healthy volunteers. Eight volunteers each received 0.2 mg, 1 mg, or 4 mg ADVAX or saline placebo via EP, or 4 mg ADVAX via standard intramuscular injection at weeks 0 and 8. A third vaccination was administered to eleven volunteers at week 36. EP was safe, well-tolerated and considered acceptable for a prophylactic vaccine. EP delivery of ADVAX increased the magnitude of HIV-1-specific cell mediated immunity by up to 70-fold over IM injection, as measured by gamma interferon ELISpot. The number of antigens to which the response was detected improved with EP and increasing dosage. Intracellular cytokine staining analysis of ELISpot responders revealed both CD4+ and CD8+ T cell responses, with co-secretion of multiple cytokines.This is the first demonstration in healthy volunteers that EP is safe, tolerable, and effective in improving the magnitude, breadth and durability of cellular immune responses to a DNA vaccine candidate.ClinicalTrials.gov NCT00545987.

Phase 1/2a study of the malaria vaccine candidate apical membrane antigen-1 (AMA-l) administered in adjuvant system AS01B or AS02A

NARCIS (Netherlands)

M.D. Spring (Michele Donna); J.F. Cummings (James); C.F. Ockenhouse (Christian); S. Dutta (Shantanu); R. Reidler (Randall); E. Angov (Evelina); E. Bergmann-Leitner (Elke); V.A. Stewart (Ann); S. Bittner (Stacey); L. Juompan (Laure); M.G. Kortepeter (Mark); R. Nielsen (Robin); U. Krzych (Urszula); E. Tierney (Ev); L.A. Ware (Lisa); M. Dowler (Megan); C.C. Hermsen (Cornelus); R.W. Sauerwein (Robert); S.J. de Vlas (Sake); O. Ofori-Anyinam (Opokua); D.E. Lanar (David); J.L. Williams (Jack); K.E. Kester (Kent); K. Tucker (Kathryn); M. Shi (Meng); E. Malkin (Elissa); C. Long (Carole); C.L. Diggs (Carter); L. Soisson (Lorraine Amory); M.C. Dubois; W.R. Ballou (Ripley); J. Cohen (Joe); D.G. Heppner (Gray)

2009-01-01

textabstractBackground: This Phase 1/2a study evaluated the safety, immunogenicity, and efficacy of an experimental malaria vaccine comprised of the recombinant Plasmodium falciparum protein apical membrane antigen-1 (AMA-1) representing the 3D7 allele formulated with either the AS01B or AS02A

Generation and Characterization of Live Attenuated Influenza A(H7N9 Candidate Vaccine Virus Based on Russian Donor of Attenuation.

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Svetlana Shcherbik

Full Text Available Avian influenza A (H7N9 virus has emerged recently and continues to cause severe disease with a high mortality rate in humans prompting the development of candidate vaccine viruses. Live attenuated influenza vaccines (LAIV are 6:2 reassortant viruses containing the HA and NA gene segments from wild type influenza viruses to induce protective immune responses and the six internal genes from Master Donor Viruses (MDV to provide temperature sensitive, cold-adapted and attenuated phenotypes.LAIV candidate A/Anhui/1/2013(H7N9-CDC-LV7A (abbreviated as CDC-LV7A, based on the Russian MDV, A/Leningrad/134/17/57 (H2N2, was generated by classical reassortment in eggs and retained MDV temperature-sensitive and cold-adapted phenotypes. CDC-LV7A had two amino acid substitutions N123D and N149D (H7 numbering in HA and one substitution T10I in NA. To evaluate the role of these mutations on the replication capacity of the reassortants in eggs, the recombinant viruses A(H7N9RG-LV1 and A(H7N9RG-LV2 were generated by reverse genetics. These changes did not alter virus antigenicity as ferret antiserum to CDC-LV7A vaccine candidate inhibited hemagglutination by homologous A(H7N9 virus efficiently. Safety studies in ferrets confirmed that CDC-LV7A was attenuated compared to wild-type A/Anhui/1/2013. In addition, the genetic stability of this vaccine candidate was examined in eggs and ferrets by monitoring sequence changes acquired during virus replication in the two host models. No changes in the viral genome were detected after five passages in eggs. However, after ten passages additional mutations were detected in the HA gene. The vaccine candidate was shown to be stable in the ferret model; post-vaccination sequence data analysis showed no changes in viruses collected in nasal washes present at day 5 or day 7.Our data indicate that the A/Anhui/1/2013(H7N9-CDC-LV7A reassortant virus is a safe and genetically stable candidate vaccine virus that is now available for

In silico analysis to identify vaccine candidates common to multiple serotypes of Shigella and evaluation of their immunogenicity

KAUST Repository

Pahil, Sapna

2017-08-02

Shigellosis or bacillary dysentery is an important cause of diarrhea, with the majority of the cases occurring in developing countries. Considering the high disease burden, increasing antibiotic resistance, serotype-specific immunity and the post-infectious sequelae associated with shigellosis, there is a pressing need of an effective vaccine against multiple serotypes of the pathogen. In the present study, we used bio-informatics approach to identify antigens shared among multiple serotypes of Shigella spp. This approach led to the identification of many immunogenic peptides. The five most promising peptides based on MHC binding efficiency were a putative lipoprotein (EL PGI I), a putative heat shock protein (EL PGI II), Spa32 (EL PGI III), IcsB (EL PGI IV) and a hypothetical protein (EL PGI V). These peptides were synthesized and the immunogenicity was evaluated in BALB/c mice by ELISA and cytokine assays. The putative heat shock protein (HSP) and the hypothetical protein elicited good humoral response, whereas putative lipoprotein, Spa32 and IcsB elicited good T-cell response as revealed by increased IFN-γ and TNF-α cytokine levels. The patient sera from confirmed cases of shigellosis were also evaluated for the presence of peptide specific antibodies with significant IgG and IgA antibodies against the HSP and the hypothetical protein, bestowing them as potential future vaccine candidates. The antigens reported in this study are novel and have not been tested as vaccine candidates against Shigella. This study offers time and cost-effective way of identifying unprecedented immunogenic antigens to be used as potential vaccine candidates. Moreover, this approach should easily be extendable to find new potential vaccine candidates for other pathogenic bacteria.

In silico analysis to identify vaccine candidates common to multiple serotypes of Shigella and evaluation of their immunogenicity.

Science.gov (United States)

Pahil, Sapna; Taneja, Neelam; Ansari, Hifzur Rahman; Raghava, G P S

2017-01-01

Shigellosis or bacillary dysentery is an important cause of diarrhea, with the majority of the cases occurring in developing countries. Considering the high disease burden, increasing antibiotic resistance, serotype-specific immunity and the post-infectious sequelae associated with shigellosis, there is a pressing need of an effective vaccine against multiple serotypes of the pathogen. In the present study, we used bio-informatics approach to identify antigens shared among multiple serotypes of Shigella spp. This approach led to the identification of many immunogenic peptides. The five most promising peptides based on MHC binding efficiency were a putative lipoprotein (EL PGI I), a putative heat shock protein (EL PGI II), Spa32 (EL PGI III), IcsB (EL PGI IV) and a hypothetical protein (EL PGI V). These peptides were synthesized and the immunogenicity was evaluated in BALB/c mice by ELISA and cytokine assays. The putative heat shock protein (HSP) and the hypothetical protein elicited good humoral response, whereas putative lipoprotein, Spa32 and IcsB elicited good T-cell response as revealed by increased IFN-γ and TNF-α cytokine levels. The patient sera from confirmed cases of shigellosis were also evaluated for the presence of peptide specific antibodies with significant IgG and IgA antibodies against the HSP and the hypothetical protein, bestowing them as potential future vaccine candidates. The antigens reported in this study are novel and have not been tested as vaccine candidates against Shigella. This study offers time and cost-effective way of identifying unprecedented immunogenic antigens to be used as potential vaccine candidates. Moreover, this approach should easily be extendable to find new potential vaccine candidates for other pathogenic bacteria.

In silico analysis to identify vaccine candidates common to multiple serotypes of Shigella and evaluation of their immunogenicity

KAUST Repository

Pahil, Sapna; Taneja, Neelam; Ansari, Hifzur Rahman; Raghava, G. P. S.

2017-01-01

Shigellosis or bacillary dysentery is an important cause of diarrhea, with the majority of the cases occurring in developing countries. Considering the high disease burden, increasing antibiotic resistance, serotype-specific immunity and the post-infectious sequelae associated with shigellosis, there is a pressing need of an effective vaccine against multiple serotypes of the pathogen. In the present study, we used bio-informatics approach to identify antigens shared among multiple serotypes of Shigella spp. This approach led to the identification of many immunogenic peptides. The five most promising peptides based on MHC binding efficiency were a putative lipoprotein (EL PGI I), a putative heat shock protein (EL PGI II), Spa32 (EL PGI III), IcsB (EL PGI IV) and a hypothetical protein (EL PGI V). These peptides were synthesized and the immunogenicity was evaluated in BALB/c mice by ELISA and cytokine assays. The putative heat shock protein (HSP) and the hypothetical protein elicited good humoral response, whereas putative lipoprotein, Spa32 and IcsB elicited good T-cell response as revealed by increased IFN-γ and TNF-α cytokine levels. The patient sera from confirmed cases of shigellosis were also evaluated for the presence of peptide specific antibodies with significant IgG and IgA antibodies against the HSP and the hypothetical protein, bestowing them as potential future vaccine candidates. The antigens reported in this study are novel and have not been tested as vaccine candidates against Shigella. This study offers time and cost-effective way of identifying unprecedented immunogenic antigens to be used as potential vaccine candidates. Moreover, this approach should easily be extendable to find new potential vaccine candidates for other pathogenic bacteria.

In silico analysis to identify vaccine candidates common to multiple serotypes of Shigella and evaluation of their immunogenicity.

Directory of Open Access Journals (Sweden)

Sapna Pahil

Full Text Available Shigellosis or bacillary dysentery is an important cause of diarrhea, with the majority of the cases occurring in developing countries. Considering the high disease burden, increasing antibiotic resistance, serotype-specific immunity and the post-infectious sequelae associated with shigellosis, there is a pressing need of an effective vaccine against multiple serotypes of the pathogen. In the present study, we used bio-informatics approach to identify antigens shared among multiple serotypes of Shigella spp. This approach led to the identification of many immunogenic peptides. The five most promising peptides based on MHC binding efficiency were a putative lipoprotein (EL PGI I, a putative heat shock protein (EL PGI II, Spa32 (EL PGI III, IcsB (EL PGI IV and a hypothetical protein (EL PGI V. These peptides were synthesized and the immunogenicity was evaluated in BALB/c mice by ELISA and cytokine assays. The putative heat shock protein (HSP and the hypothetical protein elicited good humoral response, whereas putative lipoprotein, Spa32 and IcsB elicited good T-cell response as revealed by increased IFN-γ and TNF-α cytokine levels. The patient sera from confirmed cases of shigellosis were also evaluated for the presence of peptide specific antibodies with significant IgG and IgA antibodies against the HSP and the hypothetical protein, bestowing them as potential future vaccine candidates. The antigens reported in this study are novel and have not been tested as vaccine candidates against Shigella. This study offers time and cost-effective way of identifying unprecedented immunogenic antigens to be used as potential vaccine candidates. Moreover, this approach should easily be extendable to find new potential vaccine candidates for other pathogenic bacteria.

Synthetic TLR4 agonists enhance functional antibodies and CD4+ T-cell responses against the Plasmodium falciparum GMZ2.6C multi-stage vaccine antigen

DEFF Research Database (Denmark)

Baldwin, Susan L; Roeffen, Will; Singh, Susheel K

2016-01-01

A subunit vaccine targeting both transmission and pathogenic asexual blood stages of Plasmodium falciparum, i.e., a multi-stage vaccine, could be a powerful tool to combat malaria. Here, we report production and characterization of the recombinant protein GMZ2.6C, which contains a fragment of the......-γ and TNF in response to GMZ2.6C. Both of these agonists have good safety records in humans....... of the sexual-stage protein Pfs48/45-6C genetically fused to GMZ2, an asexual vaccine antigen in advanced clinical development. To select the most suitable vaccine formulation for downstream clinical studies, GMZ2.6C was tested with various immune modulators in different adjuvant formulations (stable emulsions......, liposomes, and alum) in C57BL/6 mice. Some, but not all, formulations containing either the synthetic TLR4 agonist GLA or SLA elicited the highest parasite-specific antibody titers, the greatest IFN-γ responses in CD4+ TH1 cells, and the highest percentage of multifunctional CD4+ T cells expressing IFN...

The fimbrial protein FlfA from Gallibacterium anatis is a virulence factor and vaccine candidate

DEFF Research Database (Denmark)

Bager, Ragnhild Jørgensen; Nesta, Barbara; Pors, Susanne Elisabeth

2013-01-01

in the natural chicken host. Furthermore, protection against G. anatis 12656-12 could be induced by immunizing chickens with recombinant FlfA. Finally, in vitro expression of FlfA homologs was observed in a genetically diverse set of G. anatis strains, suggesting the potential of FlfA as a serotype-independent...... vaccine candidate This is the first study describing a fimbrial subunit protein of G. anatis with a clear potential as a vaccine antigen....

Vacuna contra la fiebre hemorrágica argentina Candid#1 producida en la Argentina: Inmunogenicidad y seguridad Candid#1 vaccine against Argentine Hemorrhagic Fever produced in Argentina: Immunogenicity and safety

Directory of Open Access Journals (Sweden)

Delia A. Enria

2010-06-01

Full Text Available Se realizó un estudio clínico en 946 voluntarios humanos sanos, donde se comparó la vacuna Candid#1 producida en Argentina con la elaborada en EE.UU., que había sido utilizada en estudios previos. Como objetivo primario se evaluó la equivalencia en la eficacia utilizando como marcador subrogante a la inmunogenicidad medida por detección de anticuerpos neutralizantes. Como objetivo secundario se evaluó la equivalencia en inocuidad comparando las tasas de reacciones adversas. Ambas vacunas mostraron una tasa equivalente de inmunogenicidad ligeramente superior al 95.5%, que es la eficacia estimada para Candid #1 en estudios previos. No se observaron eventos adversos graves relacionados con la vacuna. Los eventos adversos generales considerados relacionados fueron de escasa significación clínica y de resolución espontánea o con tratamiento sintomático; se presentaron en los receptores de ambas vacunas en tasas equivalentes (29.9% para la vacuna fabricada en la Argentina y 35.0% para la fabricada en EE.UU., e incluyeron: cefalea, decaimiento, mialgias, plaquetopenia leve (A clinical study in 946 human volunteers was done to compare Candid #1 vaccine manufactured in Argentina with the vaccine produced in USA that had been previously used. The efficacy was evaluated using immunogenicity measured by the detection of neutralizing antibodies as a subrogate marker. Safety was evaluated comparing the rate of adverse events. Both vaccines showed a comparable rate of seroconversion, slighty higher than the efficacy estimated from previous studies (95.5%. There were no severe adverse events related to the vaccines. The general events considered related to the vaccines were not clinically relevant and disappeared either spontaneously or with symptomatic treatment. Similar rates of adverse events (29.9% for the Argentine vaccine and 35.0% for the USA vaccine were found for both vaccines. These included: headache, weakness, myalgias, mild low blood

A Rapid and Improved Method to Generate Recombinant Dengue Virus Vaccine Candidates.

Directory of Open Access Journals (Sweden)

Dhanasekaran Govindarajan

Full Text Available Dengue is one of the most important mosquito-borne infections accounting for severe morbidity and mortality worldwide. Recently, the tetravalent chimeric live attenuated Dengue vaccine Dengvaxia® was approved for use in several dengue endemic countries. In general, live attenuated vaccines (LAV are very efficacious and offer long-lasting immunity against virus-induced disease. Rationally designed LAVs can be generated through reverse genetics technology, a method of generating infectious recombinant viruses from full length cDNA contained in bacterial plasmids. In vitro transcribed (IVT viral RNA from these infectious clones is transfected into susceptible cells to generate recombinant virus. However, the generation of full-length dengue virus cDNA clones can be difficult due to the genetic instability of viral sequences in bacterial plasmids. To circumvent the need for a single plasmid containing a full length cDNA, in vitro ligation of two or three cDNA fragments contained in separate plasmids can be used to generate a full-length dengue viral cDNA template. However, in vitro ligation of multiple fragments often yields low quality template for IVT reactions, resulting in inconsistent low yield RNA. These technical difficulties make recombinant virus recovery less efficient. In this study, we describe a simple, rapid and efficient method of using LONG-PCR to recover recombinant chimeric Yellow fever dengue (CYD viruses as potential dengue vaccine candidates. Using this method, we were able to efficiently generate several viable recombinant viruses without introducing any artificial mutations into the viral genomes. We believe that the techniques reported here will enable rapid and efficient recovery of recombinant flaviviruses for evaluation as vaccine candidates and, be applicable to the recovery of other RNA viruses.

Preclinical assessment of viral vectored and protein vaccines targeting the Duffy-binding protein region II of Plasmodium vivax

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Simone C de Cassan

2015-07-01

Full Text Available Malaria vaccine development has largely focused on Plasmodium falciparum; however a reawakening to the importance of P. vivax has spurred efforts to develop vaccines against this difficult to treat and at times severe form of relapsing malaria, which constitutes a significant proportion of human malaria cases worldwide. The almost complete dependence of P. vivax red blood cell invasion on the interaction of the P. vivax Duffy-binding protein region II (PvDBP_RII with the human Duffy antigen receptor for chemokines (DARC, makes this antigen an attractive vaccine candidate against blood-stage P. vivax. Here, we generated both preclinical and clinically-compatible adenoviral and poxviral vectored vaccine candidates expressing the Salvador I allele of PvDBP_RII – including human adenovirus serotype 5 (HAdV5, chimpanzee adenovirus serotype 63 (ChAd63 and modified vaccinia virus Ankara (MVA vectors. We report on the antibody and T cell immunogenicity of these vaccines in mice or rabbits, either used alone in a viral vectored prime-boost regime, or in ‘mixed-modality’ adenovirus prime – protein-in-adjuvant boost regimes (using a recombinant protein PvDBP_RII protein antigen formulated in Montanide®ISA720 or Abisco®100 adjuvants. Antibodies induced by these regimes were found to bind to native parasite antigen from P. vivax infected Thai patients and were capable of inhibiting the binding of PvDBP_RII to its receptor DARC using an in vitro binding inhibition assay. In recent years, recombinant ChAd63 and MVA vectors have been quickly translated into human clinical trials for numerous antigens from P. falciparum as well as a growing number of other pathogens. The vectors reported here are immunogenic in small animals, elicit antibodies against PvDBP_RII and have recently entered clinical trials which will provide the first assessment of the safety and immunogenicity of the PvDBP_RII antigen in humans.

An assessment of enterotoxigenic Escherichia coli and Shigella vaccine candidates for infants and children.

Science.gov (United States)

Walker, Richard I

2015-02-18

Despite improvements to water quality, sanitation, and the implementation of current prevention and treatment interventions, diarrhea remains a major cause of illness and death, especially among children less than five years of age in the developing world. Rotavirus vaccines have already begun making a real impact on diarrhea, but several more enteric vaccines will be necessary to achieve broader reductions of illness and death. Among the many causes of diarrheal disease, enterotoxigenic Escherichia coli (ETEC) and Shigella are the two most important bacterial pathogens for which there are no currently licensed vaccines. Vaccines against these two pathogens could greatly reduce the impact of disease caused by these infections. This review describes the approaches to ETEC and Shigella vaccines that are currently under development, including a range of both cellular and subunit approaches for each pathogen. In addition, the review discusses strategies for maximizing the potential benefit of these vaccines, which includes the feasibility of co-administration, consolidation, and combination of vaccine candidates, as well as issues related to effective administration of enteric vaccines to infants. Recent impact studies indicate that ETEC and Shigella vaccines could significantly benefit global public health. Either vaccine, particularly if they could be combined together or with another enteric vaccine, would be an extremely valuable tool for saving lives and promoting the health of infants and children in the developing world, as well as potentially providing protection to travelers and military personnel visiting endemic areas. Copyright © 2014 Elsevier Ltd. All rights reserved.

Oral administration of live Shigella vaccine candidates in rhesus monkeys show no evidence of competition for colonization and immunogenicity between different serotypes.

Science.gov (United States)

Ranallo, R T; Kaminski, R; Baqar, S; Dutta, M; Lugo-Roman, L A; Boren, T; Barnoy, S; Venkatesan, M M

2014-03-26

Live oral monovalent Shigella flexneri 2a vaccine candidates as well as bivalent formulations with Shigella sonnei were evaluated in a rhesus monkey model for colonization and immunogenicity. Freshly harvested suspensions of S. flexneri 2a vaccine candidates WRSf2G12 and WRSf2G15 as well as S. sonnei vaccine candidate WRSs3 were nasogastrically administered to groups of rhesus monkeys, Macaca mulatta, either in a monovalent form or when combined with each other. The animals were monitored daily for physical well-being, stools were subjected to quantitative colony immunoblot assays for bacterial excretion and blood and stools were evaluated for humoral and mucosal immune responses. No clinical symptoms were noted in any group of animals and the vaccine candidates were excreted robustly for 48-72h without significant changes in either the magnitude or duration of excretion when given as a monovalent or as bivalent mixtures. Similarly, immunological interferences were not apparent in the magnitude of humoral and mucosal immune responses observed toward Shigella-specific antigens when monkeys were fed monovalent or bivalent formulations. These results predict that a multivalent live oral vaccine of more than one serotype can have a favorable outcome for protection against shigellosis. Published by Elsevier Ltd.

Lipoprotein NMB0928 from Neisseria meningitidis serogroup B as a novel vaccine candidate.

Science.gov (United States)

Delgado, Maité; Yero, Daniel; Niebla, Olivia; González, Sonia; Climent, Yanet; Pérez, Yusleydis; Cobas, Karem; Caballero, Evelín; García, Darien; Pajón, Rolando

2007-12-05

Polysaccharide-based vaccines for serogroup B Neisseria meningitidis have failed to induce protective immunity. As a result, efforts to develop vaccines for serogroup B meningococcal disease have mostly focused on outer membrane proteins (OMP). Vaccine candidates based on meningococcal OMP have emerged in the form of outer membrane vesicles (OMVs) or, more recently, purified recombinant proteins, as alternative strategies for serogroup B vaccine development. In our group, the protein composition of the Cuban OMVs-based vaccine VA-MENGOC-BC was elucidated using two-dimensional gel electrophoresis and mass spectrometry. The proteomic map of this product allowed the identification of new putative protective proteins not previously reported as components of an antimeningococcal vaccine. In the present study, we have determined the immunogenicity and protective capacity of NMB0928, one of those proteins present in the OMVs. The antigen was obtained as a recombinant protein in Escherichia coli, purified and used to immunize mice. The antiserum produced against the protein was capable to recognize the natural protein in different meningococcal strains by whole-cell ELISA and Western blotting. After immunization, recombinant NMB0928 induced bactericidal antibodies, and when the protein was administered inserted into liposomes, the elicited antibodies were protective in the infant rat model. These results suggest that NMB0928 is a novel antigen worth to be included in a broadly protective meningococcal vaccine.

Construction and characterization of human rotavirus recombinant VP8* subunit parenteral vaccine candidates.

Science.gov (United States)

Wen, Xiaobo; Cao, Dianjun; Jones, Ronald W; Li, Jianping; Szu, Shousun; Hoshino, Yasutaka

2012-09-21

Two currently licensed live oral rotavirus vaccines (Rotarix® and RotaTeq®) are highly efficacious against severe rotavirus diarrhea. However, the efficacy of such vaccines in selected low-income African and Asian countries is much lower than that in middle or high-income countries. Additionally, these two vaccines have recently been associated with rare case of intussusception in vaccinated infants. We developed a novel recombinant subunit parenteral rotavirus vaccine which may be more effective in low-income countries and also avert the potential problem of intussusception. Truncated recombinant VP8* (ΔVP8*) protein of human rotavirus strain Wa P[8], DS-1 P[4] or 1076 P[6] expressed in Escherichia coli was highly soluble and was generated in high yield. Guinea pigs hyperimmunized intramuscularly with each of the ΔVP8* proteins (i.e., P[8], P[4] or P[6]) developed high levels of homotypic as well as variable levels of heterotypic neutralizing antibodies. Moreover, the selected ΔVP8* proteins when administered to mice at a clinically relevant dosage, route and schedule, elicited high levels of serum anti-VP8* IgG and/or neutralizing antibodies. Our data indicated that the ΔVP8* proteins may be a plausible additional candidate as new parenteral rotavirus vaccines. Published by Elsevier Ltd.

In silico discovery of transcription regulatory elements in Plasmodium falciparum

Directory of Open Access Journals (Sweden)

Le Roch Karine G

2008-02-01

Full Text Available Abstract Background With the sequence of the Plasmodium falciparum genome and several global mRNA and protein life cycle expression profiling projects now completed, elucidating the underlying networks of transcriptional control important for the progression of the parasite life cycle is highly pertinent to the development of new anti-malarials. To date, relatively little is known regarding the specific mechanisms the parasite employs to regulate gene expression at the mRNA level, with studies of the P. falciparum genome sequence having revealed few cis-regulatory elements and associated transcription factors. Although it is possible the parasite may evoke mechanisms of transcriptional control drastically different from those used by other eukaryotic organisms, the extreme AT-rich nature of P. falciparum intergenic regions (~90% AT presents significant challenges to in silico cis-regulatory element discovery. Results We have developed an algorithm called Gene Enrichment Motif Searching (GEMS that uses a hypergeometric-based scoring function and a position-weight matrix optimization routine to identify with high-confidence regulatory elements in the nucleotide-biased and repeat sequence-rich P. falciparum genome. When applied to promoter regions of genes contained within 21 co-expression gene clusters generated from P. falciparum life cycle microarray data using the semi-supervised clustering algorithm Ontology-based Pattern Identification, GEMS identified 34 putative cis-regulatory elements associated with a variety of parasite processes including sexual development, cell invasion, antigenic variation and protein biosynthesis. Among these candidates were novel motifs, as well as many of the elements for which biological experimental evidence already exists in the Plasmodium literature. To provide evidence for the biological relevance of a cell invasion-related element predicted by GEMS, reporter gene and electrophoretic mobility shift assays

The Plasmodium falciparum erythrocyte invasion ligand Pfrh4 as a target of functional and protective human antibodies against malaria.

Directory of Open Access Journals (Sweden)

Linda Reiling

Full Text Available BACKGROUND: Acquired antibodies are important in human immunity to malaria, but key targets remain largely unknown. Plasmodium falciparum reticulocyte-binding-homologue-4 (PfRh4 is important for invasion of human erythrocytes and may therefore be a target of protective immunity. METHODS: IgG and IgG subclass-specific responses against different regions of PfRh4 were determined in a longitudinal cohort of 206 children in Papua New Guinea (PNG. Human PfRh4 antibodies were tested for functional invasion-inhibitory activity, and expression of PfRh4 by P. falciparum isolates and sequence polymorphisms were determined. RESULTS: Antibodies to PfRh4 were acquired by children exposed to P. falciparum malaria, were predominantly comprised of IgG1 and IgG3 subclasses, and were associated with increasing age and active parasitemia. High levels of antibodies, particularly IgG3, were strongly predictive of protection against clinical malaria and high-density parasitemia. Human affinity-purified antibodies to the binding region of PfRh4 effectively inhibited erythrocyte invasion by P. falciparum merozoites and antibody levels in protected children were at functionally-active concentrations. Although expression of PfRh4 can vary, PfRh4 protein was expressed by most isolates derived from the cohort and showed limited sequence polymorphism. CONCLUSIONS: Evidence suggests that PfRh4 is a target of antibodies that contribute to protective immunity to malaria by inhibiting erythrocyte invasion and preventing high density parasitemia. These findings advance our understanding of the targets and mechanisms of human immunity and evaluating the potential of PfRh4 as a component of candidate malaria vaccines.

Impact on malaria parasite multiplication rates in infected volunteers of the protein-in-adjuvant vaccine AMA1-C1/Alhydrogel+CPG 7909.

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Christopher J A Duncan

Full Text Available Inhibition of parasite growth is a major objective of blood-stage malaria vaccines. The in vitro assay of parasite growth inhibitory activity (GIA is widely used as a surrogate marker for malaria vaccine efficacy in the down-selection of candidate blood-stage vaccines. Here we report the first study to examine the relationship between in vivo Plasmodium falciparum growth rates and in vitro GIA in humans experimentally infected with blood-stage malaria.In this phase I/IIa open-label clinical trial five healthy malaria-naive volunteers were immunised with AMA1/C1-Alhydrogel+CPG 7909, and together with three unvaccinated controls were challenged by intravenous inoculation of P. falciparum infected erythrocytes.A significant correlation was observed between parasite multiplication rate in 48 hours (PMR and both vaccine-induced growth-inhibitory activity (Pearson r = -0.93 [95% CI: -1.0, -0.27] P = 0.02 and AMA1 antibody titres in the vaccine group (Pearson r = -0.93 [95% CI: -0.99, -0.25] P = 0.02. However immunisation failed to reduce overall mean PMR in the vaccine group in comparison to the controls (vaccinee 16 fold [95% CI: 12, 22], control 17 fold [CI: 0, 65] P = 0.70. Therefore no impact on pre-patent period was observed (vaccine group median 8.5 days [range 7.5-9], control group median 9 days [range 7-9].Despite the first observation in human experimental malaria infection of a significant association between vaccine-induced in vitro growth inhibitory activity and in vivo parasite multiplication rate, this did not translate into any observable clinically relevant vaccine effect in this small group of volunteers.ClinicalTrials.gov [NCT00984763].

Phase 1b randomized trial and follow-up study in Uganda of the blood-stage malaria vaccine candidate BK-SE36.

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Palacpac, Nirianne Marie Q; Ntege, Edward; Yeka, Adoke; Balikagala, Betty; Suzuki, Nahoko; Shirai, Hiroki; Yagi, Masanori; Ito, Kazuya; Fukushima, Wakaba; Hirota, Yoshio; Nsereko, Christopher; Okada, Takuya; Kanoi, Bernard N; Tetsutani, Kohhei; Arisue, Nobuko; Itagaki, Sawako; Tougan, Takahiro; Ishii, Ken J; Ueda, Shigeharu; Egwang, Thomas G; Horii, Toshihiro

2013-01-01

Up to now a malaria vaccine remains elusive. The Plasmodium falciparum serine repeat antigen-5 formulated with aluminum hydroxyl gel (BK-SE36) is a blood-stage malaria vaccine candidate that has undergone phase 1a trial in malaria-naive Japanese adults. We have now assessed the safety and immunogenicity of BK-SE36 in a malaria endemic area in Northern Uganda. We performed a two-stage, randomized, single-blinded, placebo-controlled phase 1b trial (Current Controlled trials ISRCTN71619711). A computer-generated sequence randomized healthy subjects for 2 subcutaneous injections at 21-day intervals in Stage1 (21-40 year-olds) to 1-mL BK-SE36 (BKSE1.0) (n = 36) or saline (n = 20) and in Stage2 (6-20 year-olds) to BKSE1.0 (n = 33), 0.5-mL BK-SE36 (BKSE0.5) (n = 33), or saline (n = 18). Subjects and laboratory personnel were blinded. Safety and antibody responses 21-days post-second vaccination (Day42) were assessed. Post-trial, to compare the risk of malaria episodes 130-365 days post-second vaccination, Stage2 subjects were age-matched to 50 control individuals. Nearly all subjects who received BK-SE36 had induration (Stage1, n = 33, 92%; Stage2, n = 63, 96%) as a local adverse event. No serious adverse event related to BK-SE36 was reported. Pre-existing anti-SE36 antibody titers negatively correlated with vaccination-induced antibody response. At Day42, change in antibody titers was significant for seronegative adults (1.95-fold higher than baseline [95% CI, 1.56-2.43], p = 0.004) and 6-10 year-olds (5.71-fold [95% CI, 2.38-13.72], p = 0.002) vaccinated with BKSE1.0. Immunogenicity response to BKSE0.5 was low and not significant (1.55-fold [95% CI, 1.24-1.94], p = 0.75). In the ancillary analysis, cumulative incidence of first malaria episodes with ≥5000 parasites/µL was 7 cases/33 subjects in BKSE1.0 and 10 cases/33 subjects in BKSE0.5 vs. 29 cases/66 subjects in the control group. Risk ratio for BKSE1.0 was 0.48 (95% CI, 0

A brief review on features of falciparum malaria during pregnancy

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Alexandre Manirakiza

2017-12-01

Full Text Available Malaria in pregnancy is a serious public health problem in tropical areas. Frequently, the placenta is infected by accumulation of Plasmodium falciparum-infected erythrocytes in the intervillous space. Falciparum malaria acts during pregnancy by a range of mechanisms, and chronic or repeated infection and co-infections have insidious effects. The susceptibility of pregnant women to malaria is due to both immunological and humoral changes. Until a malaria vaccine becomes available, the deleterious effects of malaria in pregnancy can be avoided by protection against infection and prompt treatment with safe, effective antimalarial agents; however, concurrent infections such as with HIV and helminths during pregnancy are jeopardizing malaria control in sub-Saharan Africa.

Live, Attenuated Influenza A H5N1 Candidate Vaccines Provide Broad Cross-Protection in Mice and Ferrets

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Mills, Kimberly L; Jin, Hong; Duke, Greg; Lu, Bin; Luke, Catherine J; Murphy, Brian; Swayne, David E; Kemble, George; Subbarao, Kanta

2006-01-01

Background Recent outbreaks of highly pathogenic influenza A H5N1 viruses in humans and avian species that began in Asia and have spread to other continents underscore an urgent need to develop vaccines that would protect the human population in the event of a pandemic. Methods and Findings Live, attenuated candidate vaccines possessing genes encoding a modified H5 hemagglutinin (HA) and a wild-type (wt) N1 neuraminidase from influenza A H5N1 viruses isolated in Hong Kong and Vietnam in 1997, 2003, and 2004, and remaining gene segments derived from the cold-adapted (ca) influenza A vaccine donor strain, influenza A/Ann Arbor/6/60 ca (H2N2), were generated by reverse genetics. The H5N1 ca vaccine viruses required trypsin for efficient growth in vitro, as predicted by the modification engineered in the gene encoding the HA, and possessed the temperature-sensitive and attenuation phenotypes specified by the internal protein genes of the ca vaccine donor strain. More importantly, the candidate vaccines were immunogenic in mice. Four weeks after receiving a single dose of 106 50% tissue culture infectious doses of intranasally administered vaccines, mice were fully protected from lethality following challenge with homologous and antigenically distinct heterologous wt H5N1 viruses from different genetic sublineages (clades 1, 2, and 3) that were isolated in Asia between 1997 and 2005. Four weeks after receiving two doses of the vaccines, mice and ferrets were fully protected against pulmonary replication of homologous and heterologous wt H5N1 viruses. Conclusions The promising findings in these preclinical studies of safety, immunogenicity, and efficacy of the H5N1 ca vaccines against antigenically diverse H5N1 vaccines provide support for their careful evaluation in Phase 1 clinical trials in humans. PMID:16968127

Live, attenuated influenza A H5N1 candidate vaccines provide broad cross-protection in mice and ferrets.

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Amorsolo L Suguitan

2006-09-01

Full Text Available Recent outbreaks of highly pathogenic influenza A H5N1 viruses in humans and avian species that began in Asia and have spread to other continents underscore an urgent need to develop vaccines that would protect the human population in the event of a pandemic.Live, attenuated candidate vaccines possessing genes encoding a modified H5 hemagglutinin (HA and a wild-type (wt N1 neuraminidase from influenza A H5N1 viruses isolated in Hong Kong and Vietnam in 1997, 2003, and 2004, and remaining gene segments derived from the cold-adapted (ca influenza A vaccine donor strain, influenza A/Ann Arbor/6/60 ca (H2N2, were generated by reverse genetics. The H5N1 ca vaccine viruses required trypsin for efficient growth in vitro, as predicted by the modification engineered in the gene encoding the HA, and possessed the temperature-sensitive and attenuation phenotypes specified by the internal protein genes of the ca vaccine donor strain. More importantly, the candidate vaccines were immunogenic in mice. Four weeks after receiving a single dose of 10(6 50% tissue culture infectious doses of intranasally administered vaccines, mice were fully protected from lethality following challenge with homologous and antigenically distinct heterologous wt H5N1 viruses from different genetic sublineages (clades 1, 2, and 3 that were isolated in Asia between 1997 and 2005. Four weeks after receiving two doses of the vaccines, mice and ferrets were fully protected against pulmonary replication of homologous and heterologous wt H5N1 viruses.The promising findings in these preclinical studies of safety, immunogenicity, and efficacy of the H5N1 ca vaccines against antigenically diverse H5N1 vaccines provide support for their careful evaluation in Phase 1 clinical trials in humans.

Limited antigenic variation in the Trypanosoma cruzi candidate vaccine antigen TSA-1.

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Knight, J M; Zingales, B; Bottazzi, M E; Hotez, P; Zhan, B

2014-12-01

Chagas disease (American trypanosomiasis caused by Trypanosoma cruzi) is one of the most important neglected tropical diseases in the Western Hemisphere. The toxicities and limited efficacies of current antitrypanosomal drugs have prompted a search for alternative technologies such as a therapeutic vaccine comprised of T. cruzi antigens, including a recombinant antigen encoding the N-terminal 65 kDa portion of Trypomastigote surface antigen-1 (TSA-1). With at least six known genetically distinct T. cruzi lineages, variability between the different lineages poses a unique challenge for the development of broadly effective therapeutic vaccine. The variability across the major lineages in the current vaccine candidate antigen TSA-1 has not previously been addressed. To assess the variation in TSA-1, we cloned and sequenced TSA-1 from several different T. cruzi strains representing three of the most clinically relevant lineages. Analysis of the different alleles showed limited variation in TSA-1 across the different strains and fit with the current theory for the evolution of the different lineages. Additionally, minimal variation in known antigenic epitopes for the HLA-A 02 allele suggests that interlineage variation in TSA-1 would not impair the range and efficacy of a vaccine containing TSA-1. © 2014 John Wiley & Sons Ltd.

Dynamic profiles of neutralizing antibody responses elicited in rhesus monkeys immunized with a combined tetravalent DTaP-Sabin IPV candidate vaccine.

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Sun, Mingbo; Ma, Yan; Xu, Yinhua; Yang, Huijuan; Shi, Li; Che, Yanchun; Liao, Guoyang; Jiang, Shude; Zhang, Shumin; Li, Qihan

2014-02-19

The World Health Organization has recommended that a Sabin inactivated polio vaccine (IPV) should gradually and synchronously replace oral polio vaccines for routine immunizations because its benefits in eliminating vaccine-associated paralytic poliomyelitis have been reported in different phases of clinical trials. It is also considered important to explore new tetravalent diphtheria, tetanus, and acellular pertussis-Sabin IPV (DTaP-sIPV) candidate vaccines for possible use in developing countries. In this study, the immunogenicity of a combined tetravalent DTaP-sIPV candidate vaccine was investigated in primates by evaluating the neutralizing antibody responses it induced. The dynamic profiles of the antibody responses to each of the separate antigenic components and serotypes of Sabin IPV were determined and their corresponding geometric mean titers were similar to those generated by the tetravalent diphtheria, tetanus, and acellular pertussis-conventional IPV (DTaP-cIPV), the tetravalent diphtheria, tetanus, and acellular pertussis (DTaP), and Sabin IPV vaccines in the control groups. This implies that protective immunogenic effects are conferred by this combined tetravalent formulation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Exoproteome and Secretome Derived Broad Spectrum Novel Drug and Vaccine Candidates in Vibrio cholerae Targeted by Piper betel Derived Compounds

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Barh, Debmalya; Barve, Neha; Gupta, Krishnakant; Chandra, Sudha; Jain, Neha; Tiwari, Sandeep; Leon-Sicairos, Nidia; Canizalez-Roman, Adrian; Rodrigues dos Santos, Anderson; Hassan, Syed Shah; Almeida, Síntia; Thiago Jucá Ramos, Rommel; Augusto Carvalho de Abreu, Vinicius; Ribeiro Carneiro, Adriana; de Castro Soares, Siomar; Luiz de Paula Castro, Thiago; Miyoshi, Anderson; Silva, Artur; Kumar, Anil; Narayan Misra, Amarendra; Blum, Kenneth; Braverman, Eric R.; Azevedo, Vasco

2013-01-01

Vibrio cholerae is the causal organism of the cholera epidemic, which is mostly prevalent in developing and underdeveloped countries. However, incidences of cholera in developed countries are also alarming. Because of the emergence of new drug-resistant strains, even though several generic drugs and vaccines have been developed over time, Vibrio infections remain a global health problem that appeals for the development of novel drugs and vaccines against the pathogen. Here, applying comparative proteomic and reverse vaccinology approaches to the exoproteome and secretome of the pathogen, we have identified three candidate targets (ompU, uppP and yajC) for most of the pathogenic Vibrio strains. Two targets (uppP and yajC) are novel to Vibrio, and two targets (uppP and ompU) can be used to develop both drugs and vaccines (dual targets) against broad spectrum Vibrio serotypes. Using our novel computational approach, we have identified three peptide vaccine candidates that have high potential to induce both B- and T-cell-mediated immune responses from our identified two dual targets. These two targets were modeled and subjected to virtual screening against natural compounds derived from Piper betel. Seven compounds were identified first time from Piper betel to be highly effective to render the function of these targets to identify them as emerging potential drugs against Vibrio. Our preliminary validation suggests that these identified peptide vaccines and betel compounds are highly effective against Vibrio cholerae. Currently we are exhaustively validating these targets, candidate peptide vaccines, and betel derived lead compounds against a number of Vibrio species. PMID:23382822

Exoproteome and secretome derived broad spectrum novel drug and vaccine candidates in Vibrio cholerae targeted by Piper betel derived compounds.

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Debmalya Barh

Full Text Available Vibrio cholerae is the causal organism of the cholera epidemic, which is mostly prevalent in developing and underdeveloped countries. However, incidences of cholera in developed countries are also alarming. Because of the emergence of new drug-resistant strains, even though several generic drugs and vaccines have been developed over time, Vibrio infections remain a global health problem that appeals for the development of novel drugs and vaccines against the pathogen. Here, applying comparative proteomic and reverse vaccinology approaches to the exoproteome and secretome of the pathogen, we have identified three candidate targets (ompU, uppP and yajC for most of the pathogenic Vibrio strains. Two targets (uppP and yajC are novel to Vibrio, and two targets (uppP and ompU can be used to develop both drugs and vaccines (dual targets against broad spectrum Vibrio serotypes. Using our novel computational approach, we have identified three peptide vaccine candidates that have high potential to induce both B- and T-cell-mediated immune responses from our identified two dual targets. These two targets were modeled and subjected to virtual screening against natural compounds derived from Piper betel. Seven compounds were identified first time from Piper betel to be highly effective to render the function of these targets to identify them as emerging potential drugs against Vibrio. Our preliminary validation suggests that these identified peptide vaccines and betel compounds are highly effective against Vibrio cholerae. Currently we are exhaustively validating these targets, candidate peptide vaccines, and betel derived lead compounds against a number of Vibrio species.

Comparison of the nucleotide sequence of wild-type hepatitis - A virus and its attenuated candidate vaccine derivative

International Nuclear Information System (INIS)

Cohen, J.I.; Rosenblum, B.; Ticehurst, J.R.; Daemer, R.; Feinstone, S.; Purcell, R.H.

1987-01-01

Development of attenuated mutants for use as vaccines is in progress for other viruses, including influenza, rotavirus, varicella-zoster, cytomegalovirus, and hepatitis-A virus (HAV). Attenuated viruses may be derived from naturally occurring mutants that infect human or nonhuman hosts. Alternatively, attenuated mutants may be generated by passage of wild-type virus in cell culture. Production of attenuated viruses in cell culture is a laborious and empiric process. Despite previous empiric successes, understanding the molecular basis for attenuation of vaccine viruses could facilitate future development and use of live-virus vaccines. Comparison of the complete nucleotide sequences of wild-type (virulent) and vaccine (attenuated) viruses has been reported for polioviruses and yellow fever virus. Here, the authors compare the nucleotide sequence of wild-type HAV HM-175 with that of a candidate vaccine derivative

Extended safety, immunogenicity and efficacy of a blood-stage malaria vaccine in malian children: 24-month follow-up of a randomized, double-blinded phase 2 trial.

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Matthew B Laurens

Full Text Available The FMP2.1/AS02A candidate malaria vaccine was tested in a Phase 2 study in Mali. Based on results from the first eight months of follow-up, the vaccine appeared well-tolerated and immunogenic. It had no significant efficacy based on the primary endpoint, clinical malaria, but marginal efficacy against clinical malaria in secondary analyses, and high allele-specific efficacy. Extended follow-up was conducted to evaluate extended safety, immunogenicity and efficacy.A randomized, double-blinded trial of safety, immunogenicity and efficacy of the candidate Plasmodium falciparum apical membrane antigen 1 (AMA1 vaccine FMP2.1/AS02A was conducted in Bandiagara, Mali. Children aged 1-6 years were randomized in a 1∶1 ratio to receive FMP2.1/AS02A or control rabies vaccine on days 0, 30 and 60. Using active and passive surveillance, clinical malaria and adverse events as well as antibodies against P. falciparum AMA1 were monitored for 24 months after the first vaccination, spanning two malaria seasons.400 children were enrolled. Serious adverse events occurred in nine participants in the FMP2.1/AS02A group and three in the control group; none was considered related to study vaccination. After two years, anti-AMA1 immune responses remained significantly higher in the FMP2.1/AS02A group than in the control group. For the entire 24-month follow-up period, vaccine efficacy was 7.6% (p = 0.51 against first clinical malaria episodes and 9.9% (p = 0.19 against all malaria episodes. For the final 16-month follow-up period, vaccine efficacy was 0.9% (p = 0.98 against all malaria episodes. Allele-specific efficacy seen in the first malaria season did not extend into the second season of follow-up.Allele-specific vaccine efficacy was not sustained in the second malaria season, despite continued high levels of anti-AMA1 antibodies. This study presents an opportunity to evaluate correlates of partial protection against clinical malaria that waned during

Plasmodium falciparum var genes expressed in children with severe malaria encode CIDRα1 domains

DEFF Research Database (Denmark)

Jespersen, Jakob S.; Wang, Christian W.; Mkumbaye, Sixbert I.

2016-01-01

Most severe Plasmodium falciparum infections are experienced by young children. Severe symptoms are precipitated by vascular sequestration of parasites expressing a particular subset of the polymorphic P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion molecules. Parasites binding hum...... the hypothesis that the CIDRα1-EPCR interaction is key to the pathogenesis of severe malaria and strengthen the rationale for pursuing a vaccine or adjunctive treatment aiming at inhibiting or reducing the damaging effects of this interaction....

Candidate mosaic proteins for a pan-filoviral cytotoxic T-Cell lymphocyte vaccine

Energy Technology Data Exchange (ETDEWEB)

Fenimore, Paul W [Los Alamos National Laboratory; Fischer, William M [Los Alamos National Laboratory; Kuiken, Carla [Los Alamos National Laboratory; Foley, Brian T [Los Alamos National Laboratory; Thurmond, J R [Los Alamos National Laboratory; Yusim, K [Los Alamos National Laboratory; Korber, B T [Los Alamos National Laboratory

2008-01-01

than is possible with a wild-type protein, (2) reducing the number of low-prevalence k-mers minimizes the likelihood of undesirable immunodominance, and (3) excluding exogenous k-mers will result in mosaic proteins whose processing for presentation is close to what occurs with wild-type proteins. The first and second applications of the mosaic method were to HIV and Hepatitis C Virus (HCV). HIV is the virus with the largest number of known sequences, and consequently a plethora of information for the CTL vaccine designer to incorporate into their mosaics. Experience with HIV and HCV mosaics supports the validity of the three conjectures above. The available FILV sequences are probably closer to the minimum amount of information needed to make a meaningful mosaic vaccine candidate. There were 532 protein sequences in the National Institutes of Health GenPept database in November 2007 when our reference set was downloaded. These sequences come from both Ebola and Marburg viruses (EBOV and MARV), representing transcripts of all 7 genes. The coverage of viral diversity by the 7 genes is variable, with genes 1 (nucleoprotein, NP), 4 (glycoprotein, GP; soluble glycoprotein, sGP) and 7 (polymerase, L) giving the best coverage. Broadly-protective vaccine candidates for diverse viruses, such as HIV or Hepatitis C virus (HCV) have required pools of antigens. FILV is similar in this regard. While we have designed CTL mosaic proteins using all 7 types of filoviral proteins, only NP, GP and L proteins are reported here. If it were important to include other proteins in a mosaic CTL vaccine, additional sequences would be required to cover the space of known viral diversity.

A malaria diagnostic tool based on computer vision screening and visualization of Plasmodium falciparum candidate areas in digitized blood smears.

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Nina Linder

Full Text Available INTRODUCTION: Microscopy is the gold standard for diagnosis of malaria, however, manual evaluation of blood films is highly dependent on skilled personnel in a time-consuming, error-prone and repetitive process. In this study we propose a method using computer vision detection and visualization of only the diagnostically most relevant sample regions in digitized blood smears. METHODS: Giemsa-stained thin blood films with P. falciparum ring-stage trophozoites (n = 27 and uninfected controls (n = 20 were digitally scanned with an oil immersion objective (0.1 µm/pixel to capture approximately 50,000 erythrocytes per sample. Parasite candidate regions were identified based on color and object size, followed by extraction of image features (local binary patterns, local contrast and Scale-invariant feature transform descriptors used as input to a support vector machine classifier. The classifier was trained on digital slides from ten patients and validated on six samples. RESULTS: The diagnostic accuracy was tested on 31 samples (19 infected and 12 controls. From each digitized area of a blood smear, a panel with the 128 most probable parasite candidate regions was generated. Two expert microscopists were asked to visually inspect the panel on a tablet computer and to judge whether the patient was infected with P. falciparum. The method achieved a diagnostic sensitivity and specificity of 95% and 100% as well as 90% and 100% for the two readers respectively using the diagnostic tool. Parasitemia was separately calculated by the automated system and the correlation coefficient between manual and automated parasitemia counts was 0.97. CONCLUSION: We developed a decision support system for detecting malaria parasites using a computer vision algorithm combined with visualization of sample areas with the highest probability of malaria infection. The system provides a novel method for blood smear screening with a significantly reduced need for

Evaluation of a Group A Streptococcus synthetic oligosaccharide as vaccine candidate.

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Kabanova, Anna; Margarit, Immaculada; Berti, Francesco; Romano, Maria R; Grandi, Guido; Bensi, Giuliano; Chiarot, Emiliano; Proietti, Daniela; Swennen, Erwin; Cappelletti, Emilia; Fontani, Paola; Casini, Daniele; Adamo, Roberto; Pinto, Vittoria; Skibinski, David; Capo, Sabrina; Buffi, Giada; Gallotta, Marilena; Christ, William J; Campbell, A Stewart; Pena, John; Seeberger, Peter H; Rappuoli, Rino; Costantino, Paolo

2010-12-10

Bacterial infections caused by Group A Streptococcus (GAS) are a serious health care concern that currently cannot be prevented by vaccination. The GAS cell-wall polysaccharide (GAS-PS) is an attractive vaccine candidate due to its constant expression pattern on different bacterial strains and protective properties of anti-GAS-PS antibodies. Here we report for the first time the immunoprotective efficacy of glycoconjugates with synthetic GAS oligosaccharides as compared to those containing the native GAS-PS. A series of hexa- and dodecasaccharides based on the GAS-PS structure were prepared by chemical synthesis and conjugated to CRM(197). When tested in mice, the conjugates containing the synthetic oligosaccharides conferred levels of immunoprotection comparable to those elicited by the native conjugate. Antisera from immunized rabbits promoted phagocytosis of encapsulated GAS strains. Furthermore we discuss variables that might correlate with glycoconjugate immunogenicity and demonstrate the potential of the synthetic approach that benefits from increased antigen purity and facilitated manufacturing. Copyright © 2010 Elsevier Ltd. All rights reserved.

Avances más recientes en el desarrollo de vacunas contra la malaria The most recent advances in developing vaccines against malaria

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Lázara Rojas Rivero

2005-02-01

Full Text Available According to reports of the Pan American Health Organization, malaria transmission continues to occur in 21 countries of the Americas. Of the 835 million inhabitants of the Region of the Americas, 293 million live in areas with some possibility of transmission of the disease. The most advanced of the candidate vaccines that have been designed based on the sequences of the circumsporozoite protein, is one based on the RTS,S/AS02A polypeptides of Plasmodium falciparum. A test of that vaccine was conducted in Mozambique with children from 1 to 4 years old. The test proved the vaccine to be safe, well tolerated, and immunogenic, but the level of protection reached was still low. However, the advantages that the RTS,S/AS02A vaccine offers to people who live in malaria-endemic areas justifies its being tested in the Americas in order to evaluate its effectiveness in the clinical and epidemiological conditions specific to the Region.

Nuclear Magnetic Resonance (NMR Study for the Detection and Quantitation of Cholesterol in HSV529 Therapeutic Vaccine Candidate

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Rahima Khatun

Full Text Available This study describes the NMR-based method to determine the limit of quantitation (LOQ and limit of detection (LOD of cholesterol, a process-related impurity in the replication-deficient Herpes Simplex Virus (HSV type 2 candidate vaccine HSV529. Three signature peaks from the 1D 1H NMR of a cholesterol reference spectrum were selected for the identification of cholesterol. The LOQ for a cholesterol working standard was found to be 1 μg/mL, and the LOD was found to be 0.1 μg/mL. The identity of cholesterol, separated from the formulation of growth supplement by thin layer chromatography (TLC, was confirmed by 1D 1H NMR and 2D 1H-13C HSQC NMR. The three signature peaks of cholesterol were detected only in a six-times concentrated sample of HSV529 candidate vaccine sample and not in the single dose HSV529 vaccine sample under similar experimental conditions. Taken together, the results demonstrated that NMR is a direct method that can successfully identify and quantify cholesterol in viral vaccine samples, such as HSV529, and as well as in the growth supplement used during the upstream stages of HSV529 manufacturing. Keywords: Herpes simplex virus type 2 (HSV-2, Viral vaccine, NMR, Residuals, LOD and LOQ, TLC, Growth supplement

Genetic Diversity and Protective Efficacy of the RTS,S/AS01 Malaria Vaccine

DEFF Research Database (Denmark)

Neafsey, Daniel E; Juraska, Michal; Bedford, Trevor

2015-01-01

Background The RTS,S/AS01 vaccine targets the circumsporozoite protein of Plasmodium falciparum and has partial protective efficacy against clinical and severe malaria disease in infants and children. We investigated whether the vaccine efficacy was specific to certain parasite genotypes at the c......Background The RTS,S/AS01 vaccine targets the circumsporozoite protein of Plasmodium falciparum and has partial protective efficacy against clinical and severe malaria disease in infants and children. We investigated whether the vaccine efficacy was specific to certain parasite genotypes...... protein had on vaccine efficacy against first episodes of clinical malaria within 1 year after vaccination. Results In the per-protocol group of 4577 RTS,S/AS01-vaccinated participants and 2335 control-vaccinated participants who were 5 to 17 months of age, the 1-year cumulative vaccine efficacy was 50.......3% (95% confidence interval [CI], 34.6 to 62.3) against clinical malaria in which parasites matched the vaccine in the entire circumsporozoite protein C-terminal (139 infections), as compared with 33.4% (95% CI, 29.3 to 37.2) against mismatched malaria (1951 infections) (P=0.04 for differential vaccine...

Characterization of Two Metal Binding Lipoproteins as Vaccine Candidates for Enterococcal Infections.

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Romero-Saavedra, Felipe; Laverde, Diana; Budin-Verneuil, Aurélie; Muller, Cécile; Bernay, Benoit; Benachour, Abdellah; Hartke, Axel; Huebner, Johannes

2015-01-01

Enterococcus faecium and faecalis are Gram-positive opportunistic pathogens that have become leading causes of nosocomial infections over the last decades. Especially multidrug resistant enterococci have become a challenging clinical problem worldwide. Therefore, new treatment options are needed and the identification of alternative targets for vaccine development has emerged as a feasible alternative to fight the infections caused by these pathogens. We extrapolate the transcriptomic data from a mice peritonitis infection model in E. faecalis to identify putative up-regulated surface proteins under infection conditions in E. faecium. After the bionformatic analyses two metal binding lipoproteins were identified to have a high homology (>72%) between the two species, the manganese ABC transporter substrate-binding lipoprotein (PsaAfm,) and the zinc ABC transporter substrate-binding lipoprotein (AdcAfm). These candidate lipoproteins were overexpressed in Escherichia coli and purified. The recombinant proteins were used to produce rabbit polyclonal antibodies that were able to induce specific opsonic antibodies that mediated killing of the homologous strain E. faecium E155 as well as clinical strains E. faecium E1162, Enterococcus faecalis 12030, type 2 and type 5. Mice were passively immunized with the antibodies raised against recombinant lipoproteins, showing significant reduction of colony counts in mice livers after the bacterial challenge and demonstrating the efficacy of these metal binding lipoproteins as promising vaccine candidates to treat infections caused by these enterococcal pathogens. Overall, our results demonstrate that these two metal binding lipoproteins elicited specific, opsonic and protective antibodies, with an extensive cross-reactivity and serotype-independent coverage among these two important nocosomial pathogens. Pointing these two protein antigens as promising immunogens, that can be used as single components or as carrier proteins

Diversity and population structure of Plasmodium falciparum in Thailand based on the spatial and temporal haplotype patterns of the C-terminal 19-kDa domain of merozoite surface protein-1.

Science.gov (United States)

Simpalipan, Phumin; Pattaradilokrat, Sittiporn; Siripoon, Napaporn; Seugorn, Aree; Kaewthamasorn, Morakot; Butcher, Robert D J; Harnyuttanakorn, Pongchai

2014-02-12

The 19-kDa C-terminal region of the merozoite surface protein-1 of the human malaria parasite Plasmodium falciparum (PfMSP-119) constitutes the major component on the surface of merozoites and is considered as one of the leading candidates for asexual blood stage vaccines. Because the protein exhibits a level of sequence variation that may compromise the effectiveness of a vaccine, the global sequence diversity of PfMSP-119 has been subjected to extensive research, especially in malaria endemic areas. In Thailand, PfMSP-119 sequences have been derived from a single parasite population in Tak province, located along the Thailand-Myanmar border, since 1995. However, the extent of sequence variation and the spatiotemporal patterns of the MSP-119 haplotypes along the Thai borders with Laos and Cambodia are unknown. Sixty-three isolates of P. falciparum from five geographically isolated populations along the Thai borders with Myanmar, Laos and Cambodia in three transmission seasons between 2002 and 2008 were collected and culture-adapted. The msp-1 gene block 17 was sequenced and analysed for the allelic diversity, frequency and distribution patterns of PfMSP-119 haplotypes in individual populations. The PfMSP-119 haplotype patterns were then compared between parasite populations to infer the population structure and genetic differentiation of the malaria parasite. Five conserved polymorphic positions, which accounted for five distinct haplotypes, of PfMSP-119 were identified. Differences in the prevalence of PfMSP-119 haplotypes were detected in different geographical regions, with the highest levels of genetic diversity being found in the Kanchanaburi and Ranong provinces along the Thailand-Myanmar border and Trat province located at the Thailand-Cambodia border. Despite this variability, the distribution patterns of individual PfMSP-119 haplotypes seemed to be very similar across the country and over the three malarial transmission seasons, suggesting that gene flow

Collaborative study to assess the suitability of a candidate International Standard for yellow fever vaccine.

Science.gov (United States)

Ferguson, Morag; Heath, Alan

2004-12-01

Yellow fever vaccines are routinely assayed by plaque assay. However, the results of these assays are then converted into mouse LD(50) using correlations/conversion factors which, in many cases, were established many years ago. The minimum required potency in WHO Recommendations is 10(3) LD(50)/dose. Thirteen participants from 8 countries participated in a collaborative study whose aim was to assess the suitability of two candidate preparations to serve as an International Standard for yellow fever vaccine. In addition, the study investigated the relationship between the mouse LD(50) test and plaque forming units with a view to updating the WHO recommendations. Plaque assays were more reproducible than mouse assays, as expected. Differences in sensitivities of plaque assays were observed between laboratories but these differences appear to be consistent within a laboratory for all samples and the expression of potency relative to the candidate standard vaccine improved the reproducibility of assays between laboratories. However, the use of potencies had little effect on the between laboratory variability in mouse LD(50) assays. There appears to be a consistent relationship between overall mean LD(50) and plaques titre for all study preparations other than sample E. The slope of the correlation curve is >1 and it would appear that 10(3) LD(50) is approximately equivalent to 10(4) plaque forming units (PFU), based on the overall means of all laboratory results. The First International Standard for yellow fever vaccine, NIBSC Code 99/616, has been established as the First International Standard for yellow fever vaccine by the Expert Committee of Biological Standards of the World Health Organisation. The International Standard has been arbitrarily assigned a potency of 10(4.5) International Units (IU) per ampoule. Manufacturers and National Control Laboratories are including the First International Standard for yellow fever vaccine in routine assays so that the minimum

The Th1 immune response to Plasmodium falciparum circumsporozoite protein is boosted by adenovirus vectors 35 and 26 with a homologous insert

NARCIS (Netherlands)

Radosevic, Katarina; Rodriguez, Ariane; Lemckert, Angelique A. C.; van der Meer, Marjolein; Gillissen, Gert; Warnar, Carolien; von Eyben, Rie; Pau, Maria Grazia; Goudsmit, Jaap

2010-01-01

The most advanced malaria vaccine, RTS,S, is comprised of an adjuvant portion of the Plasmodium falciparum circumsporozoite (CS) protein fused to and admixed with the hepatitis B virus surface antigen. This vaccine confers short-term protection against malaria infection, with an efficacy of about

Bioinformatics analysis of Brucella vaccines and vaccine targets using VIOLIN.

Science.gov (United States)

He, Yongqun; Xiang, Zuoshuang

2010-09-27

Brucella spp. are Gram-negative, facultative intracellular bacteria that cause brucellosis, one of the commonest zoonotic diseases found worldwide in humans and a variety of animal species. While several animal vaccines are available, there is no effective and safe vaccine for prevention of brucellosis in humans. VIOLIN (http://www.violinet.org) is a web-based vaccine database and analysis system that curates, stores, and analyzes published data of commercialized vaccines, and vaccines in clinical trials or in research. VIOLIN contains information for 454 vaccines or vaccine candidates for 73 pathogens. VIOLIN also contains many bioinformatics tools for vaccine data analysis, data integration, and vaccine target prediction. To demonstrate the applicability of VIOLIN for vaccine research, VIOLIN was used for bioinformatics analysis of existing Brucella vaccines and prediction of new Brucella vaccine targets. VIOLIN contains many literature mining programs (e.g., Vaxmesh) that provide in-depth analysis of Brucella vaccine literature. As a result of manual literature curation, VIOLIN contains information for 38 Brucella vaccines or vaccine candidates, 14 protective Brucella antigens, and 68 host response studies to Brucella vaccines from 97 peer-reviewed articles. These Brucella vaccines are classified in the Vaccine Ontology (VO) system and used for different ontological applications. The web-based VIOLIN vaccine target prediction program Vaxign was used to predict new Brucella vaccine targets. Vaxign identified 14 outer membrane proteins that are conserved in six virulent strains from B. abortus, B. melitensis, and B. suis that are pathogenic in humans. Of the 14 membrane proteins, two proteins (Omp2b and Omp31-1) are not present in B. ovis, a Brucella species that is not pathogenic in humans. Brucella vaccine data stored in VIOLIN were compared and analyzed using the VIOLIN query system. Bioinformatics curation and ontological representation of Brucella vaccines

Evidence that Plasmodium falciparum diacylglycerol acyltransferase is essential for intraerythrocytic proliferation

International Nuclear Information System (INIS)

Palacpac, Nirianne Marie Q.; Hiramine, Yasushi; Seto, Shintaro; Hiramatsu, Ryuji; Horii, Toshihiro; Mitamura, Toshihide

2004-01-01

In triacylglycerol (TAG)-accumulating organisms, the physiological roles of diacylglycerol acyltransferase (DGAT), a principal enzyme in the major biosynthetic pathway for TAG, appear to be diverse. Apicomplexan parasite, Plasmodium falciparum, shows unique features in TAG metabolism and trafficking during intraerythrocytic development, and unlike most eukaryotes, only one open reading frame (ORF) encoding a candidate DGAT could be found in its genome. However, whether this candidate ORF encodes P. falciparum DGAT and its physiological relevance have not been assessed. Here, we demonstrate that the ORF is transcribed as a ∼3.6 kb single mRNA throughout intraerythrocytic development, markedly elevated at trophozoite, schizont, and segmented schizont, and indeed encodes a protein exhibiting DGAT activity. Further, we provide evidence that the parasite in which the ORF was disrupted via double crossover recombination cannot be enriched, implying a fundamental role of PfDGAT in intraerythrocytic proliferation

IgG2 antibodies against a clinical grade Plasmodium falciparum CSP vaccine antigen associate with protection against transgenic sporozoite challenge in mice.

Directory of Open Access Journals (Sweden)

Robert Schwenk

Full Text Available The availability of a highly purified and well characterized circumsporozoite protein (CSP is essential to improve upon the partial success of recombinant CSP-based malaria vaccine candidates. Soluble, near full-length, Plasmodium falciparum CSP vaccine antigen (CS/D was produced in E. coli under bio-production conditions that comply with current Good Manufacturing Practices (cGMP. A mouse immunogenicity study was conducted using a stable oil-in-water emulsion (SE of CS/D in combination with the Toll-Like Receptor 4 (TLR4 agonist Glucopyranosyl Lipid A (GLA/SE, or one of two TLR7/8 agonists: R848 (un-conjugated or 3M-051 (covalently conjugated. Compared to Alum and SE, GLA/SE induced higher CS/D specific antibody response in Balb/c mice. Subclass analysis showed higher IgG2:IgG1 ratio of GLA/SE induced antibodies as compared to Alum and SE. TLR synergy was not observed when soluble R848 was mixed with GLA/SE. Antibody response of 3M051 formulations in Balb/c was similar to GLA/SE, except for the higher IgG2:IgG1 ratio and a trend towards higher T cell responses in 3M051 containing groups. However, no synergistic enhancement of antibody and T cell response was evident when 3M051 conjugate was mixed with GLA/SE. In C57Bl/6 mice, CS/D adjuvanted with 3M051/SE or GLA/SE induced higher CSP repeat specific titers compared to SE. While, 3M051 induced antibodies had high IgG2c:IgG1 ratio, GLA/SE promoted high levels of both IgG1 and IgG2c. GLA/SE also induced more potent T-cell responses compared to SE in two independent C57/BL6 vaccination studies, suggesting a balanced and productive T(H1/T(H2 response. GLA and 3M-051 similarly enhanced the protective efficacy of CS/D against challenge with a transgenic P. berghei parasite and most importantly, high levels of cytophilic IgG2 antibodies were associated with protection in this model. Our data indicated that the cGMP-grade, soluble CS/D antigen combined with the TLR4-containing adjuvant GLA/SE warrants

Revealing the sequence and resulting cellular morphology of receptor-ligand interactions during Plasmodium falciparum invasion of erythrocytes.

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Greta E Weiss

2015-02-01

Full Text Available During blood stage Plasmodium falciparum infection, merozoites invade uninfected erythrocytes via a complex, multistep process involving a series of distinct receptor-ligand binding events. Understanding each element in this process increases the potential to block the parasite's life cycle via drugs or vaccines. To investigate specific receptor-ligand interactions, they were systematically blocked using a combination of genetic deletion, enzymatic receptor cleavage and inhibition of binding via antibodies, peptides and small molecules, and the resulting temporal changes in invasion and morphological effects on erythrocytes were filmed using live cell imaging. Analysis of the videos have shown receptor-ligand interactions occur in the following sequence with the following cellular morphologies; 1 an early heparin-blockable interaction which weakly deforms the erythrocyte, 2 EBA and PfRh ligands which strongly deform the erythrocyte, a process dependant on the merozoite's actin-myosin motor, 3 a PfRh5-basigin binding step which results in a pore or opening between parasite and host through which it appears small molecules and possibly invasion components can flow and 4 an AMA1-RON2 interaction that mediates tight junction formation, which acts as an anchor point for internalization. In addition to enhancing general knowledge of apicomplexan biology, this work provides a rational basis to combine sequentially acting merozoite vaccine candidates in a single multi-receptor-blocking vaccine.

Comparative genomics study for the identification of drug and vaccine targets in Staphylococcus aureus: MurA ligase enzyme as a proposed candidate.

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Ghosh, Soma; Prava, Jyoti; Samal, Himanshu Bhusan; Suar, Mrutyunjay; Mahapatra, Rajani Kanta

2014-06-01

Now-a-days increasing emergence of antibiotic-resistant pathogenic microorganisms is one of the biggest challenges for management of disease. In the present study comparative genomics, metabolic pathways analysis and additional parameters were defined for the identification of 94 non-homologous essential proteins in Staphylococcus aureus genome. Further study prioritized 19 proteins as vaccine candidates where as druggability study reports 34 proteins suitable as drug targets. Enzymes from peptidoglycan biosynthesis, folate biosynthesis were identified as candidates for drug development. Furthermore, bacterial secretory proteins and few hypothetical proteins identified in our analysis fulfill the criteria of vaccine candidates. As a case study, we built a homology model of one of the potential drug target, MurA ligase, using MODELLER (9v12) software. The model has been further selected for in silico docking study with inhibitors from the DrugBank database. Results from this study could facilitate selection of proteins for entry into drug design and vaccine production pipelines. Copyright © 2014 Elsevier B.V. All rights reserved.

Replacement of the Ectodomains of the Hemagglutinin-Neuraminidase and Fusion Glycoproteins of Recombinant Parainfluenza Virus Type 3 (PIV3) with Their Counterparts from PIV2 Yields Attenuated PIV2 Vaccine Candidates

OpenAIRE

Tao, Tao; Skiadopoulos, Mario H.; Davoodi, Fatemeh; Riggs, Jeffrey M.; Collins, Peter L.; Murphy, Brian R.

2000-01-01

We sought to develop a live attenuated parainfluenza virus type 2 (PIV2) vaccine strain for use in infants and young children, using reverse genetic techniques that previously were used to rapidly produce a live attenuated PIV1 vaccine candidate. The PIV1 vaccine candidate, designated rPIV3-1cp45, was generated by substituting the full-length HN and F proteins of PIV1 for those of PIV3 in the attenuated cp45 PIV3 vaccine candidate (T. Tao et al., J. Virol. 72:2955–2961, 1998; M. H. Skiadopoul...

NSR-seq transcriptional profiling enables identification of a gene signature of Plasmodium falciparum parasites infecting children.

Science.gov (United States)

Vignali, Marissa; Armour, Christopher D; Chen, Jingyang; Morrison, Robert; Castle, John C; Biery, Matthew C; Bouzek, Heather; Moon, Wonjong; Babak, Tomas; Fried, Michal; Raymond, Christopher K; Duffy, Patrick E

2011-03-01

Malaria caused by Plasmodium falciparum results in approximately 1 million annual deaths worldwide, with young children and pregnant mothers at highest risk. Disease severity might be related to parasite virulence factors, but expression profiling studies of parasites to test this hypothesis have been hindered by extensive sequence variation in putative virulence genes and a preponderance of host RNA in clinical samples. We report here the application of RNA sequencing to clinical isolates of P. falciparum, using not-so-random (NSR) primers to successfully exclude human ribosomal RNA and globin transcripts and enrich for parasite transcripts. Using NSR-seq, we confirmed earlier microarray studies showing upregulation of a distinct subset of genes in parasites infecting pregnant women, including that encoding the well-established pregnancy malaria vaccine candidate var2csa. We also describe a subset of parasite transcripts that distinguished parasites infecting children from those infecting pregnant women and confirmed this observation using quantitative real-time PCR and mass spectrometry proteomic analyses. Based on their putative functional properties, we propose that these proteins could have a role in childhood malaria pathogenesis. Our study provides proof of principle that NSR-seq represents an approach that can be used to study clinical isolates of parasites causing severe malaria syndromes as well other blood-borne pathogens and blood-related diseases.

NSR-seq transcriptional profiling enables identification of a gene signature of Plasmodium falciparum parasites infecting children

Science.gov (United States)

Vignali, Marissa; Armour, Christopher D.; Chen, Jingyang; Morrison, Robert; Castle, John C.; Biery, Matthew C.; Bouzek, Heather; Moon, Wonjong; Babak, Tomas; Fried, Michal; Raymond, Christopher K.; Duffy, Patrick E.

2011-01-01

Malaria caused by Plasmodium falciparum results in approximately 1 million annual deaths worldwide, with young children and pregnant mothers at highest risk. Disease severity might be related to parasite virulence factors, but expression profiling studies of parasites to test this hypothesis have been hindered by extensive sequence variation in putative virulence genes and a preponderance of host RNA in clinical samples. We report here the application of RNA sequencing to clinical isolates of P. falciparum, using not-so-random (NSR) primers to successfully exclude human ribosomal RNA and globin transcripts and enrich for parasite transcripts. Using NSR-seq, we confirmed earlier microarray studies showing upregulation of a distinct subset of genes in parasites infecting pregnant women, including that encoding the well-established pregnancy malaria vaccine candidate var2csa. We also describe a subset of parasite transcripts that distinguished parasites infecting children from those infecting pregnant women and confirmed this observation using quantitative real-time PCR and mass spectrometry proteomic analyses. Based on their putative functional properties, we propose that these proteins could have a role in childhood malaria pathogenesis. Our study provides proof of principle that NSR-seq represents an approach that can be used to study clinical isolates of parasites causing severe malaria syndromes as well other blood-borne pathogens and blood-related diseases. PMID:21317536

Top Down Tandem Mass Spectrometric Analysis of a Chemically Modified Rough-Type Lipopolysaccharide Vaccine Candidate

Science.gov (United States)

Oyler, Benjamin L.; Khan, Mohd M.; Smith, Donald F.; Harberts, Erin M.; Kilgour, David P. A.; Ernst, Robert K.; Cross, Alan S.; Goodlett, David R.

2018-02-01

Recent advances in lipopolysaccharide (LPS) biology have led to its use in drug discovery pipelines, including vaccine and vaccine adjuvant discovery. Desirable characteristics for LPS vaccine candidates include both the ability to produce a specific antibody titer in patients and a minimal host inflammatory response directed by the innate immune system. However, in-depth chemical characterization of most LPS extracts has not been performed; hence, biological activities of these extracts are unpredictable. Additionally, the most widely adopted workflow for LPS structure elucidation includes nonspecific chemical decomposition steps before analyses, making structures inferred and not necessarily biologically relevant. In this work, several different mass spectrometry workflows that have not been previously explored were employed to show proof-of-principle for top down LPS primary structure elucidation, specifically for a rough-type mutant (J5) E. coli-derived LPS component of a vaccine candidate. First, ion mobility filtered precursor ions were subjected to collision induced dissociation (CID) to define differences in native J5 LPS v. chemically detoxified J5 LPS (dLPS). Next, ultra-high mass resolving power, accurate mass spectrometry was employed for unequivocal precursor and product ion empirical formulae generation. Finally, MS3 analyses in an ion trap instrument showed that previous knowledge about dissociation of LPS components can be used to reconstruct and sequence LPS in a top down fashion. A structural rationale is also explained for differential inflammatory dose-response curves, in vitro, when HEK-Blue hTLR4 cells were administered increasing concentrations of native J5 LPS v. dLPS, which will be useful in future drug discovery efforts. [Figure not available: see fulltext.

Phase 1/2a Trial of Plasmodium vivax Malaria Vaccine Candidate VMP001/AS01B in Malaria-Naive Adults: Safety, Immunogenicity, and Efficacy.

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Jason W Bennett

2016-02-01

Full Text Available A vaccine to prevent infection and disease caused by Plasmodium vivax is needed both to reduce the morbidity caused by this parasite and as a key component in efforts to eradicate malaria worldwide. Vivax malaria protein 1 (VMP001, a novel chimeric protein that incorporates the amino- and carboxy- terminal regions of the circumsporozoite protein (CSP and a truncated repeat region that contains repeat sequences from both the VK210 (type 1 and the VK247 (type 2 parasites, was developed as a vaccine candidate for global use.We conducted a first-in-human Phase 1 dose escalation vaccine study with controlled human malaria infection (CHMI of VMP001 formulated in the GSK Adjuvant System AS01B. A total of 30 volunteers divided into 3 groups (10 per group were given 3 intramuscular injections of 15 μg, 30 μg, or 60 μg respectively of VMP001, all formulated in 500 μL of AS01B at each immunization. All vaccinated volunteers participated in a P. vivax CHMI 14 days following the third immunization. Six non-vaccinated subjects served as infectivity controls.The vaccine was shown to be well tolerated and immunogenic. All volunteers generated robust humoral and cellular immune responses to the vaccine antigen. Vaccination did not induce sterile protection; however, a small but significant delay in time to parasitemia was seen in 59% of vaccinated subjects compared to the control group. An association was identified between levels of anti-type 1 repeat antibodies and prepatent period.This trial was the first to assess the efficacy of a P. vivax CSP vaccine candidate by CHMI. The association of type 1 repeat-specific antibody responses with delay in the prepatency period suggests that augmenting the immune responses to this domain may improve strain-specific vaccine efficacy. The availability of a P. vivax CHMI model will accelerate the process of P. vivax vaccine development, allowing better selection of candidate vaccines for advancement to field trials.

An Investigation of Immunogenicity of Chitosan-Based Botulinum Neurotoxin E Binding Domain Recombinant Candidate Vaccine via Mucosal Route

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Mohammad Javad Bagheripour

2017-01-01

Full Text Available Background and Objectives: Botulism syndrome is caused by serotypes A-G of neurotoxins of Clostridium genus. Neurotoxin binding domain is an appropriate vaccine candidate due to its immunogenic activity. In this study, the immunogenicity of chitosan-based botulinum neurotoxin E binding domain recombinant candidate vaccine was investigated via mucosal route of administration. Methods: In this experimental study, chitosan nanoparticles containing rBoNT/E protein were synthesized by ionic gelation method and were administered orally and intranasally to mice. After each administration, IgG antibody titer was measured by ELISA method. Finally, all groups were challenged with active botulinum neurotoxin type E. Data were analyzed using Duncan and repeated ANOVA tests. The significance level was considered as p0.05, even intranasal route reduced the immunogenicity.

Characterization of Brucella abortus mutant strain Δ22915, a potential vaccine candidate.

Science.gov (United States)

Bao, Yanqing; Tian, Mingxing; Li, Peng; Liu, Jiameng; Ding, Chan; Yu, Shengqing

2017-04-04

Brucellosis, caused by Brucella spp., is an important zoonosis worldwide. Vaccination is an effective strategy for protection against Brucella infection in livestock in developing countries and in wildlife in developed countries. However, current vaccine strains including S19 and RB51 are pathogenic to humans and pregnant animals, limiting their use. In this study, we constructed the Brucella abortus (B. abortus) S2308 mutant strain Δ22915, in which the putative lytic transglycosylase gene BAB_RS22915 was deleted. The biological properties of mutant strain Δ22915 were characterized and protection of mice against virulent S2308 challenge was evaluated. The mutant strain Δ22915 showed reduced survival within RAW264.7 cells and survival in vivo in mice. In addition, the mutant strain Δ22915 failed to escape fusion with lysosomes within host cells, and caused no observable pathological damage. RNA-seq analysis indicated that four genes associated with amino acid/nucleotide transport and metabolism were significantly upregulated in mutant strain Δ22915. Furthermore, inoculation of ∆22915 at 10 5 colony forming units induced effective host immune responses and long-term protection of BALB/c mice. Therefore, mutant strain ∆22915 could be used as a novel vaccine candidate in the future to protect animals against B. abortus infection.

Cytoadhesion of Plasmodium falciparum-infected erythrocytes and the infected placenta: a two-way pathway

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F.T.M. Costa

2006-12-01

Full Text Available Malaria is undoubtedly the world's most devastating parasitic disease, affecting 300 to 500 million people every year. Some cases of Plasmodium falciparum infection progress to the deadly forms of the disease responsible for 1 to 3 million deaths annually. P. falciparum-infected erythrocytes adhere to host receptors in the deep microvasculature of several organs. The cytoadhesion of infected erythrocytes to placental syncytiotrophoblast receptors leads to pregnancy-associated malaria (PAM. This specific maternal-fetal syndrome causes maternal anemia, low birth weight and the death of 62,000 to 363,000 infants per year in sub-Saharan Africa, and thus has a poor outcome for both mother and fetus. However, PAM and non-PAM parasites have been shown to differ antigenically and genetically. After multiple pregnancies, women from different geographical areas develop adhesion-blocking antibodies that protect against placental parasitemia and clinical symptoms of PAM. The recent description of a new parasite ligand encoded by the var2CSA gene as the only gene up-regulated in PAM parasites renders the development of an anti-PAM vaccine more feasible. The search for a vaccine to prevent P. falciparum sequestration in the placenta by eliciting adhesion-blocking antibodies and a cellular immune response, and the development of new methods for evaluating such antibodies should be key priorities in mother-child health programs in areas of endemic malaria. This review summarizes the main molecular, immunological and physiopathological aspects of PAM, including findings related to new targets in the P. falciparum var gene family. Finally, we focus on a new methodology for mimicking cytoadhesion under blood flow conditions in human placental tissue.

A microscale human liver platform that supports the hepatic stages of Plasmodium falciparum and vivax.

Science.gov (United States)

March, Sandra; Ng, Shengyong; Velmurugan, Soundarapandian; Galstian, Ani; Shan, Jing; Logan, David J; Carpenter, Anne E; Thomas, David; Sim, B Kim Lee; Mota, Maria M; Hoffman, Stephen L; Bhatia, Sangeeta N

2013-07-17

The Plasmodium liver stage is an attractive target for the development of antimalarial drugs and vaccines, as it provides an opportunity to interrupt the life cycle of the parasite at a critical early stage. However, targeting the liver stage has been difficult. Undoubtedly, a major barrier has been the lack of robust, reliable, and reproducible in vitro liver-stage cultures. Here, we establish the liver stages for both Plasmodium falciparum and Plasmodium vivax in a microscale human liver platform composed of cryopreserved, micropatterned human primary hepatocytes surrounded by supportive stromal cells. Using this system, we have successfully recapitulated the full liver stage of P. falciparum, including the release of infected merozoites and infection of overlaid erythrocytes, as well as the establishment of small forms in late liver stages of P. vivax. Finally, we validate the potential of this platform as a tool for medium-throughput antimalarial drug screening and vaccine development. Copyright © 2013 Elsevier Inc. All rights reserved.

Generation of transgenic corn-derived Actinobacillus pleuropneumoniae ApxIIA fused with the cholera toxin B subunit as a vaccine candidate

Science.gov (United States)

Shin, Min-Kyoung; Jung, Myung Hwan; Lee, Won-Jung; Choi, Pil Son; Jang, Yong-Suk

2011-01-01

Corn, one of the most important forage crops worldwide, has proven to be a useful expression vehicle due to the availability of established transformation procedures for this well-studied plant. The exotoxin Apx, a major virulence factor, is recognized as a common antigen of Actinobacillus (A.) pleuropneumoniae, the causative agent of porcine pleuropneumonia. In this study, a cholera toxin B (CTB)-ApxIIA#5 fusion protein and full-size ApxIIA expressed in corn seed, as a subunit vaccine candidate, were observed to induce Apx-specific immune responses in mice. These results suggest that transgenic corn-derived ApxIIA and CTB-ApxIIA#5 proteins are potential vaccine candidates against A. pleuropneumoniae infection. PMID:22122907

Efficacy of RTS,S/AS01E Vaccine against Malaria in Children 5 to 17 Months of Age

Science.gov (United States)

Bejon, Philip; Lusingu, John; Olotu, Ally; Leach, Amanda; Lievens, Marc; Vekemans, Johan; Mshamu, Salum; Lang, Trudie; Gould, Jayne; Dubois, Marie-Claude; Demoitié, Marie-Ange; Stallaert, Jean-Francois; Vansadia, Preeti; Carter, Terrell; Njuguna, Patricia; Awuondo, Ken O.; Malabeja, Anangisye; Abdul, Omar; Gesase, Samwel; Mturi, Neema; Drakeley, Chris J.; Savarese, Barbara; Villafana, Tonya; Ballou, W. Ripley; Cohen, Joe; Riley, Eleanor M.; Lemnge, Martha M.; Marsh, Kevin; von Seidlein, Lorenz

2009-01-01

BACKGROUND Plasmodium falciparum malaria is a pressing global health problem. A previous study of the malaria vaccine RTS,S (which targets the circumsporozoite protein), given with an adjuvant system (AS02A), showed a 30% rate of protection against clinical malaria in children 1 to 4 years of age. We evaluated the efficacy of RTS,S given with a more immunogenic adjuvant system (AS01E) in children 5 to 17 months of age, a target population for vaccine licensure. METHODS We conducted a double-blind, randomized trial of RTS,S/AS01E vaccine as compared with rabies vaccine in children in Kilifi, Kenya, and Korogwe, Tanzania. The primary end point was fever with a falciparum parasitemia density of more than 2500 parasites per microliter, and the mean duration of follow-up was 7.9 months (range, 4.5 to 10.5). RESULTS A total of 894 children were randomly assigned to receive the RTS,S/AS01E vaccine or the control (rabies) vaccine. Among the 809 children who completed the study procedures according to the protocol, the cumulative number in whom clinical malaria developed was 32 of 402 assigned to receive RTS,S/AS01E and 66 of 407 assigned to receive the rabies vaccine; the adjusted efficacy rate for RTS,S/AS01E was 53% (95% confidence interval [CI], 28 to 69; P<0.001) on the basis of Cox regression. Overall, there were 38 episodes of clinical malaria among recipients of RTS,S/AS01E, as compared with 86 episodes among recipients of the rabies vaccine, with an adjusted rate of efficacy against all malarial episodes of 56% (95% CI, 31 to 72; P<0.001). All 894 children were included in the intention-to-treat analysis, which showed an unadjusted efficacy rate of 49% (95% CI, 26 to 65; P<0.001). There were fewer serious adverse events among recipients of RTS,S/AS01E, and this reduction was not only due to a difference in the number of admissions directly attributable to malaria. CONCLUSIONS RTS,S/AS01E shows promise as a candidate malaria vaccine. (ClinicalTrials.gov number, NCT

HIV-1 Immunogen: an overview of almost 30 years of clinical testing of a candidate therapeutic vaccine.

Science.gov (United States)

Graziani, Gina M; Angel, Jonathan B

2016-07-01

Although current antiretroviral therapy (ART) has transformed HIV infection into a chronic, manageable disease, ART does not cure HIV infection. Furthermore, the majority of the world's infected individuals live in resource-limited countries in which access to ART is limited. Thus, the development of an effective therapeutic HIV vaccine would be an invaluable treatment alternative. Developed by the late Dr. Jonas Salk, HIV-1 Immunogen (Remune®) is a candidate therapeutic vaccine that has been studied in thousands of HIV-infected individuals in more than a dozen clinical trials during almost three decades. This Drug Evaluation, which summarizes the results of these trials that have shown the vaccine to be safe and immunogenic, also discusses the contradictory and controversial conclusions drawn from the phases 2, 2/3 and 3 trials that assessed the clinical efficacy of this vaccine. Given the lack of unequivocal clinical benefits of HIV-1 Immunogen despite almost 30 years of extensive testing, it does not appear, in our view, that this vaccine is a clinically effective immunotherapy. However, inclusion of this vaccine in the newly proposed 'Kick/Shock and Kill' strategy for HIV eradication, or use as a prophylactic vaccine, could be considered for future trials.

Points for Consideration for dengue vaccine introduction - recommendations by the Dengue Vaccine Initiative.

Science.gov (United States)

Lim, Jacqueline Kyungah; Lee, Yong-Seok; Wilder-Smith, Annelies; Thiry, Georges; Mahoney, Richard; Yoon, In-Kyu

2016-01-01

Dengue is a public health problem in the tropics and subtropics. There are several vaccine candidates in clinical development. However, there may be gaps in the new vaccine introduction after vaccine licensure before it becomes available in developing countries. In anticipation of the first dengue vaccine candidate to be licensed, Dengue Vaccine Initiative (DVI) and, its predecessor, Pediatric Dengue Vaccine Initiative (PDVI) have been working on points for consideration to accelerate evidence-based dengue vaccine introduction, once a vaccine becomes available. In this paper, we review the history of PDVI and its successor, the DVI, and elaborate on the points of consideration for dengue vaccine introduction.

Transmission-blocking activity of antibodies to Plasmodium falciparum GLURP.10C chimeric protein formulated in different adjuvants

DEFF Research Database (Denmark)

Roeffen, Will; Theisen, Michael; van de Vegte-Bolmer, Marga

2015-01-01

BACKGROUND: Plasmodium falciparum is transmitted from person to person by Anopheles mosquitoes after completing its sexual reproductive cycle within the infected mosquito. An efficacious vaccine holds the potential to interrupt development of the parasite in the mosquito leading to control and po...

Phase 1/2a study of the malaria vaccine candidate apical membrane antigen-1 (AMA-1 administered in adjuvant system AS01B or AS02A.

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Michele D Spring

Full Text Available This Phase 1/2a study evaluated the safety, immunogenicity, and efficacy of an experimental malaria vaccine comprised of the recombinant Plasmodium falciparum protein apical membrane antigen-1 (AMA-1 representing the 3D7 allele formulated with either the AS01B or AS02A Adjuvant Systems.After a preliminary safety evaluation of low dose AMA-1/AS01B (10 microg/0.5 mL in 5 adults, 30 malaria-naïve adults were randomly allocated to receive full dose (50 microg/0.5 mL of AMA-1/AS01B (n = 15 or AMA-1/AS02A (n = 15, followed by a malaria challenge. All vaccinations were administered intramuscularly on a 0-, 1-, 2-month schedule. All volunteers experienced transient injection site erythema, swelling and pain. Two weeks post-third vaccination, anti-AMA-1 Geometric Mean Antibody Concentrations (GMCs with 95% Confidence Intervals (CIs were high: low dose AMA-1/AS01B 196 microg/mL (103-371 microg/mL, full dose AMA-1/AS01B 279 microg/mL (210-369 microg/mL and full dose AMA-1/AS02A 216 microg/mL (169-276 microg/mL with no significant difference among the 3 groups. The three vaccine formulations elicited equivalent functional antibody responses, as measured by growth inhibition assay (GIA, against homologous but not against heterologous (FVO parasites as well as demonstrable interferon-gamma (IFN-gamma responses. To assess efficacy, volunteers were challenged with P. falciparum-infected mosquitoes, and all became parasitemic, with no significant difference in the prepatent period by either light microscopy or quantitative polymerase chain reaction (qPCR. However, a small but significant reduction of parasitemia in the AMA-1/AS02A group was seen with a statistical model employing qPCR measurements.All three vaccine formulations were found to be safe and highly immunogenic. These immune responses did not translate into significant vaccine efficacy in malaria-naïve adults employing a primary sporozoite challenge model, but encouragingly, estimation of parasite

Safety of the malaria vaccine candidate, RTS,S/AS01E in 5 to 17 month old Kenyan and Tanzanian Children.

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John Lusingu

2010-11-01

Full Text Available The malaria vaccine candidate, RTS,S/AS01(E, showed promising protective efficacy in a trial of Kenyan and Tanzanian children aged 5 to 17 months. Here we report on the vaccine's safety and tolerability. The experimental design was a Phase 2b, two-centre, double-blind (observer- and participant-blind, randomised (1∶1 ratio controlled trial. Three doses of study or control (rabies vaccines were administered intramuscularly at 1 month intervals. Solicited adverse events (AEs were collected for 7 days after each vaccination. There was surveillance and reporting for unsolicited adverse events for 30 days after each vaccination. Serious adverse events (SAEs were recorded throughout the study period which lasted for 14 months after dose 1 in Korogwe, Tanzania and an average of 18 months post-dose 1 in Kilifi, Kenya. Blood samples for safety monitoring of haematological, renal and hepatic functions were taken at baseline, 3, 10 and 14 months after dose 1. A total of 894 children received RTS,S/AS01(E or rabies vaccine between March and August 2007. Overall, children vaccinated with RTS,S/AS01(E had fewer SAEs (51/447 than children in the control group (88/447. One SAE episode in a RTS,S/AS01(E recipient and nine episodes among eight rabies vaccine recipients met the criteria for severe malaria. Unsolicited AEs were reported in 78% of subjects in the RTS,S/AS01(E group and 74% of subjects in the rabies vaccine group. In both vaccine groups, gastroenteritis and pneumonia were the most frequently reported unsolicited AE. Fever was the most frequently observed solicited AE and was recorded after 11% of RTS,S/AS01(E doses compared to 31% of doses of rabies vaccine. The candidate vaccine RTS,S/AS01(E showed an acceptable safety profile in children living in a malaria-endemic area in East Africa. More data on the safety of RTS,S/AS01(E will become available from the Phase 3 programme.

Assessment of severe malaria in a multicenter, phase III, RTS, S/AS01 malaria candidate vaccine trial: case definition, standardization of data collection and patient care.

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Vekemans, Johan; Marsh, Kevin; Greenwood, Brian; Leach, Amanda; Kabore, William; Soulanoudjingar, Solange; Asante, Kwaku Poku; Ansong, Daniel; Evans, Jennifer; Sacarlal, Jahit; Bejon, Philip; Kamthunzi, Portia; Salim, Nahya; Njuguna, Patricia; Hamel, Mary J; Otieno, Walter; Gesase, Samwel; Schellenberg, David

2011-08-04

An effective malaria vaccine, deployed in conjunction with other malaria interventions, is likely to substantially reduce the malaria burden. Efficacy against severe malaria will be a key driver for decisions on implementation. An initial study of an RTS, S vaccine candidate showed promising efficacy against severe malaria in children in Mozambique. Further evidence of its protective efficacy will be gained in a pivotal, multi-centre, phase III study. This paper describes the case definitions of severe malaria used in this study and the programme for standardized assessment of severe malaria according to the case definition. Case definitions of severe malaria were developed from a literature review and a consensus meeting of expert consultants and the RTS, S Clinical Trial Partnership Committee, in collaboration with the World Health Organization and the Malaria Clinical Trials Alliance. The same groups, with input from an Independent Data Monitoring Committee, developed and implemented a programme for standardized data collection.The case definitions developed reflect the typical presentations of severe malaria in African hospitals. Markers of disease severity were chosen on the basis of their association with poor outcome, occurrence in a significant proportion of cases and on an ability to standardize their measurement across research centres. For the primary case definition, one or more clinical and/or laboratory markers of disease severity have to be present, four major co-morbidities (pneumonia, meningitis, bacteraemia or gastroenteritis with severe dehydration) are excluded, and a Plasmodium falciparum parasite density threshold is introduced, in order to maximize the specificity of the case definition. Secondary case definitions allow inclusion of co-morbidities and/or allow for the presence of parasitaemia at any density. The programmatic implementation of standardized case assessment included a clinical algorithm for evaluating seriously sick children

Heterologous Protection against Malaria after Immunization with Plasmodium falciparum Sporozoites.

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Remko Schats

Full Text Available Sterile protection in >90% of volunteers against homologous Plasmodium falciparum infection has been achieved only using the controlled human malaria infection (CHMI model. This efficient model involves whole parasite immunizations under chloroquine prophylaxis (CPS-immunization, requiring only 30-45 mosquitoes bites infected with P. falciparum-sporozoites. Given the large diversity of P. falciparum parasites, it is essential to assess protection against heterologous parasite strains.In an open-label follow-up study, 16 volunteers previously CPS-immunized and challenged with P. falciparum NF54 (West-Africa in a dose de-escalation and challenge trial were re-challenged with clone NF135.C10 (Cambodia at 14 months after the last immunization (NCT01660854.Two out of thirteen NF54 protected volunteers previously fully protected against NF54 were also fully protected against NF135.C10, while 11/13 showed a delayed patency (median prepatent period of 10.5 days (range 9.0-15.5 versus 8.5 days in 5 malaria-naïve controls (p = 0.0005. Analysis of patency by qPCR indicated a 91 to >99% estimated reduction of liver parasite load in 7/11 partially protected subjects. Three volunteers previously not protected against NF54, were also not protected against NF135.C10.This study shows that CPS-immunization can induce heterologous protection for a period of more than one year, which is a further impetus for clinical development of whole parasite vaccines.Clinicaltrials.gov NCT01660854.

Leishmaniasis vaccine candidates for development: a global overview.

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Khamesipour, Ali; Rafati, Sima; Davoudi, Noushin; Maboudi, Fereidoun; Modabber, Farrokh

2006-03-01

A vaccine against different forms of leishmaniasis should be feasible considering the wealth of information on genetics and biology of the parasite, clinical and experimental immunology of leishmaniasis, and the availability of vaccines that can protect experimental animals against challenge with different Leishmania species. However, there is no vaccine against any form of leishmaniasis for general human use. One major factor is the lack of a conceived market for human leishmaniasis vaccines. Hence pharmaceutical industries involved in vaccine development are not interested in investing millions of dollars and a decade that is required for developing a new vaccine. Besides, leishmaniasis is a local/regional problem and not a global one. According to the estimates of the World Health Organization, 90 per cent of visceral leishmaniasis occurs in five countries (Bangladesh, Brazil, India, Nepal and Sudan). Those in need are amongst the poorest people in these countries. It should therefore be the objectives of these countries to develop a vaccine. Fortunately, both Brazil and India have designated the control of visceral leishmaniasis as a top priority for their respective Ministries of Health. The purpose of this review is to present only the vaccines in use and those in development for use in dogs or humans. This is not an exhaustive review of vaccine discovery or the principles of clinical immunology underlying vaccine development.

Effect of vaccine dose on the safety and immunogenicity of a candidate TB vaccine, MVA85A, in BCG vaccinated UK adults.

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Pathan, Ansar A; Minassian, Angela M; Sander, Clare R; Rowland, Rosalind; Porter, David W; Poulton, Ian D; Hill, Adrian V S; Fletcher, Helen A; McShane, Helen

2012-08-17

A non-randomised, open-label, Phase I safety and immunogenicity dose-finding study to assess the safety and immunogenicity of the candidate TB vaccine Modified Vaccinia virus Ankara expressing Antigen 85A (MVA85A) from Mycobacterium tuberculosis (MTB) in healthy adult volunteers previously vaccinated with BCG. Healthy BCG-vaccinated volunteers were vaccinated with either 1×10(7) or 1×10(8)PFU of MVA85A. All adverse events were documented and antigen specific T cell responses were measured using an ex vivo IFN-γ ELISPOT assay. Safety and immunogenicity were compared between the 2 dose groups and with a previous trial in which a dose of 5×10(7)PFU MVA85A had been administered. There were no serious adverse events recorded following administration of either 1×10(7) or 1×10(8)PFU of MVA85A. Systemic adverse events were more frequently reported following administration of 1×10(8)PFU of MVA85A when compared to either 5×10(7) or 1×10(7)PFU of MVA85A but were mild or moderate in severity and resolved completely within 7 days of immunisation. Antigen specific T cell responses as measured by the IFN-γ ELISPOT were significantly higher following immunisation in adults receiving 1×10(8)PFU compared to the 5×10(7) and 1×10(7) doses. Additionally, a broader range of Ag85A epitopes are detected following 1×10(8)PFU of MVA85A. A higher dose of 1×10(8)PFU of MVA85A is well-tolerated, increases the frequency of IFN-γ secreting T cells detected following immunisation and broadens the range of Ag85A epitopes detected. Copyright © 2012 Elsevier Ltd. All rights reserved.

Optimization of HIV-1 Envelope DNA Vaccine Candidates within Three Different Animal Models, Guinea Pigs, Rabbits and Cynomolgus Macaques.

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Borggren, Marie; Vinner, Lasse; Andresen, Betina Skovgaard; Grevstad, Berit; Repits, Johanna; Melchers, Mark; Elvang, Tara Laura; Sanders, Rogier W; Martinon, Frédéric; Dereuddre-Bosquet, Nathalie; Bowles, Emma Joanne; Stewart-Jones, Guillaume; Biswas, Priscilla; Scarlatti, Gabriella; Jansson, Marianne; Heyndrickx, Leo; Grand, Roger Le; Fomsgaard, Anders

2013-07-19

HIV-1 DNA vaccines have many advantageous features. Evaluation of HIV-1 vaccine candidates often starts in small animal models before macaque and human trials. Here, we selected and optimized DNA vaccine candidates through systematic testing in rabbits for the induction of broadly neutralizing antibodies (bNAb). We compared three different animal models: guinea pigs, rabbits and cynomolgus macaques. Envelope genes from the prototype isolate HIV-1 Bx08 and two elite neutralizers were included. Codon-optimized genes, encoded secreted gp140 or membrane bound gp150, were modified for expression of stabilized soluble trimer gene products, and delivered individually or mixed. Specific IgG after repeated i.d. inoculations with electroporation confirmed in vivo expression and immunogenicity. Evaluations of rabbits and guinea pigs displayed similar results. The superior DNA construct in rabbits was a trivalent mix of non-modified codon-optimized gp140 envelope genes. Despite NAb responses with some potency and breadth in guinea pigs and rabbits, the DNA vaccinated macaques displayed less bNAb activity. It was concluded that a trivalent mix of non-modified gp140 genes from rationally selected clinical isolates was, in this study, the best option to induce high and broad NAb in the rabbit model, but this optimization does not directly translate into similar responses in cynomolgus macaques.

Optimization of HIV-1 Envelope DNA Vaccine Candidates within Three Different Animal Models, Guinea Pigs, Rabbits and Cynomolgus Macaques

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Roger Le Grand

2013-07-01

Full Text Available HIV-1 DNA vaccines have many advantageous features. Evaluation of HIV-1 vaccine candidates often starts in small animal models before macaque and human trials. Here, we selected and optimized DNA vaccine candidates through systematic testing in rabbits for the induction of broadly neutralizing antibodies (bNAb. We compared three different animal models: guinea pigs, rabbits and cynomolgus macaques. Envelope genes from the prototype isolate HIV-1 Bx08 and two elite neutralizers were included. Codon-optimized genes, encoded secreted gp140 or membrane bound gp150, were modified for expression of stabilized soluble trimer gene products, and delivered individually or mixed. Specific IgG after repeated i.d. inoculations with electroporation confirmed in vivo expression and immunogenicity. Evaluations of rabbits and guinea pigs displayed similar results. The superior DNA construct in rabbits was a trivalent mix of non-modified codon-optimized gp140 envelope genes. Despite NAb responses with some potency and breadth in guinea pigs and rabbits, the DNA vaccinated macaques displayed less bNAb activity. It was concluded that a trivalent mix of non-modified gp140 genes from rationally selected clinical isolates was, in this study, the best option to induce high and broad NAb in the rabbit model, but this optimization does not directly translate into similar responses in cynomolgus macaques.

Cellular and humoral immune responses in sheep vaccinated with candidate antigens MAP2698c and MAP3567 from Mycobacterium avium subspecies paratuberculosis

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Gurung, Ratna B.; Purdie, Auriol C.; Whittington, Richard J.; Begg, Douglas J.

2014-01-01

Control of Johne's disease, caused by Mycobacterium avium subspecies paratuberculosis (MAP) in ruminants using commercially available vaccine reduces production losses, mortality, fecal shedding and histopathological lesions but does not provide complete protection from infection and interferes with serological diagnosis of Johne's disease and bovine tuberculosis. At this time no recombinant antigens have been found to provide superior protection compared to whole killed or live-attenuated MAP vaccines. Therefore, there is a need to evaluate more candidate MAP antigens. In this study recombinant MAP antigens MAP2698c and MAP3567 were formulated with four different MONTANIDE™ (ISA 50V2, 61VG, 71VG, and 201VG) adjuvants and evaluated for their ability to produce specific immune responses in vaccinated sheep. The cellular immune response was measured with an interferon-gamma (IFN-γ) release assay and the humoral immune response was measured by antibody detection enzyme linked immunosorbent assay. Recombinant vaccine formulation with the antigen MAP2698c and MONTANIDE™ ISA 201VG adjuvant produced strong whole-MAP as well as MAP2698c-specific IFN-γ responses in a high proportion of the vaccinated sheep. The formulation caused less severe injection site lesions in comparison to other formulations. The findings from this study suggest that the MAP2698c + 201VG should be evaluated in a challenge trial to determine the efficacy of this vaccine candidate. PMID:25077074

Attenuated Mycobacterium tuberculosis SO2 vaccine candidate is unable to induce cell death.

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Adriana Aporta

Full Text Available It has been proposed that Mycobacterium tuberculosis virulent strains inhibit apoptosis and trigger cell death by necrosis of host macrophages to evade innate immunity, while non-virulent strains induce typical apoptosis activating a protective host response. As part of the characterization of a novel tuberculosis vaccine candidate, the M. tuberculosis phoP mutant SO2, we sought to evaluate its potential to induce host cell death. The parental M. tuberculosis MT103 strain and the current vaccine against tuberculosis Bacillus Calmette-Guérin (BCG were used as comparators in mouse models in vitro and in vivo. Our data reveal that attenuated SO2 was unable to induce apoptotic events neither in mouse macrophages in vitro nor during lung infection in vivo. In contrast, virulent MT103 triggers typical apoptotic events with phosphatidylserine exposure, caspase-3 activation and nuclear condensation and fragmentation. BCG strain behaved like SO2 and did not induce apoptosis. A clonogenic survival assay confirmed that viability of BCG- or SO2-infected macrophages was unaffected. Our results discard apoptosis as the protective mechanism induced by SO2 vaccine and provide evidence for positive correlation between classical apoptosis induction and virulent strains, suggesting apoptosis as a possible virulence determinant during M. tuberculosis infection.

Drug and Vaccine evaluation in the Human Aotus Plasmodium falciparum Model

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2011-05-01

and phenyl ring systems is anticipated to yield a valuable new antimalarial drug (33). The antimalarial activity and pharmacology of a series of...remains essentially unchanged since 1976, viz. to ascertain the antimalarial activity of drugs against P. falciparum and P. vivax in Aotus. The...Present data on the evaluation of potential antimalarial activity of drugs in the pre-clinical model of Aotus l. lemurinus (Panamanian night

Pro-inflammatory Cytokine Response and Genetic Diversity in Merozoite Surface Protein 2 of Plasmodium falciparum Isolates from Nigeria.

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Ajibaye, Olusola; Osuntoki, Akinniyi A; Ebuehi, Albert Ot; Iwalokun, Bamidele A; Balogun, Emmanuel O; Egbuna, Kathleen N

2017-01-01

Polymorphisms in Plasmodium falciparum merozoite surface protein-2 ( msp -2) and associated parasite genetic diversity which varies between malaria-endemic regions remain a limitation in malaria vaccine development. Pro-inflammatory cytokines are important in immunity against malaria, understanding the influence of genetic diversity on cytokine response is important for effective vaccine design. P. falciparum isolates obtained from 300 Nigerians with uncomplicated falciparum malaria at Ijede General Hospital, Ijede (IJE), General Hospital Ajeromi, Ajeromi (AJE) and Saint Kizito Mission Hospital, Lekki, were genotyped by nested polymerase chain reaction of msp -2 block 3 while ELISA was used to determine the pro-inflammatory cytokine response to describe the genetic diversity of P. falciparum . Eighteen alleles were observed for msp -2 loci. Of the 195 isolates, 61 (31.0%) had only FC27-type alleles, 38 (19.7%) had only 3D7-type alleles, and 49.3% had multiple parasite lines with both alleles. Band sizes were 275-625 bp for FC27 and 150-425 bp for 3D7. Four alleles were observed from LEK, 2 (375-425 bp) and 2 (275-325 bp) of FC27-and 3D7-types, respectively; 12 alleles from AJE, 9 (275-625 bp) and 3 (325-425 bp) of FC27-types and 3D7-types, respectively; while IJE had a total of 12 alleles, 9 (275-625 bp) and 3 (325-425 bp) of FC27-types and 3D7-types, respectively. Mean multiplicity of infection (MOI) was 1.54. Heterozygosity ( H E ) ranged from 0.77 to 0.87 and was highest for IJE (0.87). Cytokine response was higher among 0.05) but with neither parasite density nor infection type. P. falciparum genetic diversity is extensive in Nigeria, protection via pro-inflammatory cytokines have little or no interplay with infection multiplicity.

Modified Vaccinia Virus Ankara: History, Value in Basic Research, and Current Perspectives for Vaccine Development.

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Volz, A; Sutter, G

2017-01-01

Safety tested Modified Vaccinia virus Ankara (MVA) is licensed as third-generation vaccine against smallpox and serves as a potent vector system for development of new candidate vaccines against infectious diseases and cancer. Historically, MVA was developed by serial tissue culture passage in primary chicken cells of vaccinia virus strain Ankara, and clinically used to avoid the undesirable side effects of conventional smallpox vaccination. Adapted to growth in avian cells MVA lost the ability to replicate in mammalian hosts and lacks many of the genes orthopoxviruses use to conquer their host (cell) environment. As a biologically well-characterized mutant virus, MVA facilitates fundamental research to elucidate the functions of poxvirus host-interaction factors. As extremely safe viral vectors MVA vaccines have been found immunogenic and protective in various preclinical infection models. Multiple recombinant MVA currently undergo clinical testing for vaccination against human immunodeficiency viruses, Mycobacterium tuberculosis or Plasmodium falciparum. The versatility of the MVA vector vaccine platform is readily demonstrated by the swift development of experimental vaccines for immunization against emerging infections such as the Middle East Respiratory Syndrome. Recent advances include promising results from the clinical testing of recombinant MVA-producing antigens of highly pathogenic avian influenza virus H5N1 or Ebola virus. This review summarizes our current knowledge about MVA as a unique strain of vaccinia virus, and discusses the prospects of exploiting this virus as research tool in poxvirus biology or as safe viral vector vaccine to challenge existing and future bottlenecks in vaccinology. © 2017 Elsevier Inc. All rights reserved.

Poly(I:C) adjuvant strongly enhances parasite-inhibitory antibodies and Th1 response against Plasmodium falciparum merozoite surface protein-1 (42-kDa fragment) in BALB/c mice.

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Mehrizi, Akram Abouie; Rezvani, Niloufar; Zakeri, Sedigheh; Gholami, Atefeh; Babaeekhou, Laleh

2018-04-01

Malaria vaccine development has been confronted with various challenges such as poor immunogenicity of malaria vaccine candidate antigens, which is considered as the main challenge. However, this problem can be managed using appropriate formulations of antigens and adjuvants. Poly(I:C) is a potent Th1 inducer and a human compatible adjuvant capable of stimulating both B- and T-cell immunity. Plasmodium falciparum merozoite surface protein 1 42 (PfMSP-1 42 ) is a promising vaccine candidate for blood stage of malaria that has faced several difficulties in clinical trials, mainly due to improper adjuvants. Therefore, in the current study, poly(I:C), as a potent Th1 inducer adjuvant, was evaluated to improve the immunogenicity of recombinant PfMSP-1 42 , when compared to CFA/IFA, as reference adjuvant. Poly(I:C) produced high level and titers of anti-PfMSP-1 42 IgG antibodies in which was comparable to CFA/IFA adjuvant. In addition, PfMSP-1 42 formulated with poly(I:C) elicited a higher ratio of IFN-γ/IL-4 (23.9) and IgG2a/IgG1 (3.77) with more persistent, higher avidity, and titer of IgG2a relative to CFA/IFA, indicating a potent Th1 immune response. Poly(I:C) could also help to induce anti-PfMSP-1 42 antibodies with higher growth-inhibitory activity than CFA/IFA. Altogether, the results of the current study demonstrated that poly(I:C) is a potent adjuvant that can be appropriate for being used in PfMSP-1 42 -based vaccine formulations.

Gene disruption of Plasmodium falciparum p52 results in attenuation of malaria liver stage development in cultured primary human hepatocytes.

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Ben C L van Schaijk

Full Text Available Difficulties with inducing sterile and long lasting protective immunity against malaria with subunit vaccines has renewed interest in vaccinations with attenuated Plasmodium parasites. Immunizations with sporozoites that are attenuated by radiation (RAS can induce strong protective immunity both in humans and rodent models of malaria. Recently, in rodent parasites it has been shown that through the deletion of a single gene, sporozoites can also become attenuated in liver stage development and, importantly, immunization with these sporozoites results in immune responses identical to RAS. The promise of vaccination using these genetically attenuated sporozoites (GAS depends on translating the results in rodent malaria models to human malaria. In this study, we perform the first essential step in this transition by disrupting, p52, in P. falciparum an ortholog of the rodent parasite gene, p36p, which we had previously shown can confer long lasting protective immunity in mice. These P. falciparum P52 deficient sporozoites demonstrate gliding motility, cell traversal and an invasion rate into primary human hepatocytes in vitro that is comparable to wild type sporozoites. However, inside the host hepatocyte development is arrested very soon after invasion. This study reveals, for the first time, that disrupting the equivalent gene in both P. falciparum and rodent malaria Plasmodium species generates parasites that become similarly arrested during liver stage development and these results pave the way for further development of GAS for human use.

Malaria in pregnancy: the relevance of animal models for vaccine development.

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Doritchamou, Justin; Teo, Andrew; Fried, Michal; Duffy, Patrick E

2017-10-06

Malaria during pregnancy due to Plasmodium falciparum or P. vivax is a major public health problem in endemic areas, with P. falciparum causing the greatest burden of disease. Increasing resistance of parasites and mosquitoes to existing tools, such as preventive antimalarial treatments and insecticide-treated bed nets respectively, is eroding the partial protection that they offer to pregnant women. Thus, development of effective vaccines against malaria during pregnancy is an urgent priority. Relevant animal models that recapitulate key features of the pathophysiology and immunology of malaria in pregnant women could be used to accelerate vaccine development. This review summarizes available rodent and nonhuman primate models of malaria in pregnancy, and discusses their suitability for studies of biologics intended to prevent or treat malaria in this vulnerable population.

CD4+ T-cell Responses Among Adults and Young Children In Response to Streptococcus pneumoniae and Haemophilus influenzae Vaccine Candidate Protein Antigens

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Sharma, Sharad K.; Roumanes, David; Almudevar, Anthony; Mosmann, Tim R.; Pichichero, Michael E.

2013-01-01

We characterized cytokine profiles of CD4+ T-helper (h) cells in adults and young children to ascertain if responses occur to next-generation candidate vaccine antigens PspA, PcpA, PhtD, PhtE, Ply, LytB of Streptococcus pneumonia (Spn) and Protein D and OMP26 of non-typeable Haemophilus influenzae (NTHi). Adults had vaccine antigen-specific Th1 - and Th2 cells responsive to all antigens evaluated whereas young children had significant numbers of vaccine antigen-specific CD4+ T cells producing...

Towards a vaccine against pregnancy-associated malaria

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Tuikue Ndam N.

2008-09-01

Full Text Available The consequences of pregnancy-associated malaria on pregnant women (anaemia, their babies (birth weight reduction, and infants (increased morbidity and mortality are well documented. Field observations during the last decade have underlined the key role of the interactions between P. falciparum variable surface antigens expressed on infected erythrocytes and a novel receptor: chondroitin sulfate A (CSA for the placental sequestration of infected erythrocytes. Identification of a distinct P. falciparum erythrocyte membrane protein 1 (PfEMP1 variant, VAR2CSA, as the dominant variant surface antigen and as a clinically important target for protective immune response to pregnancy-associated malaria has raised hope for developing a new preventive strategy based on inducing these immune responses by vaccination. However, despite particular structure and interclonal conservation of VAR2CSA among other PfEMP1, significant challenges still exist concerning the development of a VAR2CSA-based vaccine with profound efficacy.

A murine model of falciparum-malaria by in vivo selection of competent strains in non-myelodepleted mice engrafted with human erythrocytes.

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Iñigo Angulo-Barturen

Full Text Available To counter the global threat caused by Plasmodium falciparum malaria, new drugs and vaccines are urgently needed. However, there are no practical animal models because P. falciparum infects human erythrocytes almost exclusively. Here we describe a reliable falciparum murine model of malaria by generating strains of P. falciparum in vivo that can infect immunodeficient mice engrafted with human erythrocytes. We infected NOD(scid/beta2m-/- mice engrafted with human erythrocytes with P. falciparum obtained from in vitro cultures. After apparent clearance, we obtained isolates of P. falciparum able to grow in peripheral blood of engrafted NOD(scid/beta2m-/- mice. Of the isolates obtained, we expanded in vivo and established the isolate Pf3D7(0087/N9 as a reference strain for model development. Pf3D7(0087/N9 caused productive persistent infections in 100% of engrafted mice infected intravenously. The infection caused a relative anemia due to selective elimination of human erythrocytes by a mechanism dependent on parasite density in peripheral blood. Using this model, we implemented and validated a reproducible assay of antimalarial activity useful for drug discovery. Thus, our results demonstrate that P. falciparum contains clones able to grow reproducibly in mice engrafted with human erythrocytes without the use of myeloablative methods.

Vaccination with Plasmodium knowlesi AMA1 formulated in the novel adjuvant co-vaccine HT™ protects against blood-stage challenge in rhesus macaques.

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Muzamil Mahdi Abdel Hamid

Full Text Available Plasmodium falciparum apical membrane antigen 1 (PfAMA1 is a leading blood stage vaccine candidate. Plasmodium knowlesi AMA1 (PkAMA1 was produced and purified using similar methodology as for clinical grade PfAMA1 yielding a pure, conformational intact protein. Combined with the adjuvant CoVaccine HT™, PkAMA1 was found to be highly immunogenic in rabbits and the efficacy of the PkAMA1 was subsequently tested in a rhesus macaque blood-stage challenge model. Six rhesus monkeys were vaccinated with PkAMA1 and a control group of 6 were vaccinated with PfAMA1. A total of 50 µg AMA1 was administered intramuscularly three times at 4 week intervals. One of six rhesus monkeys vaccinated with PkAMA1 was able to control parasitaemia, upon blood stage challenge with P. knowlesi H-strain. Four out of the remaining five showed a delay in parasite onset that correlated with functional antibody titres. In the PfAMA1 vaccinated control group, five out of six animals had to be treated with antimalarials 8 days after challenge; one animal did not become patent during the challenge period. Following a rest period, animals were boosted and challenged again. Four of the six rhesus monkeys vaccinated with PkAMA1 were able to control the parasitaemia, one had a delayed onset of parasitaemia and one animal was not protected, while all control animals required treatment. To confirm that the control of parasitaemia was AMA1-related, animals were allowed to recover, boosted and re-challenged with P. knowlesi Nuri strain. All control animals had to be treated with antimalarials by day 8, while five out of six PkAMA1 vaccinated animals were able to control parasitaemia. This study shows that: i Yeast-expressed PkAMA1 can protect against blood stage challenge; ii Functional antibody levels as measured by GIA correlated inversely with the day of onset and iii GIA IC(50 values correlated with estimated in vivo growth rates.

Liposomes containing monophosphoryl lipid A and QS-21 serve as an effective adjuvant for soluble circumsporozoite protein malaria vaccine FMP013.

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Genito, Christopher J; Beck, Zoltan; Phares, Timothy W; Kalle, Fanta; Limbach, Keith J; Stefaniak, Maureen E; Patterson, Noelle B; Bergmann-Leitner, Elke S; Waters, Norman C; Matyas, Gary R; Alving, Carl R; Dutta, Sheetij

2017-07-05

Malaria caused by Plasmodium falciparum continues to threaten millions of people living in the tropical parts of the world. A vaccine that confers sterile and life-long protection remains elusive despite more than 30years of effort and resources invested in solving this problem. Antibodies to a malaria vaccine candidate circumsporozoite protein (CSP) can block invasion and can protect humans against malaria. We have manufactured the Falciparum Malaria Protein-013 (FMP013) vaccine based on the nearly full-length P. falciparum CSP 3D7 strain sequence. We report here immunogenicity and challenge data on FMP013 antigen in C57BL/6 mice formulated with two novel adjuvants of the Army Liposome Formulation (ALF) series and a commercially available adjuvant Montanide ISA 720 (Montanide) as a control. ALF is a liposomal adjuvant containing a synthetic monophosphoryl lipid A (3D-PHAD®). In our study, FMP013 was adjuvanted with ALF alone, ALF containing aluminum hydroxide (ALFA) or ALF containing QS-21 (ALFQ). Adjuvants ALF and ALFA induced similar antibody titers and protection against transgenic parasite challenge that were comparable to Montanide. ALFQ was superior to the other three adjuvants as it induced higher antibody titers with improved boosting after the third immunization, higher serum IgG2c titers, and enhanced protection. FMP013+ALFQ also augmented the numbers of splenic germinal center-derived activated B-cells and antibody secreting cells compared to Montanide. Further, FMP013+ALFQ induced antigen-specific IFN-γ ELISPOT activity, CD4 + T-cells and a T H 1-biased cytokine profile. These results demonstrate that soluble CSP can induce a potent and sterile protective immune response when formulated with the QS-21 containing adjuvant ALFQ. Comparative mouse immunogenicity data presented here were used as the progression criteria for an ongoing non-human primate study and a regulatory toxicology study in preparation for a controlled human malaria infection (CHMI

Protection against Fasciola gigantica using paramyosin antigen as a candidate for vaccine production.

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Abou-Elhakam, H; Rabee, I; El Deeb, S; El Amir, A

2013-11-15

Yet no vaccine to protect ruminants against liver fluke infection has been commercialized. In an attempt to develop a suitable vaccine against Fasciola gigantica (F. gigantica) infection in rabbits, using 97 kDa Pmy antigen. It was found that, the mean worm burdens and bile egg count after challenge were reduced significantly by 58.40 and 61.40%, respectively. On the other hand, immunization of rabbits with Pmy induced a significant expression of humoral antibodies (IgM, total IgG, IgG1, IgG2 and IgG4) and different cytokines (IL-6, IL-10, L-12 and TNF-alpha). Among Ig isotypes, IgG2 and IgG4 were most dominant Post-infection (PI) while, recording a low IgG1 level. The dominance of IgG2 and IgG4 suggested late T helper1 (Th1) involvement in rabbit's cellular response. While, the low IgG1 level suggested Th2 response to adult F. gigantica worm Pmy. Among all cytokines, IL-10 was the highest in rabbits immunized with Pmy PI suggesting also the enhancement of Th2 response. It was clear that the native F. gigantica Pmy is considered as a relevant candidate for vaccination against fascioliasis. Also, these data suggested the immunoprophylactic effect of the native F. gigantica Pmy which is mediated by a mixed Th1/Th2 response.

Pulmonary immunity and durable protection induced by the ID93/GLA-SE vaccine candidate against the hyper-virulent Korean Beijing Mycobacterium tuberculosis strain K.

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Cha, Seung Bin; Kim, Woo Sik; Kim, Jong-Seok; Kim, Hongmin; Kwon, Kee Woong; Han, Seung Jung; Cho, Sang-Nae; Coler, Rhea N; Reed, Steven G; Shin, Sung Jae

2016-04-27

The majority of tuberculosis (TB) vaccine candidates advanced to clinical trials have been evaluated preclinically using laboratory-adapted strains. However, it has been proposed that challenge with clinical isolates in preclinical vaccine testing could provide further and more practical validation. Here, we tested the ID93/GLA-SE TB vaccine candidate against the clinical Mycobacterium tuberculosis (Mtb) strain K (Mtb K) belonging to the Beijing family, the most prevalent Mtb strain in South Korea. Mice immunized with ID93/GLA-SE exhibited a significant reduction in bacteria and reduced lung inflammation against Mtb K when compared to non-immunized controls. In addition, we analyzed the immune responses in the lungs of ID93/GLA-SE-immunized mice, and showed that ID93/GLA-SE was able to elicit sustained Th1-biased immune responses including antigen-specific multifunctional CD4(+) T cell co-producing IFN-γ, TNF-α, and IL-2 as well as a high magnitude of IFN-γ response for up to 10 weeks post-challenge. Notably, further investigation of T cell subsets in the lung following challenge showed remarkable generation of CD8(+) central memory T cells by ID93/GLA-SE-immunization. Our findings showed that ID93/GLA-SE vaccine confers a high level of robust protection against the hypervirulent Mtb Beijing infection which was characterized by pulmonary Th1-polarized T-cell immune responses. These findings may also provide relevant information for potential utility of this vaccine candidate in East-Asian countries where the Beijing genotype is highly prevalent. Copyright © 2016 Elsevier Ltd. All rights reserved.

AFCo1, a meningococcal B-derived cochleate adjuvant, strongly enhances antibody and T-cell immunity against Plasmodium falciparum merozoite surface protein 4 and 5.

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Bracho, Gustavo; Zayas, Caridad; Wang, Lina; Coppel, Ross; Pérez, Oliver; Petrovsky, Nikolai

2009-02-27

Whilst a large number of malaria antigens are being tested as candidate malaria vaccines, a major barrier to the development of an effective vaccine is the lack of a suitable human adjuvant capable of inducing a strong and long lasting immune response. In this study, the ability of AFCo1, a potent T and B cell adjuvant based on cochleate structures derived from meningococcal B outer membrane proteoliposomes (MBOMP), to boost the immune response against two Plasmodium falciparum antigens, merozoite surface protein 4 (MSP4) and 5 (MSP5), was evaluated. Complete Freund's adjuvant (CFA), which is able to confer protection against malaria in animal MSP4/5 vaccine challenge models, was used as positive control adjuvant. MSP4 and 5-specific IgG, delayed-type hypersensitivity (DTH), T-cell proliferation, and cytokine production were evaluated in parallel in mice immunized three times intramuscularly with MSP4 or MSP5 incorporated into AFCo1, synthetic cochleate structures, CFA or phosphate buffered saline. AFCo1 significantly enhanced the IgG and T-cell response against MSP4 and MSP5, with a potency equivalent to CFA, with the response being characterized by both IgG1 and IgG2a isotypes, increased interferon gamma production and a strong DTH response, consistent with the ability of AFCo1 to induce Th1-like immune responses. Given the proven safety of MBOMP, which is already in use in a licensed human vaccine, AFCo1 could assist the development of human malaria vaccines that require a potent and safe adjuvant.

Alga-Produced Cholera Toxin-Pfs25 Fusion Proteins as Oral Vaccines

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Gregory, James A.; Topol, Aaron B.; Doerner, David Z.

2013-01-01

Infectious diseases disproportionately affect indigent regions and are the greatest cause of childhood mortality in developing countries. Practical, low-cost vaccines for use in these countries are paramount to reducing disease burdens and concomitant poverty. Algae are a promising low-cost system for producing vaccines that can be orally delivered, thereby avoiding expensive purification and injectable delivery. We engineered the chloroplast of the eukaryotic alga Chlamydomonas reinhardtii to produce a chimeric protein consisting of the 25-kDa Plasmodium falciparum surface protein (Pfs25) fused to the β subunit of the cholera toxin (CtxB) to investigate an alga-based whole-cell oral vaccine. Pfs25 is a promising malaria transmission-blocking vaccine candidate that has been difficult to produce in traditional recombinant systems due to its structurally complex tandem repeats of epidermal growth factor-like domains. The noncatalytic CtxB domain of the cholera holotoxin assembles into a pentameric structure and acts as a mucosal adjuvant by binding GM1 ganglioside receptors on gut epithelial cells. We demonstrate that CtxB-Pfs25 accumulates as a soluble, properly folded and functional protein within algal chloroplasts, and it is stable in freeze-dried alga cells at ambient temperatures. In mice, oral vaccination using freeze-dried algae that produce CtxB-Pfs25 elicited CtxB-specific serum IgG antibodies and both CtxB- and Pfs25-specific secretory IgA antibodies. These data suggest that algae are a promising system for production and oral delivery of vaccine antigens, but as an orally delivered adjuvant, CtxB is best suited for eliciting secretory IgA antibodies for vaccine antigens against pathogens that invade mucosal surfaces using this strategy. PMID:23603678

Immunoprotective efficacy of Acinetobacter baumannii outer membrane protein, FilF, predicted in silico as a potential vaccine candidate

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Ravinder eSingh

2016-02-01

Full Text Available Acinetobacter baumannii is emerging as a serious nosocomial pathogen with multidrug resistance that has made it difficult to cure and development of efficacious treatment against this pathogen is direly needed. This has led to investigate vaccine approach to prevent and treat A. baumannii infections. In this work, an outer membrane putative pilus assembly protein, FilF, was predicted as vaccine candidate by in silico analysis of A. baumannii proteome and was found to be conserved among the A. baumannii strains. It was cloned and expressed in E. coli BL21(DE3 and purified by Ni-NTA chromatography. Immunization with FilF generated high antibody titer (>64000 and provided 50% protection against a standardized lethal dose (10*8 CFU of A. baumannii in murine pneumonia model. FilF immunization reduced the bacterial load in lungs by 2 and 4 log cycles, 12 and 24 h post infection as compared to adjuvant control; reduced the levels of pro-inflammatory cytokines TNF-α, IL-6, IL-33, IFN-γ and IL-1β significantly and histology of lung tissue supported the data by showing considerably reduced damage and infiltration of neutrophils in lungs. These results demonstrate the in vivo validation of immunoprotective efficacy of a protein predicted as a vaccine candidate by in silico proteomic analysis and open the possibilities for exploration of a large array of uncharacterized proteins.

Conservation and diversity of influenza A H1N1 HLA-restricted T cell epitope candidates for epitope-based vaccines.

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Paul Thiamjoo Tan

2010-01-01

Full Text Available The immune-related evolution of influenza viruses is exceedingly complex and current vaccines against influenza must be reformulated for each influenza season because of the high degree of antigenic drift among circulating influenza strains. Delay in vaccine production is a serious problem in responding to a pandemic situation, such as that of the current H1N1 strain. Immune escape is generally attributed to reduced antibody recognition of the viral hemagglutinin and neuraminidase proteins whose rate of mutation is much greater than that of the internal non-structural proteins. As a possible alternative, vaccines directed at T cell epitope domains of internal influenza proteins, that are less susceptible to antigenic variation, have been investigated.HLA transgenic mouse strains expressing HLA class I A*0201, A*2402, and B*0702, and class II DRB1*1501, DRB1*0301 and DRB1*0401 were immunized with 196 influenza H1N1 peptides that contained residues of highly conserved proteome sequences of the human H1N1, H3N2, H1N2, H5N1, and avian influenza A strains. Fifty-four (54 peptides that elicited 63 HLA-restricted peptide-specific T cell epitope responses were identified by IFN-gamma ELISpot assay. The 54 peptides were compared to the 2007-2009 human H1N1 sequences for selection of sequences in the design of a new candidate H1N1 vaccine, specifically targeted to highly-conserved HLA-restricted T cell epitopes.Seventeen (17 T cell epitopes in PB1, PB2, and M1 were selected as vaccine targets based on sequence conservation over the past 30 years, high functional avidity, non-identity to human peptides, clustered localization, and promiscuity to multiple HLA alleles. These candidate vaccine antigen sequences may be applicable to any avian or human influenza A virus.

GapA, a potential vaccine candidate antigen against Streptococcus agalactiae in Nile tilapia (Oreochromis niloticus).

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Zhang, Ze; Yu, Angen; Lan, Jiangfeng; Zhang, Hua; Hu, Minqiang; Cheng, Jiewei; Zhao, Lijuan; Lin, Li; Wei, Shun

2017-04-01

Streptococcosis due to the bacterium Streptococcus agalactiae (S. agalactiae) has resulted in enormous economic losses in aquaculture worldwide, especially in the tilapia culture industry. Previously, there were limited vaccines that could be employed against streptococcosis in tilapia. This study aimed to develop a vaccine candidate using the glyceraldehyde-phosphate dehydrogenase protein (GapA) of S. agalactiae encoded by the gapA gene. Tilapia were intraperitoneally injected with PBS, PBS + Freund's adjuvant, PBS + Montanide's adjuvant, GapA + Freund's adjuvant, GapA + Montanide's adjuvant, killed S. agalactiae whole cells (WC)+Freund's adjuvant, or killed S. agalactiae whole cells (WC)+ Montanide's adjuvant. They were then challenged with S. agalactiae, and the relative percentage survival (RPS) was monitored 14 days after the challenge. The highest RPSs were observed in the WC groups, with 76.7% in WC + Freund's adjuvant and 74.4% in WC + Montanide's adjuvant groups; these were followed by the GapA groups, with 63.3% in GapA + Freund's adjuvant and 45.6% in GapA + Montanide's adjuvant groups. The RPS of the PBS group was 0%, and those of PBS + Freund's adjuvant and PBS + Montanide's adjuvant groups were 6.7% and 3.3%, respectively. Additionally, the IgM antibody responses elicited in GapA groups and WC groups were significantly higher than those in PBS groups. Furthermore, the expressions of cytokine (IL-1β and TNF-α) mRNAs in the GapA groups and WC groups were significantly higher than those in the PBS groups. Taken together, these results reveal that the GapA protein is a promising vaccine candidate that could be used to prevent streptococcosis in tilapia. Copyright © 2017 Elsevier Ltd. All rights reserved.

Safety and tolerability of a live oral Salmonella typhimurium vaccine candidate in SIV-infected nonhuman primates.

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Ault, Alida; Tennant, Sharon M; Gorres, J Patrick; Eckhaus, Michael; Sandler, Netanya G; Roque, Annelys; Livio, Sofie; Bao, Saran; Foulds, Kathryn E; Kao, Shing-Fen; Roederer, Mario; Schmidlein, Patrick; Boyd, Mary Adetinuke; Pasetti, Marcela F; Douek, Daniel C; Estes, Jacob D; Nabel, Gary J; Levine, Myron M; Rao, Srinivas S

2013-12-02

Nontyphoidal Salmonella (NTS) serovars are a common cause of acute food-borne gastroenteritis worldwide and can cause invasive systemic disease in young infants, the elderly, and immunocompromised hosts, accompanied by high case fatality. Vaccination against invasive NTS disease is warranted where the disease incidence and mortality are high and multidrug resistance is prevalent, as in sub-Saharan Africa. Live-attenuated vaccines that mimic natural infection constitute one strategy to elicit protection. However, they must particularly be shown to be adequately attenuated for consideration of immunocompromised subjects. Accordingly, we examined the safety and tolerability of an oral live attenuated Salmonella typhimurium vaccine candidate, CVD 1921, in an established chronic simian immunodeficiency virus (SIV)-infected rhesus macaque model. We evaluated clinical parameters, histopathology, and measured differences in mucosal permeability to wild-type and vaccine strains. Compared to the wild-type S. typhimurium strain I77 in both SIV-infected and SIV-uninfected nonhuman primate hosts, this live-attenuated vaccine shows reduced shedding and systemic spread, exhibits limited pathological disease manifestations in the digestive tract, and induces low levels of cellular infiltration in tissues. Furthermore, wild-type S. typhimurium induces increased intestinal epithelial damage and permeability, with infiltration of neutrophils and macrophages in both SIV-infected and SIV-uninfected nonhuman primates compared to the vaccine strain. Based on shedding, systemic spread, and histopathology, the live-attenuated S. typhimurium strain CVD 1921 appears to be safe and well-tolerated in the nonhuman primate model, including chronically SIV-infected rhesus macaques. Copyright © 2013. Published by Elsevier Ltd.

Humoral immune responses to a single allele PfAMA1 vaccine in healthy malaria-naïve adults.

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Edmond J Remarque

Full Text Available Plasmodium falciparum: apical membrane antigen 1 (AMA1 is a candidate malaria vaccine antigen expressed on merozoites and sporozoites. The polymorphic nature of AMA1 may compromise vaccine induced protection. The humoral response induced by two dosages (10 and 50 µg of a single allele AMA1 antigen (FVO formulated with Alhydrogel, Montanide ISA 720 or AS02 was investigated in 47 malaria-naïve adult volunteers. Volunteers were vaccinated 3 times at 4 weekly intervals and serum samples obtained four weeks after the third immunization were analysed for (i Antibody responses to various allelic variants, (ii Domain specificity, (iii Avidity, (iv IgG subclass levels, by ELISA and (v functionality of antibody responses by Growth Inhibition Assay (GIA. About half of the antibodies induced by vaccination cross reacted with heterologous AMA1 alleles. The choice of adjuvant determined the magnitude of the antibody response, but had only a marginal influence on specificity, avidity, domain recognition or subclass responses. The highest antibody responses were observed for AMA1 formulated with AS02. The Growth Inhibition Assay activity of the antibodies was proportional to the amount of antigen specific IgG and the functional capacity of the antibodies was similar for heterologous AMA1-expressing laboratory strains.ClinicalTrials.gov NCT00730782.

A glycolipid adjuvant, 7DW8-5, enhances CD8+ T cell responses induced by an adenovirus-vectored malaria vaccine in non-human primates.

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Padte, Neal N; Boente-Carrera, Mar; Andrews, Chasity D; McManus, Jenny; Grasperge, Brooke F; Gettie, Agegnehu; Coelho-dos-Reis, Jordana G; Li, Xiangming; Wu, Douglass; Bruder, Joseph T; Sedegah, Martha; Patterson, Noelle; Richie, Thomas L; Wong, Chi-Huey; Ho, David D; Vasan, Sandhya; Tsuji, Moriya

2013-01-01

A key strategy to a successful vaccine against malaria is to identify and develop new adjuvants that can enhance T-cell responses and improve protective immunity. Upon co-administration with a rodent malaria vaccine in mice, 7DW8-5, a recently identified novel analog of α-galactosylceramide (α-GalCer), enhances the level of malaria-specific protective immune responses more strongly than the parent compound. In this study, we sought to determine whether 7DW8-5 could provide a similar potent adjuvant effect on a candidate human malaria vaccine in the more relevant non-human primate (NHP) model, prior to committing to clinical development. The candidate human malaria vaccine, AdPfCA (NMRC-M3V-Ad-PfCA), consists of two non-replicating recombinant adenoviral (Ad) vectors, one expressing the circumsporozoite protein (CSP) and another expressing the apical membrane antigen-1 (AMA1) of Plasmodium falciparum. In several phase 1 clinical trials, AdPfCA was well tolerated and demonstrated immunogenicity for both humoral and cell-mediated responses. In the study described herein, 25 rhesus macaques received prime and boost intramuscular (IM) immunizations of AdPfCA alone or with an ascending dose of 7DW8-5. Our results indicate that 7DW8-5 is safe and well-tolerated and provides a significant enhancement (up to 9-fold) in malaria-specific CD8+ T-cell responses after both priming and boosting phases, supporting further clinical development.

A glycolipid adjuvant, 7DW8-5, enhances CD8+ T cell responses induced by an adenovirus-vectored malaria vaccine in non-human primates.

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Neal N Padte

Full Text Available A key strategy to a successful vaccine against malaria is to identify and develop new adjuvants that can enhance T-cell responses and improve protective immunity. Upon co-administration with a rodent malaria vaccine in mice, 7DW8-5, a recently identified novel analog of α-galactosylceramide (α-GalCer, enhances the level of malaria-specific protective immune responses more strongly than the parent compound. In this study, we sought to determine whether 7DW8-5 could provide a similar potent adjuvant effect on a candidate human malaria vaccine in the more relevant non-human primate (NHP model, prior to committing to clinical development. The candidate human malaria vaccine, AdPfCA (NMRC-M3V-Ad-PfCA, consists of two non-replicating recombinant adenoviral (Ad vectors, one expressing the circumsporozoite protein (CSP and another expressing the apical membrane antigen-1 (AMA1 of Plasmodium falciparum. In several phase 1 clinical trials, AdPfCA was well tolerated and demonstrated immunogenicity for both humoral and cell-mediated responses. In the study described herein, 25 rhesus macaques received prime and boost intramuscular (IM immunizations of AdPfCA alone or with an ascending dose of 7DW8-5. Our results indicate that 7DW8-5 is safe and well-tolerated and provides a significant enhancement (up to 9-fold in malaria-specific CD8+ T-cell responses after both priming and boosting phases, supporting further clinical development.

Safety and Immunogenicity of EBA-175 RII-NG Malaria Vaccine Administered Intramuscularly in Semi-Immune Adults: A Phase 1, Double-Blinded Placebo Controlled Dosage Escalation Study.

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Koram, Kwadwo A; Adu, Bright; Ocran, Josephine; Karikari, Yaa S; Adu-Amankwah, Susan; Ntiri, Michael; Abuaku, Benjamin; Dodoo, Daniel; Gyan, Ben; Kronmann, Karl C; Nkrumah, Francis

2016-01-01

The erythrocyte binding antigen region II (EBA-175 RII) is a Plasmodium falciparum ligand that mediates erythrocyte invasion and is considered an important malaria vaccine candidate. A phase Ia trial in malaria naïve adults living in the United States found the recombinant non-glycosylated vaccine antigen, EBA-175 RII-NG adjuvanted with aluminium phosphate to be safe, immunogenic and capable of inducing biologically active antibodies that can inhibit parasite growth in vitro. The aim of the current study was to assess the safety and immunogenicity of this vaccine in malaria exposed semi-immune healthy adults living in a malaria endemic country, Ghana. In this double-blinded, placebo controlled, dose escalation phase I trial, eighteen subjects per group received ascending dose concentrations (5 μg, 20 μg or 80 μg) of the vaccine intramuscularly at 0, 1 and 6 months, while 6 subjects received placebo (normal saline). The primary end point was the number of subjects experiencing Grade 3 systemic or local adverse events within 14 days post-vaccination. Serious adverse events were assessed throughout the study period. Blood samples for immunological analyses were collected at days 0, 14, 28, 42, 180 and 194. A total of 52 subjects received three doses of the vaccine in the respective groups. No serious adverse events were reported. The majority of all adverse events reported were mild to moderate in severity, with local pain and tenderness being the most common. All adverse events, irrespective of severity, resolved without any sequelae. Subjects who received any of the EBA-175 RII-NG doses had high immunoglobulin G levels which moderately inhibited P. falciparum growth in vitro, compared to those in the placebo group. In conclusion, the EBA-175 RII-NG vaccine was safe, well tolerated and immunogenic in malaria semi-immune Ghanaian adults. Its further development is recommended. ClinicalTrials.gov. Identifier: NCT01026246.

Safety and Immunogenicity of EBA-175 RII-NG Malaria Vaccine Administered Intramuscularly in Semi-Immune Adults: A Phase 1, Double-Blinded Placebo Controlled Dosage Escalation Study.

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Kwadwo A Koram

Full Text Available The erythrocyte binding antigen region II (EBA-175 RII is a Plasmodium falciparum ligand that mediates erythrocyte invasion and is considered an important malaria vaccine candidate. A phase Ia trial in malaria naïve adults living in the United States found the recombinant non-glycosylated vaccine antigen, EBA-175 RII-NG adjuvanted with aluminium phosphate to be safe, immunogenic and capable of inducing biologically active antibodies that can inhibit parasite growth in vitro. The aim of the current study was to assess the safety and immunogenicity of this vaccine in malaria exposed semi-immune healthy adults living in a malaria endemic country, Ghana. In this double-blinded, placebo controlled, dose escalation phase I trial, eighteen subjects per group received ascending dose concentrations (5 μg, 20 μg or 80 μg of the vaccine intramuscularly at 0, 1 and 6 months, while 6 subjects received placebo (normal saline. The primary end point was the number of subjects experiencing Grade 3 systemic or local adverse events within 14 days post-vaccination. Serious adverse events were assessed throughout the study period. Blood samples for immunological analyses were collected at days 0, 14, 28, 42, 180 and 194. A total of 52 subjects received three doses of the vaccine in the respective groups. No serious adverse events were reported. The majority of all adverse events reported were mild to moderate in severity, with local pain and tenderness being the most common. All adverse events, irrespective of severity, resolved without any sequelae. Subjects who received any of the EBA-175 RII-NG doses had high immunoglobulin G levels which moderately inhibited P. falciparum growth in vitro, compared to those in the placebo group. In conclusion, the EBA-175 RII-NG vaccine was safe, well tolerated and immunogenic in malaria semi-immune Ghanaian adults. Its further development is recommended.ClinicalTrials.gov. Identifier: NCT01026246.

Chimeric Pestivirus Experimental Vaccines.

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Reimann, Ilona; Blome, Sandra; Beer, Martin

2016-01-01

Chimeric pestiviruses have shown great potential as marker vaccine candidates against pestiviral infections. Exemplarily, we describe here the construction and testing of the most promising classical swine fever vaccine candidate "CP7_E2alf" in detail. The description is focused on classical cloning technologies in combination with reverse genetics.

Variation in the immune responses against Plasmodium falciparum merozoite surface protein-1 and apical membrane antigen-1 in children residing in the different epidemiological strata of malaria in Cameroon.

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Kwenti, Tebit Emmanuel; Moye, Adzemye Linus; Wiylanyuy, Adzemye Basil; Njunda, Longdoh Anna; Nkuo-Akenji, Theresa

2017-11-09

Studies to assess the immune responses against malaria in Cameroonian children are limited. The purpose of this study was to assess the immune responses against Plasmodium falciparum merozoite surface protein-1 (MSP-1 19 ) and apical membrane antigen-1 (AMA-1) in children residing in the different epidemiological strata of malaria in Cameroon. In a cross-sectional survey performed between April and July 2015, 602 children between 2 and 15 years (mean ± SD = 5.7 ± 3.7), comprising 319 (53%) males were enrolled from five epidemiological strata of malaria in Cameroon including: the sudano-sahelian (SS) strata, the high inland plateau (HIP) strata, the south Cameroonian equatorial forest (SCEF) strata, the high western plateau (HWP) strata, and the coastal (C) strata. The children were screened for clinical malaria (defined by malaria parasitaemia ≥ 5000 parasites/µl plus axillary temperature ≥ 37.5 °C). Their antibody responses were measured against P. falciparum MSP-1 19 and AMA-1 vaccine candidate antigens using standard ELISA technique. A majority of the participants were IgG responders 72.1% (95% CI 68.3-75.6). The proportion of responders was higher in females (p = 0.002) and in children aged 10 years and above (p = 0.005). The proportion of responders was highest in Limbe (C strata) and lowest in Ngaoundere (HIP strata) (p malaria (p malaria parasites. The immune responses varied considerably across the different strata: the highest levels observed in the C strata and the lowest in the HIP strata. Furthermore, malaria transmission in Cameroon could be categorized into two major groups based on the serological reaction of the children: the southern (comprising C and SCEF strata) and northern (comprising HWP, HIP and SS strata) groups. These findings may have significant implications in the design of future trials for evaluating malaria vaccine candidates in Cameroon.

Antimalarial drug targets in Plasmodium falciparum predicted by stage-specific metabolic network analysis

OpenAIRE

Huthmacher, Carola; Hoppe, Andreas; Bulik, Sascha; Holzh?tter, Hermann-Georg

2010-01-01

Abstract Background Despite enormous efforts to combat malaria the disease still afflicts up to half a billion people each year of which more than one million die. Currently no approved vaccine is available and resistances to antimalarials are widely spread. Hence, new antimalarial drugs are urgently needed. Results Here, we present a computational analysis of the metabolism of Plasmodium falciparum, the deadliest malaria pathogen. We assembled a compartmentalized metabolic model and predicte...

Steady progress toward a malaria vaccine.

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Lyke, Kirsten E

2017-10-01

Great progress has been made in reducing malaria morbidity and mortality, yet the parasite continues to cause a startling 200 million infections and 500 000 deaths annually. Malaria vaccine development is pushing new boundaries by steady advancement toward a licensed product. Despite 50 years of research, the complexity of Plasmoidum falciparum confounds all attempts to eradicate the organism. This very complexity has pushed the boundaries of vaccine development to new heights, yet it remains to be seen if an affordable vaccine can provide durable and high-level protection. Novel vaccines such as RTS,S/AS01E are on the edge of licensure, but old techniques have resurged with the ability to deliver vialed, whole organism vaccines. Novel adjuvants, multistage/multiantigen approaches and transmission blocking vaccines all contribute to a multipronged battle plan to conquer malaria. Vaccines are the most cost-effective tools to control infectious diseases, yet the complexity of malaria has frustrated all attempts to develop an effective product. This review concentrates on recent advances in malaria vaccine development that lend hope that a vaccine can be produced and malaria eradicated.

Evaluation of a genetically modified foot-and-mouth disease virus vaccine candidate generated by reverse genetics

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2012-01-01

. Thus, the full-length cDNA clone of FMDV can be a useful tool to develop genetically engineered FMDV vaccine candidates to help control porcinophilic FMD epidemics in China. PMID:22591597

Evaluation of a genetically modified foot-and-mouth disease virus vaccine candidate generated by reverse genetics

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Li Pinghua

2012-05-01

wild O/HN/CHA/93 virus. Thus, the full-length cDNA clone of FMDV can be a useful tool to develop genetically engineered FMDV vaccine candidates to help control porcinophilic FMD epidemics in China.

The evolution and diversity of a low complexity vaccine candidate, merozoite surface protein 9 (MSP-9), in Plasmodium vivax and closely related species.

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Chenet, Stella M; Pacheco, M Andreína; Bacon, David J; Collins, William E; Barnwell, John W; Escalante, Ananias A

2013-12-01

The merozoite surface protein-9 (MSP-9) has been considered a target for an anti-malarial vaccine since it is one of many proteins involved in the erythrocyte invasion, a critical step in the parasite life cycle. Orthologs encoding this antigen have been found in all known species of Plasmodium parasitic to primates. In order to characterize and investigate the extent and maintenance of MSP-9 genetic diversity, we analyzed DNA sequences of the following malaria parasite species: Plasmodium falciparum, Plasmodium reichenowi, Plasmodium chabaudi, Plasmodium yoelii, Plasmodium berghei, Plasmodium coatneyi, Plasmodium gonderi, Plasmodium knowlesi, Plasmodium inui, Plasmodium simiovale, Plasmodium fieldi, Plasmodium cynomolgi and Plasmodium vivax and evaluated the signature of natural selection in all MSP-9 orthologs. Our findings suggest that the gene encoding MSP-9 is under purifying selection in P. vivax and closely related species. We further explored how selection affected different regions of MSP-9 by comparing the polymorphisms in P. vivax and P. falciparum, and found contrasting patterns between these two species that suggest differences in functional constraints. This observation implies that the MSP-9 orthologs in human parasites may interact differently with the host immune response. Thus, studies carried out in one species cannot be directly translated into the other. Copyright © 2013 Elsevier B.V. All rights reserved.

Next-Generation Dengue Vaccines: Novel Strategies Currently Under Development

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Anna P. Durbin

2011-09-01

Full Text Available Dengue has become the most important arboviral infection worldwide with more than 30 million cases of dengue fever estimated to occur each year. The need for a dengue vaccine is great and several live attenuated dengue candidate vaccines are proceeding through clinical evaluation. The need to induce a balanced immune response against all four DENV serotypes with a single vaccine has been a challenge for dengue vaccine developers. A live attenuated DENV chimeric vaccine produced by Sanofi Pasteur has recently entered Phase III evaluation in numerous dengue-endemic regions of the world. Viral interference between serotypes contained in live vaccines has required up to three doses of the vaccine be given over a 12-month period of time. For this reason, novel DENV candidate vaccines are being developed with the goal of achieving a protective immune response with an immunization schedule that can be given over the course of a few months. These next-generation candidates include DNA vaccines, recombinant adenovirus vectored vaccines, alphavirus replicons, and sub-unit protein vaccines. Several of these novel candidates will be discussed.

Next-generation dengue vaccines: novel strategies currently under development.

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Durbin, Anna P; Whitehead, Stephen S

2011-10-01

Dengue has become the most important arboviral infection worldwide with more than 30 million cases of dengue fever estimated to occur each year. The need for a dengue vaccine is great and several live attenuated dengue candidate vaccines are proceeding through clinical evaluation. The need to induce a balanced immune response against all four DENV serotypes with a single vaccine has been a challenge for dengue vaccine developers. A live attenuated DENV chimeric vaccine produced by Sanofi Pasteur has recently entered Phase III evaluation in numerous dengue-endemic regions of the world. Viral interference between serotypes contained in live vaccines has required up to three doses of the vaccine be given over a 12-month period of time. For this reason, novel DENV candidate vaccines are being developed with the goal of achieving a protective immune response with an immunization schedule that can be given over the course of a few months. These next-generation candidates include DNA vaccines, recombinant adenovirus vectored vaccines, alphavirus replicons, and sub-unit protein vaccines. Several of these novel candidates will be discussed.

The effect of current Schistosoma mansoni infection on the immunogenicity of a candidate TB vaccine, MVA85A, in BCG-vaccinated adolescents: An open-label trial.

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Anne Wajja

2017-05-01

Full Text Available Helminth infection may affect vaccine immunogenicity and efficacy. Adolescents, a target population for tuberculosis booster vaccines, often have a high helminth burden. We investigated effects of Schistosoma mansoni (Sm on the immunogenicity and safety of MVA85A, a model candidate tuberculosis vaccine, in BCG-vaccinated Ugandan adolescents.In this phase II open label trial we enrolled 36 healthy, previously BCG-vaccinated adolescents, 18 with no helminth infection detected, 18 with Sm only. The primary outcome was immunogenicity measured by Ag85A-specific interferon gamma ELISpot assay. Tuberculosis and schistosome-specific responses were also assessed by whole-blood stimulation and multiplex cytokine assay, and by antibody ELISAs.Ag85A-specific cellular responses increased significantly following immunisation but with no differences between the two groups. Sm infection was associated with higher pre-immunisation Ag85A-specific IgG4 but with no change in antibody levels following immunisation. There were no serious adverse events. Most reactogenicity events were of mild or moderate severity and resolved quickly.The significant Ag85A-specific T cell responses and lack of difference between Sm-infected and uninfected participants is encouraging for tuberculosis vaccine development. The implications of pre-existing Ag85A-specific IgG4 antibodies for protective immunity against tuberculosis among those infected with Sm are not known. MVA85A was safe in this population.ClinicalTrials.gov NCT02178748.

Potential public health impact of RTS,S malaria candidate vaccine in sub-Saharan Africa: a modelling study.

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Sauboin, Christophe J; Van Bellinghen, Laure-Anne; Van De Velde, Nicolas; Van Vlaenderen, Ilse

2015-12-23

Adding malaria vaccination to existing interventions could help to reduce the health burden due to malaria. This study modelled the potential public health impact of the RTS,S candidate malaria vaccine in 42 malaria-endemic countries in sub-Saharan Africa. An individual-based Markov cohort model was constructed with three categories of malaria transmission intensity and six successive malaria immunity levels. The cycle time was 5 days. Vaccination was assumed to reduce the risk of infection, with no other effects. Vaccine efficacy was assumed to wane exponentially over time. Malaria incidence and vaccine efficacy data were taken from a Phase III trial of the RTS,S vaccine with 18 months of follow-up (NCT00866619). The model was calibrated to reproduce the malaria incidence in the control arm of the trial in each transmission category and published age distribution data. Individual-level heterogeneity in malaria exposure and vaccine protection was accounted for. Parameter uncertainty and variability were captured by using stochastic model transitions. The model followed a cohort from birth to 10 years of age without malaria vaccination, or with RTS,S malaria vaccination administered at age 6, 10 and 14 weeks or at age 6, 7-and-a-half and 9 months. Median and 95% confidence intervals were calculated for the number of clinical malaria cases, severe cases, malaria hospitalizations and malaria deaths expected to be averted by each vaccination strategy. Univariate sensitivity analysis was conducted by varying the values of key input parameters. Vaccination assuming the coverage of diphtheria-tetanus-pertussis (DTP3) at age 6, 10 and 14 weeks is estimated to avert over five million clinical malaria cases, 119,000 severe malaria cases, 98,600 malaria hospitalizations and 31,000 malaria deaths in the 42 countries over the 10-year period. Vaccination at age 6, 7-and-a-half and 9 months with 75% of DTP3 coverage is estimated to avert almost 12.5 million clinical malaria cases

A controlled human malaria infection model enabling evaluation of transmission-blocking interventions

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Collins, K.A.; Wang, C.Y.; Adams, M.; Mitchell, H.; Rampton, M.; Elliott, S.; Reuling, I.J.; Bousema, T.; Sauerwein, R.; Chalon, S.; Mohrle, J.J.; McCarthy, J.S.

2018-01-01

BACKGROUND: Drugs and vaccines that can interrupt the transmission of Plasmodium falciparum will be important for malaria control and elimination. However, models for early clinical evaluation of candidate transmission-blocking interventions are currently unavailable. Here, we describe a new model

AFCo1, a meningococcal B-derived cochleate adjuvant, strongly enhances antibody and T-cell immunity against Plasmodium falciparum merozoite surface protein 4 and 5

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Pérez Oliver

2009-02-01

Full Text Available Abstract Background Whilst a large number of malaria antigens are being tested as candidate malaria vaccines, a major barrier to the development of an effective vaccine is the lack of a suitable human adjuvant capable of inducing a strong and long lasting immune response. In this study, the ability of AFCo1, a potent T and B cell adjuvant based on cochleate structures derived from meningococcal B outer membrane proteoliposomes (MBOMP, to boost the immune response against two Plasmodium falciparum antigens, merozoite surface protein 4 (MSP4 and 5 (MSP5, was evaluated. Methods Complete Freund's adjuvant (CFA, which is able to confer protection against malaria in animal MSP4/5 vaccine challenge models, was used as positive control adjuvant. MSP4 and 5-specific IgG, delayed-type hypersensitivity (DTH, T-cell proliferation, and cytokine production were evaluated in parallel in mice immunized three times intramuscularly with MSP4 or MSP5 incorporated into AFCo1, synthetic cochleate structures, CFA or phosphate buffered saline. Results AFCo1 significantly enhanced the IgG and T-cell response against MSP4 and MSP5, with a potency equivalent to CFA, with the response being characterized by both IgG1 and IgG2a isotypes, increased interferon gamma production and a strong DTH response, consistent with the ability of AFCo1 to induce Th1-like immune responses. Conclusion Given the proven safety of MBOMP, which is already in use in a licensed human vaccine, AFCo1 could assist the development of human malaria vaccines that require a potent and safe adjuvant.

Safety and immunogenicity of an AMA-1 malaria vaccine in Malian adults: results of a phase 1 randomized controlled trial.

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Mahamadou A Thera

2008-01-01

Full Text Available The objective was to evaluate the safety, reactogenicity and immunogenicity of the AMA-1-based blood-stage malaria vaccine FMP2.1/AS02A in adults exposed to seasonal malaria.A phase 1 double blind randomized controlled dose escalation trial was conducted in Bandiagara, Mali, West Africa, a rural town with intense seasonal transmission of Plasmodium falciparum malaria. The malaria vaccine FMP2.1/AS02A is a recombinant protein (FMP2.1 based on apical membrane antigen-1 (AMA-1 from the 3D7 clone of P. falciparum, adjuvanted with AS02A. The comparator vaccine was a cell-culture rabies virus vaccine (RabAvert. Sixty healthy, malaria-experienced adults aged 18-55 y were recruited into 2 cohorts and randomized to receive either a half dose or full dose of the malaria vaccine (FMP2.1 25 microg/AS02A 0.25 mL or FMP2.1 50 microg/AS02A 0.5 mL or rabies vaccine given in 3 doses at 0, 1 and 2 mo, and were followed for 1 y. Solicited symptoms were assessed for 7 d and unsolicited symptoms for 30 d after each vaccination. Serious adverse events were assessed throughout the study. Titers of anti-AMA-1 antibodies were measured by ELISA and P. falciparum growth inhibition assays were performed on sera collected at pre- and post-vaccination time points. Transient local pain and swelling were common and more frequent in both malaria vaccine dosage groups than in the comparator group. Anti-AMA-1 antibodies increased significantly in both malaria vaccine groups, peaking at nearly 5-fold and more than 6-fold higher than baseline in the half-dose and full-dose groups, respectively.The FMP2.1/AS02A vaccine had a good safety profile, was well-tolerated, and was highly immunogenic in malaria-exposed adults. This malaria vaccine is being evaluated in Phase 1 and 2 trials in children at this site.

Development of fluorescent Plasmodium falciparum for in vitro growth inhibition assays

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Crabb Brendan S

2010-06-01

Full Text Available Abstract Background Plasmodium falciparum in vitro growth inhibition assays are widely used to evaluate and quantify the functional activity of acquired and vaccine-induced antibodies and the anti-malarial activity of known drugs and novel compounds. However, several constraints have limited the use of these assays in large-scale population studies, vaccine trials and compound screening for drug discovery and development. Methods The D10 P. falciparum line was transfected to express green fluorescent protein (GFP. In vitro growth inhibition assays were performed over one or two cycles of P. falciparum asexual replication using inhibitory polyclonal antibodies raised in rabbits, an inhibitory monoclonal antibody, human serum samples, and anti-malarials. Parasitaemia was evaluated by microscopy and flow cytometry. Results Transfected parasites expressed GFP throughout all asexual stages and were clearly detectable by flow cytometry and fluorescence microscopy. Measurement of parasite growth inhibition was the same when determined by detection of GFP fluorescence or staining with ethidium bromide. There was no difference in the inhibitory activity of samples when tested against the transfected parasites compared to the parental line. The level of fluorescence of GFP-expressing parasites increased throughout the course of asexual development. Among ring-stages, GFP-fluorescent parasites were readily separated from uninfected erythrocytes by flow cytometry, whereas this was less clear using ethidium bromide staining. Inhibition by serum and antibody samples was consistently higher when tested over two cycles of growth compared to one, and when using a 1 in 10 sample dilution compared to 1 in 20, but there was no difference detected when using a different starting parasitaemia to set-up growth assays. Flow cytometry based measurements of parasitaemia proved more reproducible than microscopy counts. Conclusions Flow cytometry based assays using GFP

Plasmodium falciparum erythrocyte invasion: combining function with immune evasion.

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Gavin J Wright

2014-03-01

Full Text Available All the symptoms and pathology of malaria are caused by the intraerythrocytic stages of the Plasmodium parasite life cycle. Because Plasmodium parasites cannot replicate outside a host cell, their ability to recognize and invade erythrocytes is an essential step for both parasite survival and malaria pathogenesis. This makes invasion a conceptually attractive vaccine target, especially because it is one of the few stages when the parasite is directly exposed to the host humoral immune system. This apparent vulnerability, however, has been countered by the parasite, which has evolved sophisticated molecular mechanisms to evade the host immune response so that parasites asymptomatically replicate within immune individuals. These mechanisms include the expansion of parasite invasion ligands, resulting in multiple and apparently redundant invasion "pathways", highly polymorphic parasite surface proteins that are immunologically distinct, and parasite proteins which are poorly immunogenic. These formidable defences have so far thwarted attempts to develop an effective blood-stage vaccine, leading many to question whether there really is an exploitable chink in the parasite's immune evasion defences. Here, we review recent advances in the molecular understanding of the P. falciparum erythrocyte invasion field, discuss some of the challenges that have so far prevented the development of blood-stage vaccines, and conclude that the parasite invasion ligand RH5 represents an essential pinch point that might be vulnerable to vaccination.

Genetic diversity of Plasmodium vivax and Plasmodium falciparum in Honduras.

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Lopez, Ana Cecilia; Ortiz, Andres; Coello, Jorge; Sosa-Ochoa, Wilfredo; Torres, Rosa E Mejia; Banegas, Engels I; Jovel, Irina; Fontecha, Gustavo A

2012-11-26

Understanding the population structure of Plasmodium species through genetic diversity studies can assist in the design of more effective malaria control strategies, particularly in vaccine development. Central America is an area where malaria is a public health problem, but little is known about the genetic diversity of the parasite's circulating species. This study aimed to investigate the allelic frequency and molecular diversity of five surface antigens in field isolates from Honduras. Five molecular markers were analysed to determine the genotypes of Plasmodium vivax and Plasmodium falciparum from endemic areas in Honduras. Genetic diversity of ama-1, msp-1 and csp was investigated for P. vivax, and msp-1 and msp-2 for P. falciparum. Allelic frequencies were calculated and sequence analysis performed. A high genetic diversity was observed within Plasmodium isolates from Honduras. A different number of genotypes were elucidated: 41 (n = 77) for pvama-1; 23 (n = 84) for pvcsp; and 23 (n = 35) for pfmsp-1. Pvcsp sequences showed VK210 as the only subtype present in Honduran isolates. Pvmsp-1 (F2) was the most polymorphic marker for P. vivax isolates while pvama-1 was least variable. All three allelic families described for pfmsp-1 (n = 30) block 2 (K1, MAD20, and RO33), and both allelic families described for the central domain of pfmsp-2 (n = 11) (3D7 and FC27) were detected. However, K1 and 3D7 allelic families were predominant. All markers were randomly distributed across the country and no geographic correlation was found. To date, this is the most complete report on molecular characterization of P. vivax and P. falciparum field isolates in Honduras with regards to genetic diversity. These results indicate that P. vivax and P. falciparum parasite populations are highly diverse in Honduras despite the low level of transmission.

Identification of mutations in the M RNA of a candidate vaccine strain of Rift Valley fever virus.

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Takehara, K; Min, M K; Battles, J K; Sugiyama, K; Emery, V C; Dalrymple, J M; Bishop, D H

1989-04-01

The M RNA species of a candidate vaccine strain of Rift Valley fever virus (RVFV ZH-548M12), derived by consecutive high level mutagenesis using 5-fluorouracil (H. Caplen, C. J. Peters, and D. H. L. Bishop, J. Gen. Virol., 66, 2271-2277, 1985), has been cloned and the cDNA sequenced. The data have been compared to those obtained for the parent virus strain RVFV ZH-548 as well as the previously published data for RVFV ZH-501 (M. S. Collett, A. F. Purchio, K. Keegan, S. Frazier, W. Hays, D. K. Anderson, M. D. Parker, C. Schmaljohn, J. Schmidt, and J. M. Dalrymple, Virology, 144, 228-245, 1985). Some eight nucleotide and three amino acid differences were identified between the M RNAs of ZH-501 and ZH-548. Between the M RNAs of ZH-548 and that of the M12 mutant there were 12 nucleotide and 7 amino acid changes. Unique to the mutant virus is a new AUG codon upstream of that which initiates the open reading frame of the RVFV M gene product (the viral glycoprotein precursor). The significance of this and other differences in the mutant RNA with regard to the derivation and potential attenuation of the candidate vaccine is discussed.

Current Ebola vaccines

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Hoenen, Thomas; Groseth, Allison; Feldmann, Heinz

2012-01-01

Introduction Ebolaviruses cause severe viral hemorrhagic fever in humans and non-human primates, with case fatality rates of up to 90%. Currently, neither a specific treatment nor a vaccine licensed for use in humans is available. However, a number of vaccine candidates have been developed in the last decade that are highly protective in non-human primates, the gold standard animal model for Ebola hemorrhagic fever. Areas covered This review analyzes a number of scenarios for the use of ebolavirus vaccines, discusses the requirements for ebolavirus vaccines in these scenarios, and describes current ebolavirus vaccines. Among these vaccines are recombinant Adenoviruses, recombinant Vesicular Stomatitis viruses, recombinant Human Parainfluenza viruses and virus-like particles. Interestingly, one of these vaccine platforms, based on recombinant Vesicular Stomatitis viruses, has also demonstrated post-exposure protection in non-human primates. Expert opinion The most pressing remaining challenge is now to move these vaccine candidates forward into human trials and towards licensure. In order to achieve this, it will be necessary to establish the mechanisms and correlates of protection for these vaccines, and to continue to demonstrate their safety, particularly in potentially immunocompromised populations. However, already now there is sufficient evidence that, from a scientific perspective, a vaccine protective against ebolaviruses is possible. PMID:22559078

Evaluation of Live Recombinant Nonpathogenic Leishmania tarentolae Expressing Cysteine Proteinase and A2 Genes as a Candidate Vaccine against Experimental Canine Visceral Leishmaniasis.

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Mehdi Shahbazi

Full Text Available Canine Visceral Leishmaniasis (CVL is a major veterinary and public health problem caused by Leishmania infantum (L. infantum in many endemic countries. It is a severe chronic disease with generalized parasite spread to the reticuloendothelial system, such as spleen, liver and bone marrow and is often fatal when left untreated. Control of VL in dogs would dramatically decrease infection pressure of L. infantum for humans, since dogs are the main domestic reservoir. In the past decade, various subunits and DNA antigens have been identified as potential vaccine candidates in experimental animal models, but none has been approved for human use so far. In this study, we vaccinated outbreed dogs with a prime-boost regimen based on recombinant L. tarentolae expressing the L. donovani A2 antigen along with cysteine proteinase genes (CPA and CPB without its unusual C-terminal extension (CPB-CTE and evaluated its immunogenicity and protective immunity against L. infantum infectious challenge. We showed that vaccinated animals produced significantly higher levels of IgG2, but not IgG1, and also IFN-γ and TNF-α, but low IL-10 levels, before and after challenge as compared to control animals. Protection in dogs was also correlated with a strong DTH response and low parasite burden in the vaccinated group. Altogether, immunization with recombinant L. tarentolae A2-CPA-CPB-CTE was proven to be immunogenic and induced partial protection in dogs, hence representing a promising live vaccine candidate against CVL.

Evaluation of Live Recombinant Nonpathogenic Leishmania tarentolae Expressing Cysteine Proteinase and A2 Genes as a Candidate Vaccine against Experimental Canine Visceral Leishmaniasis

Science.gov (United States)

Shahbazi, Mehdi; Zahedifard, Farnaz; Taheri, Tahereh; Taslimi, Yasaman; Jamshidi, Shahram; Shirian, Sadegh; Mahdavi, Niousha; Hassankhani, Mehdi; Daneshbod, Yahya; Zarkesh-Esfahani, Sayyed Hamid; Papadopoulou, Barbara; Rafati, Sima

2015-01-01

Canine Visceral Leishmaniasis (CVL) is a major veterinary and public health problem caused by Leishmania infantum (L. infantum) in many endemic countries. It is a severe chronic disease with generalized parasite spread to the reticuloendothelial system, such as spleen, liver and bone marrow and is often fatal when left untreated. Control of VL in dogs would dramatically decrease infection pressure of L. infantum for humans, since dogs are the main domestic reservoir. In the past decade, various subunits and DNA antigens have been identified as potential vaccine candidates in experimental animal models, but none has been approved for human use so far. In this study, we vaccinated outbreed dogs with a prime-boost regimen based on recombinant L. tarentolae expressing the L. donovani A2 antigen along with cysteine proteinase genes (CPA and CPB without its unusual C-terminal extension (CPB-CTE) and evaluated its immunogenicity and protective immunity against L. infantum infectious challenge. We showed that vaccinated animals produced significantly higher levels of IgG2, but not IgG1, and also IFN-γ and TNF-α, but low IL-10 levels, before and after challenge as compared to control animals. Protection in dogs was also correlated with a strong DTH response and low parasite burden in the vaccinated group. Altogether, immunization with recombinant L. tarentolae A2-CPA-CPB-CTE was proven to be immunogenic and induced partial protection in dogs, hence representing a promising live vaccine candidate against CVL. PMID:26197085

Structure-activity-based design of a synthetic malaria peptide eliciting sporozoite inhibitory antibodies in a virosomal formulation.

NARCIS (Netherlands)

Okitsu, S.L.; Kienzl, U.; Moehle, K.; Silvie, O.; Peduzzi, E.; Mueller, M.S.; Sauerwein, R.W.; Matile, H.; Zurbriggen, R.; Mazier, D.; Robinson, J.A.; Pluschke, G.

2007-01-01

The circumsporozoite protein (CSP) of Plasmodium falciparum is a leading candidate antigen for inclusion in a malaria subunit vaccine. We describe here the design of a conformationally constrained synthetic peptide, designated UK-39, which has structural and antigenic similarity to the NPNA-repeat

Limited variation of the 5'cis-control region of the transmission ...

African Journals Online (AJOL)

SERVER

2008-03-04

Mar 4, 2008 ... transmission blocking vaccine candidate Pfs25 amid great genetic diversity of Plasmodium falciparum in ... enzymes were selected whose sequences produced or abolished restriction sites ... as chemotherapy and protection against vectors have ..... acquisition of immunity to malaria infection giving to the.

Virosome-formulated Plasmodium falciparum AMA-1 & CSP derived peptides as malaria vaccine: randomized phase 1b trial in semi-immune adults & children.

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Patrick Georges Cech

Full Text Available This trial was conducted to evaluate the safety and immunogenicity of two virosome formulated malaria peptidomimetics derived from Plasmodium falciparum AMA-1 and CSP in malaria semi-immune adults and children.The design was a prospective randomized, double-blind, controlled, age-deescalating study with two immunizations. 10 adults and 40 children (aged 5-9 years living in a malaria endemic area were immunized with PEV3B or virosomal influenza vaccine Inflexal®V on day 0 and 90.No serious or severe adverse events (AEs related to the vaccines were observed. The only local solicited AE reported was pain at injection site, which affected more children in the Inflexal®V group compared to the PEV3B group (p = 0.014. In the PEV3B group, IgG ELISA endpoint titers specific for the AMA-1 and CSP peptide antigens were significantly higher for most time points compared to the Inflexal®V control group. Across all time points after first immunization the average ratio of endpoint titers to baseline values in PEV3B subjects ranged from 4 to 15 in adults and from 4 to 66 in children. As an exploratory outcome, we found that the incidence rate of clinical malaria episodes in children vaccinees was half the rate of the control children between study days 30 and 365 (0.0035 episodes per day at risk for PEV3B vs. 0.0069 for Inflexal®V; RR  = 0.50 [95%-CI: 0.29-0.88], p = 0.02.These findings provide a strong basis for the further development of multivalent virosomal malaria peptide vaccines.ClinicalTrials.gov NCT00513669.

Algae-Produced Pfs25 Elicits Antibodies That Inhibit Malaria Transmission

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Gregory, James A.; Li, Fengwu; Tomosada, Lauren M.; Cox, Chesa J.; Topol, Aaron B.; Vinetz, Joseph M.; Mayfield, Stephen

2012-01-01

Subunit vaccines are significantly more expensive to produce than traditional vaccines because they are based primarily on recombinant proteins that must be purified from the expression system. Despite the increased cost, subunit vaccines are being developed because they are safe, effective, and can elicit antibodies that confer protection against diseases that are not currently vaccine-preventable. Algae are an attractive platform for producing subunit vaccines because they are relatively inexpensive to grow, genetically tractable, easily scaled to large volumes, have a short generation time, and are devoid of inflammatory, viral, or prion contaminants often present in other systems. We tested whether algal chloroplasts can produce malaria transmission blocking vaccine candidates, Plasmodium falciparum surface protein 25 (Pfs25) and 28 (Pfs28). Antibodies that recognize Pfs25 and Pfs28 disrupt the sexual development of parasites within the mosquito midgut, thus preventing transmission of malaria from one human host to the next. These proteins have been difficult to produce in traditional recombinant systems because they contain tandem repeats of structurally complex epidermal growth factor-like domains, which cannot be produced in bacterial systems, and because they are not glycosylated, so they must be modified for production in eukaryotic systems. Production in algal chloroplasts avoids these issues because chloroplasts can fold complex eukaryotic proteins and do not glycosylate proteins. Here we demonstrate that algae are the first recombinant system to successfully produce an unmodified and aglycosylated version of Pfs25 or Pfs28. These antigens are structurally similar to the native proteins and antibodies raised to these recombinant proteins recognize Pfs25 and Pfs28 from P. falciparum. Furthermore, antibodies to algae-produced Pfs25 bind the surface of in-vitro cultured P. falciparum sexual stage parasites and exhibit transmission blocking activity. Thus

Safety and immunogenicity of an AMA1 malaria vaccine in Malian children: results of a phase 1 randomized controlled trial.

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Mahamadou A Thera

2010-02-01

Full Text Available The objective was to evaluate the safety and immunogenicity of the AMA1-based malaria vaccine FMP2.1/AS02(A in children exposed to seasonal falciparum malaria.A Phase 1 double blind randomized controlled dose escalation trial was conducted in Bandiagara, Mali, West Africa, a rural town with intense seasonal transmission of Plasmodium falciparum malaria. The malaria vaccine FMP2.1/AS02(A is a recombinant protein (FMP2.1 based on apical membrane antigen 1 (AMA1 from the 3D7 clone of P. falciparum, formulated in the Adjuvant System AS02(A. The comparator vaccine was a cell-culture rabies virus vaccine (RabAvert. One hundred healthy Malian children aged 1-6 years were recruited into 3 cohorts and randomized to receive either 10 microg FMP2.1 in 0.1 mL AS02(A, or 25 microg FMP2.1 in 0.25 mL AS02(A, or 50 microg FMP2.1 50 microg in 0.5 mL AS02(A, or rabies vaccine. Three doses of vaccine were given at 0, 1 and 2 months, and children were followed for 1 year. Solicited symptoms were assessed for 7 days and unsolicited symptoms for 30 days after each vaccination. Serious adverse events were assessed throughout the study. Transient local pain and swelling were common and more frequent in all malaria vaccine dosage groups than in the comparator group, but were acceptable to parents of participants. Levels of anti-AMA1 antibodies measured by ELISA increased significantly (at least 100-fold compared to baseline in all 3 malaria vaccine groups, and remained high during the year of follow up.The FMP2.1/AS02(A vaccine had a good safety profile, was well-tolerated, and induced high and sustained antibody levels in malaria-exposed children. This malaria vaccine is being evaluated in a Phase 2 efficacy trial in children at this site.ClinicalTrials.gov NCT00358332 [NCT00358332].

Assessment of Lactobacillus gasseri as a candidate oral vaccine vector.

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Stoeker, Laura; Nordone, Shila; Gunderson, Sara; Zhang, Lin; Kajikawa, Akinobu; LaVoy, Alora; Miller, Michael; Klaenhammer, Todd R; Dean, Gregg A

2011-11-01

Lactobacillus species are commensal bacteria that have long been recognized as probiotic microbes and are generally regarded as safe (GRAS) for human consumption. We have investigated the use of L. gasseri as a vaccine vector for oral immunization against mucosal pathogens. Recent research has shown that the immune response to different lactobacilli can vary widely depending on the species or subspecies of Lactobacillus being studied. While some lactobacilli seem to induce oral tolerance, others induce an adaptive immune response. This study characterized the systemic and mucosal immune response to wild-type and genetically modified L. gasseri. L. gasseri primarily activates TLR2/6, with additional activation through the TLR2 homodimer. To expand the Toll-like receptor (TLR) activation profile of L. gasseri and the immunogenicity of the vector, a plasmid containing fliC, the gene encoding bacterial flagellin, was introduced which resulted in the strong activation of TLR5. The treatment of human myeloid dendritic cells with recombinant lactobacilli expressing flagellin triggered phenotypic maturation and the release of proinflammatory cytokines. In contrast, bacterial treatment also resulted in a statistically significant increase in IL-10 production. In vivo studies established that treatment with L. gasseri led to a diversification of B-cell populations in the lamina propria of the murine colon. Furthermore, treatment with genetically modified L. gasseri led to a significant decrease in the percentage of FoxP3(+) colonic lymphocytes. Taken together, these data clarify the interaction of L. gasseri with the host immune system and support further investigation of the in vivo immunogenicity of L. gasseri expressing both flagellin and candidate vaccine antigens.

Differing Efficacies of Lead Group A Streptococcal Vaccine Candidates and Full-Length M Protein in Cutaneous and Invasive Disease Models

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Tania Rivera-Hernandez

2016-06-01

Full Text Available Group A Streptococcus (GAS is an important human pathogen responsible for both superficial infections and invasive diseases. Autoimmune sequelae may occur upon repeated infection. For this reason, development of a vaccine against GAS represents a major challenge, since certain GAS components may trigger autoimmunity. We formulated three combination vaccines containing the following: (i streptolysin O (SLO, interleukin 8 (IL-8 protease (Streptococcus pyogenes cell envelope proteinase [SpyCEP], group A streptococcal C5a peptidase (SCPA, arginine deiminase (ADI, and trigger factor (TF; (ii the conserved M-protein-derived J8 peptide conjugated to ADI; and (iii group A carbohydrate lacking the N-acetylglucosamine side chain conjugated to ADI. We compared these combination vaccines to a “gold standard” for immunogenicity, full-length M1 protein. Vaccines were adjuvanted with alum, and mice were immunized on days 0, 21, and 28. On day 42, mice were challenged via cutaneous or subcutaneous routes. High-titer antigen-specific antibody responses with bactericidal activity were detected in mouse serum samples for all vaccine candidates. In comparison with sham-immunized mice, all vaccines afforded protection against cutaneous challenge. However, only full-length M1 protein provided protection in the subcutaneous invasive disease model.

Broadly reactive antibodies specific for Plasmodium falciparum MSP-119 are associated with the protection of naturally exposed children against infection

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Dent Arlene E

2012-08-01

Full Text Available Abstract Background The 19 kDa C-terminal region of Plasmodium falciparum Merozoite Surface Protein-1 is a known target of naturally acquired humoral immunity and a malaria vaccine candidate. MSP-119 has four predominant haplotypes resulting in amino acid changes labelled EKNG, QKNG, QTSR and ETSR. IgG antibodies directed against all four variants have been detected, but it is not known if these variant specific antibodies are associated with haplotype-specific protection from infection. Methods Blood samples from 201 healthy Kenyan adults and children who participated in a 12-week treatment time-to-infection study were evaluated. Venous blood drawn at baseline (week 0 was examined for functional and serologic antibodies to MSP-119 and MSP-142 variants. MSP-119 haplotypes were detected by a multiplex PCR assay at baseline and weekly throughout the study. Generalized linear models controlling for age, baseline MSP-119 haplotype and parasite density were used to determine the relationship between infecting P. falciparum MSP-119 haplotype and variant-specific antibodies. Results A total of 964 infections resulting in 1,533 MSP-119 haplotypes detected were examined. The most common haplotypes were EKNG and QKNG, followed by ETSR and QTSR. Children had higher parasite densities, greater complexity of infection (>1 haplotype, and more frequent changes in haplotypes over time compared to adults. Infecting MSP-119 haplotype at baseline (week 0 had no influence on haplotypes detected over the subsequent 11 weeks among children or adults. Children but not adults with MSP-119 and some MSP-142 variant antibodies detected by serology at baseline had delayed time-to-infection. There was no significant association of variant-specific serology or functional antibodies at baseline with infecting haplotype at baseline or during 11 weeks of follow up among children or adults. Conclusions Variant transcending IgG antibodies to MSP-119 are associated with protection

Conventional influenza vaccines influence the performance of a universal influenza vaccine in mice.

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Rowell, Janelle; Lo, Chia-Yun; Price, Graeme E; Misplon, Julia A; Epstein, Suzanne L; Garcia, Mayra

2018-02-08

Universal influenza vaccines are designed to protect against diverse strains of influenza virus. Preclinical testing of new vaccine candidates is usually done in naïve animals, despite intended use in the human population with its varied immune history including responses to previous vaccinations. As an approach more relevant to human use, we tested a candidate universal influenza vaccine in mice with a history of conventional vaccination. Female BALB/c mice were given two intramuscular doses of inactivated influenza vaccine (IIV) or diphtheria and tetanus toxoids vaccine (DT), one month apart. Another group was given two intranasal doses of live attenuated influenza virus (LAIV). One month after the second dose, mice were given the universal influenza vaccine: recombinant adenoviruses expressing influenza A nucleoprotein (A/NP) and matrix 2 (M2) (A/NP + M2-rAd). Immune responses to universal vaccine antigens A/NP and M2 were assessed by ELISA and interferon-γ ELISPOT. Protection was tested by challenge with mouse-adapted A/FM/1/47 (H1N1) and monitoring for weight loss and survival. Universal vaccine performance was enhanced, inhibited or unaffected by particular prior vaccinations. Mice given Afluria IIV and LAIV had greater antibody and T-cell response to A/NP than mice without prior vaccination, providing examples of enhanced A/NP + M2-rAd performance. Though Fluvirin IIV partially inhibited, the universal vaccine still provided considerable protection unlike conventional vaccination. Fluzone IIV and DT had no effect on A/NP + M2-rAd performance. Thus our results demonstrate that universal vaccine candidate A/NP + M2-rAd was at least partially effective in mice with diverse prior histories. However, the degree of protection and nature of the immune responses may be affected by a history of conventional vaccination and suggests that performance in humans would be influenced by immune history. Published by Elsevier Ltd.

Plasmodium falciparum field isolates from South America use an atypical red blood cell invasion pathway associated with invasion ligand polymorphisms.

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Mary Lopez-Perez

Full Text Available Studies of Plasmodium falciparum invasion pathways in field isolates have been limited. Red blood cell (RBC invasion is a complex process involving two invasion protein families; Erythrocyte Binding-Like (EBL and the Reticulocyte Binding-Like (PfRh proteins, which are polymorphic and not fully characterized in field isolates. To determine the various P. falciparum invasion pathways used by parasite isolates from South America, we studied the invasion phenotypes in three regions: Colombia, Peru and Brazil. Additionally, polymorphisms in three members of the EBL (EBA-181, EBA-175 and EBL-1 and five members of the PfRh (PfRh1, PfRh2a, PfRh2b, PfRh4, PfRh5 families were determined. We found that most P. falciparum field isolates from Colombia and Peru invade RBCs through an atypical invasion pathway phenotypically characterized as resistant to all enzyme treatments (NrTrCr. Moreover, the invasion pathways and the ligand polymorphisms differed substantially among the Colombian and Brazilian isolates while the Peruvian isolates represent an amalgam of those present in the Colombian and Brazilian field isolates. The NrTrCr invasion profile was associated with the presence of the PfRh2a pepC variant, the PfRh5 variant 1 and EBA-181 RVNKN variant. The ebl and Pfrh expression levels in a field isolate displaying the NrTrCr profile also pointed to PfRh2a, PfRh5 and EBA-181 as being possibly the major players in this invasion pathway. Notably, our studies demonstrate the uniqueness of the Peruvian P. falciparum field isolates in terms of their invasion profiles and ligand polymorphisms, and present a unique opportunity for studying the ability of P. falciparum parasites to expand their invasion repertoire after being reintroduced to human populations. The present study is directly relevant to asexual blood stage vaccine design focused on invasion pathway proteins, suggesting that regional invasion variants and global geographical variation are likely to

The establishment of a WHO Reference Reagent for anti-malaria (Plasmodium falciparum) human serum.

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Bryan, Donna; Silva, Nilupa; Rigsby, Peter; Dougall, Thomas; Corran, Patrick; Bowyer, Paul W; Ho, Mei Mei

2017-08-05

At a World Health Organization (WHO) sponsored meeting it was concluded that there is an urgent need for a reference preparation that contains antibodies against malaria antigens in order to support serology studies and vaccine development. It was proposed that this reference would take the form of a lyophilized serum or plasma pool from a malaria-endemic area. In response, an immunoassay standard, comprising defibrinated human plasma has been prepared and evaluated in a collaborative study. A pool of human plasma from a malaria endemic region was collected from 140 single plasma donations selected for reactivity to Plasmodium falciparum apical membrane antigen-1 (AMA-1) and merozoite surface proteins (MSP-1 19 , MSP-1 42 , MSP-2 and MSP-3). This pool was defibrinated, filled and freeze dried into a single batch of ampoules to yield a stable source of naturally occurring antibodies to P. falciparum. The preparation was evaluated by an enzyme-linked immunosorbent assay (ELISA) in a collaborative study with sixteen participants from twelve different countries. This anti-malaria human serum preparation (NIBSC Code: 10/198) was adopted by the WHO Expert Committee on Biological Standardization (ECBS) in October 2014, as the first WHO reference reagent for anti-malaria (Plasmodium falciparum) human serum with an assigned arbitrary unitage of 100 units (U) per ampoule. Analysis of the reference reagent in a collaborative study has demonstrated the benefit of this preparation for the reduction in inter- and intra-laboratory variability in ELISA. Whilst locally sourced pools are regularly use for harmonization both within and between a few laboratories, the presence of a WHO-endorsed reference reagent should enable optimal harmonization of malaria serological assays either by direct use of the reference reagent or calibration of local standards against this WHO reference. The intended uses of this reference reagent, a multivalent preparation, are (1) to allow cross

Development and evaluation of novel recombinant adenovirus-based vaccine candidates for infectious bronchitis virus and Mycoplasma gallisepticum in chickens.

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Zhang, Dongchao; Long, Yuqing; Li, Meng; Gong, Jianfang; Li, Xiaohui; Lin, Jing; Meng, Jiali; Gao, Keke; Zhao, Ruili; Jin, Tianming

2018-04-01

Avian infectious bronchitis caused by the infectious bronchitis virus (IBV), and mycoplasmosis caused by Mycoplasma gallisepticum (MG) are two major respiratory diseases in chickens that have resulted in severe economic losses in the poultry industry. We constructed a recombinant adenovirus that simultaneously expresses the S1 spike glycoprotein of IBV and the TM-1 protein of MG (pBH-S1-TM-1-EGFP). For comparison, we constructed two recombinant adenoviruses (pBH-S1-EGFP and pBH-TM-1-EGFP) that express either the S1 spike glycoprotein or the TM-1 protein alone. The protective efficacy of these three vaccine constructs against challenge with IBV and/or MG was evaluated in specific pathogen free chickens. Groups of seven-day-old specific pathogen free chicks were immunized twice, two weeks apart, via the oculonasal route with the pBH-S1-TM-1-EGFP, pBH-S1-EGFP, or pBH-TM-1-EGFP vaccine candidates or the commercial attenuated infectious bronchitis vaccine strain H52 and MG vaccine strain F-36 (positive controls), and challenged with virulent IBV or MG two weeks later. Interestingly, by days 7 and 14 after the booster immunization, pBH-S1-TM-1-EGFP-induced antibody titre was significantly higher (P attenuated commercial IBV vaccine; however, there was no significant difference between the pBH-S1-TM-1-EGFP and attenuated commercial MG vaccine groups (P > 0.05). The clinical signs, the gross, and histopathological lesions scores of the adenovirus vaccine constructs were not significantly different from that of the attenuated commercial IBV or MG vaccines (positive controls) (P > 0.05). These results demonstrate the potential of the bivalent pBH-S1-TM-1-EGFP adenovirus construct as a combination vaccine against IB and mycoplasmosis.

Quantitative PCR evaluation of cellular immune responses in Kenyan children vaccinated with a candidate malaria vaccine.

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Jedidah Mwacharo

2009-12-01

Full Text Available The T-cell mediated immune response plays a central role in the control of malaria after natural infection or vaccination. There is increasing evidence that T-cell responses are heterogeneous and that both the quality of the immune response and the balance between pro-inflammatory and regulatory T-cells determines the outcome of an infection. As Malaria parasites have been shown to induce immunosuppressive responses to the parasite and non-related antigens this study examined T-cell mediated pro-inflammatory and regulatory immune responses induced by malaria vaccination in children in an endemic area to determine if these responses were associated with vaccine immunogenicity.Using real-time RT- PCR we profiled the expression of a panel of key markers of immunogenecity at different time points after vaccination with two viral vector vaccines expressing the malaria TRAP antigen (FP9-TRAP and MVA-TRAP or following rabies vaccination as a control.The vaccine induced modest levels of IFN-gamma mRNA one week after vaccination. There was also an increase in FoxP3 mRNA expression in both TRAP stimulated and media stimulated cells in the FFM ME-TRAP vaccine group; however, this may have been driven by natural exposure to parasite rather than by vaccination.Quantitative PCR is a useful method for evaluating vaccine induced cell mediated immune responses in frozen PBMC from children in a malaria endemic country. Future studies should seek to use vaccine vectors that increase the magnitude and quality of the IFN-gamma immune response in naturally exposed populations and should monitor the induction of a regulatory T cell response.

Identification of potential new protein vaccine candidates through pan-surfomic analysis of pneumococcal clinical isolates from adults.

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Alfonso Olaya-Abril

Full Text Available Purified polysaccharide and conjugate vaccines are widely used for preventing infections in adults and in children against the Gram-positive bacterium Streptococcus pneumoniae, a pathogen responsible for high morbidity and mortality rates, especially in developing countries. However, these polysaccharide-based vaccines have some important limitations, such as being serotype-dependent, being subjected to losing efficacy because of serotype replacement and high manufacturing complexity and cost. It is expected that protein-based vaccines will overcome these issues by conferring a broad coverage independent of serotype and lowering production costs. In this study, we have applied the "shaving" proteomic approach, consisting of the LC/MS/MS analysis of peptides generated by protease treatment of live cells, to a collection of 16 pneumococcal clinical isolates from adults, representing the most prevalent strains circulating in Spain during the last years. The set of unique proteins identified in all the isolates, called "pan-surfome", consisted of 254 proteins, which included most of the protective protein antigens reported so far. In search of new candidates with vaccine potential, we identified 32 that were present in at least 50% of the clinical isolates analyzed. We selected four of them (Spr0012, Spr0328, Spr0561 and SP670_2141, whose protection capacity has not yet been tested, for assaying immunogenicity in human sera. All of them induced the production of IgM antibodies in infected patients, thus indicating that they could enter the pipeline for vaccine studies. The pan-surfomic approach shows its utility in the discovery of new proteins that can elicit protection against infectious microorganisms.

Successes and failures in human tuberculosis vaccine development.

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Zenteno-Cuevas, Roberto

2017-12-01

Tuberculosis (TB) is an infectious disease caused mainly by Mycobacterium tuberculosis. In 2016, the WHO estimated 10.5 million new cases and 1.8 million deaths, making this disease the leading cause of death by an infectious agent. The current and projected TB situation necessitates the development of new vaccines with improved attributes compared to the traditional BCG method. Areas covered: In this review, the authors describe the most promising candidate vaccines against TB and discuss additional key elements in vaccine development, such as animal models, new adjuvants and immunization routes and new strategies for the identification of candidate vaccines. Expert opinion: At present, around 13 candidate vaccines for TB are in the clinical phase of evaluation; however, there is still no substitute for the BCG vaccine. One major impediment to developing an effective vaccine is our lack of understanding of several of the mechanisms associated with infection and the immune response against TB. However, the recent implementation of an entirely new set of technological advances will facilitate the proposal of new candidates. Finally, development of a new vaccine will require a major coordination of effort in order to achieve its effective administration to the people most in need of it.

A 52 Kilodalton Protein Vaccine Candidate for Francisella tularensis

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2004-12-01

du vaccin vivant F. tularensis (LVS). Soixante pourcent (60%) des souris vaccindes ont survdcu la dose ltale multiple alors que toutes les souris non...le lysat des cellules de cultures vivantes du vaccin vivant F. tularensis. Plusieurs composants de Francisella tularensis ont dt6 identifids par cet...antiserum. Le s6rum de souris provenant de souris vaccin6es avec F. tularensis non- vivant n’a pas identifid ces composants. A partir de ces prot6ines

The recent progress in RSV vaccine technology.

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Fretzayas, Andrew; Papadopoulou, Anna; Kotzia, Doxa; Moustaki, Maria

2012-12-01

The most effective way to control RSV infection would be the development of an expedient and safe vaccine. Subunit vaccines, live attenuated RSV vaccines, plasmid DNA vaccines have been tested either in human or in mouse models without reaching the ultimate goal of efficacy and safety, at least in humans. Viruses such as adenovirus, sendai virus, measles virus were also used as vectors for the generation of RSV vaccines with promising results in animal models. Recent patents describe new techniques for the generation of candidate vaccines. These patents include virus like particles as vaccine platforms, recombinant RSVs or modified RSV F protein as component of the vaccine. Despite the number of the candidate vaccines, the new RSV vaccines should overcome many obstacles before being established as effective vaccines for the control of RSV infections especially for the young infants who are more susceptible to the virus.

Attenuation and efficacy of human parainfluenza virus type 1 (HPIV1 vaccine candidates containing stabilized mutations in the P/C and L genes

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Skiadopoulos Mario H

2007-07-01

Full Text Available Abstract Background Two recombinant, live attenuated human parainfluenza virus type 1 (rHPIV1 mutant viruses have been developed, using a reverse genetics system, for evaluation as potential intranasal vaccine candidates. These rHPIV1 vaccine candidates have two non-temperature sensitive (non-ts attenuating (att mutations primarily in the P/C gene, namely CR84GHNT553A (two point mutations used together as a set and CΔ170 (a short deletion mutation, and two ts att mutations in the L gene, namely LY942A (a point mutation, and LΔ1710–11 (a short deletion, the last of which has not been previously described. The latter three mutations were specifically designed for increased genetic and phenotypic stability. These mutations were evaluated on the HPIV1 backbone, both individually and in combination, for attenuation, immunogenicity, and protective efficacy in African green monkeys (AGMs. Results The rHPIV1 mutant bearing the novel LΔ1710–11 mutation was highly ts and attenuated in AGMs and was immunogenic and efficacious against HPIV1 wt challenge. The rHPIV1-CR84G/Δ170HNT553ALY942A and rHPIV1-CR84G/Δ170HNT553ALΔ1710–11 vaccine candidates were highly ts, with shut-off temperatures of 38°C and 35°C, respectively, and were highly attenuated in AGMs. Immunization with rHPIV1-CR84G/Δ170HNT553ALY942A protected against HPIV1 wt challenge in both the upper and lower respiratory tracts. In contrast, rHPIV1-CR84G/Δ170HNT553ALΔ1710–11 was not protective in AGMs due to over-attenuation, but it is expected to replicate more efficiently and be more immunogenic in the natural human host. Conclusion The rHPIV1-CR84G/Δ170HNT553ALY942A and rHPIV1-CR84G/Δ170HNT553ALΔ1710–11 vaccine candidates are clearly highly attenuated in AGMs and clinical trials are planned to address safety and immunogenicity in humans.

High-yield production of a stable Vero cell-based vaccine candidate against the highly pathogenic avian influenza virus H5N1

International Nuclear Information System (INIS)

Zhou, Fangye; Zhou, Jian; Ma, Lei; Song, Shaohui; Zhang, Xinwen; Li, Weidong; Jiang, Shude; Wang, Yue; Liao, Guoyang

2012-01-01

Highlights: ► Vero cell-based HPAI H5N1 vaccine with stable high yield. ► Stable high yield derived from the YNVa H3N2 backbone. ► H5N1/YNVa has a similar safety and immunogenicity to H5N1delta. -- Abstract: Highly pathogenic avian influenza (HPAI) viruses pose a global pandemic threat, for which rapid large-scale vaccine production technology is critical for prevention and control. Because chickens are highly susceptible to HPAI viruses, the supply of chicken embryos for vaccine production might be depleted during a virus outbreak. Therefore, developing HPAI virus vaccines using other technologies is critical. Meeting vaccine demand using the Vero cell-based fermentation process has been hindered by low stability and yield. In this study, a Vero cell-based HPAI H5N1 vaccine candidate (H5N1/YNVa) with stable high yield was achieved by reassortment of the Vero-adapted (Va) high growth A/Yunnan/1/2005(H3N2) (YNVa) virus with the A/Anhui/1/2005(H5N1) attenuated influenza vaccine strain (H5N1delta) using the 6/2 method. The reassorted H5N1/YNVa vaccine maintained a high hemagglutination (HA) titer of 1024. Furthermore, H5N1/YNVa displayed low pathogenicity and uniform immunogenicity compared to that of the parent virus.

Ensayo preclínico de la vacuna candid #1 producida en Argentina contra la Fiebre Hemorrágica Argentina Preclinical assay of Candid #1 vaccine against Argentine Hemorrhagic Fever made in Argentina

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Ana M. Ambrosio

2005-08-01

Full Text Available Se comparó en cobayos la seguridad, inmunogenicidad y eficacia protectora de un lote de vacuna Candid #1(C#1 fabricada en Estados Unidos de América (EE.UU. y distintos lotes de la misma vacuna fabricados en Argentina (Arg. El lote TSI 5-1-92 (EE.UU. y los lotes Exp Nº 3, 7A y 8A (Arg fueron inoculados (0.5 ml, IM en cobayos de 250-400 g. Para cada ensayo diez animales recibieron solución fisiológica y sirvieron como control. Todos fueron desafiados con la cepa patógena P23790 de virus Junin. Se registró: a temperatura rectal, b peso corporal, c presencia de anticuerpos neutralizantes (AcNT pre y post-vacunación, d respuesta al desafío. Todos los animales vacunados desarrollaron AcNT anti virus Junin (rango = 40- 81920 y sobrevivieron al desafío. En cada grupo control 8/10 animales murieron (día 23.3 ± 5.4 post-desafío. Los cobayos resultaron idénticamente protegidos de una descarga letal de virus Junin por la vacuna importada y los diferentes lotes de C#1 producidos en Argentina.Candid #1 vaccine against Argentine Hemorrhagic Fever produced in USA versus lots of the same vaccine made in Argentina were compared in guinea pigs regarding safety, immunogenicity and protective efficacy against a challenge with pathogenic Junin virus. Lots Nº Exp 3, 7A and 8A of Argentine origin as well as lot TSI 5-1-92 from USA were inoculated in guinea pigs of 250-400 g in two consecutive assays. Ten animals inoculated with saline performed as normal controls in each experiment. Parameters studied were: a temperature; b body weight; c neutralizing antibodies to Junin virus; d response to viral challenge. Animals gained weight and remained normothermic up to the challenge. Guinea pigs that received Candid #1 from any manufacturer elicited neutralizing antibodies to Junin virus (titles from 40 to 81920 and survived to challenge whilst 8/10 animals died in each control group. Data presented demonstrated that Candid #1 vaccines from USA or Argentine

Identification of Two New Protective Pre-erythrocytic Malaria Vaccine Antigen Candidates

Science.gov (United States)

2011-01-01

Anthony R, Grainger M, Haynes J, Moch J, Muster N, Sacci J, Tabb D, Witney A, Wolters D, Wu Y, Gardner M, Holder A, Sinden R, Yates J, Carucci D: A...proteomic view of the Plasmodium falciparum life cycle. Nature 2002, 419:520-526. 16. LeRoch D, Zhou Y, Blair P, Grainger M, Moch J, Haynes J, De La Vega P

Phase 1 trial of AMA1-C1/Alhydrogel plus CPG 7909: an asexual blood-stage vaccine for Plasmodium falciparum malaria.

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Gregory E D Mullen

2008-08-01

Full Text Available Apical Membrane Antigen 1 (AMA1, a polymorphic merozoite surface protein, is a leading blood-stage malaria vaccine candidate. This is the first reported use in humans of an investigational vaccine, AMA1-C1/Alhydrogel, with the novel adjuvant CPG 7909.A phase 1 trial was conducted at the University of Rochester with 75 malaria-naive volunteers to assess the safety and immunogenicity of the AMA1-C1/Alhydrogel+CPG 7909 malaria vaccine. Participants were sequentially enrolled and randomized within dose escalating cohorts to receive three vaccinations on days 0, 28 and 56 of either 20 microg of AMA1-C1/Alhydrogel+564 microg CPG 7909 (n = 15, 80 microg of AMA1-C1/Alhydrogel (n = 30, or 80 microg of AMA1-C1/Alhydrogel+564 microg CPG 7909 (n = 30.Local and systemic adverse events were significantly more likely to be of higher severity with the addition of CPG 7909. Anti-AMA1 immunoglobulin G (IgG were detected by enzyme-linked immunosorbent assay (ELISA, and the immune sera of volunteers that received 20 microg or 80 microg of AMA1-C1/Alhydrogel+CPG 7909 had up to 14 fold significant increases in anti-AMA1 antibody concentration compared to 80 microg of AMA1-C1/Alhydrogel alone. The addition of CPG 7909 to the AMA1-C1/Alhydrogel vaccine in humans also elicited AMA1 specific immune IgG that significantly and dramatically increased the in vitro growth inhibition of homologous parasites to levels as high as 96% inhibition.The safety profile of the AMA1-C1/Alhydrogel+CPG 7909 malaria vaccine is acceptable, given the significant increase in immunogenicity observed. Further clinical development is ongoing.ClinicalTrials.gov NCT00344539.

Expression, Purification and Characterization of GMZ2'.10C, a Complex Disulphide-Bonded Fusion Protein Vaccine Candidate against the Asexual and Sexual Life-Stages of the Malaria-Causing Plasmodium falciparum Parasite.

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Mistarz, Ulrik H; Singh, Susheel K; Nguyen, Tam T T N; Roeffen, Will; Yang, Fen; Lissau, Casper; Madsen, Søren M; Vrang, Astrid; Tiendrebeogo, Régis W; Kana, Ikhlaq H; Sauerwein, Robert W; Theisen, Michael; Rand, Kasper D

2017-09-01

Production and characterization of a chimeric fusion protein (GMZ2'.10C) which combines epitopes of key malaria parasite antigens: glutamate-rich protein (GLURP), merozoite surface protein 3 (MSP3), and the highly disulphide bonded Pfs48/45 (10C). GMZ2'.10C is a potential candidate for a multi-stage malaria vaccine that targets both transmission and asexual life-cycle stages of the parasite. GMZ2'.10C was produced in Lactococcus lactis and purified using either an immunoaffinity purification (IP) or a conventional purification (CP) method. Protein purity and stability was analysed by RP-HPLC, SEC-HPLC, 2-site ELISA, gel-electrophoresis and Western blotting. Structural characterization (mass analysis, peptide mapping and cysteine connectivity mapping) was performed by LC-MS/MS. CP-GMZ2'.10C resulted in similar purity, yield, structure and stability as compared to IP-GMZ2'.10C. CP-GMZ2'.10C and IP-GMZ2'.10C both elicited a high titer of transmission blocking (TB) antibodies in rodents. The intricate disulphide-bond connectivity of C-terminus Pfs48/45 was analysed by tandem mass spectrometry and was established for GMZ2'.10C and two reference fusion proteins encompassing similar parts of Pfs48/45. GMZ2'.10C, combining GMZ2' and correctly-folded Pfs48/45 can be produced by the Lactoccus lactis P170 based expression system in purity and quality for pharmaceutical development and elicit high level of TB antibodies. The cysteine connectivity for the 10C region of Pfs48/45 was revealed experimentally, providing an important guideline for employing the Pfs48/45 antigen in vaccine design.

Interferon-γ, a valuable surrogate marker of Plasmodium falciparum pre-erythrocytic stages protective immunity

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BenMohamed Lbachir

2011-02-01

Full Text Available Abstract Immunity against the pre-erythrocytic stages of malaria is the most promising, as it is strong and fully sterilizing. Yet, the underlying immune effectors against the human Plasmodium falciparum pre-erythrocytic stages remain surprisingly poorly known and have been little explored, which in turn prevents any rational vaccine progress. Evidence that has been gathered in vitro and in vivo, in higher primates and in humans, is reviewed here, emphasizing the significant role of IFN-γ, either as a critical immune mediator or at least as a valuable surrogate marker of protection. One may hope that these results will trigger investigations in volunteers immunized either by optimally irradiated or over-irradiated sporozoites, to quickly delineate better surrogates of protection, which are essential for the development of a successful malaria vaccine.

Assessment of Lactobacillus gasseri as a Candidate Oral Vaccine Vector ▿

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Stoeker, Laura; Nordone, Shila; Gunderson, Sara; Zhang, Lin; Kajikawa, Akinobu; LaVoy, Alora; Miller, Michael; Klaenhammer, Todd R.; Dean, Gregg A.

2011-01-01

Lactobacillus species are commensal bacteria that have long been recognized as probiotic microbes and are generally regarded as safe (GRAS) for human consumption. We have investigated the use of L. gasseri as a vaccine vector for oral immunization against mucosal pathogens. Recent research has shown that the immune response to different lactobacilli can vary widely depending on the species or subspecies of Lactobacillus being studied. While some lactobacilli seem to induce oral tolerance, others induce an adaptive immune response. This study characterized the systemic and mucosal immune response to wild-type and genetically modified L. gasseri. L. gasseri primarily activates TLR2/6, with additional activation through the TLR2 homodimer. To expand the Toll-like receptor (TLR) activation profile of L. gasseri and the immunogenicity of the vector, a plasmid containing fliC, the gene encoding bacterial flagellin, was introduced which resulted in the strong activation of TLR5. The treatment of human myeloid dendritic cells with recombinant lactobacilli expressing flagellin triggered phenotypic maturation and the release of proinflammatory cytokines. In contrast, bacterial treatment also resulted in a statistically significant increase in IL-10 production. In vivo studies established that treatment with L. gasseri led to a diversification of B-cell populations in the lamina propria of the murine colon. Furthermore, treatment with genetically modified L. gasseri led to a significant decrease in the percentage of FoxP3+ colonic lymphocytes. Taken together, these data clarify the interaction of L. gasseri with the host immune system and support further investigation of the in vivo immunogenicity of L. gasseri expressing both flagellin and candidate vaccine antigens. PMID:21900526

Impact of child malnutrition on the specific anti-Plasmodium falciparum antibody response

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Fillol Florie

2009-06-01

Full Text Available Abstract Background In sub-Saharan Africa, preschool children represent the population most vulnerable to malaria and malnutrition. It is widely recognized that malnutrition compromises the immune function, resulting in higher risk of infection. However, very few studies have investigated the relationship between malaria, malnutrition and specific immunity. In the present study, the anti-Plasmodium falciparum IgG antibody (Ab response was evaluated in children according to the type of malnutrition. Methods Anthropometric assessment and blood sample collection were carried out during a cross-sectional survey including rural Senegalese preschool children. This cross-sectional survey was conducted in July 2003 at the onset of the rainy season. Malnutrition was defined as stunting (height-for-age P. falciparum whole extracts (schizont antigens was assessed by ELISA in sera of the included children. Results Both the prevalence of anti-malarial immune responders and specific IgG Ab levels were significantly lower in malnourished children than in controls. Depending on the type of malnutrition, wasted children and stunted children presented a lower specific IgG Ab response than their respective controls, but this difference was significant only in stunted children (P = 0.026. This down-regulation of the specific Ab response seemed to be explained by severely stunted children (HAZ ≤ -2.5 compared to their controls (P = 0.03, while no significant difference was observed in mildly stunted children (-2.5 P. falciparum Ab response appeared to be independent of the intensity of infection. Conclusion Child malnutrition, and particularly stunting, may down-regulate the anti-P. falciparum Ab response, both in terms of prevalence of immune responders and specific IgG Ab levels. This study provides further evidence for the influence of malnutrition on the specific anti-malarial immune response and points to the importance of taking into account child

A phase I randomized clinical trial of candidate human immunodeficiency virus type 1 vaccine MVA.HIVA administered to Gambian infants.

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Muhammed O Afolabi

Full Text Available A vaccine to decrease transmission of human immunodeficiency virus type 1 (HIV-1 during breast-feeding would complement efforts to eliminate infant HIV-1 infection by antiretroviral therapy. Relative to adults, infants have distinct immune development, potentially high-risk of transmission when exposed to HIV-1 and rapid progression to AIDS when infected. To date, there have been only three published HIV-1 vaccine trials in infants.We conducted a randomized phase I clinical trial PedVacc 001 assessing the feasibility, safety and immunogenicity of a single dose of candidate vaccine MVA.HIVA administered intramuscularly to 20-week-old infants born to HIV-1-negative mothers in The Gambia.Infants were followed to 9 months of age with assessment of safety, immunogenicity and interference with Expanded Program on Immunization (EPI vaccines. The trial is the first stage of developing more complex prime-boost vaccination strategies against breast milk transmission of HIV-1.From March to October 2010, 48 infants (24 vaccine and 24 no-treatment were enrolled with 100% retention. The MVA.HIVA vaccine was safe with no difference in adverse events between vaccinees and untreated infants. Two vaccine recipients (9% and no controls had positive ex vivo interferon-γ ELISPOT assay responses. Antibody levels elicited to the EPI vaccines, which included diphtheria, tetanus, whole-cell pertussis, hepatitis B virus, Haemophilus influenzae type b and oral poliovirus, reached protective levels for the vast majority and were similar between the two arms.A single low-dose of MVA.HIVA administered to 20-week-old infants in The Gambia was found to be safe and without interference with the induction of protective antibody levels by EPI vaccines, but did not alone induce sufficient HIV-1-specific responses. These data support the use of MVA carrying other transgenes as a boosting vector within more complex prime-boost vaccine strategies against transmission of HIV-1 and

Rotavirus vaccines

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Kang G

2006-01-01

Full Text Available Rotavirus, the most common cause of severe diarrhea and a leading cause of mortality in children, has been a priority target for vaccine development for the past several years. The first rotavirus vaccine licensed in the United States was withdrawn because of an association of the vaccine with intussusception. However, the need for a vaccine is greatest in the developing world, because the benefits of preventing deaths due to rotavirus disease are substantially greater than the risk of intussusception. Early vaccines were based on animal strains. More recently developed and licenced vaccines are either animal-human reassortants or are based on human strains. In India, two candidate vaccines are in the development process, but have not yet reached efficacy trials. Many challenges regarding vaccine efficacy and safety remain. In addition to completing clinical evaluations of vaccines in development in settings with the highest disease burden and virus diversity, there is also a need to consider alternative vaccine development strategies.

VIOLIN: vaccine investigation and online information network.

Science.gov (United States)

Xiang, Zuoshuang; Todd, Thomas; Ku, Kim P; Kovacic, Bethany L; Larson, Charles B; Chen, Fang; Hodges, Andrew P; Tian, Yuying; Olenzek, Elizabeth A; Zhao, Boyang; Colby, Lesley A; Rush, Howard G; Gilsdorf, Janet R; Jourdian, George W; He, Yongqun

2008-01-01

Vaccines are among the most efficacious and cost-effective tools for reducing morbidity and mortality caused by infectious diseases. The vaccine investigation and online information network (VIOLIN) is a web-based central resource, allowing easy curation, comparison and analysis of vaccine-related research data across various human pathogens (e.g. Haemophilus influenzae, human immunodeficiency virus (HIV) and Plasmodium falciparum) of medical importance and across humans, other natural hosts and laboratory animals. Vaccine-related peer-reviewed literature data have been downloaded into the database from PubMed and are searchable through various literature search programs. Vaccine data are also annotated, edited and submitted to the database through a web-based interactive system that integrates efficient computational literature mining and accurate manual curation. Curated information includes general microbial pathogenesis and host protective immunity, vaccine preparation and characteristics, stimulated host responses after vaccination and protection efficacy after challenge. Vaccine-related pathogen and host genes are also annotated and available for searching through customized BLAST programs. All VIOLIN data are available for download in an eXtensible Markup Language (XML)-based data exchange format. VIOLIN is expected to become a centralized source of vaccine information and to provide investigators in basic and clinical sciences with curated data and bioinformatics tools for vaccine research and development. VIOLIN is publicly available at http://www.violinet.org.

Reverse Vaccinology: An Approach for Identifying Leptospiral Vaccine Candidates

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Odir A. Dellagostin

2017-01-01

Full Text Available Leptospirosis is a major public health problem with an incidence of over one million human cases each year. It is a globally distributed, zoonotic disease and is associated with significant economic losses in farm animals. Leptospirosis is caused by pathogenic Leptospira spp. that can infect a wide range of domestic and wild animals. Given the inability to control the cycle of transmission among animals and humans, there is an urgent demand for a new vaccine. Inactivated whole-cell vaccines (bacterins are routinely used in livestock and domestic animals, however, protection is serovar-restricted and short-term only. To overcome these limitations, efforts have focused on the development of recombinant vaccines, with partial success. Reverse vaccinology (RV has been successfully applied to many infectious diseases. A growing number of leptospiral genome sequences are now available in public databases, providing an opportunity to search for prospective vaccine antigens using RV. Several promising leptospiral antigens were identified using this approach, although only a few have been characterized and evaluated in animal models. In this review, we summarize the use of RV for leptospirosis and discuss the need for potential improvements for the successful development of a new vaccine towards reducing the burden of human and animal leptospirosis.

Quantifying the importance of MSP1-19 as a target of growth-inhibitory and protective antibodies against Plasmodium falciparum in humans.

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Danny W Wilson

Full Text Available BACKGROUND: Antibodies targeting blood stage antigens are important in protection against malaria, but the key targets and mechanisms of immunity are not well understood. Merozoite surface protein 1 (MSP1 is an abundant and essential protein. The C-terminal 19 kDa region (MSP1-19 is regarded as a promising vaccine candidate and may also be an important target of immunity. METHODOLOGY/FINDINGS: Growth inhibitory antibodies against asexual-stage parasites and IgG to recombinant MSP1-19 were measured in plasma samples from a longitudinal cohort of 206 children in Papua New Guinea. Differential inhibition by samples of mutant P. falciparum lines that expressed either the P. falciparum or P. chabaudi form of MSP1-19 were used to quantify MSP1-19 specific growth-inhibitory antibodies. The great majority of children had detectable IgG to MSP1-19, and high levels of IgG were significantly associated with a reduced risk of symptomatic P. falciparum malaria during the 6-month follow-up period. However, there was little evidence of PfMSP1-19 specific growth inhibition by plasma samples from children. Similar results were found when testing non-dialysed or dialysed plasma, or purified antibodies, or when measuring growth inhibition in flow cytometry or microscopy-based assays. Rabbit antisera generated by immunization with recombinant MSP1-19 demonstrated strong MSP1-19 specific growth-inhibitory activity, which appeared to be due to much higher antibody levels than human samples; antibody avidity was similar between rabbit antisera and human plasma. CONCLUSIONS/SIGNIFICANCE: These data suggest that MSP1-19 is not a major target of growth inhibitory antibodies and that the protective effects of antibodies to MSP1-19 are not due to growth inhibitory activity, but may instead be mediated by other mechanisms. Alternatively, antibodies to MSP1-19 may act as a marker of protective immunity.

High-yield production of a stable Vero cell-based vaccine candidate against the highly pathogenic avian influenza virus H5N1

Energy Technology Data Exchange (ETDEWEB)

Zhou, Fangye; Zhou, Jian; Ma, Lei; Song, Shaohui; Zhang, Xinwen; Li, Weidong; Jiang, Shude [No. 5, Department of Bioproducts, Institute of Medical Biology, Chinese Academy of Medical Science and Pecking Union Medical College, Jiaoling Avenue 935, Kunming, Yunnan Province 650102, People' s Republic of China (China); Wang, Yue [National Institute for Viral Disease Control and Prevention, China Center for Disease Control and Prevention, Yingxin Lane 100, Xicheng District, Beijing 100052, People' s Republic of China (China); Liao, Guoyang [No. 5, Department of Bioproducts, Institute of Medical Biology, Chinese Academy of Medical Science and Pecking Union Medical College, Jiaoling Avenue 935, Kunming, Yunnan Province 650102, People' s Republic of China (China)

2012-05-18

Highlights: Black-Right-Pointing-Pointer Vero cell-based HPAI H5N1 vaccine with stable high yield. Black-Right-Pointing-Pointer Stable high yield derived from the YNVa H3N2 backbone. Black-Right-Pointing-Pointer H5N1/YNVa has a similar safety and immunogenicity to H5N1delta. -- Abstract: Highly pathogenic avian influenza (HPAI) viruses pose a global pandemic threat, for which rapid large-scale vaccine production technology is critical for prevention and control. Because chickens are highly susceptible to HPAI viruses, the supply of chicken embryos for vaccine production might be depleted during a virus outbreak. Therefore, developing HPAI virus vaccines using other technologies is critical. Meeting vaccine demand using the Vero cell-based fermentation process has been hindered by low stability and yield. In this study, a Vero cell-based HPAI H5N1 vaccine candidate (H5N1/YNVa) with stable high yield was achieved by reassortment of the Vero-adapted (Va) high growth A/Yunnan/1/2005(H3N2) (YNVa) virus with the A/Anhui/1/2005(H5N1) attenuated influenza vaccine strain (H5N1delta) using the 6/2 method. The reassorted H5N1/YNVa vaccine maintained a high hemagglutination (HA) titer of 1024. Furthermore, H5N1/YNVa displayed low pathogenicity and uniform immunogenicity compared to that of the parent virus.

The clinical development process for a novel preventive vaccine: An overview

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K Singh

2016-01-01

Full Text Available Each novel vaccine candidate needs to be evaluated for safety, immunogenicity, and protective efficacy in humans before it is licensed for use. After initial safety evaluation in healthy adults, each vaccine candidate follows a unique development path. This article on clinical development gives an overview on the development path based on the expectations of various guidelines issued by the World Health Organization (WHO, the European Medicines Agency (EMA, and the United States Food and Drug Administration (USFDA. The manuscript describes the objectives, study populations, study designs, study site, and outcome(s of each phase (Phase I-III of a clinical trial. Examples from the clinical development of a malaria vaccine candidate, a rotavirus vaccine, and two vaccines approved for human papillomavirus (HPV have also been discussed. The article also tabulates relevant guidelines, which can be referred to while drafting the development path of a novel vaccine candidate.

Cellular responses to modified Plasmodium falciparum MSP119 antigens in individuals previously exposed to natural malaria infection

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Awobode Henrietta O

2009-11-01

Full Text Available Abstract Background MSP1 processing-inhibitory antibodies bind to epitopes on the 19 kDa C-terminal region of the Plasmodium falciparum merozoite surface protein 1 (MSP119, inhibiting erythrocyte invasion. Blocking antibodies also bind to this antigen but prevent inhibitory antibodies binding, allowing invasion to proceed. Recombinant MSP119 had been modified previously to allow inhibitory but not blocking antibodies to continue to bind. Immunization with these modified proteins, therefore, has the potential to induce more effective protective antibodies. However, it was unclear whether the modification of MSP119 would affect critical T-cell responses to epitopes in this antigen. Methods The cellular responses to wild-type MSP119 and a panel of modified MSP119 antigens were measured using an in-vitro assay for two groups of individuals: the first were malaria-naïve and the second had been naturally exposed to Plasmodium falciparum infection. The cellular responses to the modified proteins were examined using cells from malaria-exposed infants and adults. Results Interestingly, stimulation indices (SI for responses induced by some of the modified proteins were at least two-fold higher than those elicited by the wild-type MSP119. A protein with four amino acid substitutions (Glu27→Tyr, Leu31→Arg, Tyr34→Ser and Glu43→Leu had the highest stimulation index (SI up to 360 and induced large responses in 64% of the samples that had significant cellular responses to the modified proteins. Conclusion This study suggests that specific MSP119 variants that have been engineered to improve their antigenicity for inhibitory antibodies, retain T-cell epitopes and the ability to induce cellular responses. These proteins are candidates for the development of MSP1-based malaria vaccines.

Optimizing expression of the pregnancy malaria vaccine candidate, VAR2CSA in Pichia pastoris.

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Avril, Marion; Hathaway, Marianne J; Cartwright, Megan M; Gose, Severin O; Narum, David L; Smith, Joseph D

2009-06-29

VAR2CSA is the main candidate for a vaccine against pregnancy-associated malaria, but vaccine development is complicated by the large size and complex disulfide bonding pattern of the protein. Recent X-ray crystallographic information suggests that domain boundaries of VAR2CSA Duffy binding-like (DBL) domains may be larger than previously predicted and include two additional cysteine residues. This study investigated whether longer constructs would improve VAR2CSA recombinant protein secretion from Pichia pastoris and if domain boundaries were applicable across different VAR2CSA alleles. VAR2CSA sequences were bioinformatically analysed to identify the predicted C11 and C12 cysteine residues at the C-termini of DBL domains and revised N- and C-termimal domain boundaries were predicted in VAR2CSA. Multiple construct boundaries were systematically evaluated for protein secretion in P. pastoris and secreted proteins were tested as immunogens. From a total of 42 different VAR2CSA constructs, 15 proteins (36%) were secreted. Longer construct boundaries, including the predicted C11 and C12 cysteine residues, generally improved expression of poorly or non-secreted domains and permitted expression of all six VAR2CSA DBL domains. However, protein secretion was still highly empiric and affected by subtle differences in domain boundaries and allelic variation between VAR2CSA sequences. Eleven of the secreted proteins were used to immunize rabbits. Antibodies reacted with CSA-binding infected erythrocytes, indicating that P. pastoris recombinant proteins possessed native protein epitopes. These findings strengthen emerging data for a revision of DBL domain boundaries in var-encoded proteins and may facilitate pregnancy malaria vaccine development.

Optimizing expression of the pregnancy malaria vaccine candidate, VAR2CSA in Pichia pastoris

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Narum David L

2009-06-01

Full Text Available Abstract Background VAR2CSA is the main candidate for a vaccine against pregnancy-associated malaria, but vaccine development is complicated by the large size and complex disulfide bonding pattern of the protein. Recent X-ray crystallographic information suggests that domain boundaries of VAR2CSA Duffy binding-like (DBL domains may be larger than previously predicted and include two additional cysteine residues. This study investigated whether longer constructs would improve VAR2CSA recombinant protein secretion from Pichia pastoris and if domain boundaries were applicable across different VAR2CSA alleles. Methods VAR2CSA sequences were bioinformatically analysed to identify the predicted C11 and C12 cysteine residues at the C-termini of DBL domains and revised N- and C-termimal domain boundaries were predicted in VAR2CSA. Multiple construct boundaries were systematically evaluated for protein secretion in P. pastoris and secreted proteins were tested as immunogens. Results From a total of 42 different VAR2CSA constructs, 15 proteins (36% were secreted. Longer construct boundaries, including the predicted C11 and C12 cysteine residues, generally improved expression of poorly or non-secreted domains and permitted expression of all six VAR2CSA DBL domains. However, protein secretion was still highly empiric and affected by subtle differences in domain boundaries and allelic variation between VAR2CSA sequences. Eleven of the secreted proteins were used to immunize rabbits. Antibodies reacted with CSA-binding infected erythrocytes, indicating that P. pastoris recombinant proteins possessed native protein epitopes. Conclusion These findings strengthen emerging data for a revision of DBL domain boundaries in var-encoded proteins and may facilitate pregnancy malaria vaccine development.

Engineering the chloroplast targeted malarial vaccine antigens in Chlamydomonas starch granules.

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David Dauvillée

2010-12-01

Full Text Available Malaria, an Anopheles-borne parasitic disease, remains a major global health problem causing illness and death that disproportionately affects developing countries. Despite the incidence of malaria, which remains one of the most severe infections of human populations, there is no licensed vaccine against this life-threatening disease. In this context, we decided to explore the expression of Plasmodium vaccine antigens fused to the granule bound starch synthase (GBSS, the major protein associated to the starch matrix in all starch-accumulating plants and algae such as Chlamydomonas reinhardtii.We describe the development of genetically engineered starch granules containing plasmodial vaccine candidate antigens produced in the unicellular green algae Chlamydomonas reinhardtii. We show that the C-terminal domains of proteins from the rodent Plasmodium species, Plasmodium berghei Apical Major Antigen AMA1, or Major Surface Protein MSP1 fused to the algal granule bound starch synthase (GBSS are efficiently expressed and bound to the polysaccharide matrix. Mice were either immunized intraperitoneally with the engineered starch particles and Freund adjuvant, or fed with the engineered particles co-delivered with the mucosal adjuvant, and challenged intraperitoneally with a lethal inoculum of P. Berghei. Both experimental strategies led to a significantly reduced parasitemia with an extension of life span including complete cure for intraperitoneal delivery as assessed by negative blood thin smears. In the case of the starch bound P. falciparum GBSS-MSP1 fusion protein, the immune sera or purified immunoglobulin G of mice immunized with the corresponding starch strongly inhibited in vitro the intra-erythrocytic asexual development of the most human deadly plasmodial species.This novel system paves the way for the production of clinically relevant plasmodial antigens as algal starch-based particles designated herein as amylosomes, demonstrating that

Engineering the chloroplast targeted malarial vaccine antigens in Chlamydomonas starch granules.

Science.gov (United States)

Dauvillée, David; Delhaye, Stéphane; Gruyer, Sébastien; Slomianny, Christian; Moretz, Samuel E; d'Hulst, Christophe; Long, Carole A; Ball, Steven G; Tomavo, Stanislas

2010-12-15

Malaria, an Anopheles-borne parasitic disease, remains a major global health problem causing illness and death that disproportionately affects developing countries. Despite the incidence of malaria, which remains one of the most severe infections of human populations, there is no licensed vaccine against this life-threatening disease. In this context, we decided to explore the expression of Plasmodium vaccine antigens fused to the granule bound starch synthase (GBSS), the major protein associated to the starch matrix in all starch-accumulating plants and algae such as Chlamydomonas reinhardtii. We describe the development of genetically engineered starch granules containing plasmodial vaccine candidate antigens produced in the unicellular green algae Chlamydomonas reinhardtii. We show that the C-terminal domains of proteins from the rodent Plasmodium species, Plasmodium berghei Apical Major Antigen AMA1, or Major Surface Protein MSP1 fused to the algal granule bound starch synthase (GBSS) are efficiently expressed and bound to the polysaccharide matrix. Mice were either immunized intraperitoneally with the engineered starch particles and Freund adjuvant, or fed with the engineered particles co-delivered with the mucosal adjuvant, and challenged intraperitoneally with a lethal inoculum of P. Berghei. Both experimental strategies led to a significantly reduced parasitemia with an extension of life span including complete cure for intraperitoneal delivery as assessed by negative blood thin smears. In the case of the starch bound P. falciparum GBSS-MSP1 fusion protein, the immune sera or purified immunoglobulin G of mice immunized with the corresponding starch strongly inhibited in vitro the intra-erythrocytic asexual development of the most human deadly plasmodial species. This novel system paves the way for the production of clinically relevant plasmodial antigens as algal starch-based particles designated herein as amylosomes, demonstrating that efficient production

Use of chloroquine in uncomplicated falciparum malaria ...

African Journals Online (AJOL)

Use of chloroquine in uncomplicated falciparum malaria chemotherapy: The past, the present and the future. ... regions. It was initially highly effective against the four Plasmodium species (P. falciparum, P. malaria, P. ovale and P. vivax) infecting human. It is also effective against gametocytes except those of P. falciparum.

Comparison of functional assays used in the clinical development of a placental malaria vaccine

DEFF Research Database (Denmark)

Pehrson, Caroline; Heno, Kristine Klysner; Adams, Yvonne

2017-01-01

BACKGROUND: Malaria in pregnancy is associated with significant morbidity in pregnant women and their offspring. Plasmodium falciparum infected erythrocytes (IE) express VAR2CSA that mediates binding to chondroitin sulphate A (CSA) in the placenta. Two VAR2CSA-based vaccines for placental malaria...

Leptospirosis vaccines: Past, present, and future

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Koizumi N

2005-01-01

Full Text Available It is well known that Leptospira vaccine prevents the disease. However specificity for serovars limits the efficacy of killed whole cell vaccines. Leptospiral antigens that induce cross-protective immunity to the various serovars are sought as new vaccine candidates. In this paper, we have summarized both past and current findings about leptospiral antigens that are conserved among pathogenic leptospires and that induce protective immunity in animal models. The full-length genome sequences of two Leptospira strains have been published and reverse vaccinology has been used to identify leptospiral vaccine candidates. Although humoral immunity is thought to be dominant in protection from leptospiral infection, a role for cell-mediated immunity is now being explored.

Technical Transformation of Biodefense Vaccines

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Lu, Shan; Wang, Shixia

2013-01-01

Biodefense vaccines are developed against a diverse group of pathogens. Vaccines were developed for some of these pathogens a long time ago but they are facing new challenges to move beyond the old manufacturing technologies. New vaccines to be developed against other pathogens have to determine whether to follow traditional vaccination strategies or to seek new approaches. Advances in basic immunology and recombinant DNA technology have fundamentally transformed the process of formulating a vaccine concept, optimizing protective antigens, and selecting the most effective vaccine delivery approach for candidate biodefense vaccines. PMID:19837293

Vaccines in a hurry.

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Søborg, Christian; Mølbak, Kåre; Doherty, T Mark; Ulleryd, Peter; Brooks, Tim; Coenen, Claudine; van der Zeijst, Ben

2009-05-26

Preparing populations for health threats, including threats from new or re-emerging infectious diseases is recognised as an important public health priority. The development, production and application of emergency vaccinations are the important measures against such threats. Vaccines are cost-effective tools to prevent disease, and emergency vaccines may be the only means to prevent a true disaster for global society in the event of a new pandemic with potential to cause morbidity and mortality comparable to the Spanish flu, the polio epidemics in the 1950s, or the SARS outbreak in 2003 if its spread had not been contained in time. Given the early recognition of a new threat, and given the advances of biotechnology, vaccinology and information systems, it is not an unrealistic goal to have promising prototype vaccine candidates available in a short time span following the identification of a new infectious agent; this is based on the assumption that the emerging infection is followed by natural immunity. However, major bottlenecks for the deployment of emergency vaccine are lack of established systems for fast-track regulatory approval of such candidates and limited international vaccine production capacity. In the present discussion paper, we propose mechanisms to facilitate development of emergency vaccines in Europe by focusing on public-private scientific partnerships, fast-track approval of emergency vaccine by regulatory agencies and proposing incentives for emergency vaccine production in private vaccine companies.

Rotavirus vaccines: an overview.

OpenAIRE

Midthun, K; Kapikian, A Z

1996-01-01

Rotavirus vaccine development has focused on the delivery of live attenuated rotavirus strains by the oral route. The initial "Jennerian" approach involving bovine (RIT4237, WC3) or rhesus (RRV) rotavirus vaccine candidates showed that these vaccines were safe, well tolerated, and immunogenic but induced highly variable rates of protection against rotavirus diarrhea. The goal of a rotavirus vaccine is to prevent severe illness that can lead to dehydration in infants and young children in both...

Ensemble modeling of the likely public health impact of a pre-erythrocytic malaria vaccine.

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Thomas Smith

2012-01-01

Full Text Available BACKGROUND: The RTS,S malaria vaccine may soon be licensed. Models of impact of such vaccines have mainly considered deployment via the World Health Organization's Expanded Programme on Immunization (EPI in areas of stable endemic transmission of Plasmodium falciparum, and have been calibrated for such settings. Their applicability to low transmission settings is unclear. Evaluations of the efficiency of different deployment strategies in diverse settings should consider uncertainties in model structure. METHODS AND FINDINGS: An ensemble of 14 individual-based stochastic simulation models of P. falciparum dynamics, with differing assumptions about immune decay, transmission heterogeneity, and treatment access, was constructed. After fitting to an extensive library of field data, each model was used to predict the likely health benefits of RTS,S deployment, via EPI (with or without catch-up vaccinations, supplementary vaccination of school-age children, or mass vaccination every 5 y. Settings with seasonally varying transmission, with overall pre-intervention entomological inoculation rates (EIRs of two, 11, and 20 infectious bites per person per annum, were considered. Predicted benefits of EPI vaccination programs over the simulated 14-y time horizon were dependent on duration of protection. Nevertheless, EPI strategies (with an initial catch-up phase averted the most deaths per dose at the higher EIRs, although model uncertainty increased with EIR. At two infectious bites per person per annum, mass vaccination strategies substantially reduced transmission, leading to much greater health effects per dose, even at modest coverage. CONCLUSIONS: In higher transmission settings, EPI strategies will be most efficient, but vaccination additional to the EPI in targeted low transmission settings, even at modest coverage, might be more efficient than national-level vaccination of infants. The feasibility and economics of mass vaccination, and the

Human monoclonal IgG selection of Plasmodium falciparum for the expression of placental malaria-specific variant surface antigens

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Soerli, J; Barfod, L; Lavstsen, T

2009-01-01

Pregnancy-associated Plasmodium falciparum malaria (PAM) is a major cause of morbidity and mortality in African women and their offspring. PAM is characterized by accumulation of infected erythrocytes (IEs) that adhere to chondroitin sulphate A (CSA) in the placental intervillous space. We show h...... transcription of var2csa. The results corroborate current efforts to develop PAM-specific vaccines based on VAR2CSA....

Protection efficacy of the Brucella abortus ghost vaccine candidate lysed by the N-terminal 24-amino acid fragment (GI24) of the 36-amino acid peptide PMAP-36 (porcine myeloid antimicrobial peptide 36) in murine models.

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Kwon, Ae Jeong; Moon, Ja Young; Kim, Won Kyong; Kim, Suk; Hur, Jin

2016-11-01

Brucella abortus cells were lysed by the N-terminal 24-amino acid fragment (GI24) of the 36-amino acid peptide PMAP-36 (porcine myeloid antimicrobial peptide 36). Next, the protection efficacy of the lysed fragment as a vaccine candidate was evaluated. Group A mice were immunized with sterile PBS, group B mice were intraperitoneally (ip) immunized with 3 × 10 8 colony-forming units (CFUs) of B. abortus strain RB51, group C mice were immunized ip with 3 × 10 8 cells of the B. abortus vaccine candidate, and group D mice were orally immunized with 3 × 10 9 cells of the B. abortus vaccine candidate. Brucella lipopolysaccharide (LPS)-specific serum IgG titers were considerably higher in groups C and D than in group A. The levels of interleukin (IL)-4, IL-10, tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) were significantly higher in groups B-D than in group A. After an ip challenge with B. abortus 544, only group C mice showed a significant level of protection as compared to group A. Overall, these results show that ip immunization with a vaccine candidate lysed by GI24 can effectively protect mice from systemic infection with virulent B. abortus.

Randomized controlled trial of RTS,S/AS02D and RTS,S/AS01E malaria candidate vaccines given according to different schedules in Ghanaian children.

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Seth Owusu-Agyei

2009-10-01

Full Text Available The target delivery channel of RTS,S candidate malaria vaccines in malaria-endemic countries in Africa is the World Health Organisation Expanded Program on Immunization. As an Adjuvant System, age de-escalation and schedule selection step, this study assessed 3 schedules of RTS,S/AS01(E and RTS,S/AS02(D in infants and young children 5-17 months of age in Ghana.A Phase II, partially-blind randomized controlled study (blind to vaccine, not to schedule, of 19 months duration was conducted in two (2 centres in Ghana between August 2006 and May 2008. Subjects were allocated randomly (1:1:1:1:1:1 to one of six study groups at each study site, each defining which vaccine should be given and by which schedule (0,1-, 0,1,2- or 0,1,7-months. For the 0,1,2-month schedule participants received RTS,S/AS01(E or rabies vaccine at one center and RTS,S/AS01(E or RTS,S/AS02(D at the other. For the other schedules at both study sites, they received RTS,S/AS01(E or RTS,S/AS02(D. The primary outcome measure was the occurrence of serious adverse events until 10 months post dose 1.The number of serious adverse events reported across groups was balanced. One child had a simple febrile convulsion, which evolved favourably without sequelae, considered to be related to RTS,S/AS01(E vaccination. Low grade reactions occurred slightly more frequently in recipients of RTS,S/AS than rabies vaccines; grade 3 reactions were infrequent. Less local reactogenicity occurred with RTS,S/AS01(E than RTS,S/AS02(D. Both candidate vaccines were highly immunogenic for anti-circumsporozoite and anti-Hepatitis B Virus surface antigen antibodies. Recipients of RTS,S/AS01(E compared to RTS,S/AS02(D had higher peak anti-circumsporozoite antibody responses for all 3 schedules. Three dose schedules were more immunogenic than 2 dose schedules. Area under the curve analyses for anti-circumsporozoite antibodies were comparable between the 0,1,2- and 0,1,7-month RTS,S/AS01(E schedules.Both candidate

Recombinant α-actinin subunit antigens of Trichomonas vaginalis as potential vaccine candidates in protecting against trichomoniasis.

Science.gov (United States)

Xie, Yi-Ting; Gao, Jiang-Mei; Wu, Ya-Ping; Tang, Petrus; Hide, Geoff; Lai, De-Hua; Lun, Zhao-Rong

2017-02-16

Human trichomoniasis caused by Trichomonas vaginalis is one of the most common sexually transmitted diseases with more than 200 million cases worldwide. It has caused a series of health problems to patients. For prevention and control of infectious diseases, vaccines are usually considered as one of the most cost-efficient tools. However, until now, work on the development of T. vaginalis vaccines is still mainly focused on the screening of potential immunogens. Alpha-actinin characterized by high immunogenicity in T. vaginalis was suggested as a promising candidate. Therefore, the purpose of this study was to evaluate the protective potency of recombinant α-actinin against T. vaginalis infection in a mouse intraperitoneal model. Two selected coding regions of α-actinin (ACT-F, 14-469 aa and ACT-T, 462-844 aa) amplified from cDNA were cloned into pET-32a (+) expression vector and transfected into BL21 cells. After induction with IPTG and purification with electroelution, the two recombinant fusion proteins were emulsified in Freund's adjuvant (FA) and used to immunize BALB/C mice. Following intraperitoneal inoculation with T. vaginalis, the survival rate of mice was monitored for the assessment of protective potency. After immunization, the antibody level in mouse serum was assessed by ELISA, splenocyte proliferation response was detected with CCK8 and cytokines in the supernatant of splenocytes were quantified with a cytometric bead-based assay. We successfully obtained purified ACT-F (70.33 kDa) and ACT-T (61.7kDa). Both recombinant proteins could provide significant protection against T. vaginalis challenge, especially ACT-T (with 100% protection within one month). Meanwhile, high levels of specific total IgG and subtypes (IgG1 > IgG2a) were detected in sera from the immunized mice. Our results also revealed a statistically significant increase in splenocyte proliferation and related cytokine (IFN-γ, IL-6, IL-17A and IL-10) production after repeated

Plasmid-free CRISPR/Cas9 genome editing in Plasmodium falciparum confirms mutations conferring resistance to the dihydroisoquinolone clinical candidate SJ733.

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Emily D Crawford

Full Text Available Genetic manipulation of the deadly malaria parasite Plasmodium falciparum remains challenging, but the rise of CRISPR/Cas9-based genome editing tools is increasing the feasibility of altering this parasite's genome in order to study its biology. Of particular interest is the investigation of drug targets and drug resistance mechanisms, which have major implications for fighting malaria. We present a new method for introducing drug resistance mutations in P. falciparum without the use of plasmids or the need for cloning homologous recombination templates. We demonstrate this method by introducing edits into the sodium efflux channel PfATP4 by transfection of a purified CRISPR/Cas9-guide RNA ribonucleoprotein complex and a 200-nucleotide single-stranded oligodeoxynucleotide (ssODN repair template. Analysis of whole genome sequencing data with the variant-finding program MinorityReport confirmed that only the intended edits were made, and growth inhibition assays confirmed that these mutations confer resistance to the antimalarial SJ733. The method described here is ideally suited for the introduction of mutations that confer a fitness advantage under selection conditions, and the novel finding that an ssODN can function as a repair template in P. falciparum could greatly simplify future editing attempts regardless of the nuclease used or the delivery method.

An FtsH protease is recruited to the mitochondrion of Plasmodium falciparum.

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Aiman Tanveer

Full Text Available The two organelles, apicoplast and mitochondrion, of the malaria parasite Plasmodium falciparum have unique morphology in liver and blood stages; they undergo complex branching and looping prior to division and segregation into daughter merozoites. Little is known about the molecular processes and proteins involved in organelle biogenesis in the parasite. We report the identification of an AAA+/FtsH protease homolog (PfFtsH1 that exhibits ATP- and Zn(2+-dependent protease activity. PfFtsH1 undergoes processing, forms oligomeric assemblies, and is associated with the membrane fraction of the parasite cell. Generation of a transfectant parasite line with hemagglutinin-tagged PfFtsH1, and immunofluorescence assay with anti-PfFtsH1 Ab demonstrated that the protein localises to P. falciparum mitochondria. Phylogenetic analysis and the single transmembrane region identifiable in PfFtsH1 suggest that it is an i-AAA like inner mitochondrial membrane protein. Expression of PfFtsH1 in Escherichia coli converted a fraction of bacterial cells into division-defective filamentous forms implying a sequestering effect of the Plasmodium factor on the bacterial homolog, indicative of functional conservation with EcFtsH. These results identify a membrane-associated mitochondrial AAA+/FtsH protease as a candidate regulatory protein for organelle biogenesis in P. falciparum.

Ligasi dan Transformasi Gen MSP1 Plasmodium falciparum Penyebab Malaria di Kota Jayapura

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Arsyam Mawardi

2017-12-01

MSP1 is the most antigenic and expressed protein on merozoite surface when it infects the erythrocytes of malaria patients which leads to its use for vaccine therapy design development. The ligation and transformation process of the MSP1 gene is a gene duplication attempt for producing  the same product during expression. This study aimed to clone P. falciparum MSP-1 gene from tropical malaria patients in Jayapura using pJET1.2/blunt vectors and E. coli DH5a competent cells, to get the recombinant plasmid propagation of MSP1 gene. Blood that was positive for P. falciparum was molecularly processed, starting with genomic DNA isolation and then followed by PCR amplification, ligation into pJET1.2/blunt vector, and transformation into E. coli DH5α using the heat shock transformation method. The process was ended with PCR confirmation to confirm MSP1 gene insertion. The results showed that the presence of the  MSP1 gene in pJET1.2/blunt was successfully confirmed through PCR. From a total of 10 positive colonies grown in liquid culture,  plasmid was isolated. Electropherogram result presented bands  of about 1049bp, indicating the presence of the MSP1 gene in plasmid. Hence, MSP1 gene cloning using pJET1.2/blunt cloning vector and competent cell E. coli DH5α has been successfully performed.  Key words: Heat shock, ligation, MSP-1, P. falciparum, transformation

The meningococcal vaccine candidate neisserial surface protein A (NspA binds to factor H and enhances meningococcal resistance to complement.

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Lisa A Lewis

2010-07-01

Full Text Available Complement forms an important arm of innate immunity against invasive meningococcal infections. Binding of the alternative complement pathway inhibitor factor H (fH to fH-binding protein (fHbp is one mechanism meningococci employ to limit complement activation on the bacterial surface. fHbp is a leading vaccine candidate against group B Neisseria meningitidis. Novel mechanisms that meningococci employ to bind fH could undermine the efficacy of fHbp-based vaccines. We observed that fHbp deletion mutants of some meningococcal strains showed residual fH binding suggesting the presence of a second receptor for fH. Ligand overlay immunoblotting using membrane fractions from one such strain showed that fH bound to a approximately 17 kD protein, identified by MALDI-TOF analysis as Neisserial surface protein A (NspA, a meningococcal vaccine candidate whose function has not been defined. Deleting nspA, in the background of fHbp deletion mutants, abrogated fH binding and mAbs against NspA blocked fH binding, confirming NspA as a fH binding molecule on intact bacteria. NspA expression levels vary among strains and expression correlated with the level of fH binding; over-expressing NspA enhanced fH binding to bacteria. Progressive truncation of the heptose (Hep I chain of lipooligosaccharide (LOS, or sialylation of lacto-N-neotetraose LOS both increased fH binding to NspA-expressing meningococci, while expression of capsule reduced fH binding to the strains tested. Similar to fHbp, binding of NspA to fH was human-specific and occurred through fH domains 6-7. Consistent with its ability to bind fH, deleting NspA increased C3 deposition and resulted in increased complement-dependent killing. Collectively, these data identify a key complement evasion mechanism with important implications for ongoing efforts to develop meningococcal vaccines that employ fHbp as one of its components.

The Influence of Sub-Unit Composition and Expression System on the Functional Antibody Response in the Development of a VAR2CSA Based Plasmodium falciparum Placental Malaria Vaccine.

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Morten A Nielsen

Full Text Available The disease caused by Plasmodium falciparum (Pf involves different clinical manifestations that, cumulatively, kill hundreds of thousands every year. Placental malaria (PM is one such manifestation in which Pf infected erythrocytes (IE bind to chondroitin sulphate A (CSA through expression of VAR2CSA, a parasite-derived antigen. Protection against PM is mediated by antibodies that inhibit binding of IE in the placental intervillous space. VAR2CSA is a large antigen incompatible with large scale recombinant protein expression. Vaccines based on sub-units encompassing the functionally constrained receptor-binding domains may, theoretically, circumvent polymorphisms, reduce the risk of escape-mutants and induce cross-reactive antibodies. However, the sub-unit composition and small differences in the borders, may lead to exposure of novel immuno-dominant antibody epitopes that lead to non-functional antibodies, and furthermore influence the folding, stability and yield of expression. Candidate antigens from the pre-clinical development expressed in High-Five insect cells using the baculovirus expression vector system were transitioned into the Drosophila Schneider-2 cell (S2 expression-system compliant with clinical development. The functional capacity of antibodies against antigens expressed in High-Five cells or in S2 cells was equivalent. This enabled an extensive down-selection of S2 insect cell-expressed antigens primarily encompassing the minimal CSA-binding region of VAR2CSA. In general, we found differential potency of inhibitory antibodies against antigens with the same borders but of different var2csa sequences. Likewise, we found that subtle size differences in antigens of the same sequence gave varying levels of inhibitory antibodies. The study shows that induction of a functional response against recombinant subunits of the VAR2CSA antigen is unpredictable, demonstrating the need for large-scale screening in order to identify antigens

Humanized HLA-DR4.RagKO.IL2RγcKO.NOD (DRAG) mice sustain the complex vertebrate life cycle of Plasmodium falciparum malaria.

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Wijayalath, Wathsala; Majji, Sai; Villasante, Eileen F; Brumeanu, Teodor D; Richie, Thomas L; Casares, Sofia

2014-09-30

Malaria is a deadly infectious disease affecting millions of people in tropical and sub-tropical countries. Among the five species of Plasmodium parasites that infect humans, Plasmodium falciparum accounts for the highest morbidity and mortality associated with malaria. Since humans are the only natural hosts for P. falciparum, the lack of convenient animal models has hindered the understanding of disease pathogenesis and prompted the need of testing anti-malarial drugs and vaccines directly in human trials. Humanized mice hosting human cells represent new pre-clinical models for infectious diseases that affect only humans. In this study, the ability of human-immune-system humanized HLA-DR4.RagKO.IL2RγcKO.NOD (DRAG) mice to sustain infection with P. falciparum was explored. Four week-old DRAG mice were infused with HLA-matched human haematopoietic stem cells (HSC) and examined for reconstitution of human liver cells and erythrocytes. Upon challenge with infectious P. falciparum sporozoites (NF54 strain) humanized DRAG mice were examined for liver stage infection, blood stage infection, and transmission to Anopheles stephensi mosquitoes. Humanized DRAG mice reconstituted human hepatocytes, Kupffer cells, liver endothelial cells, and erythrocytes. Upon intravenous challenge with P. falciparum sporozoites, DRAG mice sustained liver to blood stage infection (average 3-5 parasites/microlitre blood) and allowed transmission to An. stephensi mosquitoes. Infected DRAG mice elicited antibody and cellular responses to the blood stage parasites and self-cured the infection by day 45 post-challenge. DRAG mice represent the first human-immune-system humanized mouse model that sustains the complex vertebrate life cycle of P. falciparum without the need of exogenous injection of human hepatocytes/erythrocytes or P. falciparum parasite adaptation. The ability of DRAG mice to elicit specific human immune responses to P. falciparum parasites may help deciphering immune correlates

Self-assembling protein nanoparticles with built-in flagellin domains increases protective efficacy of a Plasmodium falciparum based vaccine.

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Kaba, Stephen A; Karch, Christopher P; Seth, Labdhi; Ferlez, Karen M B; Storme, Casey K; Pesavento, Danielle M; Laughlin, Paige Y; Bergmann-Leitner, Elke S; Burkhard, Peter; Lanar, David E

2018-02-01

To eliminate the problems associated with the use of extraneous adjuvants we have designed a Self-Assembling Protein Nanoparticle (SAPN) containing epitopes from the Plasmodium falciparum circumsporozoite protein (PfCSP) (designated FMP014) and portions of the TLR5 agonist flagellin (designated FMP014 D0D1 ) as an intrinsic adjuvant. By combining different molar ratios of FMP014 to FMP014 D0D1 monomers before self-assembly, we generated multiple nanoparticles and investigated their biophysical characteristics, immunogenicity and protective efficacy. Immunization with the construct formulated with the ratio 58:2 of FMP014 to FMP014 D0D1 had the highest protective efficacy against a challenge with a transgenic P. berghei sporozoite expressing PfCSP. Increasing the proportion of flagellin per particle resulted in an inverse relationship with levels of both antibody titers and protection. The cytokine profiles of the various immunization groups were evaluated and quantitative amounts of the cytokines IL-2, IFN-γ, IL-12/p70 (Th1); IL4, IL5 (Th2); TNF-α, IL1β, IL-6, KC/GRO (pro-inflammatory), and IL-10 (immunomodulatory) were measured. The relationship of the cytokines to each other revealed a strong immunomodulatory effect depending on the proportion of flagellin in the construct. Our results demonstrate that SAPNs with flagellin may be a promising strategy for the development and delivery of a safe vaccine for infectious diseases. Published by Elsevier Ltd.

Working towards dengue as a vaccine-preventable disease: challenges and opportunities.

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Shrivastava, Ambuj; Tripathi, Nagesh K; Dash, Paban K; Parida, Manmohan

2017-10-01

Dengue is an emerging viral disease that affects the human population around the globe. Recent advancements in dengue virus research have opened new avenues for the development of vaccines against dengue. The development of a vaccine against dengue is a challenging task because any of the four serotypes of dengue viruses can cause disease. The development of a dengue vaccine aims to provide balanced protection against all the serotypes. Several dengue vaccine candidates are in the developmental stages such as inactivated, live attenuated, recombinant subunit, and plasmid DNA vaccines. Area covered: The authors provide an overview of the progress made in the development of much needed dengue vaccines. The authors include their expert opinion and their perspectives for future developments. Expert opinion: Human trials of a live attenuated tetravalent chimeric vaccine have clearly demonstrated its potential as a dengue vaccine. Other vaccine candidate molecules such as DENVax, a recombinant chimeric vaccine andTetraVax, are at different stages of development at this time. The authors believe that the novel strategies for testing and improving the immune response of vaccine candidates in humans will eventually lead to the development of a successful dengue vaccine in future.

Serum-free microcarrier based production of replication deficient Influenza vaccine candidate virus lacking NS1 using Vero cells

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Yan Mylene L

2011-08-01

Full Text Available Abstract Background Influenza virus is a major health concern that has huge impacts on the human society, and vaccination remains as one of the most effective ways to mitigate this disease. Comparing the two types of commercially available Influenza vaccine, the live attenuated virus vaccine is more cross-reactive and easier to administer than the traditional inactivated vaccines. One promising live attenuated Influenza vaccine that has completed Phase I clinical trial is deltaFLU, a deletion mutant lacking the viral Nonstructural Protein 1 (NS1 gene. As a consequence of this gene deletion, this mutant virus can only propagate effectively in cells with a deficient interferon-mediated antiviral response. To demonstrate the manufacturability of this vaccine candidate, a batch bioreactor production process using adherent Vero cells on microcarriers in commercially available animal-component free, serum-free media is described. Results Five commercially available animal-component free, serum-free media (SFM were evaluated for growth of Vero cells in agitated Cytodex 1 spinner flask microcarrier cultures. EX-CELL Vero SFM achieved the highest cell concentration of 2.6 × 10^6 cells/ml, whereas other SFM achieved about 1.2 × 10^6 cells/ml. Time points for infection between the late exponential and stationary phases of cell growth had no significant effect in the final virus titres. A virus yield of 7.6 Log10 TCID50/ml was achieved using trypsin concentration of 10 μg/ml and MOI of 0.001. The Influenza vaccine production process was scaled up to a 3 liter controlled stirred tank bioreactor to achieve a cell density of 2.7 × 10^6 cells/ml and virus titre of 8.3 Log10 TCID50/ml. Finally, the bioreactor system was tested for the production of the corresponding wild type H1N1 Influenza virus, which is conventionally used in the production of inactivated vaccine. High virus titres of up to 10 Log10 TCID50/ml were achieved. Conclusions We describe for the

Hepatitis B vaccination: Efficiency of pretesting by RIA-methods

Energy Technology Data Exchange (ETDEWEB)

Hale, T I; Schmid, B

1984-04-01

Vaccination of individuals who possess antibodies against HBs virus from a previous infection is not necessary. Health-care personnel represents a large population of potential vaccine recipients. The risk of developing hepatitis B among these workers is proportional to the degree of their exposure to both blood and blood products as well as to patients with hepatitis B. The decision to screen before vaccination depends on the costs of screening, the costs of vaccination, and the likelihood of vaccination candidates having had hepatitis B. We have demonstrated the cost effective use of screening using RIA-methods in a group of health workers for anti-HBs. If care is taken in the organization of the vaccination program, prevaccination screening of vaccine candidates can save considerable amounts of money.

Qualification of standard membrane-feeding assay with Plasmodium falciparum malaria and potential improvements for future assays.

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Kazutoyo Miura

Full Text Available Vaccines that interrupt malaria transmission are of increasing interest and a robust functional assay to measure this activity would promote their development by providing a biologically relevant means of evaluating potential vaccine candidates. Therefore, we aimed to qualify the standard membrane-feeding assay (SMFA. The assay measures the transmission-blocking activity of antibodies by feeding cultured P. falciparum gametocytes to Anopheles mosquitoes in the presence of the test antibodies and measuring subsequent mosquito infection. The International Conference on Harmonisation (ICH Harmonised Tripartite Guideline Q2(R1 details characteristics considered in assay validation. Of these characteristics, we decided to qualify the SMFA for Precision, Linearity, Range and Specificity. The transmission-blocking 4B7 monoclonal antibody was tested over 6 feeding experiments at several concentrations to determine four suitable concentrations that were tested in triplicate in the qualification experiments (3 additional feeds to evaluate Precision, Linearity and Range. For Specificity, 4B7 was tested in the presence of normal mouse IgG. We determined intra- and inter-assay variability of % inhibition of mean oocyst intensity at each concentration of 4B7 (lower concentrations showed higher variability. We also showed that % inhibition was dependent on 4B7 concentration and the activity is specific to 4B7. Since obtaining empirical data is time-consuming, we generated a model using data from all 9 feeds and simulated the effects of different parameters on final readouts to improve the assay procedure and analytical methods for future studies. For example, we estimated the effect of number of mosquitoes dissected on variability of % inhibition, and simulated the relationship between % inhibition in oocyst intensity and % inhibition of prevalence of infected mosquitos at different mean oocysts in the control. SMFA is one of the few biological assays used in

Safety and immunogenicity of three different formulations of an adjuvanted varicella-zoster virus subunit candidate vaccine in older adults: a phase II, randomized, controlled study

NARCIS (Netherlands)

Chlibek, Roman; Smetana, Jan; Pauksens, Karlis; Rombo, Lars; van den Hoek, J. Anneke R.; Richardus, Jan H.; Plassmann, Georg; Schwarz, Tino F.; Ledent, Edouard; Heineman, Thomas C.

2014-01-01

This study investigated the safety and immunogenicity of different formulations and schedules of a candidate subunit herpes zoster vaccine containing varicella-zoster virus glycoprotein E (gE) with or without the adjuvant system AS01B. In this phase II, single-blind, randomized, controlled study,

Malaria Vaccine Development: The Need for Novel Approach-es: A Review Article

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Shima MAHMOUDI

2018-03-01

Full Text Available Background: Although rigorous efforts have substantially decreased the malaria burden through decades, it still threatens the lives of millions of children. Development of an effective vaccine can provide important approach in malaria control strategies. Unfortunately, development of an effective vaccine for falciparum malaria has been hindered by the extreme complexity of malaria parasite biology, complex and diverse parasite genomes, and immune evasion by the parasites as well as the intricate nature of the parasites infection cycle. The aim of this review was to discuss the different approaches to malaria vaccine development until now.Methods: Scientific databases, including MEDLINE (via PubMed and SCOPUS were searched up to 30 Jan 2017 and the articles regarding malaria vaccine development were taken into examination.Results: Several strategies for malaria vaccine development including pre-erythrocytic vaccines, antibody-based subunit vaccines, vectored vaccines, whole sporozoite vaccines, genetically Attenuated parasites and sporozoite subunit vaccine, erythrocytic vaccines, sexual stage vaccine, transmission-blocking vaccine as well as synthetic peptides and conjugate vaccine has been introduced. However, the success has been limited thus far.Conclusion: Although development of malaria vaccine over the past 70 year has been continued, the discovery, development, and licensing of a malaria vaccine formulation, which meets safety, affordability, accessibility, applicability, and efficacy has not yet been achieved.

Post-Genomics and Vaccine Improvement for Leishmania

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Seyed, Negar; Taheri, Tahereh; Rafati, Sima

2016-01-01

Leishmaniasis is a parasitic disease that primarily affects Asia, Africa, South America, and the Mediterranean basin. Despite extensive efforts to develop an effective prophylactic vaccine, no promising vaccine is available yet. However, recent advancements in computational vaccinology on the one hand and genome sequencing approaches on the other have generated new hopes in vaccine development. Computational genome mining for new vaccine candidates is known as reverse vaccinology and is believed to further extend the current list of Leishmania vaccine candidates. Reverse vaccinology can also reduce the intrinsic risks associated with live attenuated vaccines. Individual epitopes arranged in tandem as polytopes are also a possible outcome of reverse genome mining. Here, we will briefly compare reverse vaccinology with conventional vaccinology in respect to Leishmania vaccine, and we will discuss how it influences the aforementioned topics. We will also introduce new in vivo models that will bridge the gap between human and laboratory animal models in future studies. PMID:27092123

Characterization of the repertoire diversity of the Plasmodium falciparum stevor multigene family in laboratory and field isolates

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Holder Anthony A

2009-06-01

Full Text Available Abstract Background The evasion of host immune response by the human malaria parasite Plasmodium falciparum has been linked to expression of a range of variable antigens on the infected erythrocyte surface. Several genes are potentially involved in this process with the var, rif and stevor multigene families being the most likely candidates and coding for rapidly evolving proteins. The high sequence diversity of proteins encoded by these gene families may have evolved as an immune evasion strategy that enables the parasite to establish long lasting chronic infections. Previous findings have shown that the hypervariable region (HVR of STEVOR has significant sequence diversity both within as well as across different P. falciparum lines. However, these studies did not address whether or not there are ancestral stevor that can be found in different parasites. Methods DNA and RNA sequences analysis as well as phylogenetic approaches were used to analyse the stevor sequence repertoire and diversity in laboratory lines and Kilifi (Kenya fresh isolates. Results Conserved stevor genes were identified in different P. falciparum isolates from different global locations. Consistent with previous studies, the HVR of the stevor gene family was found to be highly divergent both within and between isolates. Importantly phylogenetic analysis shows some clustering of stevor sequences both within a single parasite clone as well as across different parasite isolates. Conclusion This indicates that the ancestral P. falciparum parasite genome already contained multiple stevor genes that have subsequently diversified further within the different P. falciparum populations. It also confirms that STEVOR is under strong selection pressure.

A randomized trial assessing the safety and immunogenicity of AS01 and AS02 adjuvanted RTS,S malaria vaccine candidates in children in Gabon.

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Bertrand Lell

2009-10-01

Full Text Available The malaria vaccine candidate antigen RTS,S includes parts of the pre-erythrocytic stage circumsporozoite protein fused to the Hepatitis B surface antigen. Two Adjuvant Systems are in development for this vaccine, an oil-in water emulsion--based formulation (AS02 and a formulation based on liposomes (AS01.In this Phase II, double-blind study (NCT00307021, 180 healthy Gabonese children aged 18 months to 4 years were randomized to receive either RTS,S/AS01(E or RTS,S/AS02(D, on a 0-1-2 month vaccination schedule. The children were followed-up daily for six days after each vaccination and monthly for 14 months. Blood samples were collected at 4 time-points. Both vaccines were well tolerated. Safety parameters were distributed similarly between the two groups. Both vaccines elicited a strong specific immune response after Doses 2 and 3 with a ratio of anti-CS GMT titers (AS02(D/AS01(E of 0.88 (95% CI: 0.68-1.15 post-Dose 3. After Doses 2 and 3 of experimental vaccines, anti-CS and anti-HBs antibody GMTs were higher in children who had been previously vaccinated with at least one dose of hepatitis B vaccine compared to those not previously vaccinated.RTS,S/AS01(E proved similarly as well tolerated and immunogenic as RTS,S/AS02(D, completing an essential step in the age de-escalation process within the RTS,S clinical development plan.ClinicalTrials.gov. NCT00307021.

Análisis de la utilidad de la vacuna Candid 1 en la prevención de la fiebre hemorrágica argentina en niños Analysis of the usefulness of Candid 1 vaccine in preventing Argentine hemorrhagic fever in children

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María Rosa Feuillade

2005-08-01

Full Text Available OBJETIVO: Determinar la estrategia más racional de vacunación con Candid 1 para prevenir la fiebre hemorrágica argentina (FHA en los menores de 15 años que viven en el área endémica. MÉTODOS: Para el análisis de la efectividad estimada se diseñó un modelo de árbol de decisión, con dos posibles opciones: vacunar a todos los menores del área endémica (vacunación ampliada o vacunar solamente a los menores de 15 años con mayor riesgo (vacunación selectiva. Estas opciones se compararon con la alternativa de no vacunar. La evaluación se complementó con un análisis de sensibilidad para identificar los valores umbral de las variables críticas que podrían modificar la decisión tomada. Las probabilidades empleadas se tomaron de estudios clínicos y epidemiológicos previos. RESULTADOS: Según el modelo empleado, la estrategia de vacunación ampliada fue la mejor opción, con una utilidad total esperada de 9,99998 (siendo 10 el valor máximo posible. El análisis de sensibilidad demostró que la vacunación selectiva sería la estrategia de mayor utilidad si la incidencia en la población de bajo riesgo se reduce a menos de 3 por 1 000 000 habitantes o si la tasa de reacciones adversas graves a la vacuna asciende a más de 9 por 100 000 habitantes. Ninguna variación de los parámetros empleados en el modelo respaldó la opción de no vacunar. CONCLUSIONES: Con los parámetros de riesgo y de beneficio empleados, se recomienda vacunar con Candid 1 a todos los menores de 15 años que viven en el área endémica de FHA. El modelo propuesto puede adaptarse a las necesidades futuras y ayudar a tomar decisiones mediante la incorporación de los datos prospectivos de la vigilancia de la enfermedad. Estos resultados pueden usarse como base para estudios de costo y eficacia y para otros análisis cuantitativos.OBJECTIVE: To determine the most rational strategy of vaccination with Candid 1 vaccine in order to prevent Argentine hemorrhagic

Isolation and Characterization of Vaccine Candidate Genes Including CSP and MSP1 in Plasmodium yoelii.

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Kim, Seon-Hee; Bae, Young-An; Seoh, Ju-Young; Yang, Hyun-Jong

2017-06-01

Malaria is an infectious disease affecting humans, which is transmitted by the bite of Anopheles mosquitoes harboring sporozoites of parasitic protozoans belonging to the genus Plasmodium . Despite past achievements to control the protozoan disease, malaria still remains a significant health threat up to now. In this study, we cloned and characterized the full-unit Plasmodium yoelii genes encoding merozoite surface protein 1 (MSP1), circumsporozoite protein (CSP), and Duffy-binding protein (DBP), each of which can be applied for investigations to obtain potent protective vaccines in the rodent malaria model, due to their specific expression patterns during the parasite life cycle. Recombinant fragments corresponding to the middle and C-terminal regions of PyMSP1 and PyCSP, respectively, displayed strong reactivity against P. yoelii -infected mice sera. Specific native antigens invoking strong humoral immune response during the primary and secondary infections of P. yoelii were also abundantly detected in experimental ICR mice. The low or negligible parasitemia observed in the secondary infected mice was likely to result from the neutralizing action of the protective antibodies. Identification of these antigenic proteins might provide the necessary information and means to characterize additional vaccine candidate antigens, selected solely on their ability to produce the protective antibodies.

Vaccination against group B streptococcus.

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Heath, Paul T; Feldman, Robert G

2005-04-01

Streptococcus agalactiae (Group B streptococcus) is an important cause of disease in infants, pregnant women, the elderly and in immunosuppressed adults. An effective vaccine is likely to prevent the majority of infant disease (both early and late onset), as well as Group B streptococcus-related stillbirths and prematurity, to avoid the current real and theoretical limitations of intrapartum antibiotic prophylaxis, and to be cost effective. The optimal time to administer such a vaccine would be in the third trimester of pregnancy. The main limitations on the production of a Group B streptococcus vaccine are not technical or scientific, but regulatory and legal. A number of candidates including capsular conjugate vaccines using traditional carrier proteins such as tetanus toxoid and mutant diphtheria toxin CRM197, as well as Group B streptococcus-specific proteins such as C5a peptidase, protein vaccines using one or more Group B streptococcus surface proteins and mucosal vaccines, have the potential to be successful vaccines. The capsular conjugate vaccines using tetanus and CRM197 carrier proteins are the most advanced candidates, having already completed Phase II human studies including use in the target population of pregnant women (tetanus toxoid conjugate), however, no definitive protein conjugates have yet been trialed. However, unless the regulatory environment is changed specifically to allow the development of a Group B streptococcus vaccine, it is unlikely that one will ever reach the market.

A Novel Domain Cassette Identifies Plasmodium falciparum PfEMP1 Proteins Binding ICAM-1 and Is a Target of Cross-Reactive, Adhesion-Inhibitory Antibodies

DEFF Research Database (Denmark)

Bengtsson, Anja; Jørgensen, Louise; Rask, Thomas Salhøj

2013-01-01

Cerebral Plasmodium falciparum malaria is characterized by adhesion of infected erythrocytes (IEs) to the cerebral microvasculature. This has been linked to parasites expressing the structurally related group A subset of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family of IE...... to ICAM-1. The ICAM-1-binding capacity of DC4 was mapped to the C-terminal third of its Duffy-binding-like beta 3 domain. DC4 was the target of broadly cross-reactive and adhesion-inhibitory IgG Abs, and levels of DC4-specific and adhesion-inhibitory IgG increased with age among P. falciparum......-exposed children. Our study challenges earlier conclusions that group A PfEMP1 proteins are not central to ICAM-1-specific IE adhesion and support the feasibility of developing a vaccine preventing cerebral malaria by inhibiting cerebral IE sequestration. The Journal of Immunology, 2013, 190: 240-249....

A live attenuated H7N7 candidate vaccine virus induces neutralizing antibody that confers protection from challenge in mice, ferrets and monkeys

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A live attenuated H7N7 candidate vaccine virus was generated by reverse genetics using the modified hemagglutinin (HA) and neuraminidase (NA) genes of HP A/Netherlands/219/03 (NL/03) (H7N7) wild-type (wt) virus and the six internal protein genes of the cold-adapted (ca) A/Ann Arbor/6/60 ca (AA ca) (...

Acquisition and decay of antibodies to pregnancy-associated variant antigens on the surface of Plasmodium falciparum-infected erythrocytes that protect against placental parasitemia

DEFF Research Database (Denmark)

Staalsoe, T; Megnekou, R; Fievét, N

2001-01-01

Otherwise clinically immune women in areas endemic for malaria are highly susceptible to Plasmodium falciparum malaria during their first pregnancy. Pregnancy-associated malaria (PAM) is characterized by placental accumulation of infected erythrocytes that adhere to chondroitin sulfate A (CSA). S...... adhesion to CSA. Data suggest that VSA(CSA) is a target for vaccination against PAM....

In silico prediction of monovalent and chimeric tetravalent vaccines for prevention and treatment of dengue fever.

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Vijayakumar, Subramaniyan; Ramesh, Venkatachalam; Prabhu, Srinivasan; Manogar, Palani

2017-11-01

Reverse vaccinology method was used to predict the monovalent peptide vaccine candidate to produce antibodies for therapeutic purpose and to predict tetravalent vaccine candidate to act as a common vaccine to cover all the fever dengue virus serotypes. Envelope (E)-proteins of DENV-1-4 serotypes were used for vaccine prediction using NCBI, Uniprot/Swissprot, Swiss-prot viewer, VaxiJen V2.0, TMHMM, BCPREDS, Propred-1, Propred and MHC Pred,. E-proteins of DENV-1-4 serotypes were identified as antigen from which T cell epitopes, through B cell epitopes, were predicted to act as peptide vaccine candidates. Each selected T cell epitope of E-protein was confirmed to act as vaccine and to induce complementary antibody against particular serotype of dengue virus. Chimeric tetravalent vaccine was formed by the conjugation of four vaccines, each from four dengue serotypes to act as a common vaccine candidate for all the four dengue serotypes. It can be justifiably concluded that the monovalent 9-mer T cell epitope for each DENV serotypes can be used to produce specific antibody agaomst dengue virus and a chimeric common tetravalent vaccine candidate to yield a comparative vaccine to cover any of the four dengue virus serotype. This vaccine is expected to act as highly immunogenic against preventing dengue fever.

Dengue Fever: Causes, Complications, and Vaccine Strategies

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Niyati Khetarpal

2016-01-01

Full Text Available Dengue is a highly endemic infectious disease of the tropical countries and is rapidly becoming a global burden. It is caused by any of the 4 serotypes of dengue virus and is transmitted within humans through female Aedes mosquitoes. Dengue disease varies from mild fever to severe conditions of dengue hemorrhagic fever and shock syndrome. Globalization, increased air travel, and unplanned urbanization have led to increase in the rate of infection and helped dengue to expand its geographic and demographic distribution. Dengue vaccine development has been a challenging task due to the existence of four antigenically distinct dengue virus serotypes, each capable of eliciting cross-reactive and disease-enhancing antibody response against the remaining three serotypes. Recently, Sanofi Pasteur’s chimeric live-attenuated dengue vaccine candidate has been approved in Mexico, Brazil, and Philippines for usage in adults between 9 and 45 years of age. The impact of its limited application to the public health system needs to be evaluated. Simultaneously, the restricted application of this vaccine candidate warrants continued efforts in developing a dengue vaccine candidate which is additionally efficacious for infants and naïve individuals. In this context, alternative strategies of developing a designed vaccine candidate which does not allow production of enhancing antibodies should be explored, as it may expand the umbrella of efficacy to include infants and naïve individuals.

Novel GMO-Based Vaccines against Tuberculosis: State of the Art and Biosafety Considerations.

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Leunda, Amaya; Baldo, Aline; Goossens, Martine; Huygen, Kris; Herman, Philippe; Romano, Marta

2014-06-16

Novel efficient vaccines are needed to control tuberculosis (TB), a major cause of morbidity and mortality worldwide. Several TB vaccine candidates are currently in clinical and preclinical development. They fall into two categories, the one of candidates designed as a replacement of the Bacille Calmette Guérin (BCG) to be administered to infants and the one of sub-unit vaccines designed as booster vaccines. The latter are designed as vaccines that will be administered to individuals already vaccinated with BCG (or in the future with a BCG replacement vaccine). In this review we provide up to date information on novel tuberculosis (TB) vaccines in development focusing on the risk assessment of candidates composed of genetically modified organisms (GMO) which are currently evaluated in clinical trials. Indeed, these vaccines administered to volunteers raise biosafety concerns with respect to human health and the environment that need to be assessed and managed.

Chikungunya Virus Vaccines: Viral Vector-Based Approaches.

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Ramsauer, Katrin; Tangy, Frédéric

2016-12-15

In 2013, a major chikungunya virus (CHIKV) epidemic reached the Americas. In the past 2 years, >1.7 million people have been infected. In light of the current epidemic, with millions of people in North and South America at risk, efforts to rapidly develop effective vaccines have increased. Here, we focus on CHIKV vaccines that use viral-vector technologies. This group of vaccine candidates shares an ability to potently induce humoral and cellular immune responses by use of highly attenuated and safe vaccine backbones. So far, well-described vectors such as modified vaccinia virus Ankara, complex adenovirus, vesicular stomatitis virus, alphavirus-based chimeras, and measles vaccine Schwarz strain (MV/Schw) have been described as potential vaccines. We summarize here the recent data on these experimental vaccines, with a focus on the preclinical and clinical activities on the MV/Schw-based candidate, which is the first CHIKV-vectored vaccine that has completed a clinical trial. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

Hepatitis B vaccination: Efficiency of pretesting by RIA-methods

International Nuclear Information System (INIS)

Hale, T.I.; Schmid, B.

1984-01-01

Vaccination of individuals who possess antibodies against HBs virus from a previous infection is not necessary. Health-care personnel represents a large population of potential vaccine recipients. The risk of developing hepatitis B among these workers is proportional to the degree of their exposure to both blood and blood products as well as to patients with hepatitis B. The decision to screen before vaccination depends on the costs of screening, the costs of vaccination, and the likelihood of vaccination candidates having had hepatitis B. We have demonstrated the cost effective use of screening using RIA-methods in a group of health workers for anti-HBs. If care is taken in the organization of the vaccination program, prevaccination screening of vaccine candidates can save considerable amounts of money. (orig.) [de

Efficacy of Artemether in Unresolving Plasmodium Falciparum Malaria

African Journals Online (AJOL)

The emergence of possible resistant Plasmodium falciparum malaria to artemisinin known for its immense benefit in malaria chemotherapy is worrisome. We report a case of unresolving Plasmodium falciparum malaria to Artesunate treatment in a 29- year old man in Enugu Nigeria. Plasmodium falciparum count of Giemsa ...

Characterization of Inherent Particles and Mechanism of Thermal Stress Induced Particle Formation in HSV-2 Viral Vaccine Candidate.

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Li, Lillian; Kirkitadze, Marina; Bhandal, Kamaljit; Roque, Cristopher; Yang, Eric; Carpick, Bruce; Rahman, Nausheen

2017-11-10

Vaccine formulations may contain visible and/or subvisible particles, which can vary in both size and morphology. Extrinsic particles, which are particles not part of the product such as foreign contaminants, are generally considered undesirable and should be eliminated or controlled in injectable products. However, biological products, in particular vaccines, may also contain particles that are inherent to the product. Here we focus on the characterization of visible and subvisible particles in a live, replication-deficient viral vaccine candidate against HSV genital herpes in an early developmental stage. HSV-2 viral vaccine was characterized using a panel of analytical methods, including Fourier transform infrared spectroscopy (FTIR), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Western blot, liquid chromatography-mass spectrometry (LC-MS), light microscopy, transmission electron microscopy (TEM), micro-flow imaging (MFI), dynamic light scattering (DLS), right angle light scattering (RALS), and intrinsic fluorescence. Particles in HSV-2 vaccine typically ranged from hundreds of nanometers to hundreds of micrometers in size and were determined to be inherent to the product. The infectious titer did not correlate with any trend in subvisible particle concentration and size distribution as shown by DLS, MFI, and TEM under stressed conditions. This suggested that particle changes in the submicron range were related to HSV-2 virion structure and had direct impact on biological activity. It was also observed that subvisible and visible particles could induce aggregation in the viral product. The temperature induced aggregation was observed by RALS, intrinsic fluorescence, and DLS. The increase of subvisible particle size with temperature could be fitted to a two-step thermokinetic model. Visible and subvisible particles were found to be inherent to the HSV-2 viral vaccine product. The mechanism of protein aggregation was discussed and a two

Efficacy of RTS,S/AS01E malaria vaccine and exploratory analysis on anti-circumsporozoite antibody titres and protection in children aged 5–17 months in Kenya and Tanzania: a randomised controlled trial

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Olotu, Ally; Lusingu, John; Leach, Amanda; Lievens, Marc; Vekemans, Johan; Msham, Salum; Lang, Trudie; Gould, Jayne; Dubois, Marie-Claude; Jongert, Erik; Vansadia, Preeti; Carter, Terrell; Njuguna, Patricia; Awuondo, Ken O; Malabeja, Anangisye; Abdul, Omar; Gesase, Samwel; Mturi, Neema; Drakeley, Chris J; Savarese, Barbara; Villafana, Tonya; Lapierre, Didier; Ballou, W Ripley; Cohen, Joe; Lemnge, Martha M; Peshu, Norbert; Marsh, Kevin; Riley, Eleanor M; von Seidlein, Lorenz; Bejon, Philip

2011-01-01

Summary Background RTS,S/AS01E is the lead candidate malaria vaccine. We recently showed efficacy against clinical falciparum malaria in 5–17 month old children, during an average of 8 months follow-up. We aimed to assess the efficacy of RTS,S/AS01E during 15 months of follow-up. Methods Between March, 2007, and October, 2008, we enrolled healthy children aged 5–17 months in Kilifi, Kenya, and Korogwe, Tanzania. Computer-generated block randomisation was used to randomly assign participants (1:1) to receive three doses (at month 0, 1, and 2) of either RTS,S/AS01E or human diploid-cell rabies vaccine. The primary endpoint was time to first clinical malaria episode, defined as the presence of fever (temperature ≥37·5°C) and a Plasmodium falciparum density of 2500/μL or more. Follow-up was 12 months for children from Korogwe and 15 months for children from Kilifi. Primary analysis was per protocol. In a post-hoc modelling analysis we characterised the associations between anti-circumsporozoite antibodies and protection against clinical malaria episodes. This study is registered with ClinicalTrials.gov, number NCT00380393. Findings 894 children were assigned, 447 in each treatment group. In the per-protocol analysis, 82 of 415 children in the RTS,S/AS01E group and 125 of 420 in the rabies vaccine group had first or only clinical malaria episode by 12 months, vaccine efficacy 39·2% (95% CI 19·5–54·1, p=0·0005). At 15 months follow-up, 58 of 209 children in the RTS,S/AS01E group and 85 of 206 in the rabies vaccine group had first or only clinical malaria episode, vaccine efficacy 45·8% (24·1–61·3, p=0·0004). At 12 months after the third dose, anti-circumsporozoite antibody titre data were available for 390 children in the RTS,S/AS01E group and 391 in the rabies group. A mean of 15 months (range 12–18 months) data were available for 172 children in the RTS,S/AS01E group and 155 in the rabies group. These titres at 1 month after the third dose were

Safety and immunogenicity of a candidate parvovirus B19 vaccine.

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Bernstein, David I; El Sahly, Hana M; Keitel, Wendy A; Wolff, Mark; Simone, Gina; Segawa, Claire; Wong, Susan; Shelly, Daniel; Young, Neal S; Dempsey, Walla

2011-10-06

Parvovirus B19 is an important human pathogen causing erythema infectiosum, transient aplastic crisis in individuals with underlying hemolytic disorders and hydropsfetalis. We therefore evaluated a parvovirus B19 virus like particle (VLP) vaccine. The safety and immunogenicity of a 25 μg dose of parvovirus B19 recombinant capsid; 2.5 and 25 μg doses of the recombinant capsid given with MF59; and saline placebo were assessed in healthy adults. Because of 3 unexplained cutaneous events the study was halted after enrollment of 43 subjects and before any subject received their third scheduled dose. The rashes developed 5-9 days after the first or second injection and were seen in one placebo recipient (without an injection site lesion) and two vaccine recipients (with injection site reactions). No clear cause was established. Other safety evaluations revealed mostly injection site reactions that were mild to moderate with an increase in pain in subjects receiving vaccine and MF59. After dose 2 the majority of vaccine recipients developed ELISA and neutralizing antibody to parvovirus B19. Given the possible severe consequences of parvovirus B19 infection, further development of a safe and effective vaccine continues to be important. Copyright © 2011 Elsevier Ltd. All rights reserved.

Broad blockade antibody responses in human volunteers after immunization with a multivalent norovirus VLP candidate vaccine: immunological analyses from a phase I clinical trial.

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Lisa C Lindesmith

2015-03-01

Full Text Available Human noroviruses (NoVs are the primary cause of acute gastroenteritis and are characterized by antigenic variation between genogroups and genotypes and antigenic drift of strains within the predominant GII.4 genotype. In the context of this diversity, an effective NoV vaccine must elicit broadly protective immunity. We used an antibody (Ab binding blockade assay to measure the potential cross-strain protection provided by a multivalent NoV virus-like particle (VLP candidate vaccine in human volunteers.Sera from ten human volunteers immunized with a multivalent NoV VLP vaccine (genotypes GI.1/GII.4 were analyzed for IgG and Ab blockade of VLP interaction with carbohydrate ligand, a potential correlate of protective immunity to NoV infection and illness. Immunization resulted in rapid rises in IgG and blockade Ab titers against both vaccine components and additional VLPs representing diverse strains and genotypes not represented in the vaccine. Importantly, vaccination induced blockade Ab to two novel GII.4 strains not in circulation at the time of vaccination or sample collection. GII.4 cross-reactive blockade Ab titers were more potent than responses against non-GII.4 VLPs, suggesting that previous exposure history to this dominant circulating genotype may impact the vaccine Ab response. Further, antigenic cartography indicated that vaccination preferentially activated preexisting Ab responses to epitopes associated with GII.4.1997. Study interpretations may be limited by the relevance of the surrogate neutralization assay and the number of immunized participants evaluated.Vaccination with a multivalent NoV VLP vaccine induces a broadly blocking Ab response to multiple epitopes within vaccine and non-vaccine NoV strains and to novel antigenic variants not yet circulating at the time of vaccination. These data reveal new information about complex NoV immune responses to both natural exposure and to vaccination, and support the potential

Plasmodium falciparum secretome in erythrocyte and beyond

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Rani eSoni

2016-02-01

Full Text Available Plasmodium falciparum is the causative agent of deadly malaria disease. It is an intracellular eukaryote and completes its multi-stage life cycle spanning the two hosts viz, mosquito and human. In order to habituate within host environment, parasite conform several strategies to evade host immune responses such as surface antigen polymorphism or modulation of host immune system and it is mediated by secretion of proteins from parasite to the host erythrocyte and beyond, collectively known as, malaria secretome. In this review, we will discuss about the deployment of parasitic secretory protein in mechanism implicated for immune evasion, protein trafficking, providing virulence, changing permeability and cyto-adherence of infected erythrocyte. We will be covering the possibilities of developing malaria secretome as a drug/vaccine target. This gathered information will be worthwhile in depicting a well-organized picture for host-pathogen interplay during the malaria infection and may also provide some clues for development of novel anti-malarial therapies.

Adjuvant-Associated Peripheral Blood mRNA Profiles and Kinetics Induced by the Adjuvanted Recombinant Protein Candidate Tuberculosis Vaccine M72/AS01 in Bacillus Calmette–Guérin-Vaccinated Adults

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Robert A. van den Berg

2018-03-01

Full Text Available Systems biology has the potential to identify gene signatures associated with vaccine immunogenicity and protective efficacy. The main objective of this study was to identify optimal postvaccination time points for evaluating peripheral blood RNA expression profiles in relation to vaccine immunogenicity and potential efficacy in recipients of the candidate tuberculosis vaccine M72/AS01. In this phase II open-label study (NCT01669096; https://clinicaltrials.gov/, healthy Bacillus Calmette–Guérin-primed, HIV-negative adults were administered two doses (30 days apart of M72/AS01. Twenty subjects completed the study and 18 subjects received two doses. Blood samples were collected pre-dose 1, pre-dose 2, and 1, 7, 10, 14, 17, and 30 days post-dose 2. RNA expression in whole blood (WB and peripheral blood mononuclear cells (PBMCs was quantified using microarray technology. Serum interferon-gamma responses and M72-specific CD4+ T cell responses to vaccination, and the observed safety profile were similar to previous trials. Two different approaches were utilized to analyze the RNA expression data. First, a kinetic analysis of RNA expression changes using blood transcription modules revealed early (1 day post-dose 2 activation of several pathways related to innate immune activation, both in WB and PBMC. Second, using a previously identified gene signature as a classifier, optimal postvaccination time points were identified. Since M72/AS01 efficacy remains to be established, a PBMC-derived gene signature associated with the protective efficacy of a similarly adjuvanted candidate malaria vaccine was used as a proxy for this purpose. This approach was based on the assumption that the AS01 adjuvant used in both studies could induce shared innate immune pathways. Subjects were classified as gene signature positive (GS+ or gene signature negative (GS−. Assignments of subjects to GS+ or GS− groups were confirmed by significant differences in RNA

Novel GMO-Based Vaccines against Tuberculosis: State of the Art and Biosafety Considerations

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Leunda, Amaya; Baldo, Aline; Goossens, Martine; Huygen, Kris; Herman, Philippe; Romano, Marta

2014-01-01

Novel efficient vaccines are needed to control tuberculosis (TB), a major cause of morbidity and mortality worldwide. Several TB vaccine candidates are currently in clinical and preclinical development. They fall into two categories, the one of candidates designed as a replacement of the Bacille Calmette Guérin (BCG) to be administered to infants and the one of sub-unit vaccines designed as booster vaccines. The latter are designed as vaccines that will be administered to individuals already vaccinated with BCG (or in the future with a BCG replacement vaccine). In this review we provide up to date information on novel tuberculosis (TB) vaccines in development focusing on the risk assessment of candidates composed of genetically modified organisms (GMO) which are currently evaluated in clinical trials. Indeed, these vaccines administered to volunteers raise biosafety concerns with respect to human health and the environment that need to be assessed and managed. PMID:26344627

Novel GMO-Based Vaccines against Tuberculosis: State of the Art and Biosafety Considerations

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Amaya Leunda

2014-06-01

Full Text Available Novel efficient vaccines are needed to control tuberculosis (TB, a major cause of morbidity and mortality worldwide. Several TB vaccine candidates are currently in clinical and preclinical development. They fall into two categories, the one of candidates designed as a replacement of the Bacille Calmette Guérin (BCG to be administered to infants and the one of sub-unit vaccines designed as booster vaccines. The latter are designed as vaccines that will be administered to individuals already vaccinated with BCG (or in the future with a BCG replacement vaccine. In this review we provide up to date information on novel tuberculosis (TB vaccines in development focusing on the risk assessment of candidates composed of genetically modified organisms (GMO which are currently evaluated in clinical trials. Indeed, these vaccines administered to volunteers raise biosafety concerns with respect to human health and the environment that need to be assessed and managed.

CD14(hi)CD16+ monocytes phagocytose antibody-opsonised Plasmodium falciparum infected erythrocytes more efficiently than other monocyte subsets, and require CD16 and complement to do so.

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Zhou, Jingling; Feng, Gaoqian; Beeson, James; Hogarth, P Mark; Rogerson, Stephen J; Yan, Yan; Jaworowski, Anthony

2015-07-07

With more than 600,000 deaths from malaria, mainly of children under five years old and caused by infection with Plasmodium falciparum, comes an urgent need for an effective anti-malaria vaccine. Limited details on the mechanisms of protective immunity are a barrier to vaccine development. Antibodies play an important role in immunity to malaria and monocytes are key effectors in antibody-mediated protection by phagocytosing antibody-opsonised infected erythrocytes (IE). Eliciting antibodies that enhance phagocytosis of IE is therefore an important potential component of an effective vaccine, requiring robust assays to determine the ability of elicited antibodies to stimulate this in vivo. The mechanisms by which monocytes ingest IE and the nature of the monocytes which do so are unknown. Purified trophozoite-stage P. falciparum IE were stained with ethidium bromide, opsonised with anti-erythrocyte antibodies and incubated with fresh whole blood. Phagocytosis of IE and TNF production by individual monocyte subsets was measured by flow cytometry. Ingestion of IE was confirmed by imaging flow cytometry. CD14(hi)CD16+ monocytes phagocytosed antibody-opsonised IE and produced TNF more efficiently than CD14(hi)CD16- and CD14(lo)CD16+ monocytes. Blocking experiments showed that Fcγ receptor IIIa (CD16) but not Fcγ receptor IIa (CD32a) or Fcγ receptor I (CD64) was necessary for phagocytosis. CD14(hi)CD16+ monocytes ingested antibody-opsonised IE when peripheral blood mononuclear cells were reconstituted with autologous serum but not heat-inactivated autologous serum. Antibody-opsonised IE were rapidly opsonised with complement component C3 in serum (t1/2 = 2-3 minutes) and phagocytosis of antibody-opsonised IE was inhibited in a dose-dependent manner by an inhibitor of C3 activation, compstatin. Compared to other monocyte subsets, CD14(hi)CD16+ monocytes expressed the highest levels of complement receptor 4 (CD11c) and activated complement receptor 3 (CD11b) subunits

Identification of synthetic vaccine candidates against SARS CoV infection

International Nuclear Information System (INIS)

Lien, Shu-Pei; Shih, Yi-Ping; Chen, Hsin-Wei; Tsai, Jy-Ping; Leng, Chih-Hsiang; Lin, Min-Han; Lin, Li-Hsiu; Liu, Hsin-Yu; Chou, Ai-Hsiang; Chang, Yu-Wen; Chen, Yi-Ming A.; Chong, Pele; Liu, Shih-Jen

2007-01-01

Three peptides, D1 (amino acid residues 175-201), D2 (a.a. 434-467), and TM (a.a. 1128-1159), corresponding to the spike protein (S) of severe acute respiratory syndrome corona virus (SARS CoV) were synthesized and their immunological functions were investigated in three different animals models (mice, guinea pigs, and rabbits). The peptides mixture formulated either with Freund's adjuvant or synthetic adjuvant Montanide ISA-51/oligodeoxy nucleotide CpG (ISA/CpG) could elicit antisera in immunized animals which were capable of inhibiting SARS/HIV pseudovirus entry into HepG2 cells. The neutralizing epitopes were identified using peptides to block the neutralizing effect of guinea pig antisera. The major neutralizing epitope was located on the D2 peptide, and the amino acid residue was fine mapped to 434-453. In BALB/c mice T-cell proliferation assay revealed that only D2 peptide contained T-cell epitope, the sequence of which corresponded to amino acid residue 434-448. The ISA/CpG formulation generated anti-D2 IgG titer comparable to those obtained from Freund's adjuvant formulation, but generated fewer antibodies against D1 or TM peptides. The highly immunogenic D2 peptide contains both neutralizing and Th cell epitopes. These results suggest that synthetic peptide D2 would be useful as a component of SARS vaccine candidates

Identification of a Major Dimorphic Region in the Functionally Critical N-Terminal ID1 Domain of VAR2CSA

DEFF Research Database (Denmark)

Doritchamou, Justin; Sabbagh, Audrey; Jespersen, Jakob S

2015-01-01

The VAR2CSA protein of Plasmodium falciparum is transported to and expressed on the infected erythrocyte surface where it plays a key role in placental malaria (PM). It is the current leading candidate for a vaccine to prevent PM. However, the antigenic polymorphism integral to VAR2CSA poses...... a challenge for vaccine development. Based on detailed analysis of polymorphisms in the sequence of its ligand-binding N-terminal region, currently the main focus for vaccine development, we assessed var2csa from parasite isolates infecting pregnant women. The results reveal for the first time the presence...

Controlled human malaria infection by intramuscular and direct venous inoculation of cryopreserved Plasmodium falciparum sporozoites in malaria-naïve volunteers: effect of injection volume and dose on infectivity rates

NARCIS (Netherlands)

Gómez-Pérez, Gloria P.; Legarda, Almudena; Muñoz, Jose; Sim, B. Kim Lee; Ballester, María Rosa; Dobaño, Carlota; Moncunill, Gemma; Campo, Joseph J.; Cisteró, Pau; Jimenez, Alfons; Barrios, Diana; Mordmüller, Benjamin; Pardos, Josefina; Navarro, Mireia; Zita, Cecilia Justino; Nhamuave, Carlos Arlindo; García-Basteiro, Alberto L.; Sanz, Ariadna; Aldea, Marta; Manoj, Anita; Gunasekera, Anusha; Billingsley, Peter F.; Aponte, John J.; James, Eric R.; Guinovart, Caterina; Antonijoan, Rosa M.; Kremsner, Peter G.; Hoffman, Stephen L.; Alonso, Pedro L.

2015-01-01

Controlled human malaria infection (CHMI) by mosquito bite is a powerful tool for evaluation of vaccines and drugs against Plasmodium falciparum malaria. However, only a small number of research centres have the facilities required to perform such studies. CHMI by needle and syringe could help to

Relationship between the entomologic inoculation rate and the force of infection for Plasmodium falciparum malaria.

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Smith, Thomas; Maire, Nicolas; Dietz, Klaus; Killeen, Gerry F; Vounatsou, Penelope; Molineaux, Louis; Tanner, Marcel

2006-08-01

We propose a stochastic model for the relationship between the entomologic inoculation rate (EIR) for Plasmodium falciparum malaria and the force of infection in endemic areas. The model incorporates effects of increased exposure to mosquito bites as a result of the growth in body surface area with the age of the host, naturally acquired pre-erythrocytic immunity, and the reduction in the proportion of entomologically assessed inoculations leading to infection, as the EIR increases. It is fitted to multiple datasets from field studies of the relationship between malaria infection and the EIR. We propose that this model can account for non-monotonic relationships between the age of the host and the parasite prevalence and incidence of disease. It provides a parsimonious explanation for the faster acquisition of natural immunity in adults than in children exposed to high EIRs. This forms one component of a new stochastic model for the entire transmission cycle of P. falciparum that we have derived to estimate the potential epidemiologic impact of malaria vaccines and other malaria control interventions.

Expression of variant surface antigens by Plasmodium falciparum parasites in the peripheral blood of clinically immune pregnant women indicates ongoing placental infection

DEFF Research Database (Denmark)

Ofori, Michael F; Staalsoe, Trine; Bam, Victoria

2003-01-01

Placenta-sequestered Plasmodium falciparum parasites that cause pregnancy-associated malaria (PAM) in otherwise clinically immune women express distinct variant surface antigens (VSA(PAM)) not expressed by parasites in nonpregnant individuals. We report here that parasites from the peripheral blood...... of clinically immune pregnant women also express VSA(PAM), making them a convenient source of VSA(PAM) expressors for PAM vaccine research....

A Novel Virus-Like Particle Based Vaccine Platform Displaying the Placental Malaria Antigen VAR2CSA.

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Susan Thrane

Full Text Available Placental malaria caused by Plasmodium falciparum is a major cause of mortality and severe morbidity. Clinical testing of a soluble protein-based vaccine containing the parasite ligand, VAR2CSA, has been initiated. VAR2CSA binds to the human receptor chondroitin sulphate A (CSA and is responsible for sequestration of Plasmodium falciparum infected erythrocytes in the placenta. It is imperative that a vaccine against malaria in pregnancy, if administered to women before they become pregnant, can induce a strong and long lasting immune response. While most soluble protein-based vaccines have failed during clinical testing, virus-like particle (VLP based vaccines (e.g., the licensed human papillomavirus vaccines have demonstrated high efficacy, suggesting that the spatial assembly of the vaccine antigen is a critical parameter for inducing an optimal long-lasting protective immune response. We have developed a VLP vaccine display platform by identifying regions of the HPV16 L1 coat protein where a biotin acceptor site (AviTagTM can be inserted without compromising VLP-assembly. Subsequent biotinylation of Avi-L1 VLPs allow us to anchor monovalent streptavidin (mSA-fused proteins to the biotin, thereby obtaining a dense and repetitive VLP-display of the vaccine antigen. The mSA-VAR2CSA antigen was delivered on the Avi-L1 VLP platform and tested in C57BL/6 mice in comparison to two soluble protein-based vaccines consisting of naked VAR2CSA and mSA-VAR2CSA. The mSA-VAR2CSA Avi-L1 VLP and soluble mSA-VAR2CSA vaccines induced higher antibody titers than the soluble naked VAR2CSA vaccine after three immunizations. The VAR2CSA Avi-L1 VLP vaccine induced statistically significantly higher endpoint titres compared to the soluble mSA-VAR2CSA vaccine, after 1st and 2nd immunization; however, this difference was not statistically significant after 3rd immunization. Importantly, the VLP-VAR2CSA induced antibodies were functional in inhibiting the binding of

Important advances in malaria vaccine research

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Priyanka Jadhav

2012-01-01

Full Text Available Malaria is one of the most widespread parasitic infection in Asian countries affecting the poor of the poor. In an effort to develop an effective vaccine for the treatment of malaria, various attempts are being made worldwide. If successful, such a vaccine can be effective for treatment of both Plasmodium vivax and Plasmodium falciparum. This would also be able to avoid complications such as drug resistance, resistance to insecticides, nonadherence to the treatment schedule, and eventually high cost of treatment in the resource-limited settings. In the current compilation, the details from the literature were collected by using PubMed and Medline as search engines and searched for terms such as malaria, vaccine, and malaria treatment. This review collates and provides glimpses of the information on the recent malaria vaccine development. The reader will be taken through the historical perspective followed by the approaches to the malaria vaccine development from pre-erythrocytic stage vaccines, asexual stage vaccines, transmission blocking vaccines, etc. Looking at the current scenario of the malaria and treatment strategies, it is an absolute need of an hour that an effective malaria vaccine should be developed. This would bring a revolutionary breakthrough in the treatment modalities especially when there is increasing emergence of resistance to existing drug therapy. It would be of great purpose to serve those living in malaria endemic region and also for travelers which are nonimmune and coming to malaria endemic region. As infection by P. vivax is more prevalent in India and other Asian subcontinent and is often prominent in areas where elimination is being attempted, special consideration is required of the role of vaccines in blocking transmission, regardless of the stages being targeted. Development of vaccines is feasible but with the support of private sector and government organization in terms of regulatory and most importantly

Vaccines: an ongoing promise?

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Alsahli, M; Farrell, R J; Michetti, P

2001-01-01

Over the past decade, intensive research has focused on developing a vaccine therapy for Helicobacter pylori. Substantial unresolved questions cloud the current approach, and the development of a vaccine against this unique organism has proved very challenging. Many candidate vaccines have been tested in animal models. The immunogenicity and the safety of some vaccine formulations have been recently evaluated through clinical trials, and the efficacy of these vaccine therapies in humans will be determined in the near future. This article will provide an overview of the current knowledge of natural and vaccine-induced immune responses to H. pylori infection. It will also review past vaccine successes and failures in animal models and the limited experience to date in using vaccine therapy in humans. Several obstacles to H. pylori vaccine development efforts along with the future direction of these efforts will be discussed. Copyright 2001 S. Karger AG, Basel

Mosquito Vectors and the Globalization of Plasmodium falciparum Malaria.

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Molina-Cruz, Alvaro; Zilversmit, Martine M; Neafsey, Daniel E; Hartl, Daniel L; Barillas-Mury, Carolina

2016-11-23

Plasmodium falciparum malaria remains a devastating public health problem. Recent discoveries have shed light on the origin and evolution of Plasmodium parasites and their interactions with their vertebrate and mosquito hosts. P. falciparum malaria originated in Africa from a single horizontal transfer between an infected gorilla and a human, and became global as the result of human migration. Today, P. falciparum malaria is transmitted worldwide by more than 70 different anopheline mosquito species. Recent studies indicate that the mosquito immune system can be a barrier to malaria transmission and that the P. falciparum Pfs47 gene allows the parasite to evade mosquito immune detection. Here, we review the origin and globalization of P. falciparum and integrate this history with analysis of the biology, evolution, and dispersal of the main mosquito vectors. This new perspective broadens our understanding of P. falciparum population structure and the dispersal of important parasite genetic traits.

Immunogenicity and Safety of Yellow Fever Vaccine (Stamaril) When Administered Concomitantly With a Tetravalent Dengue Vaccine Candidate in Healthy Toddlers at 12-13 Months of Age in Colombia and Peru: A Randomized Trial.

Science.gov (United States)

López, Pio; Lanata, Claudio F; Zambrano, Betzana; Cortés, Margarita; Andrade, Teresa; Amemiya, Isabel; Terrones, Cynthia; Gil, Ana I; Verastegui, Hector; Marquez, Viviana; Crevat, Denis; Jezorwski, John; Noriega, Fernando

2016-10-01

Dengue and yellow fever (YF) viruses are closely related members of the Flaviviridae family. Given the inherent similarities between the YF vaccine and dengue vaccine (CYD-TDV) candidate, it is possible that the latter could interfere with the response to the licensed YF vaccine when coadministered. In this randomized, observer-blind, controlled, phase III trial, conducted in Colombia and Peru, 787 toddlers were administered YF vaccine concomitantly with CYD-TDV (group 1) or placebo (group 2), followed by CYD-TDV after 6 and 12 months. YF and dengue neutralizing antibody titers were determined using a 50% plaque reduction neutralization test. Noninferiority was demonstrated if the lower limit of the 2-sided 95% confidence interval of the difference in seroconversion rates [(YF + CYD-TDV) - YF alone] was greater than -10%. The safety of both vaccines was also assessed. Concomitant administration of YF with either CYD-TDV or placebo yielded YF seroconversion rates of 100.0% and 99.7%, respectively. The difference in YF seroconversion rates between the 2 groups was 0.33% (95% confidence interval:0.98; 1.87), demonstrating that the immune response against YF administered concomitantly with CYD-TDV was noninferior to YF administered with placebo. After 2 injections of CYD-TDV, the percentage of participants with dengue titres ≥10 (1/dil) for the 4 dengue serotypes were 91.2%-100% for group 1 and 97.2%-100% in group 2. There were no safety concerns during the study period. Concomitant administration of YF vaccine with CYD-TDV has no relevant impact on the immunogenicity or safety profile of the YF vaccine.

Immunogenicity and Efficacy of Live L. tarentolae Expressing KMP11-NTGP96-GFP Fusion as a Vaccine Candidate against Experimental Visceral Leishmaniasis Caused by L. infantum

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Vahid NASIRI

2016-10-01

Full Text Available Background: The aim of present study was to evaluate the protective efficacy of live recombinant L. tarentolae expressing KMP11-NTGP96-GFP fusion as candidates for live engineered recombinant vaccine against visceral leishmaniasis in BALB/c mice.Methods: KMP-11 and NT-GP96 genes cloned into the pJET1.2/blunt cloning vector and then into pEGFP-N1 expression vector. The KMP-11, NT-GP96 and GFP fused in pEGFP-N1 and subcloned into Leishmanian pLEXSY-neo vector. Finally this construct was transferred to L. tarentolae by electroporation. Tranfection was confirmed by SDS-PAGE, WESTERN blot, flowcytometry and RT-PCR. Protective efficacy of this construct was evaluated as a vaccine candidate against visceral leishmaniasis. Parasite burden, humoral and cellular immune responses were assessed before and at 4 weeks after challenge.Results: KMP- NT-Gp96-GFP Fusion was cloned successfully into pLEXSY -neo vector and this construct successfully transferred to L. tarentolae. Finding indicated that immunization with L. tarentolae tarentolae-KMP11-NTGP96-GFP provides significant protection against visceral leishmaniasis and was able to induce an increased expression of IFN-γ and IgG2a. Following challenge, a reduced parasite load in the spleen of the KMP11-NTGP96-GFP immunized group was detected.Conclusion: The present study is the first to use a combination of a Leishmania antigen with an immunologic antigen in live recombinant L. tarentolae and results suggest that L. tarentolae-KMP11-NTGP96-GFP could be considered as a potential tool in vaccination against visceral leishmaniasis and this vaccination strategy could provide a potent rout for future vaccine development. 

In-depth comparative analysis of malaria parasite genomes reveals protein-coding genes linked to human disease in Plasmodium falciparum genome.

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Liu, Xuewu; Wang, Yuanyuan; Liang, Jiao; Wang, Luojun; Qin, Na; Zhao, Ya; Zhao, Gang

2018-05-02

Plasmodium falciparum is the most virulent malaria parasite capable of parasitizing human erythrocytes. The identification of genes related to this capability can enhance our understanding of the molecular mechanisms underlying human malaria and lead to the development of new therapeutic strategies for malaria control. With the availability of several malaria parasite genome sequences, performing computational analysis is now a practical strategy to identify genes contributing to this disease. Here, we developed and used a virtual genome method to assign 33,314 genes from three human malaria parasites, namely, P. falciparum, P. knowlesi and P. vivax, and three rodent malaria parasites, namely, P. berghei, P. chabaudi and P. yoelii, to 4605 clusters. Each cluster consisted of genes whose protein sequences were significantly similar and was considered as a virtual gene. Comparing the enriched values of all clusters in human malaria parasites with those in rodent malaria parasites revealed 115 P. falciparum genes putatively responsible for parasitizing human erythrocytes. These genes are mainly located in the chromosome internal regions and participate in many biological processes, including membrane protein trafficking and thiamine biosynthesis. Meanwhile, 289 P. berghei genes were included in the rodent parasite-enriched clusters. Most are located in subtelomeric regions and encode erythrocyte surface proteins. Comparing cluster values in P. falciparum with those in P. vivax and P. knowlesi revealed 493 candidate genes linked to virulence. Some of them encode proteins present on the erythrocyte surface and participate in cytoadhesion, virulence factor trafficking, or erythrocyte invasion, but many genes with unknown function were also identified. Cerebral malaria is characterized by accumulation of infected erythrocytes at trophozoite stage in brain microvascular. To discover cerebral malaria-related genes, fast Fourier transformation (FFT) was introduced to extract

The Capricious Nature of Bacterial Pathogens: Phasevarions and Vaccine Development

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Aimee Tan

2016-12-01

Full Text Available Infectious diseases are a leading cause of morbidity and mortality worldwide, and vaccines are one of the most successful and cost-effective tools for disease prevention. One of the key considerations for rational vaccine development is the selection of appropriate antigens. Antigens must induce a protective immune response, and this response should be directed to stably expressed antigens so the target microbe can always be recognized by the immune system. Antigens with variable expression, due to environmental signals or phase variation (i.e., high frequency, random switching of expression, are not ideal vaccine candidates because variable expression could lead to immune evasion. Phase variation is often mediated by the presence of highly mutagenic simple tandem DNA repeats, and genes containing such sequences can be easily identified, and their use discounted as vaccine antigens reconsidered. Recent research has identified phase variably expressed DNA methyltransferases that act as global epigenetic regulators. These phase variable regulons, known as phasevarions, are associated with altered virulence phenotypes and/or expression of vaccine candidates. As such, genes encoding candidate vaccine antigens that have no obvious mechanism of phase variation may be subject to indirect, epigenetic control as part of a phasevarion. Bioinformatic and experimental studies are required to elucidate the distribution and mechanism of action of these DNA methyltransferases, and most importantly, whether they mediate epigenetic regulation of potential and current vaccine candidates. This process is essential to define the stably expressed antigen target profile of bacterial pathogens and thereby facilitate efficient, rational selection of vaccine antigens.

Malaria falciparum y síndrome nefrótico: nuestras experiencias Falciparum malaria and nephrotic Síndrome: Our experience

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Jesús Juan Rodríguez

2007-03-01

Full Text Available Las especies de Plasmodium que infectan al hombre son: P. vivax, P. Malariae, P. Ovale y P. Falciparum. En Mozambique, como en la mayor parte de la llamada África Subsahariana, la especie predominante es P. falciparum cloroquina resistente. La infección por P. falciparum es potencialmente mortal, tiende a manifestarse como una enfermedad febril sin signos localizados o específicos. En los casos más graves, sin embargo puede presentarse asociada a variados síndromes clínicos que plantean serios retos terapéuticos.Es reconocido que la malaria o paludismo puede asociarse a síndrome nefrótico y se han dado explicaciones de esta relación patogénica. En Mozambique, en un período de seis meses, tuvimos la oportunidad de tratar tres casos de Malaria falciparum grave, asociado a síndrome nefrótico.Divulgar y trasmitir las experiencias prácticas y consideraciones teóricas a propósito de uno de estos casos es la motivación de los autores de este trabajo.Plasmodiumspecies infecting man are the following: P.vivax, P. Malariae, P. Ovale and P. Falciparum. In Mozambique, like the biggest area from the so called Subsaharian Africa,the resistent-chloroquine P. Falciparum is the predominating specie in this area. The P. Falciparum infection is potentially fatal, with a trend to show as a febrile condition with no localized or specific signs. In more severe cases, however, it may be presented in association with different clinical syndromes which represent serious therapeutic challenges. It is not unknown that Malaria or Paludism may be associated with the Nephrotic Syndrome, and many explanations have been given on this pathogenic relatioship. In a sixth month's period in Mozambique we had the chance to test three severe cases of Falciparum Malaria associated with a Nephrotic Syndrome. Spreading the practical experience and theoretic considerations on one of these cases is the aim of this work.

Chimeric peptide constructs comprising linear B-cell epitopes: application to the serodiagnosis of infectious diseases.

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Lu, Yudong; Li, Zhong; Teng, Huan; Xu, Hongke; Qi, Songnan; He, Jian'an; Gu, Dayong; Chen, Qijun; Ma, Hongwei

2015-08-21

Linear B-cell epitopes are ideal biomarkers for the serodiagnosis of infectious diseases. However, the long-predicted diagnostic value of epitopes has not been realized. Here, we demonstrated a method, diagnostic epitopes in four steps (DEIFS), that delivers a combination of epitopes for the serodiagnosis of infectious diseases with a high success rate. Using DEIFS for malaria, we identified 6 epitopes from 8 peptides and combined them into 3 chimeric peptide constructs. Along with 4 other peptides, we developed a rapid diagnostic test (RDT), which is able to differentiate Plasmodium falciparum (P. falciparum) from Plasmodium vivax (P. vivax) infections with 95.6% overall sensitivity and 99.1% overall specificity. In addition to applications in diagnosis, DEIFS could also be used in the diagnosis of virus and bacterium infections, discovery of vaccine candidates, evaluation of vaccine potency, and study of disease progression.

Idala: An unnamed Function Peptide Vaccine for Tuberculosis

African Journals Online (AJOL)

Color development in a microplate reader was ... peptide vaccine for tuberculosis tested by mice immunogenicity experiment. Keywords: ... potential new tuberculosis vaccine candidate. [3]. ..... New York and London: Garland Science,.

Modeling metabolism and stage-specific growth of Plasmodium falciparum HB3 during the intraerythrocytic developmental cycle.

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Fang, Xin; Reifman, Jaques; Wallqvist, Anders

2014-10-01

The human malaria parasite Plasmodium falciparum goes through a complex life cycle, including a roughly 48-hour-long intraerythrocytic developmental cycle (IDC) in human red blood cells. A better understanding of the metabolic processes required during the asexual blood-stage reproduction will enhance our basic knowledge of P. falciparum and help identify critical metabolic reactions and pathways associated with blood-stage malaria. We developed a metabolic network model that mechanistically links time-dependent gene expression, metabolism, and stage-specific growth, allowing us to predict the metabolic fluxes, the biomass production rates, and the timing of production of the different biomass components during the IDC. We predicted time- and stage-specific production of precursors and macromolecules for P. falciparum (strain HB3), allowing us to link specific metabolites to specific physiological functions. For example, we hypothesized that coenzyme A might be involved in late-IDC DNA replication and cell division. Moreover, the predicted ATP metabolism indicated that energy was mainly produced from glycolysis and utilized for non-metabolic processes. Finally, we used the model to classify the entire tricarboxylic acid cycle into segments, each with a distinct function, such as superoxide detoxification, glutamate/glutamine processing, and metabolism of fumarate as a byproduct of purine biosynthesis. By capturing the normal metabolic and growth progression in P. falciparum during the IDC, our model provides a starting point for further elucidation of strain-specific metabolic activity, host-parasite interactions, stress-induced metabolic responses, and metabolic responses to antimalarial drugs and drug candidates.

AIDS vaccine: Present status and future challenges

Directory of Open Access Journals (Sweden)

Nigam P

2006-01-01

Full Text Available Development of a preventive vaccine for HIV is the best hope of controlling the AIDS pandemic. HIV has, however, proved a difficult pathogen to vaccinate against because of its very high mutation rate and capability to escape immune responses. Neutralizing antibodies that can neutralize diverse field strains have so far proved difficult to induce. Adjuvanting these vaccines with cytokine plasmids and a "prime-boost," approach is being evaluated in an effort to induce both CTL and antibody responses and thereby have immune responses active against both infected cells and free viral particles, thereby necessitating fewer doses of recombinant protein to reach maximum antibodies titers. Although obstacles exist in evaluation of candidate HIV vaccines, evidence from natural history studies, new molecular tools in virology and immunology, new adjuvants, new gene expression systems, new antigen delivery systems, recent discoveries in HIV entry and pathogenesis, and promising studies of candidate vaccines in animal models have provided reasons to hope that developing a safe and effective AIDS vaccine is possible and within reach.

A novel chimeric protein composed of recombinant Mycoplasma hyopneumoniae antigens as a vaccine candidate evaluated in mice.

Science.gov (United States)

de Oliveira, Natasha Rodrigues; Jorge, Sérgio; Gomes, Charles Klazer; Rizzi, Caroline; Pacce, Violetta Dias; Collares, Thais Farias; Monte, Leonardo Garcia; Dellagostin, Odir Antônio

2017-03-01

Enzootic Pneumonia (EP) is caused by the Mycoplasma hyopneumoniae pathogenic bacteria, and it represents a significant respiratory disease that is responsible for major economic losses within the pig industry throughout the world. The bacterins that are currently commercially available have been proven to offer only partial protection against M. hyopneumoniae, and the development of more efficient vaccines is required. Several recombinant antigens have been evaluated via different immunization strategies and have been found to be highly immunogenic. This work describes the construction and immunological characterization of a multi-antigen chimera composed of four M. hyopneumoniae antigens: P97R1, P46, P95, and P42. Immunogenic regions of each antigen were selected and combined to encode a single polypeptide. The gene was cloned and expressed in Escherichia coli, and the chimeric protein was recognized by specific antibodies against each subunit, as well as by convalescent pig sera. The immunogenic properties of the chimera were then evaluated in a mice model through two recombinant vaccines that were formulated as follows: (1) purified chimeric protein plus adjuvant or (2) recombinant Escherichia coli bacterin. The immune response induced in BALB/c mice immunized with each formulation was characterized in terms of total IgG levels, IgG1, and IgG2a isotypes against each antigen present in the chimera. The results of the study indicated that novel chimeric protein is a potential candidate for the future development of a more effective vaccine against EP. Copyright © 2017 Elsevier B.V. All rights reserved.

From genomes to vaccines: Leishmania as a model.

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Almeida, Renata; Norrish, Alan; Levick, Mark; Vetrie, David; Freeman, Tom; Vilo, Jaak; Ivens, Alasdair; Lange, Uta; Stober, Carmel; McCann, Sharon; Blackwell, Jenefer M

2002-01-01

The 35 Mb genome of Leishmania should be sequenced by late 2002. It contains approximately 8500 genes that will probably translate into more than 10 000 proteins. In the laboratory we have been piloting strategies to try to harness the power of the genome-proteome for rapid screening of new vaccine candidate. To this end, microarray analysis of 1094 unique genes identified using an EST analysis of 2091 cDNA clones from spliced leader libraries prepared from different developmental stages of Leishmania has been employed. The plan was to identify amastigote-expressed genes that could be used in high-throughput DNA-vaccine screens to identify potential new vaccine candidates. Despite the lack of transcriptional regulation that polycistronic transcription in Leishmania dictates, the data provide evidence for a high level of post-transcriptional regulation of RNA abundance during the developmental cycle of promastigotes in culture and in lesion-derived amastigotes of Leishmania major. This has provided 147 candidates from the 1094 unique genes that are specifically upregulated in amastigotes and are being used in vaccine studies. Using DNA vaccination, it was demonstrated that pooling strategies can work to identify protective vaccines, but it was found that some potentially protective antigens are masked by other disease-exacerbatory antigens in the pool. A total of 100 new vaccine candidates are currently being tested separately and in pools to extend this analysis, and to facilitate retrospective bioinformatic analysis to develop predictive algorithms for sequences that constitute potentially protective antigens. We are also working with other members of the Leishmania Genome Network to determine whether RNA expression determined by microarray analyses parallels expression at the protein level. We believe we are making good progress in developing strategies that will allow rapid translation of the sequence of Leishmania into potential interventions for disease

Spatial and temporal distribution of falciparum malaria in China

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Lin Hualiang

2009-06-01

Full Text Available Abstract Background Falciparum malaria is the most deadly among the four main types of human malaria. Although great success has been achieved since the launch of the National Malaria Control Programme in 1955, malaria remains a serious public health problem in China. This paper aimed to analyse the geographic distribution, demographic patterns and time trends of falciparum malaria in China. Methods The annual numbers of falciparum malaria cases during 1992–2003 and the individual case reports of each clinical falciparum malaria during 2004–2005 were extracted from communicable disease information systems in China Center for Diseases Control and Prevention. The annual number of cases and the annual incidence were mapped by matching them to corresponding province- and county-level administrative units in a geographic information system. The distribution of falciparum malaria by age, gender and origin of infection was analysed. Time-series analysis was conducted to investigate the relationship between the falciparum malaria in the endemic provinces and the imported falciparum malaria in non-endemic provinces. Results Falciparum malaria was endemic in two provinces of China during 2004–05. Imported malaria was reported in 26 non-endemic provinces. Annual incidence of falciparum malaria was mapped at county level in the two endemic provinces of China: Yunnan and Hainan. The sex ratio (male vs. female for the number of cases in Yunnan was 1.6 in the children of 0–15 years and it reached 5.7 in the adults over 15 years of age. The number of malaria cases in Yunnan was positively correlated with the imported malaria of concurrent months in the non-endemic provinces. Conclusion The endemic area of falciparum malaria in China has remained restricted to two provinces, Yunnan and Hainan. Stable transmission occurs in the bordering region of Yunnan and the hilly-forested south of Hainan. The age and gender distribution in the endemic area is

Dengue human infection models to advance dengue vaccine development.

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Larsen, Christian P; Whitehead, Stephen S; Durbin, Anna P

2015-12-10

Dengue viruses (DENV) currently infect approximately 400 million people each year causing millions to seek care and overwhelming the health care infrastructure in endemic areas. Vaccines to prevent dengue and therapeutics to treat dengue are not currently available. The efficacy of the most advanced candidate vaccine against symptomatic dengue in general and DENV-2 in particular was much lower than expected, despite the ability of the vaccine to induce neutralizing antibody against all four DENV serotypes. Because seroconversion to the DENV serotypes following vaccination was thought to be indicative of induced protection, these results have made it more difficult to assess which candidate vaccines should or should not be evaluated in large studies in endemic areas. A dengue human infection model (DHIM) could be extremely valuable to down-select candidate vaccines or therapeutics prior to engaging in efficacy trials in endemic areas. Two DHIM have been developed to assess the efficacy of live attenuated tetravalent (LATV) dengue vaccines. The first model, developed by the Laboratory of Infectious Diseases at the U. S. National Institutes of Health, utilizes a modified DENV-2 strain DEN2Δ30. This virus was derived from the DENV-2 Tonga/74 that caused only very mild clinical infection during the outbreak from which it was recovered. DEN2Δ30 induced viremia in 100%, rash in 80%, and neutropenia in 27% of the 30 subjects to whom it was given. The Walter Reed Army Institute of Research (WRAIR) is developing a DHIM the goal of which is to identify DENV that cause symptomatic dengue fever. WRAIR has evaluated seven viruses and has identified two that meet dengue fever criteria. Both of these models may be very useful in the evaluation and down-selection of candidate dengue vaccines and therapeutics. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

A cross strain Plasmodium falciparum microarray optimized for the transcriptome analysis of Plasmodium falciparum patient derived isolates

KAUST Repository

Subudhi, Amit

2016-07-20

Malarial parasite P. falciparum, an apicomplexan protozoan has a 23.3 MB nuclear genome and encodes ~ 5600 transcripts. The genetic diversity of the parasite within and across geographical zones is a challenge to gene expression studies which are essential for understanding of disease process, outcome and developing markers for diagnostics and prognostics. Here, we describe the strategy involved in designing a custom P. falciparum 15K array using the Agilent platform and Genotypic\\'s Right Design methodology to study the transcriptome of Indian field isolates for which genome sequence information is limited. The array contains probes representing genome sequences of two distinct geographical isolates (i.e. 3D7 and HB3) and sub-telomeric var gene sequences of a third isolate (IT4) known to adhere in culture condition. Probes in the array have been selected based on their efficiency to detect transcripts through a 244K array experimentation. Array performance for the 15K array, was evaluated and validated using RNA materials from P. falciparum clinical isolates. A large percentage (91%) of the represented transcripts was detected from Indian P. falciparum patient isolates. Replicated probes and multiple probes representing the same gene showed perfect correlation between them suggesting good probe performance. Additional transcripts could be detected due to inclusion of unique probes representing HB3 strain transcripts. Variant surface antigen (VSA) transcripts were detected by optimized probes representing the VSA genes of three geographically distinct strains. The 15K cross strain P. falciparum array has shown good efficiency in detecting transcripts from P. falciparum parasite samples isolated from patients. The low parasite loads and presence of host RNA makes arrays a preferred platform for gene expression studies over RNA-Seq.

A cross strain Plasmodium falciparum microarray optimized for the transcriptome analysis of Plasmodium falciparum patient derived isolates

KAUST Repository

Subudhi, Amit; Boopathi, P.A.; Middha, Sheetal; Acharya, Jyoti; Rao, Sudha Narayana; Mugasimangalam, Raja C.; Sirohi, Paramendra; Kochar, Sanjay K.; Kochar, Dhanpat K.; Das, Ashis

2016-01-01

Malarial parasite P. falciparum, an apicomplexan protozoan has a 23.3 MB nuclear genome and encodes ~ 5600 transcripts. The genetic diversity of the parasite within and across geographical zones is a challenge to gene expression studies which are essential for understanding of disease process, outcome and developing markers for diagnostics and prognostics. Here, we describe the strategy involved in designing a custom P. falciparum 15K array using the Agilent platform and Genotypic's Right Design methodology to study the transcriptome of Indian field isolates for which genome sequence information is limited. The array contains probes representing genome sequences of two distinct geographical isolates (i.e. 3D7 and HB3) and sub-telomeric var gene sequences of a third isolate (IT4) known to adhere in culture condition. Probes in the array have been selected based on their efficiency to detect transcripts through a 244K array experimentation. Array performance for the 15K array, was evaluated and validated using RNA materials from P. falciparum clinical isolates. A large percentage (91%) of the represented transcripts was detected from Indian P. falciparum patient isolates. Replicated probes and multiple probes representing the same gene showed perfect correlation between them suggesting good probe performance. Additional transcripts could be detected due to inclusion of unique probes representing HB3 strain transcripts. Variant surface antigen (VSA) transcripts were detected by optimized probes representing the VSA genes of three geographically distinct strains. The 15K cross strain P. falciparum array has shown good efficiency in detecting transcripts from P. falciparum parasite samples isolated from patients. The low parasite loads and presence of host RNA makes arrays a preferred platform for gene expression studies over RNA-Seq.

Safety and Immunogenicity of Pfs25-EPA/Alhydrogel®, a Transmission Blocking Vaccine against Plasmodium falciparum: An Open Label Study in Malaria Naïve Adults.

Directory of Open Access Journals (Sweden)

Kawsar R Talaat

Full Text Available Transmission-blocking vaccines (TBVs that target sexual stage parasite development could be an integral part of measures for malaria elimination. Pfs25 is a leading TBV candidate, and previous studies conducted in animals demonstrated an improvement of its functional immunogenicity after conjugation to EPA, a recombinant, detoxified ExoProtein A from Pseudomonas aeruginosa. In this report, we describe results of an open-label, dose-escalating Phase 1 trial to assess the safety and immunogenicity of Pfs25-EPA conjugates formulated with Alhydrogel®. Thirty malaria-naïve healthy adults received up to four doses of the conjugate vaccine, with 8, 16, or 47 μg of conjugated Pfs25 mass, at 0, 2, 4, and 10 months. Vaccinations were generally well tolerated. The majority of solicited adverse events were mild in severity with pain at the injection site the most common complaint. Anemia was the most common laboratory abnormality, but was considered possibly related to the study in only a minority of cases. No vaccine-related serious adverse events occurred. The peak geometric mean anti-Pfs25 antibody level in the highest dose group was 88 (95% CI 53, 147 μg/mL two weeks after the 4th vaccination, and declined to near baseline one year later. Antibody avidity increased over successive vaccinations. Transmission blocking activity demonstrated in a standard membrane feeding assay (SMFA also increased from the second to the third dose, and correlated with antibody titer and, after the final dose, with antibody avidity. These results support the further evaluation of Pfs25-EPA/Alhydrogel® in a malaria-endemic population.

Evaluating Controlled Human Malaria Infection in Kenyan Adults with Varying Degrees of Prior Exposure to Plasmodium falciparum using sporozoites administered by intramuscular injection

Directory of Open Access Journals (Sweden)

Susanne Helena Hodgson

2014-12-01

Full Text Available Background: Controlled human malaria infection (CHMI studies are a vital tool to accelerate vaccine and drug development. As CHMI trials are performed in a controlled environment, they allow unprecedented, detailed evaluation of parasite growth dynamics (PGD and immunological responses. However, CHMI studies have not been routinely performed in malaria-endemic countries or used to investigate mechanisms of naturally-acquired immunity (NAI to Plasmodium falciparum. Methods: We conducted an open-label, randomized CHMI pilot-study using aseptic, cryopreserved P. falciparum sporozoites (PfSPZ Challenge to evaluate safety, infectivity and PGD in Kenyan adults with low to moderate prior exposure to P. falciparum (Pan African Clinical Trial Registry: PACTR20121100033272. Results: All participants developed blood-stage infection confirmed by qPCR. However one volunteer (110 remained asymptomatic and blood-film negative until day 21 post-injection of PfSPZ Challenge. This volunteer had a reduced parasite multiplication rate (PMR (1.3 in comparison to the other 27 volunteers (median 11.1. A significant correlation was seen between PMR and screening anti-schizont ELISA OD (p=0.044, R=-0.384 but not when volunteer 110 was excluded from the analysis (p=0.112, R=-0.313. Conclusions: PfSPZ Challenge is safe and infectious in malaria-endemic populations and could be used to assess the efficacy of malaria vaccines and drugs in African populations. Whilst our findings are limited by sample size, our pilot study has demonstrated for the first time that NAI may impact on PMR post-CHMI in a detectable fashion, an important finding that should be evaluated in further CHMI studies.

Prescreening of Nicotine Hapten Linkers in Vitro To Select Hapten-Conjugate Vaccine Candidates for Pharmacokinetic Evaluation in Vivo.

Science.gov (United States)

Arutla, Viswanath; Leal, Joseph; Liu, Xiaowei; Sokalingam, Sriram; Raleigh, Michael; Adaralegbe, Adejimi; Liu, Li; Pentel, Paul R; Hecht, Sidney M; Chang, Yung

2017-05-08

Since the demonstration of nicotine vaccines as a possible therapeutic intervention for the effects of tobacco smoke, extensive effort has been made to enhance nicotine specific immunity. Linker modifications of nicotine haptens have been a focal point for improving the immunogenicity of nicotine, in which the evaluation of these modifications usually relies on in vivo animal models, such as mice, rats or nonhuman primates. Here, we present two in vitro screening strategies to estimate and predict the immunogenic potential of our newly designed nicotine haptens. One utilizes a competition enzyme-linked immunoabsorbent assay (ELISA) to profile the interactions of nicotine haptens or hapten-protein conjugates with nicotine specific antibodies, both polyclonal and monoclonal. Another relies on computational modeling of the interactions between haptens and amino acid residues near the conjugation site of the carrier protein to infer linker-carrier protein conjugation effect on antinicotine antibody response. Using these two in vitro methods, we ranked the haptens with different linkers for their potential as viable vaccine candidates. The ELISA-based hapten ranking was in an agreement with the results obtained by in vivo nicotine pharmacokinetic analysis. A correlation was found between the average binding affinity (IC 50 ) of the haptens to an anti-Nic monoclonal antibody and the average brain nicotine concentration in the immunized mice. The computational modeling of hapten and carrier protein interactions helps exclude conjugates with strong linker-carrier conjugation effects and low in vivo efficacy. The simplicity of these in vitro screening strategies should facilitate the selection and development of more effective nicotine conjugate vaccines. In addition, these data highlight a previously under-appreciated contribution of linkers and hapten-protein conjugations to conjugate vaccine immunogenicity by virtue of their inclusion in the epitope that binds and

A new strategy based on SmRho protein loaded chitosan nanoparticles as a candidate oral vaccine against schistosomiasis.

Directory of Open Access Journals (Sweden)

Carolina R Oliveira

Full Text Available BACKGROUND: Schistosomiasis is one of the most important neglected tropical diseases and an effective control is unlikely in the absence of improved sanitation and vaccination. A new approach of oral vaccination with alginate coated chitosan nanoparticles appears interesting because their great stability and the ease of target accessibility, besides of chitosan and alginate immunostimulatory properties. Here we propose a candidate vaccine based on the combination of chitosan-based nanoparticles containing the antigen SmRho and coated with sodium alginate. METHODS AND FINDINGS: Our results showed an efficient performance of protein loading of nanoparticles before and after coating with alginate. Characterization of the resulting nanoparticles reported a size around 430 nm and a negative zeta potential. In vitro release studies of protein showed great stability of coated nanoparticles in simulated gastric fluid (SGF and simulated intestinal fluid (SIF. Further in vivo studies was performed with different formulations of chitosan nanoparticles and it showed that oral immunization was not able to induce high levels of antibodies, otherwise intramuscular immunization induced high levels of both subtypes IgG1 and IgG2a SmRho specific antibodies. Mice immunized with nanoparticles associated to CpG showed significant modulation of granuloma reaction. Mice from all groups immunized orally with nanoparticles presented significant levels of protection against infection challenge with S. mansoni worms, suggesting an important role of chitosan in inducing a protective immune response. Finally, mice immunized with nanoparticles associated with the antigen SmRho plus CpG had 38% of the granuloma area reduced and also presented 48% of protection against of S. mansoni infection. CONCLUSIONS: Taken together, this results support this new strategy as an efficient delivery system and a potential vaccine against schistosomiasis.

Vaccines. An Ebola whole-virus vaccine is protective in nonhuman primates.

Science.gov (United States)

Marzi, Andrea; Halfmann, Peter; Hill-Batorski, Lindsay; Feldmann, Friederike; Shupert, W Lesley; Neumann, Gabriele; Feldmann, Heinz; Kawaoka, Yoshihiro

2015-04-24

Zaire ebolavirus is the causative agent of the current outbreak of hemorrhagic fever disease in West Africa. Previously, we showed that a whole Ebola virus (EBOV) vaccine based on a replication-defective EBOV (EBOVΔVP30) protects immunized mice and guinea pigs against lethal challenge with rodent-adapted EBOV. Here, we demonstrate that EBOVΔVP30 protects nonhuman primates against lethal infection with EBOV. Although EBOVΔVP30 is replication-incompetent, we additionally inactivated the vaccine with hydrogen peroxide; the chemically inactivated vaccine remained antigenic and protective in nonhuman primates. EBOVΔVP30 thus represents a safe, efficacious, whole-EBOV vaccine candidate that differs from other EBOV vaccine platforms in that it presents all viral proteins and the viral RNA to the host immune system, which might contribute to protective immune responses. Copyright © 2015, American Association for the Advancement of Science.

A specific PfEMP1 is expressed in P. falciparum sporozoites and plays a role in hepatocyte infection

DEFF Research Database (Denmark)

Zanghì, Gigliola; Vembar, Shruthi S; Baumgarten, Sebastian

2018-01-01

Heterochromatin plays a central role in the process of immune evasion, pathogenesis, and transmission of the malaria parasite Plasmodium falciparum during blood stage infection. Here, we use ChIP sequencing to demonstrate that sporozoites from mosquito salivary glands expand heterochromatin......_SpzPfEMP1. Overall, we show that the epigenetic signature of var genes is reset in mosquito stages. Moreover, the identification of a strain-specific sporozoite PfEMP1 is highly relevant for vaccine design based on sporozoites....

Ebolavirus Vaccines: Progress in the Fight Against Ebola Virus Disease

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Xiao-Xin Wu

2015-11-01

Full Text Available Ebolaviruses are highly infectious pathogens that cause lethal Ebola virus disease (EVD in humans and non-human primates (NHPs. Due to their high pathogenicity and transmissibility, as well as the potential to be misused as a bioterrorism agent, ebolaviruses would threaten the health of global populations if not controlled. In this review, we describe the origin and structure of ebolaviruses and the development of vaccines from the beginning of the 1980s, including conventional ebolavirus vaccines, DNA vaccines, Ebola virus-like particles (VLPs, vaccinia virus-based vaccines, Venezuelan equine encephalitis virus (VEEV-like replicon particles, Kunjin virus-based vaccine, recombinant Zaire Ebolavirus∆VP30, recombinant cytomegalovirus (CMV-based vaccines, recombinant rabies virus (RABV-based vaccines, recombinant paramyxovirus-based vaccines, adenovirus-based vaccines and vesicular stomatitis virus (VSV-based vaccines. No licensed vaccine or specific treatment is currently available to counteract ebolavirus infection, although DNA plasmids and several viral vector approaches have been evaluated as promising vaccine platforms. These vaccine candidates have been confirmed to be successful in protecting NHPs against lethal infection. Moreover, these vaccine candidates were successfully advanced to clinical trials. The present review provides an update of the current research on Ebola vaccines, with the aim of providing an overview on current prospects in the fight against EVD.

Antibiotic Resistance Determinant-Focused Acinetobacter baumannii Vaccine Designed Using Reverse Vaccinology.

Science.gov (United States)

Ni, Zhaohui; Chen, Yan; Ong, Edison; He, Yongqun

2017-02-21

As one of the most influential and troublesome human pathogens, Acinetobacter baumannii ( A. baumannii ) has emerged with many multidrug-resistant strains. After collecting 33 complete A. baumannii genomes and 84 representative antibiotic resistance determinants, we used the Vaxign reverse vaccinology approach to predict classical type vaccine candidates against A. baumannii infections and new type vaccine candidates against antibiotic resistance. Our genome analysis identified 35 outer membrane or extracellular adhesins that are conserved among all 33 genomes, have no human protein homology, and have less than 2 transmembrane helices. These 35 antigens include 11 TonB dependent receptors, 8 porins, 7 efflux pump proteins, and 2 fimbrial proteins (FilF and CAM87009.1). CAM86003.1 was predicted to be an adhesin outer membrane protein absent from 3 antibiotic-sensitive strains and conserved in 21 antibiotic-resistant strains. Feasible anti-resistance vaccine candidates also include one extracellular protein (QnrA), 3 RND type outer membrane efflux pump proteins, and 3 CTX-M type β-lactamases. Among 39 β-lactamases, A. baumannii CTX-M-2, -5, and -43 enzymes are predicted as adhesins and better vaccine candidates than other β-lactamases to induce preventive immunity and enhance antibiotic treatments. This report represents the first reverse vaccinology study to systematically predict vaccine antigen candidates against antibiotic resistance for a microbial pathogen.

Atypical and classical memory B cells produce Plasmodium falciparum neutralizing antibodies

DEFF Research Database (Denmark)

Muellenbeck, Matthias F; Ueberheide, Beatrix; Amulic, Borko

2013-01-01

signs of active antibody secretion. AtM and CM were also different in their IgG gene repertoire, suggesting that they develop from different precursors. The findings provide direct evidence that natural Pf infection leads to the development of protective memory B cell antibody responses and suggest......Antibodies can protect from Plasmodium falciparum (Pf) infection and clinical malaria disease. However, in the absence of constant reexposure, serum immunoglobulin (Ig) levels rapidly decline and full protection from clinical symptoms is lost, suggesting that B cell memory is functionally impaired...... that constant immune activation rather than impaired memory function leads to the accumulation of AtM in malaria. Understanding the memory B cell response to natural Pf infection may be key to the development of a malaria vaccine that induces long-lived protection....

Third generation DIVA vaccine towards classical swine fever virus. Efficacy in face of maternal immunity

DEFF Research Database (Denmark)

Rangelova, Desislava Yordanova

General purpose and objectives Classical swine fever (CSF) is a highly contagious disease that causes huge economical losses and animal welfare concerns worldwide. Generally, vaccination is an effective and safe method to control the disease. Following vaccination the pig’s immune system develops...... a new DIVA vaccine candidate. The vaccine candidate “CP7E2alf” is intended for either intramuscular vaccination of domestic pig or for bait vaccination of wild boar. In this thesis as part of the clinical testing of the injection vaccine the efficacy of “CP7E2alf” was evaluated in young piglets...

Sequential, ordered acquisition of antibodies to Plasmodium falciparum erythrocyte membrane protein 1 domains

DEFF Research Database (Denmark)

Cham, Gerald K K; Turner, Louise; Lusingu, John

2009-01-01

The binding of erythrocytes infected with mature blood stage parasites to the vascular bed is key to the pathogenesis of malignant malaria. The binding is mediated by members of Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family. PfEMP1s can be divided into groups, and it has pr....... The identification of PfEMP1 domains expressed by parasites causing disease in infants and young children is important for development of vaccines protecting against severe malaria.......The binding of erythrocytes infected with mature blood stage parasites to the vascular bed is key to the pathogenesis of malignant malaria. The binding is mediated by members of Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family. PfEMP1s can be divided into groups, and it has...... previously been suggested that parasites expressing group A or B/A PfEMP1s are most pathogenic. To test the hypothesis that the first malaria infections in infants and young children are dominated by parasites expressing A and B/A PfEMP1s, we measured the plasma Ab level against 48 recombinant PfEMP1 domains...

Genetic diversity of the Plasmodium falciparum apical membrane antigen I gene in parasite population from the China-Myanmar border area.

Science.gov (United States)

Zhu, Xiaotong; Zhao, Zhenjun; Feng, Yonghui; Li, Peipei; Liu, Fei; Liu, Jun; Yang, Zhaoqing; Yan, Guiyun; Fan, Qi; Cao, Yaming; Cui, Liwang

2016-04-01

To investigate the genetic diversity of the Plasmodium falciparum apical membrane antigen 1 (PfAMA1) gene in Southeast Asia, we determined PfAMA1 sequences from 135 field isolates collected from the China-Myanmar border area and compared them with 956 publically available PfAMA1 sequences from seven global P. falciparum populations. This analysis revealed high genetic diversity of PfAMA1 in global P. falciparum populations with a total of 229 haplotypes identified. The genetic diversity of PfAMA1 gene from the China-Myanmar border is not evenly distributed in the different domains of this gene. Sequence diversity in PfAMA1 from the China-Myanmar border is lower than that observed in Thai, African and Oceanian populations, but higher than that in the South American population. This appeared to correlate well with the levels of endemicity of different malaria-endemic regions, where hyperendemic regions favor genetic cross of the parasite isolates and generation of higher genetic diversity. Neutrality tests show significant departure from neutrality in the entire ectodomain and Domain I of PfAMA1 in the China-Myanmar border parasite population. We found evidence supporting a substantial continent-wise genetic structure among P. falciparum populations, with the highest genetic differentiation detected between the China-Myanmar border and the South American populations. Whereas no alleles were unique to a specific region, there were considerable geographical differences in major alleles and their frequencies, highlighting further necessity to include more PfAMA1 alleles in vaccine designs. Copyright © 2016 Elsevier B.V. All rights reserved.

Juxtamembrane shedding of Plasmodium falciparum AMA1 is sequence independent and essential, and helps evade invasion-inhibitory antibodies.

Directory of Open Access Journals (Sweden)

Anna Olivieri

2011-12-01

Full Text Available The malarial life cycle involves repeated rounds of intraerythrocytic replication interspersed by host cell rupture which releases merozoites that rapidly invade fresh erythrocytes. Apical membrane antigen-1 (AMA1 is a merozoite protein that plays a critical role in invasion. Antibodies against AMA1 prevent invasion and can protect against malaria in vivo, so AMA1 is of interest as a malaria vaccine candidate. AMA1 is efficiently shed from the invading parasite surface, predominantly through juxtamembrane cleavage by a membrane-bound protease called SUB2, but also by limited intramembrane cleavage. We have investigated the structural requirements for shedding of Plasmodium falciparum AMA1 (PfAMA1, and the consequences of its inhibition. Mutagenesis of the intramembrane cleavage site by targeted homologous recombination abolished intramembrane cleavage with no effect on parasite viability in vitro. Examination of PfSUB2-mediated shedding of episomally-expressed PfAMA1 revealed that the position of cleavage is determined primarily by its distance from the parasite membrane. Certain mutations at the PfSUB2 cleavage site block shedding, and parasites expressing these non-cleavable forms of PfAMA1 on a background of expression of the wild type gene invade and replicate normally in vitro. The non-cleavable PfAMA1 is also functional in invasion. However - in contrast to the intramembrane cleavage site - mutations that block PfSUB2-mediated shedding could not be stably introduced into the genomic pfama1 locus, indicating that some shedding of PfAMA1 by PfSUB2 is essential. Remarkably, parasites expressing shedding-resistant forms of PfAMA1 exhibit enhanced sensitivity to antibody-mediated inhibition of invasion. Drugs that inhibit PfSUB2 activity should block parasite replication and may also enhance the efficacy of vaccines based on AMA1 and other merozoite surface proteins.

Flow cytometric readout based on Mitotracker Red CMXRos staining of live asexual blood stage malarial parasites reliably assesses antibody dependent cellular inhibition

DEFF Research Database (Denmark)

Jogdand, Prajakta S; Singh, Susheel K; Christiansen, Michael

2012-01-01

asynchronous and tightly synchronized asexual blood stage cultures of Plasmodium falciparum were stained with CMXRos and subjected to detection by flow cytometry and fluorescence microscopy. The parasite counts obtained by flow cytometry were compared to standard microscopic counts obtained through examination......ABSTRACT: BACKGROUND: Functional in vitro assays could provide insights into the efficacy of malaria vaccine candidates. For estimating the anti-parasite effect induced by a vaccine candidate, an accurate determination of live parasite count is an essential component of most in vitro bioassays....... Although traditionally parasites are counted microscopically, a faster, more accurate and less subjective method for counting parasites is desirable. In this study mitochondrial dye (Mitotracker Red CMXRos) was used for obtaining reliable live parasite counts through flow cytometry. METHODS: Both...

AEROMONAS SALMONICIDA INFECTION IN VACCINATED RAINBOW TROUT

DEFF Research Database (Denmark)

Chettri, Jiwan Kumar; Skov, Jakob; Mohammad, Rezkar Jaafar

In vivo testing of any candidate vaccine is influenced by the choice of challenge method and the external environmental conditions. In the present study, a comparative challenge study was performed to evaluate the efficacy of different vaccines against the bacterial pathogen Aeromonas salmonicida...

Next generation vaccines.

Science.gov (United States)

Riedmann, Eva M

2011-07-01

In February this year, about 100 delegates gathered for three days in Vienna (Austria) for the Next Generation Vaccines conference. The meeting held in the Vienna Hilton Hotel from 23rd-25th February 2011 had a strong focus on biotech and industry. The conference organizer Jacob Fleming managed to put together a versatile program ranging from the future generation of vaccines to manufacturing, vaccine distribution and delivery, to regulatory and public health issues. Carefully selected top industry experts presented first-hand experience and shared solutions for overcoming the latest challenges in the field of vaccinology. The program also included several case study presentations on novel vaccine candidates in different stages of development. An interactive pre-conference workshop as well as interactive panel discussions during the meeting allowed all delegates to gain new knowledge and become involved in lively discussions on timely, interesting and sometimes controversial topics related to vaccines.

Evaluation of smallpox vaccines using variola neutralization.

Science.gov (United States)

Damon, Inger K; Davidson, Whitni B; Hughes, Christine M; Olson, Victoria A; Smith, Scott K; Holman, Robert C; Frey, Sharon E; Newman, Frances; Belshe, Robert B; Yan, Lihan; Karem, Kevin

2009-08-01

The search for a 'third'-generation smallpox vaccine has resulted in the development and characterization of several vaccine candidates. A significant barrier to acceptance is the absence of challenge models showing induction of correlates of protective immunity against variola virus. In this light, virus neutralization provides one of few experimental methods to show specific 'in vitro' activity of vaccines against variola virus. Here, we provide characterization of the ability of a modified vaccinia virus Ankara vaccine to induce variola virus-neutralizing antibodies, and we provide comparison with the neutralization elicited by standard Dryvax vaccination.

Molecular signature of high yield (growth influenza a virus reassortants prepared as candidate vaccine seeds.

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Manojkumar Ramanunninair

Full Text Available Human influenza virus isolates generally grow poorly in embryonated chicken eggs. Hence, gene reassortment of influenza A wild type (wt viruses is performed with a highly egg adapted donor virus, A/Puerto Rico/8/1934 (PR8, to provide the high yield reassortant (HYR viral 'seeds' for vaccine production. HYR must contain the hemagglutinin (HA and neuraminidase (NA genes of wt virus and one to six 'internal' genes from PR8. Most studies of influenza wt and HYRs have focused on the HA gene. The main objective of this study is the identification of the molecular signature in all eight gene segments of influenza A HYR candidate vaccine seeds associated with high growth in ovo.The genomes of 14 wt parental viruses, 23 HYRs (5 H1N1; 2, 1976 H1N1-SOIV; 2, 2009 H1N1pdm; 2 H2N2 and 12 H3N2 and PR8 were sequenced using the high-throughput sequencing pipeline with big dye terminator chemistry.Silent and coding mutations were found in all internal genes derived from PR8 with the exception of the M gene. The M gene derived from PR8 was invariant in all 23 HYRs underlining the critical role of PR8 M in high yield phenotype. None of the wt virus derived internal genes had any silent change(s except the PB1 gene in X-157. The highest number of recurrent silent and coding mutations was found in NS. With respect to the surface antigens, the majority of HYRs had coding mutations in HA; only 2 HYRs had coding mutations in NA.In the era of application of reverse genetics to alter influenza A virus genomes, the mutations identified in the HYR gene segments associated with high growth in ovo may be of great practical benefit to modify PR8 and/or wt virus gene sequences for improved growth of vaccine 'seed' viruses.

Development of an epitope-based HIV-1 vaccine strategy from HIV-1 lipopeptide to dendritic-based vaccines.

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Surenaud, Mathieu; Lacabaratz, Christine; Zurawski, Gérard; Lévy, Yves; Lelièvre, Jean-Daniel

2017-10-01

Development of a safe, effective and globally affordable Human Immunodeficiency Virus strain 1 (HIV-1) vaccine offers the best hope for future control of the HIV-1 pandemic. However, with the exception of the recent RV144 trial, which elicited a modest level of protection against infection, no vaccine candidate has shown efficacy in preventing HIV-1 infection or in controlling virus replication in humans. There is also a great need for a successful immunotherapeutic vaccine since combination antiretroviral therapy (cART) does not eliminate the reservoir of HIV-infected cells. But to date, no vaccine candidate has proven to significantly alter the natural history of an individual with HIV-1 infection. Areas covered: For over 25 years, the ANRS (France Recherche Nord&Sud Sida-HIV hépatites) has been committed to an original program combining basic science and clinical research developing an epitope-based vaccine strategy to induce a multiepitopic cellular response against HIV-1. This review describes the evolution of concepts, based on strategies using HIV-1 lipopeptides towards the use of dendritic cell (DC) manipulation. Expert commentary: Understanding the crucial role of DCs in immune responses allowed moving from the non-specific administration of HIV-1 sequences with lipopeptides to DC-based vaccines. These DC-targeting strategies should improve HIV-1 vaccine efficacy.

Characterization and protective efficacy in an animal model of a novel truncated rotavirus VP8 subunit parenteral vaccine candidate.

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Xue, Miaoge; Yu, Linqi; Che, Yaojian; Lin, Haijun; Zeng, Yuanjun; Fang, Mujin; Li, Tingdong; Ge, Shengxiang; Xia, Ningshao

2015-05-21

The cell-attachment protein VP8* of rotavirus is a potential candidate parenteral vaccine. However, the yield of full-length VP8 protein (VP8*, residues 1-231) expressed in Escherichia coli was low, and a truncated VP8 protein (ΔVP8*, residues 65-231) cannot elicit efficient protective immunity in a mouse model. In this study, tow novel truncated VP8 proteins, VP8-1 (residues 26-231) and VP8-2 (residues 51-231), were expressed in E. coli and evaluated for immunogenicity and protective efficacy, compared with VP8* and ΔVP8*. As well as ΔVP8*, the protein VP8-1 and VP8-2 were successfully expressed in high yield and purified in homogeneous dimeric forms, while the protein VP8* was expressed with lower yield and prone to aggregation and degradation in solution. Although the immunogenicity of the protein VP8*, VP8-1, VP8-2 and ΔVP8* was comparable, immunization of VP8* and VP8-1 elicited significantly higher neutralizing antibody titers than that of VP8-2 and ΔVP8* in mice. Furthermore, when assessed using a mouse maternal antibody model, the efficacy of VP8-1 to protect against rotavirus-induced diarrhea in pups was comparable to that of VP8*, both were dramatically higher than that of VP8-2 and ΔVP8*. Taken together, the novel truncated protein VP8-1, with increased yield, improved homogeneity and high protective efficacy, is a viable candidate for further development of a parenterally administrated prophylactic vaccine against rotavirus infection. Copyright © 2015 Elsevier Ltd. All rights reserved.

Novel CTL epitopes identified through a Y. pestis proteome-wide analysis in the search for vaccine candidates against plague.

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Zvi, Anat; Rotem, Shahar; Zauberman, Ayelet; Elia, Uri; Aftalion, Moshe; Bar-Haim, Erez; Mamroud, Emanuelle; Cohen, Ofer

2017-10-20

The causative agent of Plague, Yersinia pestis, is a highly virulent pathogen and a potential bioweapon. Depending on the route of infection, two prevalent occurrences of the disease are known, bubonic and pneumonic. The latter has a high fatality rate. In the absence of a licensed vaccine, intense efforts to develop a safe and efficacious vaccine have been conducted, and humoral-driven subunit vaccines containing the F1 and LcrV antigens are currently under clinical trials. It is well known that a cellular immune response might have an essential additive value to immunity and protection against Y. pestis infection. Nevertheless, very few documented epitopes eliciting a protective T-cell response have been reported. Here, we present a combined high throughput computational and experimental effort towards identification of CD8 T-cell epitopes. All 4067 proteins of Y. pestis were analyzed with state-of-the-art recently developed prediction algorithms aimed at mapping potential MHC class I binders. A compilation of the results obtained from several prediction methods revealed a total of 238,000 peptide candidates, which necessitated downstream filtering criteria. Our previously established and proven approach for enrichment of true positive CTL epitopes, which relies on mapping clusters rich in tandem or overlapping predicted MHC binders ("hotspots"), was applied, as well as considerations of predicted binding affinity. A total of 1532 peptides were tested for their ability to elicit a specific T-cell response by following the production of IFNγ from splenocytes isolated from vaccinated mice. Altogether, the screen resulted in 178 positive responders (11.8%), all novel Y. pestis CTL epitopes. These epitopes span 113 Y. pestis proteins. Substantial enrichment of membrane-associated proteins was detected for epitopes selected from hotspots of predicted MHC binders. These results considerably expand the repertoire of known CTL epitopes in Y. pestis and pave the way to

Production optimisation of a DNA vaccine candidate against ...

African Journals Online (AJOL)

Plasmid DNA (pDNA) vaccines are promising means to prevent and treat infectious diseases, such as leishmaniasis, but immunisation protocols require large amounts of supercoiled plasmid DNA (scpDNA). Although pDNA can be produced at a reasonable cost in bioreactors; this scale of production may not be the best ...

Subunit vaccine candidates against Aeromonas salmonicida in rainbow trout Oncorhynchus mykiss.

Science.gov (United States)

Marana, Moonika Haahr; Jørgensen, Louise von Gersdorff; Skov, Jakob; Chettri, Jiwan Kumar; Holm Mattsson, Andreas; Dalsgaard, Inger; Kania, Per Walter; Buchmann, Kurt

2017-01-01

Aeromonas salmonicida subsp. salmonicida is the etiological agent of furunculosis and a major fish health problem in salmonid aquaculture worldwide. Injection vaccination with commercial mineral oil-adjuvanted bacterin vaccines has been partly successful in preventing the disease but in Danish rainbow trout (Oncorhynchus mykiss, Walbaum) aquaculture furunculosis outbreaks still occur. In this study we tested the efficacy of experimental subunit vaccines against A. salmonicida infection in rainbow trout. We utilized in silico screening of the proteome of A. salmonicida subsp. salmonicida strain A449 and identified potential protective protein antigens that were tested by in vivo challenge trial. A total of 14 proteins were recombinantly expressed in Escherichia coli and prepared in 3 different subunit vaccine combinations to immunize 3 groups of rainbow trout by intraperitoneal (i.p.) injection. The fish were exposed to virulent A. salmonicida 7 weeks after immunization. To assess the efficacy of the subunit vaccines we evaluated the immune response in fish after immunization and challenge infection by measuring the antibody levels and monitoring the survival of fish in different groups. The survival of fish at 3 weeks after challenge infection showed that all 3 groups of fish immunized with 3 different protein combinations exhibited significantly lower mortalities (17-30%) compared to the control groups (48% and 56%). The ELISA results revealed significantly elevated antibody levels in fish against several protein antigens, which in some cases were positively correlated to the survival.

Construction and evaluation of novel rhesus monkey adenovirus vaccine vectors.

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Abbink, Peter; Maxfield, Lori F; Ng'ang'a, David; Borducchi, Erica N; Iampietro, M Justin; Bricault, Christine A; Teigler, Jeffrey E; Blackmore, Stephen; Parenteau, Lily; Wagh, Kshitij; Handley, Scott A; Zhao, Guoyan; Virgin, Herbert W; Korber, Bette; Barouch, Dan H

2015-02-01

Adenovirus vectors are widely used as vaccine candidates for a variety of pathogens, including HIV-1. To date, human and chimpanzee adenoviruses have been explored in detail as vaccine vectors. The phylogeny of human and chimpanzee adenoviruses is overlapping, and preexisting humoral and cellular immunity to both are exhibited in human populations worldwide. More distantly related adenoviruses may therefore offer advantages as vaccine vectors. Here we describe the primary isolation and vectorization of three novel adenoviruses from rhesus monkeys. The seroprevalence of these novel rhesus monkey adenovirus vectors was extremely low in sub-Saharan Africa human populations, and these vectors proved to have immunogenicity comparable to that of human and chimpanzee adenovirus vaccine vectors in mice. These rhesus monkey adenoviruses phylogenetically clustered with the poorly described adenovirus species G and robustly stimulated innate immune responses. These novel adenoviruses represent a new class of candidate vaccine vectors. Although there have been substantial efforts in the development of vaccine vectors from human and chimpanzee adenoviruses, far less is known about rhesus monkey adenoviruses. In this report, we describe the isolation and vectorization of three novel rhesus monkey adenoviruses. These vectors exhibit virologic and immunologic characteristics that make them attractive as potential candidate vaccine vectors for both HIV-1 and other pathogens. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Comparative genomic analysis of Brucella abortus vaccine strain 104M reveals a set of candidate genes associated with its virulence attenuation.

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Yu, Dong; Hui, Yiming; Zai, Xiaodong; Xu, Junjie; Liang, Long; Wang, Bingxiang; Yue, Junjie; Li, Shanhu

2015-01-01

The Brucella abortus strain 104M, a spontaneously attenuated strain, has been used as a vaccine strain in humans against brucellosis for 6 decades in China. Despite many studies, the molecular mechanisms that cause the attenuation are still unclear. Here, we determined the whole-genome sequence of 104M and conducted a comprehensive comparative analysis against the whole genome sequences of the virulent strain, A13334, and other reference strains. This analysis revealed a highly similar genome structure between 104M and A13334. The further comparative genomic analysis between 104M and A13334 revealed a set of genes missing in 104M. Some of these genes were identified to be directly or indirectly associated with virulence. Similarly, a set of mutations in the virulence-related genes was also identified, which may be related to virulence alteration. This study provides a set of candidate genes associated with virulence attenuation in B.abortus vaccine strain 104M.

Ebolavirus Vaccines: Progress in the Fight Against Ebola Virus Disease.

Science.gov (United States)

Wu, Xiao-Xin; Yao, Hang-Ping; Wu, Nan-Ping; Gao, Hai-Nv; Wu, Hai-Bo; Jin, Chang-Zhong; Lu, Xiang-Yun; Xie, Tian-Shen; Li, Lan-Juan

2015-01-01

Ebolaviruses are highly infectious pathogens that cause lethal Ebola virus disease (EVD) in humans and non-human primates (NHPs). Due to their high pathogenicity and transmissibility, as well as the potential to be misused as a bioterrorism agent, ebolaviruses would threaten the health of global populations if not controlled. In this review, we describe the origin and structure of ebolaviruses and the development of vaccines from the beginning of the 1980s, including conventional ebolavirus vaccines, DNA vaccines, Ebola virus-like particles (VLPs), vaccinia virus-based vaccines, Venezuelan equine encephalitis virus (VEEV)-like replicon particles, Kunjin virus-based vaccine, recombinant Zaire Ebolavirusx2206;VP30, recombinant cytomegalovirus (CMV)-based vaccines, recombinant rabies virus (RABV)-based vaccines, recombinant paramyxovirus-based vaccines, adenovirus-based vaccines and vesicular stomatitis virus (VSV)-based vaccines. No licensed vaccine or specific treatment is currently available to counteract ebolavirus infection, although DNA plasmids and several viral vector approaches have been evaluated as promising vaccine platforms. These vaccine candidates have been confirmed to be successful in protecting NHPs against lethal infection. Moreover, these vaccine candidates were successfully advanced to clinical trials. The present review provides an update of the current research on Ebola vaccines, with the aim of providing an overview on current prospects in the fight against EVD. © 2015 The Author(s) Published by S. Karger AG, Basel.

Prophylactic Hepatitis E Vaccine.

Science.gov (United States)

Zhang, Jun; Zhao, Qinjian; Xia, Ningshao

2016-01-01

Hepatitis E has been increasingly recognized as an underestimated global disease burden in recent years. Subpopulations with more serious infection-associated damage or death include pregnant women, patients with basic liver diseases, and elderly persons. Vaccine would be the most effective means for prevention of HEV infection. The lack of an efficient cell culture system for HEV makes the development of classic inactive or attenuated vaccine infeasible. Hence, the recombinant vaccine approaches are explored deeply. The neutralizing sites are located almost exclusively in the capsid protein, pORF2, of the virion. Based on pORF2, many vaccine candidates showed potential of protecting primate animals; two of them were tested in human and evidenced to be well tolerated in adults and highly efficacious in preventing hepatitis E. The world's first hepatitis E vaccine, Hecolin ® (HEV 239 vaccine), was licensed in China and launched in 2012.

A recombinant pseudorabies virus co-expressing capsid proteins precursor P1-2A of FMDV and VP2 protein of porcine parvovirus: a trivalent vaccine candidate.

Science.gov (United States)

Hong, Qi; Qian, Ping; Li, Xiang-Min; Yu, Xiao-Lan; Chen, Huan-Chun

2007-11-01

Pseudorabies (PR), foot-and-mouth disease (FMD), and porcine parvovirus disease are three important infectious diseases in swine worldwide. The gene-deleted pseudorabies virus (PRV) has been used as a live-viral vector to develop multivalent genetic engineering vaccine. In this study, a recombinant PRV, which could co-express protein precursor P1-2A of FMDV and VP2 protein of PPV, was constructed using PRV TK(-)/gE(-)/LacZ(+) mutant as the vector. After homologous recombination and plaque purification, recombinant virus PRV TK(-)/gE(-)/P1-2A-VP2 was acquired and identified. Immunogenicity, safety of the recombinant PRV and its protection against PRV were confirmed in a mouse model by indirect ELISA and serum neutralization test. The results show that the recombinant PRV is a candidate vaccine strain to develop a novel trivalent vaccine against PRV, FMDV and PPV in swine.

Targeting the Conserved Fusion Loop of HAP2 Inhibits the Transmission of Plasmodium berghei and falciparum

Directory of Open Access Journals (Sweden)

Fiona Angrisano

2017-12-01

Full Text Available Summary: Inhibiting transmission of Plasmodium is a central strategy in malarial eradication, and the biological process of gamete fusion during fertilization is a proven target for this approach. The lack of a structure or known molecular function of current anti-malarial vaccine targets has previously been a hindrance in the development of transmission-blocking vaccines. Structure/function studies have indicated that the conserved gamete membrane fusion protein HAP2 is a class II viral fusion protein. Here, we demonstrate that targeting a function-critical site of the fusion/cd loop with species-specific antibodies reduces Plasmodium berghei transmission in vivo by 58.9% and in vitro fertilization by up to 89.9%. A corresponding reduction in P. falciparum transmission (75.5%/36.4% reductions in intensity/prevalence is observed in complimentary field studies. These results emphasize conserved mechanisms of fusion in Apicomplexa, while highlighting an approach to design future anti-malarial transmission-blocking vaccines. : Angrisano et al. find that the HAP2 cd-loop can be targeted as an anti-malarial intervention, is immunogenic across multiple plasmodial species, can induce antibodies that specifically recognize the sexual stages of the parasitic life cycle, and can mediate transmission-blocking immunity in the lab and the field. Keywords: HAP2, malaria, transmission, fusion, vaccine

Advances in the development of vaccines for dengue fever

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Simmons M

2012-05-01

Full Text Available Monika Simmons1, Nimfa Teneza-Mora1, Robert Putnak21Viral and Rickettsial Diseases Department, Naval Medical Research Center, 2Division of Viral Diseases, Walter Reed Army Institute of Research, Silver Spring, MD, USAAbstract: Dengue fever is caused by the mosquito-borne dengue virus (DENV serotypes 1–4, and is the most common arboviral infection of humans in subtropical and tropical regions of the world. There are currently no prophylaxis or treatment options in the form of vaccines or antivirals, leaving vector control the only method of prevention. A particular challenge with DENV is that a successful vaccine has to be effective against all four serotypes without predisposing for antibody-mediated enhanced disease. In this review, we discuss the current lead vaccine candidates in clinical trials, as well as some second-generation vaccine candidates undergoing preclinical evaluation. In addition, we discuss DENV epidemiology, clinical disease and strategies used for Flavivirus antivirals in the past, the development of new DENV therapeutics, and their potential usefulness for prophylaxis and treatment.Keywords: tetravalent dengue vaccine, live attenuated vaccine, purified inactivated vaccine, DNA vaccine, antibody-dependent enhancement, antivirals

Genetic polymorphism of Plasmodium falciparum isolates from Loreto, Peru.

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Hijar, Gisely; Padilla, Carlos; Marquiño, Wilmer; Falconi, Eduardo; Montoya, Ysabel

2002-04-01

Eight genotypes of Plasmodium falciparum were detected after analysing blood samples obtained from 30 Peruvian jungle-dwelling patients in Loreto, a high transmission area for P. falciparum, using amplification of the polymorphic marker gene GLURP (glutamate-rich protein). Genotypes I (GLURP450) and VIII (GLURP800) were the most common (15/30 and 13/30, respectively). This single copy gene showed 15 patients to be infected with a single genotype of P. falciparum; the other 15 were infected with mixed genotypes, one of them with 4 genotypes. These findings are compatible with a high genetic complexity of P. falciparum. Further investigations are needed, using this and other markers, in order to design malaria control measures in Peru.

Optimising Controlled Human Malaria Infection Studies Using Cryopreserved P. falciparum Parasites Administered by Needle and Syringe.

Directory of Open Access Journals (Sweden)

Susanne H Sheehy

Full Text Available Controlled human malaria infection (CHMI studies have become a routine tool to evaluate efficacy of candidate anti-malarial drugs and vaccines. To date, CHMI trials have mostly been conducted using the bite of infected mosquitoes, restricting the number of trial sites that can perform CHMI studies. Aseptic, cryopreserved P. falciparum sporozoites (PfSPZ Challenge provide a potentially more accurate, reproducible and practical alternative, allowing a known number of sporozoites to be administered simply by injection.We sought to assess the infectivity of PfSPZ Challenge administered in different dosing regimens to malaria-naive healthy adults (n = 18. Six participants received 2,500 sporozoites intradermally (ID, six received 2,500 sporozoites intramuscularly (IM and six received 25,000 sporozoites IM.Five out of six participants receiving 2,500 sporozoites ID, 3/6 participants receiving 2,500 sporozoites IM and 6/6 participants receiving 25,000 sporozoites IM were successfully infected. The median time to diagnosis was 13.2, 17.8 and 12.7 days for 2,500 sporozoites ID, 2,500 sporozoites IM and 25,000 sporozoites IM respectively (Kaplan Meier method; p = 0.024 log rank test.2,500 sporozoites ID and 25,000 sporozoites IM have similar infectivities. Given the dose response in infectivity seen with IM administration, further work should evaluate increasing doses of PfSPZ Challenge IM to identify a dosing regimen that reliably infects 100% of participants.ClinicalTrials.gov NCT01465048.

Hendra and Nipah viruses: pathogenesis, animal models and recent breakthroughs in vaccination

Directory of Open Access Journals (Sweden)

Weingartl HM

2015-09-01

Full Text Available Hana M Weingartl National Centre for Foreign Animal Disease, Canadian Food Inspection Agency, Winnipeg, MB, Canada Abstract: Hendra and Nipah viruses are two highly pathogenic zoonotic members of the genus Henipavirus, family Paramyxoviridae, requiring work under biosafety level 4 conditions due to a lack of effective therapy and human vaccines. Several vaccine candidates were protective in animal models: recombinant vaccinia virus expressing Nipah virus (NiV F and G proteins in hamsters against NiV; recombinant ALVAC–NiV F and G in swine against NiV; recombinant Hendra virus (HeV soluble G protein (sGHeV against HeV and NiV in cats, ferrets, horses, and African green monkeys (AGM; recombinant vesicular stomatitis virus-based vectors expressing NiV F or G against NiV in hamsters and ferrets; measles virus-based NiV G vaccine candidate in hamsters and AGMs against NiV; and adenoassociated virus expressing NiG protein, which protected hamsters against NiV. The sGHeV was licensed for use in horses (Equivac HeV® in 2012. It is the first vaccine candidate licensed against a biosafety level 4 agent. With the development of suitable animal models (ferret, hamster and, importantly, AGM, progress can be made toward development of a human vaccine.Keywords: henipavirus, equine, swine, human infection, animal models, vaccine candidates

New vaccines against otitis media: projected benefits and cost-effectiveness.

Science.gov (United States)

O'Brien, Megan A; Prosser, Lisa A; Paradise, Jack L; Ray, G Thomas; Kulldorff, Martin; Kurs-Lasky, Marcia; Hinrichsen, Virginia L; Mehta, Jyotsna; Colborn, D Kathleen; Lieu, Tracy A

2009-06-01

New vaccines that offer protection against otitis media caused by nontypeable Haemophilus influenzae and by Moraxella catarrhalis are under development. However, the potential health benefits and economic effects of such candidate vaccines have not been systematically assessed. We created a computerized model to compare the projected benefits and costs of (1) the currently available 7-valent pneumococcal conjugate vaccine, (2) a candidate pneumococcal-nontypeable H influenzae vaccine that has been tested in Europe, (3) a hypothetical pneumococcal-nontypeable H influenzae-Moraxella vaccine, and (4) no vaccination. The clinical probabilities of acute otitis media and of otitis media with effusion were generated from multivariate analyses of data from 2 large health maintenance organizations and from the Pittsburgh Child Development/Otitis Media Study cohort. Other probabilities, costs, and quality-of-life values were derived from published and unpublished sources. The base-case analysis assumed vaccine dose costs of $65 for the 7-valent pneumococcal conjugate vaccine, $100 for the pneumococcal-nontypeable H influenzae vaccine, and $125 for the pneumococcal-nontypeable H influenzae-Moraxella vaccine. With no vaccination, we projected that 13.7 million episodes of acute otitis media would occur annually in US children aged 0 to 4 years, at an annual cost of $3.8 billion. The 7-valent pneumococcal conjugate vaccine was projected to prevent 878,000 acute otitis media episodes, or 6.4% of those that would occur with no vaccination; the corresponding value for the pneumococcal-nontypeable H influenzae vaccine was 3.7 million (27%) and for the pneumococcal-nontypeable H influenzae-Moraxella vaccine was 4.2 million (31%). Using the base-case vaccine costs, pneumococcal-nontypeable H influenzae vaccine use would result in net savings compared with nontypeable 7-valent pneumococcal conjugate use. Conversely, pneumococcal-nontypeable H influenzae-Moraxella vaccine use would not

Comparative evaluation of the protective efficacy of two formulations of a recombinant Chlamydia abortus subunit candidate vaccine in a mouse model.

Science.gov (United States)

Pan, Qing; Pais, Roshan; Ohandjo, Adaugo; He, Cheng; He, Qing; Omosun, Yusuf; Igietseme, J U; Eko, F O

2015-04-08

Chlamydia abortus (C. abortus) is the causative agent of ovine enzootic abortion (OEA) and poses a zoonotic risk to pregnant women. Current live attenuated 1B vaccines are efficacious but cause disease in vaccinated animals and inactivated vaccines are only marginally protective. We tested the ability of a new C. abortus subunit vaccine candidate based on the conserved and immunogenic polymorphic membrane protein D (Pmp18D) formulated in CpG1826+FL (Fms-like tyrosine kinase 3 Ligand; Flt3L) or Vibrio cholerae ghosts (VCG) to induce innate and cross protective immunity against genital C. abortus infection. We found that delivery of rPmp18D with VCG was more effective than with CpG+FL in up-regulating the expression of molecules critically involved in T cell activation and differentiation, including MHC II, CD40, CD80, and CD86, activation of TLRs and NLRP3 inflammasome engagement, and secretion of IL-1β and TNF-α but not IL-10 and IL-4. rVCG-Pmp18D-immunized mice elicited more robust antigen-specific IFN-γ, IgA and IgG2c antibody responses compared to CpG+FL-delivered rPmp18D. Based on the number of mice with positive vaginal cultures, length of vaginal shedding, and number of inclusion forming units recovered following challenge with the heterologous C. abortus strain B577, vaccine delivery with VCG induced superior protective immunity than delivery with a combination of CpG1826 and FL, a nasal DC-targeting adjuvant. These results demonstrate that the ability of VCG to enhance protective immunity against genital C. abortus infection is superior to that of CpG+FL adjuvants. Copyright © 2015 Elsevier Ltd. All rights reserved.

Progress in Brucella vaccine development

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YANG, Xinghong; SKYBERG, Jerod A.; CAO, Ling; CLAPP, Beata; THORNBURG, Theresa; PASCUAL, David W.

2012-01-01

Brucella spp. are zoonotic, facultative intracellular pathogens, which cause animal and human disease. Animal disease results in abortion of fetuses; in humans, it manifests flu-like symptoms with an undulant fever, with osteoarthritis as a common complication of infection. Antibiotic regimens for human brucellosis patients may last several months and are not always completely effective. While there are no vaccines for humans, several licensed live Brucella vaccines are available for use in livestock. The performance of these animal vaccines is dependent upon the host species, dose, and route of immunization. Newly engineered live vaccines, lacking well-defined virulence factors, retain low residual virulence, are highly protective, and may someday replace currently used animal vaccines. These also have possible human applications. Moreover, due to their enhanced safety and efficacy in animal models, subunit vaccines for brucellosis show great promise for their application in livestock and humans. This review summarizes the progress of brucellosis vaccine development and presents an overview of candidate vaccines. PMID:23730309

Adhesion of Plasmodium falciparum infected erythrocytes in ex vivo perfused placental tissue

DEFF Research Database (Denmark)