Potential Impact of Seasonal Malaria Chemoprevention on the Acquisition of Antibodies Against Glutamate-Rich Protein and Apical Membrane Antigen 1 in Children Living in Southern Senegal

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Ndiaye, Magatte; Sylla, Khadime; Sow, Doudou

2015-01-01

Seasonal malaria chemoprevention (SMC) is defined as the intermittent administration of full treatment courses of an antimalarial drug to children during the peak of malaria transmission season with the aim of preventing malaria-associated mortality and morbidity. SMC using sulfadoxine-pyrimetham......Seasonal malaria chemoprevention (SMC) is defined as the intermittent administration of full treatment courses of an antimalarial drug to children during the peak of malaria transmission season with the aim of preventing malaria-associated mortality and morbidity. SMC using sulfadoxine......-pyrimethamine (SP) combined with amodiaquine (AQ) is a promising strategy to control malaria morbidity in areas of highly seasonal malaria transmission. However, a concern is whether SMC can delay the natural acquisition of immunity toward malaria parasites in areas with intense SMC delivery. To investigate this......, total IgG antibody (Ab) responses to Plasmodium falciparum antigens glutamate-rich protein R0 (GLURP-R0) and apical membrane antigen 1 (AMA-1) were measured by enzyme-linked immunosorbent assay in Senegalese children under the age of 10 years in 2010 living in Saraya and Velingara districts (with SMC...

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

Antibody isotype analysis of malaria-nematode co-infection: problems and solutions associated with cross-reactivity

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Graham Andrea L

2010-02-01

Full Text Available Abstract Background Antibody isotype responses can be useful as indicators of immune bias during infection. In studies of parasite co-infection however, interpretation of immune bias is complicated by the occurrence of cross-reactive antibodies. To confidently attribute shifts in immune bias to the presence of a co-infecting parasite, we suggest practical approaches to account for antibody cross-reactivity. The potential for cross-reactive antibodies to influence disease outcome is also discussed. Results Utilising two murine models of malaria-helminth co-infection we analysed antibody responses of mice singly- or co-infected with Plasmodium chabaudi chabaudi and Nippostrongylus brasiliensis or Litomosoides sigmodontis. We observed cross-reactive antibody responses that recognised antigens from both pathogens irrespective of whether crude parasite antigen preparations or purified recombinant proteins were used in ELISA. These responses were not apparent in control mice. The relative strength of cross-reactive versus antigen-specific responses was determined by calculating antibody titre. In addition, we analysed antibody binding to periodate-treated antigens, to distinguish responses targeted to protein versus carbohydrate moieties. Periodate treatment affected both antigen-specific and cross-reactive responses. For example, malaria-induced cross-reactive IgG1 responses were found to target the carbohydrate component of the helminth antigen, as they were not detected following periodate treatment. Interestingly, periodate treatment of recombinant malaria antigen Merozoite Surface Protein-119 (MSP-119 resulted in increased detection of antigen-specific IgG2a responses in malaria-infected mice. This suggests that glycosylation may have been masking protein epitopes and that periodate-treated MSP-119 may more closely reflect the natural non-glycosylated antigen seen during infection. Conclusions In order to utilize antibody isotypes as a measure of

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

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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.

Seasonal variations in antibody response to a Plasmodium ...

African Journals Online (AJOL)

An Enzyme Linked Immunosorbent Assay (ELISA), employing a recombinant peptide capture antigen (R32tet32) was used to detect antibodies against the circumsporozoite protein (CSP) of the malaria parasite, Plasmodium falciparum in 169 ...

A threshold concentration of anti-merozoite antibodies is required for protection from clinical episodes of malaria

DEFF Research Database (Denmark)

Murungi, Linda M; Kamuyu, Gathoni; Lowe, Brett

2013-01-01

Antibodies to selected Plasmodium falciparum merozoite antigens are often reported to be associated with protection from malaria in one epidemiological cohort, but not in another. Here, we sought to understand this paradox by exploring the hypothesis that a threshold concentration of antibodies i...

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

Human antibodies fix complement to inhibit Plasmodium falciparum invasion of erythrocytes and are associated with protection against malaria.

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Boyle, Michelle J; Reiling, Linda; Feng, Gaoqian; Langer, Christine; Osier, Faith H; Aspeling-Jones, Harvey; Cheng, Yik Sheng; Stubbs, Janine; Tetteh, Kevin K A; Conway, David J; McCarthy, James S; Muller, Ivo; Marsh, Kevin; Anders, Robin F; Beeson, James G

2015-03-17

Antibodies play major roles in immunity to malaria; however, a limited understanding of mechanisms mediating protection is a major barrier to vaccine development. We have demonstrated that acquired human anti-malarial antibodies promote complement deposition on the merozoite to mediate inhibition of erythrocyte invasion through C1q fixation and activation of the classical complement pathway. Antibody-mediated complement-dependent (Ab-C') inhibition was the predominant invasion-inhibitory activity of human antibodies; most antibodies were non-inhibitory without complement. Inhibitory activity was mediated predominately via C1q fixation, and merozoite surface proteins 1 and 2 were identified as major targets. Complement fixation by antibodies was very strongly associated with protection from both clinical malaria and high-density parasitemia in a prospective longitudinal study of children. Ab-C' inhibitory activity could be induced by human immunization with a candidate merozoite surface-protein vaccine. Our findings demonstrate that human anti-malarial antibodies have evolved to function by fixing complement for potent invasion-inhibitory activity and protective immunity. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Antibody responses to two new Lactococcus lactis-produced recombinant Pfs48/45 and Pfs230 proteins increase with age in malaria patients living in the Central Region of Ghana.

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Acquah, Festus K; Obboh, Evans K; Asare, Kwame; Boampong, Johnson N; Nuvor, Samuel Victor; Singh, Susheel K; Theisen, Michael; Williamson, Kim C; Amoah, Linda Eva

2017-08-01

Recent advances in malaria control efforts have led to an increased number of national malaria control programmes implementing pre-elimination measures and demonstrated the need to develop new tools to track and control malaria transmission. Key to understanding transmission is monitoring the prevalence and immune response against the sexual stages of the parasite, known as gametocytes, which are responsible for transmission. Sexual-stage specific antigens, Pfs230 and Pfs48/45, have been identified and shown to be targets for transmission blocking antibodies, but they have been difficult to produce recombinantly in the absence of a fusion partner. Regions of Pfs48/45 and Pfs230 known to contain transmission blocking epitopes, 6C and C0, respectively, were produced in a Lactococcus lactis expression system and used in enzyme linked immunosorbent assays to determine the seroreactivity of 95 malaria patients living in the Central Region of Ghana. Pfs48/45.6C and Pfs230.C0 were successfully produced in L. lactis in the absence of a fusion partner using a simplified purification scheme. Seroprevalence for L. lactis-produced Pfs48/45.6C and Pfs230.C0 in the study population was 74.7 and 72.8%, respectively. A significant age-dependent increase in antibody titers was observed, which suggests a vaccine targeting these antigens could be boosted during a natural infection in the field.

Assessment of the quality and quantity of naturally induced antibody responses to EBA175RIII-V in Ghanaian children living in two communities with varying malaria transmission patterns

DEFF Research Database (Denmark)

Abagna, Hamza B; Acquah, Festus K; Okonu, Ruth

2018-01-01

of malaria parasites, which can enhance immune responses against parasite antigens. This study determined the prevalence and relative avidities of naturally induced antibodies to EBA175RIII-VLl in asymptomatic children living in two communities with varying malaria transmission patterns. METHODS: An asexual...... each study site however, children living in Obom had significantly higher EBA175RIII-VLl antibody concentrations than children living in Abura (P 0.05, Mann-Whitney test). Over the course of the study, the relative antibody avidities of EBA175RIII-VLl IgG antibodies were similar within and between......BACKGROUND: Recent global reports on malaria suggest significant decrease in disease severity and an increase in control interventions in many malaria endemic countries, including Ghana. However, a major driving force sustaining malaria transmission in recent times is the asymptomatic carriage...

The effect of daily co-trimoxazole prophylaxis on natural development of antibody-mediated immunity against P. falciparum malaria infection in HIV-exposed uninfected Malawian children.

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Longwe, Herbert; Jambo, Kondwani C; Phiri, Kamija S; Mbeye, Nyanyiwe; Gondwe, Thandile; Hall, Tom; Tetteh, Kevin K A; Drakeley, Chris; Mandala, Wilson L

2015-01-01

Co-trimoxazole prophylaxis, currently recommended in HIV-exposed, uninfected (HEU) children as protection against opportunistic infections, also has some anti-malarial efficacy. We determined whether daily co-trimoxazole prophylaxis affects the natural development of antibody-mediated immunity to blood-stage Plasmodium falciparum malaria infection. Using an enzyme-linked immunosorbent assay, we measured antibodies to 8 Plasmodium falciparum antigens (AMA-1, MSP-119, MSP-3, PfSE, EBA-175RII, GLURP R0, GLURP R2 and CSP) in serum samples from 33 HEU children and 31 HIV-unexposed, uninfected (HUU) children, collected at 6, 12 and 18 months of age. Compared to HIV-uninfected children, HEU children had significantly lower levels of specific IgG against AMA-1 at 6 months (p = 0.001), MSP-119 at 12 months (p = 0.041) and PfSE at 6 months (p = 0.038), 12 months (p = 0.0012) and 18 months (p = 0.0097). No differences in the IgG antibody responses against the rest of the antigens were observed between the two groups at all time points. The breadth of specificity of IgG response was reduced in HEU children compared to HUU children during the follow up period. Co-trimoxazole prophylaxis seems to reduce IgG antibody responses to P. falciparum blood stage antigens, which could be as a result of a reduction in exposure of those children under this regime. Although antibody responses were regarded as markers of exposure in this study, further studies are required to establish whether these responses are correlated in any way to clinical immunity to malaria.

Seroprevalence of Antibodies against Plasmodium falciparum Sporozoite Antigens as Predictive Disease Transmission Markers in an Area of Ghana with Seasonal Malaria Transmission.

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Kwadwo A Kusi

Full Text Available As an increasing number of malaria-endemic countries approach the disease elimination phase, sustenance of control efforts and effective monitoring are necessary to ensure success. Mathematical models that estimate anti-parasite antibody seroconversion rates are gaining relevance as more sensitive transmission intensity estimation tools. Models however estimate yearly seroconversion and seroreversion rates and usually predict long term changes in transmission, occurring years before the time of sampling. Another challenge is the identification of appropriate antigen targets since specific antibody levels must directly reflect changes in transmission patterns. We therefore investigated the potential of antibodies to sporozoite and blood stage antigens for detecting short term differences in malaria transmission in two communities in Northern Ghana with marked, seasonal transmission.Cross-sectional surveys were conducted during the rainy and dry seasons in two communities, one in close proximity to an irrigation dam and the other at least 20 Km away from the dam. Antibodies against the sporozoite-specific antigens circumsporozoite protein (CSP and Cell traversal for ookinetes and sporozoites (CelTOS and the classical blood stage antigen apical membrane antigen 1 (AMA1 were measured by indirect ELISA. Antibody levels and seroprevalence were compared between surveys and between study communities. Antibody seroprevalence data were fitted to a modified reversible catalytic model to estimate the seroconversion and seroreversion rates.Changes in sporozoite-specific antibody levels and seroprevalence directly reflected differences in parasite prevalence between the rainy and dry seasons and hence the extent of malaria transmission. Seroconversion rate estimates from modelled seroprevalence data did not however support the above observation.The data confirms the potential utility of sporozoite-specific antigens as useful markers for monitoring short term

Effect of seasonal malaria chemoprevention on the acquisition of antibodies to Plasmodium falciparum antigens in Ouelessebougou, Mali.

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Mahamar, Almahamoudou; Issiaka, Djibrilla; Barry, Amadou; Attaher, Oumar; Dembele, Adama B; Traore, Tiangoua; Sissoko, Adama; Keita, Sekouba; Diarra, Bacary Soumana; Narum, David L; Duffy, Patrick E; Dicko, Alassane; Fried, Michal

2017-07-18

Seasonal malaria chemoprevention (SMC) is a new strategy to reduce malaria burden in young children in Sahelian countries. It consists of the administration of full treatment courses of sulfadoxine-pyrimethamine plus amodiaquine to children at monthly intervals during the malaria season. However, it is not clear if there is a cumulative effect of SMC over time on acquisition of antibodies to malaria antigens. A cross-sectional serosurvey was carried out 1 month after the last dose of SMC in 2016. Children aged 3-4 years were randomly selected from areas where SMC was given for 1, 2 or 3 years during the malaria season. Children in the areas where SMC had been implemented for 1 year but who failed to receive SMC were used as comparison group. Antibody extracted from dry blood spots was used to measure IgG levels to CSP, MSP-1 42 and AMA1. The prevalence of antibodies to AMA-1 were high and similar in children who received SMC for 1, 2 or 3 years and also when compared to those who never received SMC (96.3 vs 97.5%, adjusted OR = 0.99, 95% CI 0.33-2.97, p = 0.99). The prevalence of antibodies to MSP-1 42 and to CSP were similar in children that received SMC for 1, 2 or 3 years, but were lower in these children compared to those who did not receive SMC (87.1 vs 91.2%, adjusted OR = 0.55, 95% CI 0.29-1.01, p = 0.05 for MSP-1 42 ; 79.8 vs 89.2%, adjusted OR = 0.52, 95% CI 0.30-0.90, p = 0.019 for CSP). SMC reduced seropositivity to MSP-1 42 and CSP, but the duration of SMC did not further reduce seropositivity. Exposure to SMC did not reduce the seropositivity to AMA1.

Naturally Acquired Antibodies to Plasmodium vivax Duffy Binding Protein (DBP) in Rural Brazilian Amazon

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Souza-Silva, Flávia A.; da Silva-Nunes, Mônica; Sanchez, Bruno A. M.; Ceravolo, Isabela P.; Malafronte, Rosely S.; Brito, Cristiana F. A.; Ferreira, Marcelo U.; Carvalho, Luzia H.

2010-01-01

Duffy binding protein (DBP), a leading malaria vaccine candidate, plays a critical role in Plasmodium vivax erythrocyte invasion. Sixty-eight of 366 (18.6%) subjects had IgG anti-DBP antibodies by enzyme-linked immunosorbent assay (ELISA) in a community-based cross-sectional survey in the Brazilian Amazon Basin. Despite continuous exposure to low-level malaria transmission, the overall seroprevalence decreased to 9.0% when the population was reexamined 12 months later. Antibodies from 16 of 50 (36.0%) subjects who were ELISA-positive at the baseline were able to inhibit erythrocyte binding to at least one of two DBP variants tested. Most (13 of 16) of these subjects still had inhibitory antibodies when reevaluated 12 months later. Cumulative exposure to malaria was the strongest predictor of DBP seropositivity identified by multiple logistic regression models in this population. The poor antibody recognition of DBP elicited by natural exposure to P. vivax in Amazonian populations represents a challenge to be addressed by vaccine development strategies. PMID:20133990

Fc gamma receptor IIIB (Fc gamma RIIIB) polymorphisms are associated with clinical malaria in Ghanaian children

DEFF Research Database (Denmark)

Adu, Bright; Dodoo, Daniel; Adukpo, Selorme

2012-01-01

Plasmodium falciparum malaria kills nearly a million people annually. Over 90% of these deaths occur in children under five years of age in sub-Saharan Africa. A neutrophil mediated mechanism, the antibody dependent respiratory burst (ADRB), was recently shown to correlate with protection from...... by allele specific restriction enzyme digestion. FCGR3B-exon 3 was sequenced in 585 children, aged 1 to 12 years living in a malaria endemic region of Ghana. Multivariate logistic regression analysis found no association between Fc¿RIIA-166H/R polymorphism and clinical malaria. The A-allele of FCGR3B-c.233C...... malaria vaccines....

The effect of daily co-trimoxazole prophylaxis on natural development of antibody-mediated immunity against P. falciparum malaria infection in HIV-exposed uninfected Malawian children.

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Herbert Longwe

Full Text Available Co-trimoxazole prophylaxis, currently recommended in HIV-exposed, uninfected (HEU children as protection against opportunistic infections, also has some anti-malarial efficacy. We determined whether daily co-trimoxazole prophylaxis affects the natural development of antibody-mediated immunity to blood-stage Plasmodium falciparum malaria infection.Using an enzyme-linked immunosorbent assay, we measured antibodies to 8 Plasmodium falciparum antigens (AMA-1, MSP-119, MSP-3, PfSE, EBA-175RII, GLURP R0, GLURP R2 and CSP in serum samples from 33 HEU children and 31 HIV-unexposed, uninfected (HUU children, collected at 6, 12 and 18 months of age.Compared to HIV-uninfected children, HEU children had significantly lower levels of specific IgG against AMA-1 at 6 months (p = 0.001, MSP-119 at 12 months (p = 0.041 and PfSE at 6 months (p = 0.038, 12 months (p = 0.0012 and 18 months (p = 0.0097. No differences in the IgG antibody responses against the rest of the antigens were observed between the two groups at all time points. The breadth of specificity of IgG response was reduced in HEU children compared to HUU children during the follow up period.Co-trimoxazole prophylaxis seems to reduce IgG antibody responses to P. falciparum blood stage antigens, which could be as a result of a reduction in exposure of those children under this regime. Although antibody responses were regarded as markers of exposure in this study, further studies are required to establish whether these responses are correlated in any way to clinical immunity to malaria.

Lipid peroxidation and antioxidant enzymes activity in Plasmodium vivax malaria patients evolving with cholestatic jaundice

Science.gov (United States)

2013-01-01

Background Plasmodium vivax infection has been considered a benign and self-limiting disease, however, recent studies highlight the association between vivax malaria and life-threatening manifestations. Increase in reactive oxygen species has already been described in vivax malaria, as a result of the increased metabolic rate triggered by the multiplying parasite, and large quantities of toxic redox-active byproducts generated. The present study aimed to study the oxidative stress responses in patients infected with P. vivax, who developed jaundice (hyperbilirubinaemia) in the course of the disease, a common clinical complication related to this species. Methods An evaluation of the lipid peroxidation and antioxidant enzymes profile was performed in 28 healthy individuals and compared with P. vivax infected patients with jaundice, i.e., bilirubin jaundice (34 patients), on day 1 (D1) and day 14 (D14) after anti-malarial therapy. Results Hyperbilirubinaemia was more frequent among women and patients experiencing their first malarial infection, and lower haemoglobin and higher lactate dehydrogenase levels were observed in this group. Malondialdehyde levels and activity of celuroplasmin and glutathione reductase were increased in the plasma from patients with P. vivax with jaundice compared to the control group on D1. However, the activity of thioredoxin reductase was decreased. The enzymes glutathione reductase, thioredoxin reductase, thiols and malondialdehyde also differed between jaundiced versus non-jaundiced patients. On D14 jaundice and parasitaemia had resolved and oxidative stress biomarkers were very similar to the control group. Conclusion Cholestatic hyperbilirubinaemia in vivax malaria cannot be totally disassociated from malaria-related haemolysis. However, significant increase of lipid peroxidation markers and changes in antioxidant enzymes in patients with P. vivax-related jaundice was observed. These results suggest oxidative processes contributing

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

DEFF Research Database (Denmark)

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...

Lack of gender-specific antibody recognition of products from domains of a var gene implicated in pregnancy-associated Plasmodium falciparum malaria

DEFF Research Database (Denmark)

Jensen, Anja T R; Zornig, Hanne D; Buhmann, Caecilie

2003-01-01

Gender-specific and parity-dependent acquired antibody recognition is characteristic of variant surface antigens (VSA) expressed by chondroitin sulfate A (CSA)-adherent Plasmodium falciparum involved in pregnancy-associated malaria (PAM). However, antibody recognition of recombinant products...

Antibody responses to a panel of Plasmodium falciparum malaria blood-stage antigens in relation to clinical disease outcome in Sudan

DEFF Research Database (Denmark)

Iriemenam, Nnaemeka C; Khirelsied, Atif H; Nasr, Amre

2009-01-01

Despite many intervention programmes aimed at curtailing the scourge, malaria remains a formidable problem of human health. Immunity to asexual blood-stage of Plasmodium falciparum malaria is thought to be associated with protective antibodies of certain immunoglobulin classes and subclasses. We ...

Immunoglobulin G antibody reactivity to a group A Plasmodium falciparum erythrocyte membrane protein 1 and protection from P. falciparum malaria

DEFF Research Database (Denmark)

Magistrado, Pamela A; Lusingu, John; Vestergaard, Lasse S

2007-01-01

where P. falciparum is endemic, parasites causing severe malaria and malaria in young children with limited immunity tend to express semiconserved PfEMP1 molecules encoded by group A var genes. Here we investigated antibody responses of Tanzanians who were 0 to 19 years old to PF11_0008, a group A Pf...

Antibodies to malaria vaccine candidates are associated with chloroquine or sulphadoxine/pyrimethamine treatment efficacy in children in an endemic area of Burkina Faso

DEFF Research Database (Denmark)

Diarra, Amidou; Nebie, Issa; Tiono, Alfred

2012-01-01

ABSTRACT: BACKGROUND: Patient immune status is thought to affect the efficacy of anti-malarial chemotherapy. This is a subject of some importance, since evidence of immunity-related interactions may influence our use of chemotherapy in populations with drug resistance, as well as assessment...... of the value of suboptimal vaccines. The study aim was to investigate relationship between antibodies and anti-malarial drug treatment outcomes. METHODS: Some 248 children aged 0.5 and 15 years were recruited prior to the high malaria transmission season. Venous blood (5 ml) was obtained from each child...... to measure antibody levels to selected malaria antigens, using ELISA. Blood smears were also performed to assess drug efficacy and malaria infection prevalence. Children were actively followed up to record clinical malaria cases. RESULTS: IgG levels to MSP3 were always higher in the successfully treated...

High Levels of Antibodies to Multiple Domains and Strains of VAR2CSA Correlate with the Absence of Placental Malaria in Cameroonian Women Living in an Area of High Plasmodium falciparum Transmission

Science.gov (United States)

Tutterrow, Yeung L.; Avril, Marion; Singh, Kavita; Long, Carole A.; Leke, Robert J.; Sama, Grace; Salanti, Ali; Smith, Joseph D.; Leke, Rose G. F.

2012-01-01

Placental malaria, caused by sequestration of Plasmodium falciparum-infected erythrocytes in the placenta, is associated with increased risk of maternal morbidity and poor birth outcomes. The parasite antigen VAR2CSA (variant surface antigen 2-chondroitin sulfate A) is expressed on infected erythrocytes and mediates binding to chondroitin sulfate A, initiating inflammation and disrupting homeostasis at the maternal-fetal interface. Although antibodies can prevent sequestration, it is unclear whether parasite clearance is due to antibodies to a single Duffy binding-like (DBL) domain or to an extensive repertoire of antibodies to multiple DBL domains and allelic variants. Accordingly, plasma samples collected longitudinally from pregnant women were screened for naturally acquired antibodies against an extensive panel of VAR2CSA proteins, including 2 to 3 allelic variants for each of 5 different DBL domains. Analyses were performed on plasma samples collected from 3 to 9 months of pregnancy from women living in areas in Cameroon with high and low malaria transmission. The results demonstrate that high antibody levels to multiple VAR2CSA domains, rather than a single domain, were associated with the absence of placental malaria when antibodies were present from early in the second trimester until term. Absence of placental malaria was associated with increasing antibody breadth to different DBL domains and allelic variants in multigravid women. Furthermore, the antibody responses of women in the lower-transmission site had both lower magnitude and lesser breadth than those in the high-transmission site. These data suggest that immunity to placental malaria results from high antibody levels to multiple VAR2CSA domains and allelic variants and that antibody breadth is influenced by malaria transmission intensity. PMID:22331427

Antibodies to malaria vaccine candidates are associated with chloroquine or sulphadoxine/pyrimethamine treatment efficacy in children in an endemic area of Burkina Faso

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Diarra Amidou

2012-03-01

Full Text Available Abstract Background Patient immune status is thought to affect the efficacy of anti-malarial chemotherapy. This is a subject of some importance, since evidence of immunity-related interactions may influence our use of chemotherapy in populations with drug resistance, as well as assessment of the value of suboptimal vaccines. The study aim was to investigate relationship between antibodies and anti-malarial drug treatment outcomes. Methods Some 248 children aged 0.5 and 15 years were recruited prior to the high malaria transmission season. Venous blood (5 ml was obtained from each child to measure antibody levels to selected malaria antigens, using ELISA. Blood smears were also performed to assess drug efficacy and malaria infection prevalence. Children were actively followed up to record clinical malaria cases. Results IgG levels to MSP3 were always higher in the successfully treated group than in the group with treatment failure. The same observation was made for GLURP but the reverse observation was noticed for MSP1-19. Cytophilic and non-cytophilic antibodies were significantly associated with protection against all three antigens, except for IgG4 to MSP1-19 and GLURP. Conclusion Acquired anti-malarial antibodies may play an important role in the efficacy of anti-malarial drugs in younger children more susceptible to the disease.

Vitamin B6-Dependent Enzymes in the Human Malaria Parasite Plasmodium falciparum: A Druggable Target?

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Thales Kronenberger

2014-01-01

Full Text Available Malaria is a deadly infectious disease which affects millions of people each year in tropical regions. There is no effective vaccine available and the treatment is based on drugs which are currently facing an emergence of drug resistance and in this sense the search for new drug targets is indispensable. It is well established that vitamin biosynthetic pathways, such as the vitamin B6 de novo synthesis present in Plasmodium, are excellent drug targets. The active form of vitamin B6, pyridoxal 5-phosphate, is, besides its antioxidative properties, a cofactor for a variety of essential enzymes present in the malaria parasite which includes the ornithine decarboxylase (ODC, synthesis of polyamines, the aspartate aminotransferase (AspAT, involved in the protein biosynthesis, and the serine hydroxymethyltransferase (SHMT, a key enzyme within the folate metabolism.

Immobilization of enzyme and antibody by low energy electron beam polymerization

International Nuclear Information System (INIS)

Kaetsu, Isao; Kumakura, Minoru

1987-01-01

Immobilization of glucoamylase and AFP-antibody was studied using an electron beam of relatively low energy. A thin polymer membrane formed by irradiation of monomer enzyme mixture in a buffer, which had a considerable enzymatic activity. A membrane of almost the same thickness and activity was obtained by repeated irradiation. The effect of irradiation conditions on the immobilization and the variations of irradiation method for immobilization were investigated. The immobilization of antibody was carried out in similar ways as for enzyme, and the product also showed a considerable activity. (author)

Antibodies from malaria-exposed pregnant women recognize trypsin resistant epitopes on the surface of Plasmodium falciparum-infected erythrocytes selected for adhesion to chondroitin sulphate A

DEFF Research Database (Denmark)

Sharling, Lisa; Enevold, Anders; Sowa, Kordai M P

2004-01-01

of CSA binding and surface recognition of CSA selected parasites by serum IgG from malaria exposed pregnant women. Thus, the complete molecular definition of an antigenic P. falciparum erythrocyte surface protein that can be used as a malaria in pregnancy vaccine has not yet been achieved.......-specific antibodies induced as a result of pregnancy associated malaria (PAM). METHODS: Fluorescence activated cell sorting (FACS) was used to measure the levels of adult Scottish and Ghanaian male, and Ghanaian pregnant female plasma immunoglobulin G (IgG) that bind to the surface of infected erythrocytes. P....... falciparum infected erythrocytes selected for adhesion to CSA were found to express trypsin-resistant VSA that are the target of naturally acquired antibodies from pregnant women living in a malaria endemic region of Ghana. However in vitro adhesion to CSA and HA was relatively trypsin sensitive. An improved...

Antibody reactivities to glutamate-rich peptides of Plasmodium falciparum parasites in humans from areas of different malaria endemicity

DEFF Research Database (Denmark)

Jakobsen, P.H.; Theander, T.G.; Hvid, L

1996-01-01

Synthetic P. falciparum peptides were evaluated as tools in epidemiological investigations of malaria. Plasma IgM and IgG antibody reactivities against synthetic peptides covering sequences of glutamate-rich protein (GLURP) and acidic-basic repeat antigen (ABRA) were measured by ELISA...

Serological markers suggest heterogeneity of effectiveness of malaria control interventions on Bioko Island, equatorial Guinea.

Directory of Open Access Journals (Sweden)

Jackie Cook

Full Text Available In order to control and eliminate malaria, areas of on-going transmission need to be identified and targeted for malaria control interventions. Immediately following intense interventions, malaria transmission can become more heterogeneous if interventions are more successful in some areas than others. Bioko Island, Equatorial Guinea, has been subject to comprehensive malaria control interventions since 2004. This has resulted in substantial reductions in the parasite burden, although this drop has not been uniform across the island.In 2008, filter paper blood samples were collected from 7387 people in a cross-sectional study incorporating 18 sentinel sites across Bioko, Equatorial Guinea. Antibodies were measured to P. falciparum Apical Membrane Antigen-1 (AMA-1 by Enzyme Linked Immunosorbent Assay (ELISA. Age-specific seropositivity rates were used to estimate seroconversion rates (SCR. Analysis indicated there had been at least a 60% decline in SCR in four out of five regions on the island. Changes in SCR showed a high degree of congruence with changes in parasite rate (PR and with regional reductions in all cause child mortality. The mean age adjusted concentration of anti-AMA-1 antibodies was mapped to identify areas where individual antibody responses were higher than expected. This approach confirmed the North West of the island as a major focus of continuing infection and an area where control interventions need to be concentrated or re-evaluated.Both SCR and PR revealed heterogeneity in malaria transmission and demonstrated the variable effectiveness of malaria control measures. This work confirms the utility of serological analysis as an adjunct measure for monitoring transmission. Age-specific seroprevalence based evidence of changes in transmission over time will be of particular value when no baseline data are available. Importantly, SCR data provide additional evidence to link malaria control activities to contemporaneous

Antibodies to variable Plasmodium falciparum-infected erythrocyte surface antigens are associated with protection from novel malaria infections

DEFF Research Database (Denmark)

Giha, H A; Staalsoe, T; Dodoo, D

2000-01-01

is maintained at low densities. Here, we test the hypothesis that the presence or absence of antibodies against variant antigens on the surface of P. falciparum-infected erythrocytes protect individuals against some infectious challenges and render them susceptible to others. Plasma collected in Daraweesh...... susceptible and protected individuals. Together, the results indicate that pre-existing anti-PfEMP1 antibodies can reduce the risk of contracting clinical malaria when challenged by novel parasite clones expressing homologous, but not heterologous variable surface antigens. The results also confirm...

Molecular definition of multiple sites of antibody inhibition of malaria transmission-blocking vaccine antigen Pfs25.

Science.gov (United States)

Scally, Stephen W; McLeod, Brandon; Bosch, Alexandre; Miura, Kazutoyo; Liang, Qi; Carroll, Sean; Reponen, Sini; Nguyen, Ngan; Giladi, Eldar; Rämisch, Sebastian; Yusibov, Vidadi; Bradley, Allan; Lemiale, Franck; Schief, William R; Emerling, Daniel; Kellam, Paul; King, C Richter; Julien, Jean-Philippe

2017-11-16

The Plasmodium falciparum Pfs25 protein (Pfs25) is a leading malaria transmission-blocking vaccine antigen. Pfs25 vaccination is intended to elicit antibodies that inhibit parasite development when ingested by Anopheles mosquitoes during blood meals. The Pfs25 three-dimensional structure has remained elusive, hampering a molecular understanding of its function and limiting immunogen design. We report six crystal structures of Pfs25 in complex with antibodies elicited by immunization via Pfs25 virus-like particles in human immunoglobulin loci transgenic mice. Our structural findings reveal the fine specificities associated with two distinct immunogenic sites on Pfs25. Importantly, one of these sites broadly overlaps with the epitope of the well-known 4B7 mouse antibody, which can be targeted simultaneously by antibodies that target a non-overlapping site to additively increase parasite inhibition. Our molecular characterization of inhibitory antibodies informs on the natural disposition of Pfs25 on the surface of ookinetes and provides the structural blueprints to design next-generation immunogens.

Native Mass Spectrometry, Ion mobility, and Collision-Induced Unfolding Categorize Malaria Antigen/Antibody Binding

Science.gov (United States)

Huang, Yining; Salinas, Nichole D.; Chen, Edwin; Tolia, Niraj H.; Gross, Michael L.

2017-09-01

Plasmodium vivax Duffy Binding Protein (PvDBP) is a promising vaccine candidate for P. vivax malaria. Recently, we reported the epitopes on PvDBP region II (PvDBP-II) for three inhibitory monoclonal antibodies (2D10, 2H2, and 2C6). In this communication, we describe the combination of native mass spectrometry and ion mobility (IM) with collision induced unfolding (CIU) to study the conformation and stabilities of three malarial antigen-antibody complexes. These complexes, when collisionally activated, undergo conformational changes that depend on the location of the epitope. CIU patterns for PvDBP-II in complex with antibody 2D10 and 2H2 are highly similar, indicating comparable binding topology and stability. A different CIU fingerprint is observed for PvDBP-II/2C6, indicating that 2C6 binds to PvDBP-II on an epitope different from 2D10 and 2H2. This work supports the use of CIU as a means of classifying antigen-antibody complexes by their epitope maps in a high throughput screening workflow. [Figure not available: see fulltext.

Maternally transmitted antibodies to pregnancy-associated variant antigens on the surface of erythrocytes infected with Plasmodium falciparum: relation to child susceptibility to malaria

DEFF Research Database (Denmark)

Cot, Michel; Le Hesran, Jean Yves; Staalsoe, Trine

2003-01-01

The consequences of pregnancy-associated malaria on a child's health have been poorly investigated. Malarial infection of the placenta seems to result in a higher susceptibility of children to the parasite during their first year of life. In 1993-1995, the authors investigated the role of antibod......The consequences of pregnancy-associated malaria on a child's health have been poorly investigated. Malarial infection of the placenta seems to result in a higher susceptibility of children to the parasite during their first year of life. In 1993-1995, the authors investigated the role......, Cameroon. These newborns were subsequently followed up for 2 years to determine the date of first occurrence of blood parasites and mean parasite density during follow-up. Maternally transmitted antibodies to VSA expressed by CSA-binding parasites, but not antibodies to any other specificity, were...... negatively related to time of first appearance of Plasmodium falciparum in a child's blood and were positively related to mean parasite density during the first 2 years of life. If maternal infection is thought to be the main mechanism influencing susceptibility of the newborn to malaria, antibodies to VSA...

Naturally acquired antibodies to the glutamate-rich protein are associated with protection against Plasmodium falciparum malaria

DEFF Research Database (Denmark)

Dodoo, D; Theisen, M; Kurtzhals, J A

2000-01-01

The development of effective malaria vaccines depends on the identification of targets of well-defined protective immune responses. Data and samples from a longitudinal study of a cohort of children from coastal Ghana were used to investigate the role of antibody responses to 3 regions of the Pla...

Malaria vaccines: immunity, models and monoclonal antibodies

DEFF Research Database (Denmark)

Hviid, Lars; Barfod, Lea

2008-01-01

Although experts in the field have agreed on the malaria vaccine technology roadmap that should be followed (http://www.malariavaccineroadmap.net/), the path towards an effective malaria vaccine remains littered with intellectual and practical pot-holes. The animal models that are currently...

The antibody response to well-defined malaria antigens after acute malaria in individuals living under continuous malaria transmission

DEFF Research Database (Denmark)

Petersen, E; Høgh, B; Dziegiel, M

1992-01-01

, and a synthetic peptide (EENV)6 representing the C-terminal repeats from Pf155/RESA, were investigated longitudinally in 13 children and 7 adults living under conditions of continuous, intense malaria transmission. Some subjects did not recognize the antigens after malaria infection, and in subjects recognizing...... elicited by natural malaria infection in previously primed donors....

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...

Design of a single-step immunoassay principle based on the combination of an enzyme-labeled antibody release coating and a hydrogel copolymerized with a fluorescent enzyme substrate in a microfluidic capillary device.

Science.gov (United States)

Wakayama, Hideki; Henares, Terence G; Jigawa, Kaede; Funano, Shun-ichi; Sueyoshi, Kenji; Endo, Tatsuro; Hisamoto, Hideaki

2013-11-21

A combination of an enzyme-labeled antibody release coating and a novel fluorescent enzyme substrate-copolymerized hydrogel in a microchannel for a single-step, no-wash microfluidic immunoassay is demonstrated. This hydrogel discriminates the free enzyme-conjugated antibody from an antigen-enzyme-conjugated antibody immunocomplex based on the difference in molecular size. A selective and sensitive immunoassay, with 10-1000 ng mL(-1) linear range, is reported.

Solid phase radioimmunoassay for detection of malaria antigen. Comparison of monoclonal and polyclonal antibodies

International Nuclear Information System (INIS)

Khusmith, S.; Tharavanij, S.; Patarapotikul, J.; Kasemsuth, R.; Bunnag, D.

1986-01-01

A solid phase competitive binding radioimmunoassay (RIA) was developed for the detection of Plasmodium falciparum in infected blood. A suspension of NP40 treated red blood cells was mixed with labelled antimalarial IgG, incubated and then added to malarial antigen coated microtitre plate. Antimalarial IgGs were purified either from high titre sera from individuals living in a malaria endemic area in Thailand or from a locally produced monoclonal antibody (MAB) which showed a bright generalized immunofluorescent staining pattern against all blood stages of P. falciparum, including gametocytes. This MAB reacted with 27 of 31 P. falciparum isolates from Thailand. Using dilution of red blood cells from in vitro cultures of P. falciparum, the test was found to detect parasites at levels equivalent to 13 and 2.2 parasites/10 6 red blood cells with labelled polyclonal IgG (PIgG) and labelled monoclonal IgG (MIgG), respectively. No false positive results were obtained among samples from non-malarial subjects. Of the samples that gave negative results upon microscopic examination, 50 and 35% were still positive with RIA using MIgG and PIgG, respectively. There was a correlation between RIA and the number of parasites, especially when MIgG was used. The results indicate that the IgG fraction of sera from individuals with natural acquired immunity to malaria showed a lower degree of sensitivity in parasite detection than the IgG from monoclonal antibody. (author)

The importance of human FcgammaRI in mediating protection to malaria.

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Richard S McIntosh

2007-05-01

Full Text Available The success of passive immunization suggests that antibody-based therapies will be effective at controlling malaria. We describe the development of fully human antibodies specific for Plasmodium falciparum by antibody repertoire cloning from phage display libraries generated from immune Gambian adults. Although these novel reagents bind with strong affinity to malaria parasites, it remains unclear if in vitro assays are predictive of functional immunity in humans, due to the lack of suitable animal models permissive for P. falciparum. A potentially useful solution described herein allows the antimalarial efficacy of human antibodies to be determined using rodent malaria parasites transgenic for P. falciparum antigens in mice also transgenic for human Fc-receptors. These human IgG1s cured animals of an otherwise lethal malaria infection, and protection was crucially dependent on human FcgammaRI. This important finding documents the capacity of FcgammaRI to mediate potent antimalaria immunity and supports the development of FcgammaRI-directed therapy for human malaria.

Assessment of humoral immune responses to blood-stage malaria antigens following ChAd63-MVA immunization, controlled human malaria infection and natural exposure.

Science.gov (United States)

Biswas, Sumi; Choudhary, Prateek; Elias, Sean C; Miura, Kazutoyo; Milne, Kathryn H; de Cassan, Simone C; Collins, Katharine A; Halstead, Fenella D; Bliss, Carly M; Ewer, Katie J; Osier, Faith H; Hodgson, Susanne H; Duncan, Christopher J A; O'Hara, Geraldine A; Long, Carole A; Hill, Adrian V S; Draper, Simon J

2014-01-01

The development of protective vaccines against many difficult infectious pathogens will necessitate the induction of effective antibody responses. Here we assess humoral immune responses against two antigens from the blood-stage merozoite of the Plasmodium falciparum human malaria parasite--MSP1 and AMA1. These antigens were delivered to healthy malaria-naïve adult volunteers in Phase Ia clinical trials using recombinant replication-deficient viral vectors--ChAd63 to prime the immune response and MVA to boost. In subsequent Phase IIa clinical trials, immunized volunteers underwent controlled human malaria infection (CHMI) with P. falciparum to assess vaccine efficacy, whereby all but one volunteer developed low-density blood-stage parasitemia. Here we assess serum antibody responses against both the MSP1 and AMA1 antigens following i) ChAd63-MVA immunization, ii) immunization and CHMI, and iii) primary malaria exposure in the context of CHMI in unimmunized control volunteers. Responses were also assessed in a cohort of naturally-immune Kenyan adults to provide comparison with those induced by a lifetime of natural malaria exposure. Serum antibody responses against MSP1 and AMA1 were characterized in terms of i) total IgG responses before and after CHMI, ii) responses to allelic variants of MSP1 and AMA1, iii) functional growth inhibitory activity (GIA), iv) IgG avidity, and v) isotype responses (IgG1-4, IgA and IgM). These data provide the first in-depth assessment of the quality of adenovirus-MVA vaccine-induced antibody responses in humans, along with assessment of how these responses are modulated by subsequent low-density parasite exposure. Notable differences were observed in qualitative aspects of the human antibody responses against these malaria antigens depending on the means of their induction and/or exposure of the host to the malaria parasite. Given the continued clinical development of viral vectored vaccines for malaria and a range of other diseases

Assessment of humoral immune responses to blood-stage malaria antigens following ChAd63-MVA immunization, controlled human malaria infection and natural exposure.

Directory of Open Access Journals (Sweden)

Sumi Biswas

Full Text Available The development of protective vaccines against many difficult infectious pathogens will necessitate the induction of effective antibody responses. Here we assess humoral immune responses against two antigens from the blood-stage merozoite of the Plasmodium falciparum human malaria parasite--MSP1 and AMA1. These antigens were delivered to healthy malaria-naïve adult volunteers in Phase Ia clinical trials using recombinant replication-deficient viral vectors--ChAd63 to prime the immune response and MVA to boost. In subsequent Phase IIa clinical trials, immunized volunteers underwent controlled human malaria infection (CHMI with P. falciparum to assess vaccine efficacy, whereby all but one volunteer developed low-density blood-stage parasitemia. Here we assess serum antibody responses against both the MSP1 and AMA1 antigens following i ChAd63-MVA immunization, ii immunization and CHMI, and iii primary malaria exposure in the context of CHMI in unimmunized control volunteers. Responses were also assessed in a cohort of naturally-immune Kenyan adults to provide comparison with those induced by a lifetime of natural malaria exposure. Serum antibody responses against MSP1 and AMA1 were characterized in terms of i total IgG responses before and after CHMI, ii responses to allelic variants of MSP1 and AMA1, iii functional growth inhibitory activity (GIA, iv IgG avidity, and v isotype responses (IgG1-4, IgA and IgM. These data provide the first in-depth assessment of the quality of adenovirus-MVA vaccine-induced antibody responses in humans, along with assessment of how these responses are modulated by subsequent low-density parasite exposure. Notable differences were observed in qualitative aspects of the human antibody responses against these malaria antigens depending on the means of their induction and/or exposure of the host to the malaria parasite. Given the continued clinical development of viral vectored vaccines for malaria and a range of other

Effect of malaria parasitaemia on materno-foetal transfer of ...

African Journals Online (AJOL)

Background: Neonatal protection from diphtheria is dependent on maternally transferred antibodies.4 Placental malaria has been reported to affect transplacental transfer of antibodies. Nigeria is endemic for malaria. In the face of recent reports of diphtheria including an epidemic in Nigeria, this study aimed to determine the ...

Application of the indirect fluorescent antibody assay in the study of malaria infection in the Yangtze River Three Gorges Reservoir, China

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Xiang Zheng

2009-08-01

Full Text Available Abstract Background China Yangtze Three Gorges Project (TGP is one of the biggest construction projects in the world. The areas around the Three Gorge Dam has a history of tertian malaria and subtertian malaria epidemic, but there are no overall data about malaria epidemics before the completion of the project. The objective of this study was to get a reliable baseline on malaria infection in the Yangtze River Three Gorges reservoir area and to provide reference data for future studies about the impact of the project on malaria epidemics. Methods Two surveys of malaria infection were carried out in area, at six-month intervals in May and October 2008. About 3,600 dual specimens blood film samples for parasite diagnosis and filter paper blood spots for serology (using the immunofluorescence antibody test were collected from the general population, including school populations, whenever possible. Results The overall percentage of positive response of the same population during post-transmission periods was about twice (1.40/0.72 of that in pre-transmission. Positive individuals under 15 years of age were detected in all the localities. Conclusion A certain extent of malaria infection existed in this area. Additional studies are needed to determine the length of malaria experience, and chemotherapeutic intervention as well as the distribution of main vectors for transmission in this area.

Immunopathology of thrombocytopenia in experimental malaria.

Science.gov (United States)

Grau, G E; Piguet, P F; Gretener, D; Vesin, C; Lambert, P H

1988-12-01

An early thrombocytopenia was observed in CBA mice during acute infection with Plasmodium berghei. This was associated with an increase in bone marrow megakaryocytes and a reduction of normal syngeneic 111Indium-labelled platelet life span. Malaria-induced thrombocytopenia was thus considered to be the result of increased peripheral platelet destruction rather than central hypoproduction. The occurrence of thrombocytopenia was modulated by T-cell depletion. Indeed, thymectomized, irradiated or anti-CD4 monoclonal antibody-treated mice failed to develop thrombocytopenia, although they were infected to the same extent. Conversely, a significant thrombocytopenia was observed in thymectomized mice reconstituted with CD4+ T cells. During the course of infection, a significant inverse correlation was found between platelet counts and platelet-associated IgG. Normal mice passively transferred with serum from syngeneic malaria-infected mice developed thrombocytopenia. The possibility to raise monoclonal anti-platelet antibodies from P. berghei-infected animals further suggested a role for an antibody-mediated platelet destruction during acute murine malaria infection. These results indicate that in murine malaria, thrombocytopenia is mediated by immune mechanisms and that CD4+ T cells might be significantly involved.

Sero-epidemiological evaluation of Plasmodium falciparum malaria in Senegal.

Science.gov (United States)

Sylla, Khadime; Tine, Roger Clément Kouly; Ndiaye, Magatte; Sow, Doudou; Sarr, Aïssatou; Mbuyi, Marie Louise Tshibola; Diouf, Ibrahima; Lô, Amy Colé; Abiola, Annie; Seck, Mame Cheikh; Ndiaye, Mouhamadou; Badiane, Aïda Sadikh; N'Diaye, Jean Louis A; Ndiaye, Daouda; Faye, Oumar; Dieng, Thérèse; Dieng, Yémou; Ndir, Oumar; Gaye, Oumar; Faye, Babacar

2015-07-16

In Senegal, a significant decrease of malaria transmission intensity has been noted the last years. Parasitaemia has become lower and, therefore, more difficult to detect by microscopy. In the context of submicroscopic parasitaemia, it has become relevant to rely on relevant malaria surveillance tools to better document malaria epidemiology in such settings. Serological markers have been proposed as an essential tool for malaria surveillance. This study aimed to evaluate the sero-epidemiological situation of Plasmodium falciparum malaria in two sentinel sites in Senegal. Cross-sectional surveys were carried out in Velingara (south Senegal) and Keur Soce (central Senegal) between September and October 2010. Children under 10 years old, living in these areas, were enrolled using two-level, random sampling methods. P. falciparum infection was diagnosed using microscopy. P. falciparum antibodies against circumsporozoite protein (CSP), apical membrane protein (AMA1) and merozoite surface protein 1_42 (MSP1_42) were measured by ELISA method. A stepwise logistic regression analysis was done to assess factors associated with P. falciparum antibodies carriage. A total of 1,865 children under 10 years old were enrolled. The overall falciparum malaria prevalence was 4.99% with high prevalence in Velingara of 10.03% compared to Keur Soce of 0.3%. Symptomatic malaria cases (fever associated with parasitaemia) represented 17.37%. Seroprevalence of anti-AMA1, anti-MSP1_42 and anti-CSP antibody was 38.12, 41.55 and 40.38%, respectively. The seroprevalence was more important in Velingara and increased with age, active malaria infection and area of residence. The use of serological markers can contribute to improved malaria surveillance in areas with declining malaria transmission. This study provided useful baseline information about the sero-epidemiological situation of malaria in Senegal and can contribute to the identification of malaria hot spots in order to concentrate

Incidence of Severe Malaria Syndromes and Status of Immune Responses among Khat Chewer Malaria Patients in Ethiopia.

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Tsige Ketema

Full Text Available Although more emphasis has been given to the genetic and environmental factors that determine host vulnerability to malaria, other factors that might have a crucial role in burdening the disease have not been evaluated yet. Therefore, this study was designed to assess the effect of khat chewing on the incidence of severe malaria syndromes and immune responses during malaria infection in an area where the two problems co-exist. Clinical, physical, demographic, hematological, biochemical and immunological data were collected from Plasmodium falciparum mono-infected malaria patients (age ≥ 10 years seeking medication in Halaba Kulito and Jimma Health Centers. In addition, incidences of severe malaria symptoms were assessed. The data were analyzed using SPSS (version 20 software. Prevalence of current khat chewer malaria patients was 57.38% (95%CI =53-61.56%. Malaria symptoms such as hyperpyrexia, prostration and hyperparasitemia were significantly lower (P0.05, IgG3 antibody was significantly higher (P<0.001 among khat chewer malaria patients. Moreover, IgM, IgG, IgG1and IgG3 antibodies had significant negative association (P<0.001 with parasite burden and clinical manifestations of severe malaria symptoms, but not with severe anemia and hypoglycemia. Additionally, a significant increment (P<0.05 in CD4+ T-lymphocyte population was observed among khat users. Khat might be an important risk factor for incidence of some severe malaria complications. Nevertheless, it can enhance induction of humoral immune response and CD4+ T-lymphocyte population during malaria infection. This calls for further investigation on the effect of khat on parasite or antigen-specifc protective malaria immunity and analysis of cytokines released upon malaria infection among khat chewers.

Insecticide-treated bed nets reduce plasma antibody levels and limit the repertoire of antibodies to Plasmodium falciparum variant surface antigens

DEFF Research Database (Denmark)

Askjaer, N; Maxwell, C; Chambo, W

2001-01-01

The use of insecticide-treated bed nets (ITN) has been documented to reduce malaria morbidity and mortality in areas with endemic malaria, but concerns have been raised that ITN usage could affect the acquisition of malaria immunity. Several lines of evidence have indicated that antibodies against...... variant surface antigens (VSA) are important in the development of naturally acquired immunity to Plasmodium falciparum malaria and may thus be good indicators of immune status. We have compared the levels of VSA antibodies in plasma from children who have used ITN for 4 years to levels in plasma from...

High avidity antibodies to full-length VAR2CSA correlate with absence of placental malaria.

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Yeung Lo Tutterrow

Full Text Available VAR2CSA mediates sequestration of Plasmodium falciparum-infected erythrocytes in the placenta, increasing the risk of poor pregnancy outcomes. Naturally acquired antibodies (Ab to placental parasites at delivery have been associated with improved pregnancy outcomes, but Ab levels and how early in pregnancy Ab must be present in order to eliminate placental parasites before delivery remains unknown. Antibodies to individual Duffy-binding like domains of VAR2CSA have been studied, but the domains lack many of the conformational epitopes present in full-length VAR2CSA (FV2. Thus, the purpose of this study was to describe the acquisition of Ab to FV2 in women residing in high and low transmission areas and determine how Ab levels during pregnancy correlate with clearance of placental parasites. Plasma samples collected monthly throughout pregnancy from pregnant women living in high and low transmission areas in Cameroon were evaluated for Ab to FV2 and the proportion of high avidity Ab (i.e., Ab that remain bound in the presence of 3M NH(4SCN was assessed. Ab levels and proportion of high avidity Ab were compared between women with placental malaria (PM(+ and those without (PM(- at delivery. Results showed that PM(- women had significantly higher Ab levels (p = 0.0047 and proportion of high avidity Ab (p = 0.0009 than PM(+ women throughout pregnancy. Specifically, women with moderate to high Ab levels (>5,000 MFI and those with ≥ 35% high avidity Ab at 5-6 months were found to have 2.3 (95% CI, 1.0-4.9 and 7.6-fold (p = 0.0013, 95% CI: 1.2-50.0 reduced risk of placental malaria, respectively. These data show that high levels of Ab to FV2, particularly those with high avidity for FV2, produced by mid-pregnancy are important in clearing parasites from the placenta. Both high Ab levels and proportion of high avidity Ab to FV2 may serve as correlates of protection for assessing immunity against placental malaria.

Analyzing actual risk in malaria-deferred donors through selective serologic testing.

Science.gov (United States)

Nguyen, Megan L; Goff, Tami; Gibble, Joan; Steele, Whitney R; Leiby, David A

2013-08-01

Approximately 150,000 US blood donors are deferred annually for travel to malaria-endemic areas. However, the majority do not travel to the high-risk areas of Africa associated with transfusion-transmitted malaria (TTM) but visit low-risk areas such as Mexico. This study tests for Plasmodium infection among malaria-deferred donors, particularly those visiting Mexico. Blood donors deferred for malaria risk (travel, residence, or previous infection) provided blood samples and completed a questionnaire. Plasma was tested for Plasmodium antibodies by enzyme immunoassay (EIA); repeat-reactive (RR) samples were considered positive and tested by real-time polymerase chain reaction (PCR). Accepted donors provided background testing data. During 2005 to 2011, a total of 5610 malaria-deferred donors were tested by EIA, including 5412 travel deferrals. Overall, 88 (1.6%) were EIA RR; none were PCR positive. Forty-nine (55.7%) RR donors previously had malaria irrespective of deferral category, including 34 deferred for travel. Among 1121 travelers to Mexico, 90% visited Quintana Roo (no or very low risk), but just 2.2% visited Oaxaca/Chiapas (moderate or high risk). Only two Mexican travelers tested RR; both previously had malaria not acquired in Mexico. Travel to Mexico represents a large percentage of US donors deferred for malaria risk; however, these donors primarily visit no- or very-low-risk areas. No malaria cases acquired in Mexico were identified thereby supporting previous risk estimates. Consideration should be given to allowing blood donations from U.S. donors who travel to Quintana Roo and other low-risk areas in Mexico. A more effective approach to preventing TTM would be to defer all donors with a history of malaria, even if remote. © 2012 American Association of Blood Banks.

Structure of malaria invasion protein RH5 with erythrocyte basigin and blocking antibodies.

Science.gov (United States)

Wright, Katherine E; Hjerrild, Kathryn A; Bartlett, Jonathan; Douglas, Alexander D; Jin, Jing; Brown, Rebecca E; Illingworth, Joseph J; Ashfield, Rebecca; Clemmensen, Stine B; de Jongh, Willem A; Draper, Simon J; Higgins, Matthew K

2014-11-20

Invasion of host erythrocytes is essential to the life cycle of Plasmodium parasites and development of the pathology of malaria. The stages of erythrocyte invasion, including initial contact, apical reorientation, junction formation, and active invagination, are directed by coordinated release of specialized apical organelles and their parasite protein contents. Among these proteins, and central to invasion by all species, are two parasite protein families, the reticulocyte-binding protein homologue (RH) and erythrocyte-binding like proteins, which mediate host-parasite interactions. RH5 from Plasmodium falciparum (PfRH5) is the only member of either family demonstrated to be necessary for erythrocyte invasion in all tested strains, through its interaction with the erythrocyte surface protein basigin (also known as CD147 and EMMPRIN). Antibodies targeting PfRH5 or basigin efficiently block parasite invasion in vitro, making PfRH5 an excellent vaccine candidate. Here we present crystal structures of PfRH5 in complex with basigin and two distinct inhibitory antibodies. PfRH5 adopts a novel fold in which two three-helical bundles come together in a kite-like architecture, presenting binding sites for basigin and inhibitory antibodies at one tip. This provides the first structural insight into erythrocyte binding by the Plasmodium RH protein family and identifies novel inhibitory epitopes to guide design of a new generation of vaccines against the blood-stage parasite.

Antibodies against PfEMP1, RIFIN, MSP3 and GLURP are acquired during controlled Plasmodium falciparum malaria infections in naïve volunteers

DEFF Research Database (Denmark)

Turner, Louise; Wang, Christian W; Lavstsen, Thomas

2011-01-01

Antibodies to polymorphic antigens expressed during the parasites erythrocytic stages are important mediators of protective immunity against P. falciparum malaria. Therefore, polymorphic blood stage antigens like MSP3, EBA-175 and GLURP and variant surface antigens PfEMP1 and RIFIN are considered...

The diagnosis of malaria infection using a solid-phase radioimmunoassay for the detection of malaria antigens

International Nuclear Information System (INIS)

Mackey, L.; Perrin, L.; Leemans, E.; Lambert, P.H.

1980-01-01

A method was devised to show that malaria parasites can be detected serologically in infected blood with a high degree of sensitivity. Using a murine malaria model, parasites were demonstrated in a solid-phase radio-immunoassay which measured antibody-binding inhibition. Lysed red blood cells (r.b.c.) were incubated with labelled specific antibody and were then reacted in antigen-coated tubes. The degree of inhibition of antibody binding in the tubes correlated with the level of parasitaemia in the test blood. Using homologous antisera the test detected infection at a level of 1 parasite/million r.b.c.. The specificity of the method was shown by comparison of antibody-binding inhibition in normal and infected r.b.c. and in r.b.c. from non-infected mice with induced reticulocytosis. The sensitivity was shown in vitro in tests of serially diluted blood of high parasitaemia and in vivo for the detection of early infection. The presence of antibody in the test blood did not significantly affect the sensitivity of parasite detection. (author)

Natural antibody responses to Plasmodium falciparum MSP3 and GLURP(R0) antigens are associated with low parasite densities in malaria patients living in the Central Region of Ghana

DEFF Research Database (Denmark)

Amoah, L. E.; Nuvor, S. V.; Obboh, E. K.

2017-01-01

Background: Plasmodium falciparum genetic diversity and multiplicity of infection (MOI) are parasite features that have been suggested to influence the acquisition of protective immunity against malaria. This study sought to assess the relationship between MOI and parasite density (PD) in malaria...... and adults diagnosed with uncomplicated P. falciparum malaria. Microscopy was used to estimate P. falciparum parasite density and polymerase chain reaction (PCR) amplification of the polymorphic regions of msp1 (PF3D7-0930300) and msp2 (PF3D7-0206800) was used for parasite genotyping and MOI determination....... The geometric mean (GM) for MOI determined by both msp1 and msp2 genotyping was 1.3 for the entire population and was generally higher in children than in adults. Seropositivity was estimated at 67 and 63% for GLURP(R0) and MSP3 antibodies, respectively, and antibody titers were negatively correlated...

Bluetongue virus: comparative evaluation of enzyme-linked immunosorbent assay, immunodiffusion, and serum neutralization for detection of viral antibodies.

OpenAIRE

Poli, G; Stott, J; Liu, Y S; Manning, J S

1982-01-01

Comparative studies on the detection of bovine serum immunoglobulin G antibodies to bluetongue virus with an enzyme-linked immunosorbent assay, an immunodiffusion method, and a serum neutralization assay demonstrated complete concordance between the enzyme-linked immunosorbent assay and the serum neutralization assay results. However, the immunodiffusion method failed to detect bluetongue virus antibody in a substantial number of sera found to possess bluetongue virus immunoglobulin G with th...

Antibody levels against GLURP R2, MSP1 block 2 hybrid and AS202.11 and the risk of malaria in children living in hyperendemic (Burkina Faso) and hypo-endemic (Ghana) areas

DEFF Research Database (Denmark)

Adu, Bright; Cherif, Mariama K; Bosomprah, Samuel

2016-01-01

therefore need to be evaluated against different malaria endemicity backgrounds. METHODS: The associations between antibody responses to the chimeric merozoite surface protein 1 block 2 hybrid (MSP1 hybrid), glutamate-rich protein region 2 (GLURP R2) and the peptide AS202.11, and the risk of malaria were...

Radiolabelling of glycosylated MFE-23::CPG2 fusion protein (MFECP1) with 99mTc for quantitation of tumour antibody-enzyme localisation in antibody-directed enzyme pro-drug therapy (ADEPT).

Science.gov (United States)

Francis, R J; Mather, S J; Chester, K; Sharma, S K; Bhatia, J; Pedley, R B; Waibel, R; Green, A J; Begent, R H J

2004-08-01

MFECP1 is a glycosylated recombinant fusion protein composed of MFE-23, a high-affinity anti-carcinoembryonic antigen (CEA) single chain Fv (scFv), fused to the enzyme carboxypeptidase G2 (CPG2), and has been constructed for use in antibody-directed enzyme pro-drug therapy (ADEPT). Radiolabelling of glycosylated MFECP1 with technetium-99m was developed for the purpose of determining tumour localisation of MFECP1 in a phase I ADEPT clinical study. The method used was 99mTc-carbonyl [99mTc(H2O)3(CO)3]+ (abbreviated to TcCO) mediated labelling of 99mTc to the hexahistidine (His) tag of MFECP1. MFECP1 fusion protein was labelled with TcCO under a variety of conditions, and this was shown to be a relatively simple and robust method. Tissue biodistribution was assessed in a CEA-expressing LS174T (human colon carcinoma) nude mouse xenograft model. Tissues were taken at 1, 4 and 6 h for assessment of distribution of radioactivity and for measurement of CPG2 enzyme levels. The amount of radioactivity retained by the tumour proved to be an accurate estimation of actual measured enzyme activity, indicating that this radiolabelling method does not appear to damage the antibody-antigen binding or the enzyme activity of MFECP1. However, correlation between CPG2 enzyme activity and measured radioactivity in liver, spleen and kidney was poor, indicating retention of radioactivity in non-tumour sites but loss of enzyme activity. The high retention of technetium radioisotope in normal tissues may limit the clinical applicability of this radiolabelling method for MFECP1; however, these results suggest that this technique does have applicability for measuring the biodistribution of His-tagged recombinant proteins.

Radiolabelling of glycosylated MFE-23::CPG2 fusion protein (MFECP1) with 99mTc for quantitation of tumour antibody-enzyme localisation in antibody-directed enzyme pro-drug therapy (ADEPT)

International Nuclear Information System (INIS)

Francis, R.J.; Chester, K.; Sharma, S.K.; Bhatia, J.; Pedley, R.B.; Green, A.J.; Begent, R.H.J.; Mather, S.J.; Waibel, R.

2004-01-01

MFECP1 is a glycosylated recombinant fusion protein composed of MFE-23, a high-affinity anti-carcinoembryonic antigen (CEA) single chain Fv (scFv), fused to the enzyme carboxypeptidase G2 (CPG2), and has been constructed for use in antibody-directed enzyme pro-drug therapy (ADEPT). Radiolabelling of glycosylated MFECP1 with technetium-99m was developed for the purpose of determining tumour localisation of MFECP1 in a phase I ADEPT clinical study. The method used was 99m Tc-carbonyl [ 99m Tc(H 2 O) 3 (CO) 3 ] + (abbreviated to TcCO) mediated labelling of 99m Tc to the hexahistidine (His) tag of MFECP1. MFECP1 fusion protein was labelled with TcCO under a variety of conditions, and this was shown to be a relatively simple and robust method. Tissue biodistribution was assessed in a CEA-expressing LS174T (human colon carcinoma) nude mouse xenograft model. Tissues were taken at 1, 4 and 6 h for assessment of distribution of radioactivity and for measurement of CPG2 enzyme levels. The amount of radioactivity retained by the tumour proved to be an accurate estimation of actual measured enzyme activity, indicating that this radiolabelling method does not appear to damage the antibody-antigen binding or the enzyme activity of MFECP1. However, correlation between CPG2 enzyme activity and measured radioactivity in liver, spleen and kidney was poor, indicating retention of radioactivity in non-tumour sites but loss of enzyme activity. The high retention of technetium radioisotope in normal tissues may limit the clinical applicability of this radiolabelling method for MFECP1; however, these results suggest that this technique does have applicability for measuring the biodistribution of His-tagged recombinant proteins. (orig.)

An enzyme-linked immuno-filtration assay used to compare infant and maternal antibody profiles in toxoplasmosis.

Science.gov (United States)

Pinon, J M; Thoannes, H; Gruson, N

1985-02-28

Enzyme-linked immuno-filtration assay is carried out on a micropore membrane. This doubly analytical technique permits simultaneous study of antibody specificity by immunoprecipitation and characterisation of antibody isotypes by immuno-filtration with enzyme-labelled antibodies. Recognition of the same T. gondii antigenic constituent by IgG, IgA, IgM or IgE antibodies produces couplets (IgG-IgM; IgG-IgA) or triplets (IgG-IgM-IgA; IgG-IgM-IgE) which identify the functional fractions of the toxoplasmosis antigen. In acquired toxoplasmosis, the persistence of IgM antibody long after infestation puts in question the implication of recent infestation normally linked to detection of this isotype. For sera of comparable titres, comparison of immunological profiles by the method described demonstrates disparities in the composition of the specific antibody content as expressed in international units. Use of the same method to detect IgM antibodies or distinguish between transmitted maternal IgG and IgG antibodies synthesised by the foetus or neonate makes a diagnosis of congenital toxoplasmosis possible in 85% of cases during the first few days of life. With the method described the diagnosis may be made on average 5 months earlier than with classical techniques. In the course of surveillance for latent congenital toxoplasmosis, the appearance of IgM or IgE antibodies raises the possibility of complications (hydrocephalus, chorioretinitis). After cessation of treatment, a rise in IgG antibodies indicating persistence of infection is detected earlier by the present than by classical methods.

Modern immunological approaches to assess malaria transmission and immunity and to diagnose plasmodial infection

Directory of Open Access Journals (Sweden)

C. T. Daniel-Ribeiro

1992-01-01

Full Text Available The present paper reviews our recent data concerning the use of immunological methods employing monoclonal antibodies and synthetic peptides to study malaria transmission and immunity and to diagnose plasmodial infection. As concerns malaria transmission, we studied the main vectors of human malaria and the plasmodial species transmitted in endemic areas of Rondônia state, Brazil. The natural infection on anopheline was evaluated by immunoradiometric assay (IRMA using monoclonal antibodies to an immunodominant sporozoite surface antigen (CS protein demonstrated to be species specific. Our results showed that among six species of Anopheles found infected, An. darlingi was the main vector transmitting Plasmodium falciparum and P. vivax malaria in the immediate vicinity of houses. In order to assess the level of anti-CS antibodies we studied, by IRMA using the synthetic peptide corresponding to the repetitive epitope of the sporozoite CS protein, sera of individuals living in the same areas where the entomological survey has been performed. In this assay the prevalence of anti-CS antibodies was very low and did not reflect the malaria transmission rate in the studied areas. In relation to malaria diagnosis, a monoclonal antibody specific to an epitope of a 50 kDa exoantigen, the major component of supernatant collected at the time of schizont rupture, was used as a probe for the detection of P. falciparum antigens. This assay seemed to be more sensitive than parasitological examination for malaria diagnosis since it was able to detect plasmodial antigens in both symptomatic and asymtomatic individuals with negative thick blood smear at different intervals after a last parasitologically confirmed confirmed attack of malaria.

A Reduced Risk of Infection with Plasmodium vivax and Clinical Protection against Malaria Are Associated with Antibodies against the N Terminus but Not the C Terminus of Merozoite Surface Protein 1†

Science.gov (United States)

Nogueira, Paulo Afonso; Piovesan Alves, Fabiana; Fernandez-Becerra, Carmen; Pein, Oliver; Rodrigues Santos, Neida; Pereira da Silva, Luiz Hildebrando; Plessman Camargo, Erney; del Portillo, Hernando A.

2006-01-01

Progress towards the development of a malaria vaccine against Plasmodium vivax, the most widely distributed human malaria parasite, will require a better understanding of the immune responses that confer clinical protection to patients in regions where malaria is endemic. The occurrence of clinical protection in P. vivax malaria in Brazil was first reported among residents of the riverine community of Portuchuelo, in Rondônia, western Amazon. We thus analyzed immune sera from this same human population to determine if naturally acquired humoral immune responses against the merozoite surface protein 1 of P. vivax, PvMSP1, could be associated with reduced risk of infection and/or clinical protection. Our results demonstrated that this association could be established with anti-PvMSP1 antibodies predominantly of the immunoglobulin G3 subclass directed against the N terminus but not against the C terminus, in spite of the latter being more immunogenic and capable of natural boosting. This is the first report of a prospective study of P. vivax malaria demonstrating an association of reduced risk of infection and clinical protection with antibodies against an antigen of this parasite. PMID:16622209

Rapid enzyme-linked immunosorbent assay (ELISA) for Aspergillus fumigatus antibodies.

OpenAIRE

Richardson, M D; Stubbins, J M; Warnock, D W

1982-01-01

A rapid enzyme-linked immunosorbent assay (ELISA) where component incubation periods were shortened to one hour, was compared with agar gel double diffusion (AGDD) and a standard ELISA procedure for detecting antibodies to Aspergillus fumigatus in 28 asthmatic patients with suspected allergic aspergillosis. Using two A fumigatus antigens the rapid ELISA compared well with AGDD and the standard ELISA method. Eleven sera that reacted with both antigens in AGDD were all positive against antigen ...

Quantification of patient specific assay interference in different formats of enzyme linked immunoassays for therapeutic monoclonal antibodies

NARCIS (Netherlands)

Grebenchtchikov, N.J.; Geurts-Moespot, A.; Heijmen, L.; Laarhoven, H.W.M. van; Herpen, C.M.L. van; Thijs, A.M.J.; Span, P.N.; Sweep, F.C.

2014-01-01

BackgroundThe use of therapeutic monoclonal antibodies for clinical purposes has significantly increased in recent years, and so has the need to monitor antibody concentrations. This may be achieved using the well-established enzyme linked immunoassay (ELISA) methods; however, these assays are

Microneedle-mediated immunization of an adenovirus-based malaria vaccine enhances antigen-specific antibody immunity and reduces anti-vector responses compared to the intradermal route.

Science.gov (United States)

Carey, John B; Vrdoljak, Anto; O'Mahony, Conor; Hill, Adrian V S; Draper, Simon J; Moore, Anne C

2014-08-21

Substantial effort has been placed in developing efficacious recombinant attenuated adenovirus-based vaccines. However induction of immunity to the vector is a significant obstacle to its repeated use. Here we demonstrate that skin-based delivery of an adenovirus-based malaria vaccine, HAdV5-PyMSP1₄₂, to mice using silicon microneedles induces equivalent or enhanced antibody responses to the encoded antigen, however it results in decreased anti-vector responses, compared to intradermal delivery. Microneedle-mediated vaccine priming and resultant induction of low anti-vector antibody titres permitted repeated use of the same adenovirus vaccine vector. This resulted in significantly increased antigen-specific antibody responses in these mice compared to ID-treated mice. Boosting with a heterologous vaccine; MVA-PyMSP1₄₂ also resulted in significantly greater antibody responses in mice primed with HAdV5-PyMSP1₄₂ using MN compared to the ID route. The highest protection against blood-stage malaria challenge was observed when a heterologous route of immunization (MN/ID) was used. Therefore, microneedle-mediated immunization has potential to both overcome some of the logistic obstacles surrounding needle-and-syringe-based immunization as well as to facilitate the repeated use of the same adenovirus vaccine thereby potentially reducing manufacturing costs of multiple vaccines. This could have important benefits in the clinical ease of use of adenovirus-based immunization strategies.

Microneedle-mediated immunization of an adenovirus-based malaria vaccine enhances antigen-specific antibody immunity and reduces anti-vector responses compared to the intradermal route

Science.gov (United States)

Carey, John B.; Vrdoljak, Anto; O'Mahony, Conor; Hill, Adrian V. S.; Draper, Simon J.; Moore, Anne C.

2014-01-01

Substantial effort has been placed in developing efficacious recombinant attenuated adenovirus-based vaccines. However induction of immunity to the vector is a significant obstacle to its repeated use. Here we demonstrate that skin-based delivery of an adenovirus-based malaria vaccine, HAdV5-PyMSP142, to mice using silicon microneedles induces equivalent or enhanced antibody responses to the encoded antigen, however it results in decreased anti-vector responses, compared to intradermal delivery. Microneedle-mediated vaccine priming and resultant induction of low anti-vector antibody titres permitted repeated use of the same adenovirus vaccine vector. This resulted in significantly increased antigen-specific antibody responses in these mice compared to ID-treated mice. Boosting with a heterologous vaccine; MVA-PyMSP142 also resulted in significantly greater antibody responses in mice primed with HAdV5-PyMSP142 using MN compared to the ID route. The highest protection against blood-stage malaria challenge was observed when a heterologous route of immunization (MN/ID) was used. Therefore, microneedle-mediated immunization has potential to both overcome some of the logistic obstacles surrounding needle-and-syringe-based immunization as well as to facilitate the repeated use of the same adenovirus vaccine thereby potentially reducing manufacturing costs of multiple vaccines. This could have important benefits in the clinical ease of use of adenovirus-based immunization strategies. PMID:25142082

Placental malaria and immunity to infant measles

NARCIS (Netherlands)

Owens, S.; Harper, G.; Amuasi, J.; Offei-Larbi, G.; Ordi, J.; Brabin, B. J.

2006-01-01

The efficiency of transplacental transfer of measles specific antibody was assessed in relation to placental malaria. Infection at delivery was associated with a 30% decrease in expected cord measles antibody titres. Uninfected women who received anti-malarial drugs during pregnancy transmitted 30%

Development of an Enzyme Linked Immunosorbent Assay to Detect Chicken Parvovirus Specific Antibodies

Science.gov (United States)

Here we report the development and application of an enzyme linked immunosorbent assay to detect parvovirus-specific antibodies in chicken sera. We used an approach previously described for other parvoviruses to clone and express viral structural proteins in insect cells from recombinant baculovirus...

Monoclonal antibodies against human angiotensinogen, their characterization and use in an angiotensinogen enzyme linked immunosorbent assay.

Science.gov (United States)

Rubin, I; Lykkegaard, S; Olsen, A A; Selmer, J; Ballegaard, M

1988-01-01

Monoclonal antibodies were produced against human angiotensinogen. An enzyme linked immunosorbent assay (ELISA) was developed using a high affinity monoclonal antibody as catching antibody and a polyclonal rabbit anti human angiotensinogen antibody as detecting antibody in a "sandwich" ELISA. Linear range of the ELISA was 15-450 pmol/l of human angiotensinogen. Intra- and inter- assay variation coefficients were in the range of 2% to 8%. A correlation coefficient, r = 0.97, (n = 20), with values obtained by radioimmunoassay. This correlation coefficient, obtained by using both normal and pregnant sera, confirmed that the ELISA fulfill the requirements for clinical useful assay. Characterization of the antibodies were performed with respect to affinity constant and epitopes.

A murine monoclonal antibody based enzyme-linked immunosorbent assay for almond (Prunus dulcis L.) detection.

Science.gov (United States)

Su, Mengna; Venkatachalam, Mahesh; Liu, Changqi; Zhang, Ying; Roux, Kenneth H; Sathe, Shridhar K

2013-11-13

A sandwich enzyme-linked immunosorbent assay (ELISA) using anti-almond soluble protein rabbit polyclonal antibodies as capture antibodies and murine monoclonal antibody 4C10 as the detection antibodies was developed. The assay is specific and sensitive (3-200 ng almond protein/mL) for almond detection. The standardized assay is accurate (assay variability assay did not register any cross-reactivity with the tested food matrices, suggesting the assay to be almond amandin specific. The assay could detect the presence of declared almond in the tested matched commercial samples. Further, the assay reliably detected the presence of almonds in the laboratory prepared food samples spiked with almond flour.

Serum protein profile of Malaria patients through SDS-PAGE method ...

African Journals Online (AJOL)

Serum protein profile of Malaria patients through SDS-PAGE method. ... reliable method in the diagnosis of antibodies produced against Plasmodium spps. ... of malaria patients may be undertaken for study to develop possible future vaccine.

Quantification of patient-specific assay interference in different formats of enzyme-linked immunoassays for therapeutic monoclonal antibodies

NARCIS (Netherlands)

Grebenchtchikov, Nicolai; Geurts-Moespot, Anneke J.; Heijmen, Linda; van Laarhoven, Hanneke W. M.; van Herpen, Carla M. L.; Thijs, Annemarie M. J.; Span, Paul N.; Sweep, Fred C. G. J.

2014-01-01

The use of therapeutic monoclonal antibodies for clinical purposes has significantly increased in recent years, and so has the need to monitor antibody concentrations. This may be achieved using the well-established enzyme linked immunoassay (ELISA) methods; however, these assays are subject to a

Plasmodium vivax VIR Proteins Are Targets of Naturally-Acquired Antibody and T Cell Immune Responses to Malaria in Pregnant Women.

Science.gov (United States)

Requena, Pilar; Rui, Edmilson; Padilla, Norma; Martínez-Espinosa, Flor E; Castellanos, Maria Eugenia; Bôtto-Menezes, Camila; Malheiro, Adriana; Arévalo-Herrera, Myriam; Kochar, Swati; Kochar, Sanjay K; Kochar, Dhanpat K; Umbers, Alexandra J; Ome-Kaius, Maria; Wangnapi, Regina; Hans, Dhiraj; Menegon, Michela; Mateo, Francesca; Sanz, Sergi; Desai, Meghna; Mayor, Alfredo; Chitnis, Chetan C; Bardají, Azucena; Mueller, Ivo; Rogerson, Stephen; Severini, Carlo; Fernández-Becerra, Carmen; Menéndez, Clara; Del Portillo, Hernando; Dobaño, Carlota

2016-10-01

P. vivax infection during pregnancy has been associated with poor outcomes such as anemia, low birth weight and congenital malaria, thus representing an important global health problem. However, no vaccine is currently available for its prevention. Vir genes were the first putative virulent factors associated with P. vivax infections, yet very few studies have examined their potential role as targets of immunity. We investigated the immunogenic properties of five VIR proteins and two long synthetic peptides containing conserved VIR sequences (PvLP1 and PvLP2) in the context of the PregVax cohort study including women from five malaria endemic countries: Brazil, Colombia, Guatemala, India and Papua New Guinea (PNG) at different timepoints during and after pregnancy. Antibody responses against all antigens were detected in all populations, with PNG women presenting the highest levels overall. P. vivax infection at sample collection time was positively associated with antibody levels against PvLP1 (fold-increase: 1.60 at recruitment -first antenatal visit-) and PvLP2 (fold-increase: 1.63 at delivery), and P. falciparum co-infection was found to increase those responses (for PvLP1 at recruitment, fold-increase: 2.25). Levels of IgG against two VIR proteins at delivery were associated with higher birth weight (27 g increase per duplicating antibody levels, ppregnant women had significantly higher antigen-specific IFN-γ TH1 responses (p=0.006) and secreted less pro-inflammatory cytokines TNF and IL-6 after PvLP2 stimulation than P. vivax-infected women (p<0.05). These data demonstrate that VIR antigens induce the natural acquisition of antibody and T cell memory responses that might be important in immunity to P. vivax during pregnancy in very diverse geographical settings.

Selective cytotoxicity of an oxygen-radical-generating enzyme conjugated to a monoclonal antibody.

Science.gov (United States)

Battelli, M G; Abbondanza, A; Tazzari, P L; Dinota, A; Rizzi, S; Grassi, G; Gobbi, M; Stirpe, F

1988-07-01

The monoclonal antibody 8A, which recognizes a human plasma cell-associated antigen, was covalently linked to xanthine oxidase in a conjugate maintaining both immunological and enzymatic properties. A significant degree of target cell lysis was obtained at an enzyme concentration that was ineffective on non-target cells and on myeloid staminal cells (CFU-GM). The cytotoxic activity was abolished by an excess of antibody, by allopurinol and by superoxide dismutase and catalase. A possible use of the conjugate for bone marrow purging in multiple myeloma patients is suggested.

Validation of a KHV antibody enzyme-linked immunosorbent assay (ELISA).

Science.gov (United States)

Bergmann, S M; Wang, Q; Zeng, W; Li, Y; Wang, Y; Matras, M; Reichert, M; Fichtner, D; Lenk, M; Morin, T; Olesen, N J; Skall, H F; Lee, P-Y; Zheng, S; Monaghan, S; Reiche, S; Fuchs, W; Kotler, M; Way, K; Bräuer, G; Böttcher, K; Kappe, A; Kielpinska, J

2017-11-01

Koi herpesvirus (KHV) causes KHV disease (KHVD). The virus is highly contagious in carp or koi and can induce a high mortality. Latency and, in some cases, a lack of signs presents a challenge for virus detection. Appropriate immunological detection methods for anti-KHV antibodies have not yet been fully validated for KHV. Therefore, it was developed and validated an enzyme-linked immunosorbent assay (ELISA) to detect KHV antibodies. The assay was optimized with respect to plates, buffers, antigens and assay conditions. It demonstrated high diagnostic and analytical sensitivity and specificity and was particularly useful at the pond or farm levels. Considering the scale of the carp and koi industry worldwide, this assay represents an important practical tool for the indirect detection of KHV, also in the absence of clinical signs. © 2017 John Wiley & Sons Ltd.

High-Throughput Testing of Antibody-Dependent Binding Inhibition of Placental Malaria Parasites

DEFF Research Database (Denmark)

Nielsen, Morten A; Salanti, Ali

2015-01-01

The particular virulence of Plasmodium falciparum manifests in diverse severe malaria syndromes as cerebral malaria, severe anemia and placental malaria. The cause of both the severity and the diversity of infection outcome, is the ability of the infected erythrocyte (IE) to bind a range......-throughput assay used in the preclinical and clinical development of a VAR2CSA based vaccine against placental malaria....

Recent advances in recombinant protein-based malaria vaccines

DEFF Research Database (Denmark)

Draper, Simon J; Angov, Evelina; Horii, Toshihiro

2015-01-01

Plasmodium parasites are the causative agent of human malaria, and the development of a highly effective vaccine against infection, disease and transmission remains a key priority. It is widely established that multiple stages of the parasite's complex lifecycle within the human host and mosquito...... vector are susceptible to vaccine-induced antibodies. The mainstay approach to antibody induction by subunit vaccination has been the delivery of protein antigen formulated in adjuvant. Extensive efforts have been made in this endeavor with respect to malaria vaccine development, especially with regard......, with the prospects for the development of a highly effective multi-component/multi-stage/multi-antigen formulation seeming ever more likely. This review will focus on recent progress in protein vaccine design, development and/or clinical testing for a number of leading malaria antigens from the sporozoite...

Laboratory diagnostics of malaria

Science.gov (United States)

Siahaan, L.

2018-03-01

Even now, malaria treatment should only be administered after laboratory confirmation. There are several principal methods for diagnosing malaria. All these methods have their disadvantages.Presumptive treatment of malaria is widely practiced where laboratory tests are not readily available. Microscopy of Giemsa-stained thick and thin blood films remains the gold standard for the diagnosis of malaria infection. The technique of slide preparation, staining and reading are well known and standardized, and so is the estimate of the parasite density and parasite stages. Microscopy is not always available or feasible at primary health services in limited resource settings due to cost, lack of skilled manpower, accessories and reagents required. Rapid diagnostic tests (RDTs) are potential tools for parasite-based diagnosis since the tests are accurate in detecting malaria infections and are easy to use. The test is based on the capture of parasite antigen that released from parasitized red blood cells using monoclonal antibodies prepared against malaria antigen target. Polymerase Chain Reaction (PCR), depend on DNA amplification approaches and have higher sensitivity than microscopy. PCR it is not widely used due to the lack of a standardized methodology, high costs, and the need for highly-trained staff.

A sensitive monoclonal antibody-based enzyme-linked immunosorbent assay for chlorpyrifos residue determination in Chinese agricultural smaples

Science.gov (United States)

A monoclonal antibody-based competitive antibody-coated enzyme-linked immunosorbent assay (ELISA) was developed and optimized for determining chlorpyrifos residue in agricultural products. The IC50 and IC10 of this ELISA were 3.3 ng/mL and 0.1 ng/mL respectively. The average recoveries recovery rate...

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

Science.gov (United States)

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

Malaria hotspots defined by clinical malaria, asymptomatic carriage, PCR and vector numbers in a low transmission area on the Kenyan Coast.

Science.gov (United States)

Kangoye, David Tiga; Noor, Abdisalan; Midega, Janet; Mwongeli, Joyce; Mkabili, Dora; Mogeni, Polycarp; Kerubo, Christine; Akoo, Pauline; Mwangangi, Joseph; Drakeley, Chris; Marsh, Kevin; Bejon, Philip; Njuguna, Patricia

2016-04-14

Targeted malaria control interventions are expected to be cost-effective. Clinical, parasitological and serological markers of malaria transmission have been used to detect malaria transmission hotspots, but few studies have examined the relationship between the different potential markers in low transmission areas. The present study reports on the relationships between clinical, parasitological, serological and entomological markers of malaria transmission in an area of low transmission intensity in Coastal Kenya. Longitudinal data collected from 831 children aged 5-17 months, cross-sectional survey data from 800 older children and adults, and entomological survey data collected in Ganze on the Kenyan Coast were used in the present study. The spatial scan statistic test used to detect malaria transmission hotspots was based on incidence of clinical malaria episodes, prevalence of asymptomatic asexual parasites carriage detected by microscopy and polymerase chain reaction (PCR), seroprevalence of antibodies to two Plasmodium falciparum merozoite antigens (AMA1 and MSP1-19) and densities of Anopheles mosquitoes in CDC light-trap catches. There was considerable overlapping of hotspots by these different markers, but only weak to moderate correlation between parasitological and serological markers. PCR prevalence and seroprevalence of antibodies to AMA1 or MSP1-19 appeared to be more sensitive markers of hotspots at very low transmission intensity. These findings may support the choice of either serology or PCR as markers in the detection of malaria transmission hotspots for targeted interventions.

Malaria in pregnancy: pathogenesis and immunity

DEFF Research Database (Denmark)

Rogerson, Stephen J; Hviid, Lars; Duffy, Patrick E

2007-01-01

Understanding of the biological basis for susceptibility to malaria in pregnancy was recently advanced by the discovery that erythrocytes infected with Plasmodium falciparum accumulate in the placenta through adhesion to molecules such as chondroitin sulphate A. Antibody recognition of placental...... infected erythrocytes is dependent on sex and gravidity, and could protect from malaria complications. Moreover, a conserved parasite gene-var2csa-has been associated with placental malaria, suggesting that its product might be an appropriate vaccine candidate. By contrast, our understanding of placental...... immunopathology and how this contributes to anaemia and low birthweight remains restricted, although inflammatory cytokines produced by T cells, macrophages, and other cells are clearly important. Studies that unravel the role of host response to malaria in pathology and protection in the placenta...

Longitudinal analysis of antibody responses in symptomatic malaria cases do not mirror parasite transmission in peri-urban area of Cote d'Ivoire between 2010 and 2013.

Directory of Open Access Journals (Sweden)

David Koffi

Full Text Available In the agenda towards malaria eradication, assessment of both malaria exposure and efficacy of anti-vectorial and therapeutic strategies is a key component of management and the follow-up of field interventions. The simultaneous use of several antigens (Ags as serological markers has the potential for accurate evaluation of malaria exposure. Here we aimed to measure the longitudinal evolution of the background levels of immunity in an urban setting in confirmed clinical cases of malaria.A retrospective serological cross-sectional study on was carried out using 234 samples taken from 2010 to 2013 in peri-urban sentinel facility of Cote d'Ivoire. Antibody responses to recombinant proteins or BSA-peptides, 8 Plasmodium falciparum (PfAMA1, PfMSP4, PfMSP1, PfEMP1-DBL1α1-PF13, PfLSA1-41, PfLSA3-NR2, PfGLURP and PfCSP, one P. malariae (PmCSP and one Anopheles gambiae salivary (gSG6-P1 antigens were measured using magnetic bead-based multiplex immunoassay (MBA. Total anti- P. falciparum IgG responses against schizont lysate from african 07/03 strain (adapted to culture and 3D7 strain was measured by ELISA.High prevalence (7-93% and levels of antibody responses to most of the antigens were evidenced. However, analysis showed only marginal decreasing trend of Ab responses from 2010 to 2013 that did not parallel the reduction of clinical malaria prevalence following the implementation of intervention in this area. There was a significant inverse correlation between Ab responses and parasitaemia (P<10-3, rho = 0.3. The particular recruitment of asymptomatic individuals in 2011 underlined a high background level of immunity almost equivalent to symptomatic patients, possibly obscuring observable yearly variations.The use of cross-sectional clinical malaria surveys and MBA can help to identify endemic sites where control measures have unequal impact providing relevant information about population immunity and possible decrease of transmission. However, when

Antibody-mediated enzyme replacement therapy targeting both lysosomal and cytoplasmic glycogen in Pompe disease.

Science.gov (United States)

Yi, Haiqing; Sun, Tao; Armstrong, Dustin; Borneman, Scott; Yang, Chunyu; Austin, Stephanie; Kishnani, Priya S; Sun, Baodong

2017-05-01

Pompe disease is characterized by accumulation of both lysosomal and cytoplasmic glycogen primarily in skeletal and cardiac muscles. Mannose-6-phosphate receptor-mediated enzyme replacement therapy (ERT) with recombinant human acid α-glucosidase (rhGAA) targets the enzyme to lysosomes and thus is unable to digest cytoplasmic glycogen. Studies have shown that anti-DNA antibody 3E10 penetrates living cells and delivers "cargo" proteins to the cytosol or nucleus via equilibrative nucleoside transporter ENT2. We speculate that 3E10-mediated ERT with GAA will target both lysosomal and cytoplasmic glycogen in Pompe disease. A fusion protein (FabGAA) containing a humanized Fab fragment derived from the murine 3E10 antibody and the 110 kDa human GAA precursor was constructed and produced in CHO cells. Immunostaining with an anti-Fab antibody revealed that the Fab signals did not co-localize with the lysosomal marker LAMP2 in cultured L6 myoblasts or Pompe patient fibroblasts after incubation with FabGAA. Western blot with an anti-GAA antibody showed presence of the 150 kDa full-length FabGAA in the cell lysates, in addition to the 95- and 76 kDa processed forms of GAA that were also seen in the rhGAA-treated cells. Blocking of mannose-6-phosphate receptor with mannose-6-phosphate markedly reduced the 95- and the 76 kDa forms but not the 150 kDa form. In GAA-KO mice, FabGAA achieved similar treatment efficacy as rhGAA at an equal molar dose in reducing tissue glycogen contents. Our data suggest that FabGAA retains the ability of rhGAA to treat lysosomal glycogen accumulation and has the beneficial potential over rhGAA to reduce cytoplasmic glycogen storage in Pompe disease. FabGAA can be delivered to both the cytoplasm and lysosomes in cultured cells. FabGAA equally reduced lysosomal glycogen accumulation as rhGAA in GAA-KO mice. FabGAA has the beneficial potential over rhGAA to clear cytoplasmic glycogen. This study suggests a novel antibody-enzyme fusion protein therapy

Enhanced immunoassay for porcine circovirus type 2 antibody using enzyme-loaded and quantum dots-embedded shell–core silica nanospheres based on enzyme-linked immunosorbent assay

International Nuclear Information System (INIS)

Wu, Long; Li, Xuepu; Shao, Kang; Ye, Shiyi; Liu, Chen; Zhang, Chenjun; Han, Heyou

2015-01-01

Boosting the detection sensitivity of enzyme-linked immunosorbent assay (ELISA) is significant to the early clinical diagnosis of various diseases. Here, we developed a versatile immunosensor using silica nanospheres as carriers for sensitive detection of porcine circovirus type 2 (PCV2) antibody. With HRP enzyme covalently immobilized on the silica nanospheres and CdSe nanocrystals embedded inside, these signal probes were successfully utilized in the sensitive detection of PCV2 antibody by ELISA, fluorometry and square-wave voltammetry (SWV). To further demonstrate the performance of the immunosensor, Human IgG (HIgG) was used as a model analyte. Since more HRP and CdSe QDs were loaded, 5-, 200- and 400-fold enhancements in amplified ELISA, fluorometry and voltammetry responses for HIgG could be achieved compared to conventional ELISA. The respective detection limits of theses methods for HIgG were 3.9, 0.1 and 0.05 ng mL −1 with a RSD below 5% for amplified ELISA, fluorescence and SWV measurements. Additionally, a 100-fold improvement was obtained in the detection sensitivity for PCV2 antibody immunoassay. The versatile immunosensor exhibits good sensitivity, stability and reproducibility, suggesting its potential applications in clinical diagnostics. - Highlights: • A versatile ELISA-based immunoassay for PCV2 antibody was developed. • Enzyme and CdSe QDs modified SiO 2 particles were used to improve sensitivity. • The simultaneous three ELISA-based techniques enhanced the detection reliability. • The biosensors strategy could provide a new avenue to ELISA-based sensors

Enhanced immunoassay for porcine circovirus type 2 antibody using enzyme-loaded and quantum dots-embedded shell–core silica nanospheres based on enzyme-linked immunosorbent assay

Energy Technology Data Exchange (ETDEWEB)

Wu, Long; Li, Xuepu; Shao, Kang; Ye, Shiyi; Liu, Chen; Zhang, Chenjun; Han, Heyou, E-mail: hyhan@mail.hzau.edu.cn

2015-08-05

Boosting the detection sensitivity of enzyme-linked immunosorbent assay (ELISA) is significant to the early clinical diagnosis of various diseases. Here, we developed a versatile immunosensor using silica nanospheres as carriers for sensitive detection of porcine circovirus type 2 (PCV2) antibody. With HRP enzyme covalently immobilized on the silica nanospheres and CdSe nanocrystals embedded inside, these signal probes were successfully utilized in the sensitive detection of PCV2 antibody by ELISA, fluorometry and square-wave voltammetry (SWV). To further demonstrate the performance of the immunosensor, Human IgG (HIgG) was used as a model analyte. Since more HRP and CdSe QDs were loaded, 5-, 200- and 400-fold enhancements in amplified ELISA, fluorometry and voltammetry responses for HIgG could be achieved compared to conventional ELISA. The respective detection limits of theses methods for HIgG were 3.9, 0.1 and 0.05 ng mL{sup −1} with a RSD below 5% for amplified ELISA, fluorescence and SWV measurements. Additionally, a 100-fold improvement was obtained in the detection sensitivity for PCV2 antibody immunoassay. The versatile immunosensor exhibits good sensitivity, stability and reproducibility, suggesting its potential applications in clinical diagnostics. - Highlights: • A versatile ELISA-based immunoassay for PCV2 antibody was developed. • Enzyme and CdSe QDs modified SiO{sub 2} particles were used to improve sensitivity. • The simultaneous three ELISA-based techniques enhanced the detection reliability. • The biosensors strategy could provide a new avenue to ELISA-based sensors.

Is Fc gamma receptor IIA (FcγRIIA) polymorphism associated with clinical malaria and Plasmodium falciparum specific antibody levels in children from Burkina Faso?

DEFF Research Database (Denmark)

Cherif, Mariama K; Sanou, Guillaume S; Bougouma, Edith C

2015-01-01

In the present study, the influences of FcγRIIA polymorphism on susceptibility to malaria and antibody responses to Plasmodium falciparum antigens were analyzed in children. We recruited 96 healthy children between 3 and 10 years at the beginning of the high transmission season and we followed up...

Antibody and B cell responses to Plasmodium sporozoites

Directory of Open Access Journals (Sweden)

Johanna N Dups

2014-11-01

Full Text Available Antibodies are capable of blocking infection of the liver by Plasmodium sporozoites. Accordingly the induction of anti-sporozoite antibodies is a major aim of various vaccine approaches to malaria. In recent years our knowledge of the specificity and quantities of antibodies required for protection has been greatly expanded by clinical trials of various whole sporozoite and subunit vaccines. Moreover, the development of humanized mouse models and transgenic parasites have also aided our ability to assess the specificity of antibodies and their ability to block infection. Nonetheless, considerable gaps remain in our knowledge - in particular in understanding what antigens are recognized by infection blocking antibodies and in knowing how we can induce robust, long-lived antibody responses. Maintaining high levels of circulating antibodies is likely to be of primary importance, as antibodies must block infection in the short time it takes for sporozoites to reach the liver from the skin. It is clear that a better understanding of the development of protective B cell-mediated immunity will aid the development and refinement of malaria vaccines.

PD-1 Dependent Exhaustion of CD8+ T Cells Drives Chronic Malaria

Directory of Open Access Journals (Sweden)

Joshua M. Horne-Debets

2013-12-01

Full Text Available Malaria is a highly prevalent disease caused by infection by Plasmodium spp., which infect hepatocytes and erythrocytes. Blood-stage infections cause devastating symptoms and can persist for years. Antibodies and CD4+ T cells are thought to protect against blood-stage infections. However, there has been considerable difficulty in developing an efficacious malaria vaccine, highlighting our incomplete understanding of immunity against this disease. Here, we used an experimental rodent malaria model to show that PD-1 mediates up to a 95% reduction in numbers and functional capacity of parasite-specific CD8+ T cells. Furthermore, in contrast to widely held views, parasite-specific CD8+ T cells are required to control both acute and chronic blood-stage disease even when parasite-specific antibodies and CD4+ T cells are present. Our findings provide a molecular explanation for chronic malaria that will be relevant to future malaria-vaccine design and may need consideration when vaccine development for other infections is problematic.

The humoral response to Plasmodium falciparum VarO rosetting variant and its association with protection against malaria in Beninese children

Directory of Open Access Journals (Sweden)

Bentley Graham

2010-10-01

Full Text Available Abstract Background The capacity of Plasmodium falciparum-infected erythrocytes to bind uninfected erythrocytes (rosetting is associated with severe malaria in African children. Rosetting is mediated by a subset of the variant surface antigens PfEMP1 targeted by protective antibody responses. Analysis of the response to rosette-forming parasites and their PfEMP1 adhesive domains is essential for understanding the acquisition of protection against severe malaria. To this end, the antibody response to a rosetting variant was analysed in children recruited with severe or uncomplicated malaria or asymptomatic P. falciparum infection. Methods Serum was collected from Beninese children with severe malaria, uncomplicated malaria or P. falciparum asymptomatic infection (N = 65, 37 and 52, respectively and from immune adults (N = 30 living in the area. Infected erythrocyte surface-reactive IgG, rosette disrupting antibodies and IgG to the parasite crude extract were analysed using the single variant Palo Alto VarO-infected line. IgG, IgG1 and IgG3 to PfEMP1-varO-derived NTS-DBL1α1, CIDRγ and DBL2βC2 recombinant domains were analysed by ELISA. Antibody responses were compared in the clinical groups. Stability of the response was studied using a blood sampling collected 14 months later from asymptomatic children. Results Seroprevalence of erythrocyte surface-reactive IgG was high in adults (100% and asymptomatic children (92.3% but low in children with severe or uncomplicated malaria (26.1% and 37.8%, respectively. The IgG, IgG1 and IgG3 antibody responses to the varO-derived PfEMP1 domains were significantly higher in asymptomatic children than in children with clinical malaria in a multivariate analysis correcting for age and parasite density at enrolment. They were essentially stable, although levels tended to decrease with time. VarO-surface reactivity correlated positively with IgG reactivity to the rosetting domain varO-NTS-DBL1α1. None of the

Accurate and High-Coverage Immune Repertoire Sequencing Reveals Characteristics of Antibody Repertoire Diversification in Young Children with Malaria

Science.gov (United States)

Jiang, Ning

Accurately measuring the immune repertoire sequence composition, diversity, and abundance is important in studying repertoire response in infections, vaccinations, and cancer immunology. Using molecular identifiers (MIDs) to tag mRNA molecules is an effective method in improving the accuracy of immune repertoire sequencing (IR-seq). However, it is still difficult to use IR-seq on small amount of clinical samples to achieve a high coverage of the repertoire diversities. This is especially challenging in studying infections and vaccinations where B cell subpopulations with fewer cells, such as memory B cells or plasmablasts, are often of great interest to study somatic mutation patterns and diversity changes. Here, we describe an approach of IR-seq based on the use of MIDs in combination with a clustering method that can reveal more than 80% of the antibody diversity in a sample and can be applied to as few as 1,000 B cells. We applied this to study the antibody repertoires of young children before and during an acute malaria infection. We discovered unexpectedly high levels of somatic hypermutation (SHM) in infants and revealed characteristics of antibody repertoire development in young children that would have a profound impact on immunization in children.

Congenital malaria in China.

Directory of Open Access Journals (Sweden)

Zhi-Yong Tao

2014-03-01

Full Text Available BACKGROUND: Congenital malaria, in which infants are directly infected with malaria parasites from their mother prior to or during birth, is a potentially life-threatening condition that occurs at relatively low rates in malaria-endemic regions. It is recognized as a serious problem in Plasmodium falciparum-endemic sub-Saharan Africa, where recent data suggests that it is more common than previously believed. In such regions where malaria transmission is high, neonates may be protected from disease caused by congenital malaria through the transfer of maternal antibodies against the parasite. However, in low P. vivax-endemic regions, immunity to vivax malaria is low; thus, there is the likelihood that congenital vivax malaria poses a more significant threat to newborn health. Malaria had previously been a major parasitic disease in China, and congenital malaria case reports in Chinese offer valuable information for understanding the risks posed by congenital malaria to neonatal health. As most of the literature documenting congenital malaria cases in China are written in Chinese and therefore are not easily accessible to the global malaria research community, we have undertaken an extensive review of the Chinese literature on this subject. METHODS/PRINCIPAL FINDINGS: Here, we reviewed congenital malaria cases from three major searchable Chinese journal databases, concentrating on data from 1915 through 2011. Following extensive screening, a total of 104 cases of congenital malaria were identified. These cases were distributed mainly in the eastern, central, and southern regions of China, as well as in the low-lying region of southwest China. The dominant species was P. vivax (92.50%, reflecting the malaria parasite species distribution in China. The leading clinical presentation was fever, and other clinical presentations were anaemia, jaundice, paleness, diarrhoea, vomiting, and general weakness. With the exception of two cases, all patients

Annual Frequency of Malaria Attack in Different Haemoglobin ...

African Journals Online (AJOL)

GREG F. FOMBO

believed to be due to the enzyme deficiency advantage against fatal malaria. However, the mechanism of this .... Fluorescence was produced due to the reduction of NADP+ to. NADPH. ... Presence of fluorescence indicated normal cells while weak fluorescence ..... Molecular Monitoring of Malaria Vaccine Trial. Trends in.

Comparison of the specificity of antibodies to VAR2CSA in Cameroonian multigravidae with and without placental malaria

DEFF Research Database (Denmark)

Babakhanyan, Anna; Fang, Rui; Wey, Andrew

2015-01-01

BACKGROUND: Antibodies (Ab) to VAR2CSA prevent Plasmodium falciparum-infected erythrocytes from sequestrating in the placenta, i.e., prevent placental malaria (PM). The specificity of Ab to VAR2CSA associated with absence of PM is unknown. Accordingly, differences in the specificity of Ab to VAR2......CSA were compared between multigravidae with and without PM who had Ab to VAR2CSA. METHODS: In a retrospective case-control study, plasma collected from Cameroonian multigravidae with (n = 96) and without (n = 324) PM were screened in 21 assays that measured antibody levels to full length VAR2CSA (FV2......), individual VAR2CSA DBL domains, VAR2CSA domains from different genetic backgrounds (variants), as well as proportion of high avidity Ab to FV2. RESULTS: Multigravidae with and without PM had similar levels of Ab to FV2, the six VAR2CSA DBL domains and different variants, while the proportion of high avidity...

Antibody levels to recombinant VAR2CSA domains vary with Plasmodium falciparum parasitaemia, gestational age, and gravidity, but do not predict pregnancy outcomes.

Science.gov (United States)

Fried, Michal; Kurtis, Jonathan D; Swihart, Bruce; Morrison, Robert; Pond-Tor, Sunthorn; Barry, Amadou; Sidibe, Youssoufa; Keita, Sekouba; Mahamar, Almahamoudou; Andemel, Naissem; Attaher, Oumar; Dembele, Adama B; Cisse, Kadidia B; Diarra, Bacary S; Kanoute, Moussa B; Narum, David L; Dicko, Alassane; Duffy, Patrick E

2018-03-09

Maternal malaria is a tropical scourge associated with poor pregnancy outcomes. Women become resistant to Plasmodium falciparum pregnancy malaria as they acquire antibodies to the variant surface antigen VAR2CSA, a leading vaccine candidate. Because malaria infection may increase VAR2CSA antibody levels and thereby confound analyses of immune protection, gravidity-dependent changes in antibody levels during and after infection, and the effect of VAR2CSA antibodies on pregnancy outcomes were evaluated. Pregnant women enrolled in a longitudinal cohort study of mother-infant pairs in Ouelessebougou, Mali provided plasma samples at enrollment, gestational week 30-32, and delivery. Antibody levels to VAR2CSA domains were measured using a multiplex bead-based assay. Antibody levels to VAR2CSA were higher in multigravidae than primigravidae. Malaria infection was associated with increased antibody levels to VAR2CSA domains. In primigravidae but not in secundigravidae or multigravidae, antibodies levels sharply declined after an infection. A relationship between any VAR2CSA antibody specificity and protection from adverse pregnancy outcomes was not detected. During malaria infection, primigravidae acquire short-lived antibodies. The lack of an association between VAR2CSA domain antibody reactivity and improved pregnancy outcomes suggests that the recombinant proteins may not present native epitopes targeted by protective antibodies.

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....

Identification of a vesicular-arbuscular mycorrhizal fungus by using monoclonal antibodies in an enzyme-linked immunosorbent assay.

Science.gov (United States)

Wright, S F; Morton, J B; Sworobuk, J E

1987-09-01

Spore morphology is currently used to identify species of vesicular-arbuscular mycorrhizal fungi. We report the first use of a highly specific immunological method for identification of a vesicular-arbuscular mycorrhizal fungus. Two monoclonal antibodies were produced against Glomus occultum. Monoclonal antibodies reacted strongly with both spores and hyphae in an indirect enzyme-linked immunosorbent assay. All other mycorrhizal (29 species) and nonmycorrhizal (5 species) fungi tested were nonreactive with the monoclonal antibodies. A single spore of G. occultum was detectable in the presence of high numbers of spores of other vesicular-arbuscular mycorrhizal fungi. Variation in the reaction of G. occultum isolates from West Virginia, Florida, and Colombia suggests that monoclonal antibodies may differentiate strains.

Novel Plasmodium falciparum malaria vaccines: evidence-based searching for variant surface antigens as candidates for vaccination against pregnancy-associated malaria

DEFF Research Database (Denmark)

Staalsoe, Trine; Jensen, Anja T R; Theander, Thor G

2002-01-01

Malaria vaccine development has traditionally concentrated on careful molecular, biochemical, and immunological characterisation of candidate antigens. In contrast, evidence of the importance of identified antigens in immunity to human infection and disease has generally been limited to statistic......Malaria vaccine development has traditionally concentrated on careful molecular, biochemical, and immunological characterisation of candidate antigens. In contrast, evidence of the importance of identified antigens in immunity to human infection and disease has generally been limited...... to statistically significant co-variation with protection rather than on demonstration of causal relationships. We have studied the relationship between variant surface antigen-specific antibodies and clinical protection from Plasmodium falciparum malaria in general, and from pregnancy-associated malaria (PAM......) in particular, to provide robust evidence of a causal link between the two in order to allow efficient and evidence-based identification of candidate antigens for malaria vaccine development....

Challenges for bovine viral diarrhoea virus antibody detection in bulk milk by antibody enzyme-linked immunosorbent assays due to changes in milk production levels

DEFF Research Database (Denmark)

Foddai, Alessandro; Enøe, Claes; Stockmarr, Anders

2015-01-01

Background: Bovine viral diarrhoea (BVD) is considered eradicated from Denmark. Currently, very few (if any) Danish cattle herds could be infected with BVD virus (BVDV). The Danish antibody blocking enzyme-linked immunosorbent assay (ELISA) has been successfully used during the Danish BVD eradica...

Single-dilution enzyme-linked immunosorbent assay for quantification of antigen-specific salmonid antibody

Science.gov (United States)

Alcorn, S.W.; Pascho, R.J.

2000-01-01

An enzyme-linked immunosorbent assay (ELISA) was developed on the basis of testing a single dilution of serum to quantify the level of antibody to the p57 protein of Renibaclerium salmoninarum in sockeye salmon (Oncorhynchus nerka). The levels of antibody were interpolated from a standard curve constructed by relating the optical densities (OD) produced by several dilutions of a high-titer rainbow trout (O. mykiss) antiserum to the p57 protein. The ELISA OD values produced by as many as 36 test sera on each microplate were compared with the standard curve to calculate the antigen-specific antibody activity. Repeated measurements of 36 samples on 3 microplates on each of 6 assay dates indicated that the mean intraassay coefficient of variation (CV) was 6.68% (range, 0-23%) and the mean interassay CV was 8.29% (range, 4-16%). The antibody levels determined for the serum sample from 24 sockeye salmon vaccinated with a recombinant p57 protein generally were correlated with the levels determined by endpoint titration (r2 = 0.936) and with results from another ELISA that was based on extrapolation of antibody levels from a standard curve (r2 = 0.956). The single-dilution antibody ELISA described here increases the number of samples that can be tested on each microplate compared with immunoassays based on analysis of several dilutions of each test serum. It includes controls for interassay standardization and can be used to test fish weighing <3 g.

Enzyme-linked immunosorbent Assay for detecting of antibody to canine distemper virus

Directory of Open Access Journals (Sweden)

Sudarisman

2006-03-01

Full Text Available Serum neutralisation test (SNT has been established for evaluating canine distemper vaccination, but until now SNT was rarely used due to the need for continuous tissue culture facilities and requires 3 days to perform. For detecting antibody to canine distemper virus, an enzyme-linked immunosorbent assay (ELISA is relatively simple and rapid seroassay. ELISA for canine immunoglobulin (Ig G antibodies to canine distemper virus (CDV was developed by using Onderstepoort strain of canine distemper virus as coating antigen. Rabbit anti canine IgG labelled with horse radish peroxidase was used as the conjugate, while phenylenediamine dihydrochloride (OPD was used as the substrate. The ELISA results were then compared with the results of the SNT, using the sera of 312 random-source dogs from West Java. The two test-results had a high degree of correlation. Very few discrepancies occurred and most of these were at the lower limits of each test. When the sera were tested at 1 : 100 dilutions, there was a 95.5% agreement between the ELISA and SNT. Their sensitivity and spesificity were 83.9 and 98.4%. Titrated SNT and ELISA also were performed on sera from 7 dogs whose lifetime medical histories were known. The antibodies were inclining up after two months of post vaccination, where the titre was not in zero/lower position at the day of vaccination. However, antibody zero or low position were found at 28 days post vaccination. All of the results indicated that ELISA can be used for evaluating antibody to canine distemper virus response, replacing the SNT.

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

Science.gov (United States)

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

Methodology and application of flow cytometry for investigation of human malaria parasites.

Science.gov (United States)

Grimberg, Brian T

2011-03-31

Historically, examinations of the inhibition of malaria parasite growth/invasion, whether using drugs or antibodies, have relied on the use of microscopy or radioactive hypoxanthine uptake. These are considered gold standards for measuring the effectiveness of antimalarial treatments, however, these methods have well known shortcomings. With the advent of flow cytometry coupled with the use of fluorescent DNA stains allowed for increased speed, reproducibility, and qualitative estimates of the effectiveness of antibodies and drugs to limit malaria parasite growth which addresses the challenges of traditional techniques. Because materials and machines available to research facilities are so varied, different methods have been developed to investigate malaria parasites by flow cytometry. This review is intended to serve as a reference guide for advanced users and importantly, as a primer for new users, to support expanded use and improvements to malaria flow cytometry, particularly in endemic countries. Copyright © 2011 Elsevier B.V. All rights reserved.

Development of replication-deficient adenovirus malaria vaccines.

Science.gov (United States)

Hollingdale, Michael R; Sedegah, Martha; Limbach, Keith

2017-03-01

Malaria remains a major threat to endemic populations and travelers, including military personnel to these areas. A malaria vaccine is feasible, as radiation attenuated sporozoites induce nearly 100% efficacy. Areas covered: This review covers current malaria clinical trials using adenoviruses and pre-clinical research. Heterologous prime-boost regimens, including replication-deficient human adenovirus 5 (HuAd5) carrying malaria antigens, are efficacious. However, efficacy appears to be adversely affected by pre-existing anti-HuAd5 antibodies. Current strategies focus on replacing HuAd5 with rarer human adenoviruses or adenoviruses isolated from non-human primates (NHPs). The chimpanzee adenovirus ChAd63 is undergoing evaluation in clinical trials including infants in malaria-endemic areas. Key antigens have been identified and are being used alone, in combination, or with protein subunit vaccines. Gorilla adenoviruses carrying malaria antigens are also currently being evaluated in preclinical models. These replacement adenovirus vectors will be successfully used to develop vaccines against malaria, as well as other infectious diseases. Expert commentary: Simplified prime-boost single shot regimens, dry-coated live vector vaccines or silicon microneedle arrays could be developed for malaria or other vaccines. Replacement vectors with similar or superior immunogenicity have rapidly advanced, and several are now in extensive Phase 2 and beyond in malaria as well as other diseases, notably Ebola.

Identification of a Vesicular-Arbuscular Mycorrhizal Fungus by Using Monoclonal Antibodies in an Enzyme-Linked Immunosorbent Assay †

OpenAIRE

Wright, Sara F.; Morton, Joseph B.; Sworobuk, Janis E.

1987-01-01

Spore morphology is currently used to identify species of vesicular-arbuscular mycorrhizal fungi. We report the first use of a highly specific immunological method for identification of a vesicular-arbuscular mycorrhizal fungus. Two monoclonal antibodies were produced against Glomus occultum. Monoclonal antibodies reacted strongly with both spores and hyphae in an indirect enzyme-linked immunosorbent assay. All other mycorrhizal (29 species) and nonmycorrhizal (5 species) fungi tested were no...

Development and application of radioimmunoassay and enzyme immunoassays in microbiological and immunological diagnosis. 3. Comparative studies for the detection of virus antibodies with passive hemagglutination test, radioimmunoassay and enzyme immunoassay, resp

Energy Technology Data Exchange (ETDEWEB)

Lauf, H; Struy, H; Morenz, J [Medizinische Akademie, Magdeburg (German Democratic Republic)

1982-06-01

Radioimmuno- and enzyme immunoassays (solid phase RIA and ELISA) developed by the authors for the determination of antibodies of adeno-2- and parainfluenza-1-viruses are described and the detection sensibility for antibodies is compared with that of the conventional passive hemagglutination test. The sensibility of the radioimmunoassay for the detection of IgG antibodies against adeno-2-viruses is nearly 10 times higher than that of the passive hemagglutination. RIA and ELISA show no essential differences in their detection sensibilities in the detection of IgG antibodies against parainfluenza-1-viruses.

Placental malaria and neonatal anti-tetanus antibody status: Any ...

African Journals Online (AJOL)

Globally, neonatal tetanus accounts for 7% of neonatal mortality,[1] ... There was a statistically significant association between type of placental malaria .... Also excluded were mothers with diabetes ..... Tetanus Vaccine: WHO Position Paper.

Memory B-Cell and Antibody Responses Induced by Plasmodium falciparum Sporozoite Immunization

NARCIS (Netherlands)

Nahrendorf, W.; Scholzen, A.; Bijker, E.M.; Teirlinck, A.C.; Bastiaens, G.J.H.; Schats, R.; Hermsen, C.C.; Visser, L.G.; Langhorne, J.; Sauerwein, R.W.

2014-01-01

BACKGROUND: Immunization of healthy volunteers during receipt of chemoprophylaxis with Plasmodium falciparum sporozoites (CPS-immunization) induces sterile protection from malaria. Antibody responses have long been known to contribute to naturally acquired immunity against malaria, but their

Microneedle-mediated immunization of an adenovirus-based malaria vaccine enhances antigen-specific antibody immunity and reduces anti-vector responses compared to the intradermal route

OpenAIRE

Carey, John B.; Vrdoljak, Anto; O'Mahony, Conor; Hill, Adrian V. S.; Draper, Simon J.; Moore, Anne C.

2014-01-01

Substantial effort has been placed in developing efficacious recombinant attenuated adenovirus-based vaccines. However induction of immunity to the vector is a significant obstacle to its repeated use. Here we demonstrate that skin-based delivery of an adenovirus-based malaria vaccine, HAdV5-PyMSP142, to mice using silicon microneedles induces equivalent or enhanced antibody responses to the encoded antigen, however it results in decreased anti-vector responses, compared to intradermal delive...

Differentiation of ruminal bacterial species by enzyme-linked immunosorbent assay using egg yolk antibodies from immunized chicken hens.

OpenAIRE

Ricke, S C; Schaefer, D M; Cook, M E; Kang, K H

1988-01-01

Cross-reactivity among four species of ruminal bacteria was examined by using egg yolk antibodies from immunized Leghorn laying hens and an enzyme-linked-immunosorbent assay. The effects of the four species on the hens were compared on various days postimmunization. Hens injected with the same bacterial species had similar apparent antibody levels over the entire postimmunization period, but only Bacteroides ruminicola B1(4) and Selenomonas ruminantium D antigens elicited early increases in a...

Does infection with Human Immunodeficiency Virus affect the antibody responses to Plasmodium falciparum antigenic determinants in asymptomatic pregnant women?

NARCIS (Netherlands)

Ayisi, J. G.; Branch, OraLee H.; Rafi-Janajreh, A.; van Eijk, A. M.; ter Kuile, F. O.; Rosen, D. H.; Kager, P. A.; Lanar, D. E.; Barbosa, A.; Kaslow, D.; Nahlen, B. L.; Lal, A. A.

2003-01-01

OBJECTIVES: HIV-seropositive pregnant women are more susceptible to malaria than HIV-seronegative women. We assessed whether HIV infection alters maternal and cord plasma malarial antibody responses and the mother-to-infant transfer of malaria antibodies. METHODS: We determined plasma levels of

A seroprevalence and descriptive epidemiological study of malaria among Indian tribes of the Amazon basin of Brazil.

Science.gov (United States)

de Arruda, M E; Aragaki, C; Gagliardi, F; Haile, R W

1996-04-01

Data on the seroprevalences of Plasmodium falciparum, P. vivax, and P. malariae in four isolated Indian tribes of the Amazon basin in Brazil, as determined by IFAT, were re-analysed. Age-, sex- and tribe-specific geometric mean antibody titres and externally standardized prevalence ratios were calculated for each parasite species. Correlation coefficients and prevalence odds ratios were also calculated for multiple infections with different combinations of the three Plasmodium species. Titres of all but one of the antibodies studied were similar in males and females; titres of antibodies to the blood stages of P. malariae were slightly higher in females than in males. Titres of antibodies to all three Plasmodium species increased with subject age, and this age effect was not confounded by sex or tribal differences. There were striking differences between tribes, with the Parakana tribe having relatively low titres of antibodies against P. falciparum and P. malariae; these tribal effects were not confounded by sex or age differences between tribes. The results indicate that conditions conductive to the transmission of P. malariae exist in this region of the Amazon. The potential for zoonotic transmission of P. brasilianum, a parasite of monkeys which is morphologically similar to P. malarie, and the generally high rates of seropositivity to all three species of Plasmodium indicate that control measures which are adequate and applicable to the region studied need to be developed.

Antibody screening by enzyme-linked immunosorbent assay using pooled soluble HLA in renal transplant candidates.

Science.gov (United States)

Zaer, F; Metz, S; Scornik, J C

1997-01-15

The enzyme-linked immunosorbent assay (ELISA) using HLA class I molecules purified from pooled platelets has the potential to detect HLA antibodies with increased efficiency without sacrificing sensitivity or specificity. This test, which was originally developed in our institution, has been independently validated by recent studies and is now commercially available. We now present evidence of its usefulness as a routine HLA antibody screening test for renal transplant patients. A total of 515 patients were tested monthly by ELISA (13.9 tests/patient) and by antiglobulin-enhanced panel reactivity (6.3 tests/patient). In patients found to be unsensitized, the incidence of false-positive results was less for ELISA than for the panel studies. In patients who were highly sensitized, both tests performed equally well, whereas discordant results were registered mainly in cases of mild sensitization. Because 66% of our patients were not sensitized, the ELISA was effective in reducing the number of more involved tests aimed at characterizing the antibodies. These results provide a foundation to use the pooled platelet HLA ELISA on a routine basis for HLA antibody screening.

Pregnancy malaria: cryptic disease, apparent solution

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Patrick Emmet Duffy

2011-08-01

Full Text Available Malaria during pregnancy can be severe in non-immune women, but in areas of stable transmission, where women are semi-immune and often asymptomatic during infection, malaria is an insidious cause of disease and death for mothers and their offspring. Sequelae, such as severe anaemia and hypertension in the mother and low birth weight and infant mortality in the offspring, are often not recognised as consequences of infection. Pregnancy malaria, caused by Plasmodium falciparum, is mediated by infected erythrocytes (IEs that bind to chondroitin sulphate A and are sequestered in the placenta. These parasites have a unique adhesion phenotype and distinct antigenicity, which indicates that novel targets may be required for development of an effective vaccine. Women become resistant to malaria as they acquire antibodies against placental IE, which leads to higher haemoglobin levels and heavier babies. Proteins exported from the placental parasites have been identified, including both variant and conserved antigens, and some of these are in preclinical development for vaccines. A vaccine that prevents P. falciparum malaria in pregnant mothers is feasible and would potentially save hundreds of thousands of lives each year.

Serodiagnosis of cutaneous leishmaniasis: assessment of an enzyme-linked immunosorbent assay using a peptide sequence from gene B protein

DEFF Research Database (Denmark)

Jensen, A T; Gaafar, A; Ismail, A

1996-01-01

An enzyme-linked immunosorbent assay (ELISA) using a 28 amino acid sequence of the repetitive element of gene B protein (GBP) from Leishmania major was developed for serodiagnosis of cutaneous leishmaniasis (CL). The assay was compared to ELISAs using crude amastigote and promastigote antigens from...... samples from healthy Sudanese individuals living in an area endemic for malaria but free of leish-maniasis were negative in all the assays. Significantly higher levels of antibodies were found in the patients who had suffered from the disease for more than eight weeks than in patients with a shorter...

An analytical approach to reduce between-plate variation in multiplex assays that measure antibodies to Plasmodium falciparum antigens.

Science.gov (United States)

Fang, Rui; Wey, Andrew; Bobbili, Naveen K; Leke, Rose F G; Taylor, Diane Wallace; Chen, John J

2017-07-17

Antibodies play an important role in immunity to malaria. Recent studies show that antibodies to multiple antigens, as well as, the overall breadth of the response are associated with protection from malaria. Yet, the variability and reliability of antibody measurements against a combination of malarial antigens using multiplex assays have not been well characterized. A normalization procedure for reducing between-plate variation using replicates of pooled positive and negative controls was investigated. Sixty test samples (30 from malaria-positive and 30 malaria-negative individuals), together with five pooled positive-controls and two pooled negative-controls, were screened for antibody levels to 9 malarial antigens, including merozoite antigens (AMA1, EBA175, MSP1, MSP2, MSP3, MSP11, Pf41), sporozoite CSP, and pregnancy-associated VAR2CSA. The antibody levels were measured in triplicate on each of 3 plates, and the experiments were replicated on two different days by the same technician. The performance of the proposed normalization procedure was evaluated with the pooled controls for the test samples on both the linear and natural-log scales. Compared with data on the linear scale, the natural-log transformed data were less skewed and reduced the mean-variance relationship. The proposed normalization procedure using pooled controls on the natural-log scale significantly reduced between-plate variation. For malaria-related research that measure antibodies to multiple antigens with multiplex assays, the natural-log transformation is recommended for data analysis and use of the normalization procedure with multiple pooled controls can improve the precision of antibody measurements.

Novel enzyme immunoassay system for simultaneous detection of six subclasses of antiphospholipid antibodies for differential diagnosis of antiphospholipid syndrome.

Science.gov (United States)

Nojima, Junzo; Motoki, Yukari; Hara, Kazusa; Sakata, Toshiyuki; Ichihara, Kiyoshi

2017-06-01

: Antiphospholipid syndrome, which often complicates systemic lupus erythematosus (SLE), features high occurrence of arterial and/or venous thrombosis and recurrent fetal loss. However, which antibody subclass contributes to which clinical event remains uncertain. We newly developed an up-to-date enzyme immunoassay system using the AcuStar automated analyzer (Instrumentation Laboratory, Bedford, Massachusetts, USA) for parallel detection of six subclasses of antiphospholipid antibodies (aPLs): anticardiolipin antibodies (aCL) of IgG, IgM, and IgA and anti-β2-glycoprotein I antibodies (aβ2GPI) of IgG, IgM, and IgA. They were measured in 276 healthy volunteers and 138 patients with SLE: 45 with thromboembolic complications (29 arterial; 16 venous) and 93 without. Lupus anticoagulant activity in their plasma was measured according to the guidelines recommended by the Subcommittee on Lupus Anticoagulant/Phospholipid-Dependent Antibodies. aCL/β2GPI was measured with a standard ELISA kit commonly used in Japan. The positive results of IgG aCL, IgA aCL, and IgG aβ2GPI were closely associated with thromboembolic complications, whereas IgM aCL and IgM aβ2GPI were not. receiver operating characteristic analysis revealed that the accuracy of predicting thromboembolic complications based on the composite test results of the former three antibodies were obviously higher than by each alone. Regarding agreement with the test results of lupus anticoagulant activity, IgG aβ2GPI showed the closest match. Patients with SLE frequently possess various combinations of the six aPL subclasses, and this antibody spectrum is closely associated with thromboembolic events in these patients. This new automated enzyme immunoassay system allows simultaneous analysis of the profile of aPL subclasses for the differential diagnosis of antiphospholipid antibody syndrome in its early stage.

Enzyme-labeled Antigen Method: Development and Application of the Novel Approach for Identifying Plasma Cells Locally Producing Disease-specific Antibodies in Inflammatory Lesions

International Nuclear Information System (INIS)

Mizutani, Yasuyoshi; Shiogama, Kazuya; Onouchi, Takanori; Sakurai, Kouhei; Inada, Ken-ichi; Tsutsumi, Yutaka

2016-01-01

In chronic inflammatory lesions of autoimmune and infectious diseases, plasma cells are frequently observed. Antigens recognized by antibodies produced by the plasma cells mostly remain unclear. A new technique identifying these corresponding antigens may give us a breakthrough for understanding the disease from a pathophysiological viewpoint, simply because the immunocytes are seen within the lesion. We have developed an enzyme-labeled antigen method for microscopic identification of the antigen recognized by specific antibodies locally produced in plasma cells in inflammatory lesions. Firstly, target biotinylated antigens were constructed by the wheat germ cell-free protein synthesis system or through chemical biotinylation. Next, proteins reactive to antibodies in tissue extracts were screened and antibody titers were evaluated by the AlphaScreen method. Finally, with the enzyme-labeled antigen method using the biotinylated antigens as probes, plasma cells producing specific antibodies were microscopically localized in fixed frozen sections. Our novel approach visualized tissue plasma cells that produced 1) autoantibodies in rheumatoid arthritis, 2) antibodies against major antigens of Porphyromonas gingivalis in periodontitis or radicular cyst, and 3) antibodies against a carbohydrate antigen, Strep A, of Streptococcus pyogenes in recurrent tonsillitis. Evaluation of local specific antibody responses expectedly contributes to clarifying previously unknown processes in inflammatory disorders

Enzyme linked immunosorbent assay for detecting antibody to Trichomonas vaginalis: use of whole cells and aqueous extract as antigen.

OpenAIRE

Alderete, J F

1984-01-01

An enzyme linked immunosorbent assay (ELISA) for detecting antibody to antigenic Trichomonas vaginalis macromolecules has been identified using whole cells or an aqueous protein extract as antigen. The test was developed under optimum conditions using serum samples from experimental animals. The sensitivity of the ELISA was equal to or greater than that obtained by radioimmunoprecipitation and electrophoresis-fluorography techniques. The ELISA was capable of assessing antibody responses durin...

Detecting Foci of Malaria Transmission with School Surveys: A Pilot Study in the Gambia.

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Ebako N Takem

Full Text Available In areas of declining malaria transmission such as in The Gambia, the identification of malaria infected individuals becomes increasingly harder. School surveys may be used to identify foci of malaria transmission in the community.The survey was carried out in May-June 2011, before the beginning of the malaria transmission season. Thirty two schools in the Upper River Region of The Gambia were selected with probability proportional to size; in each school approximately 100 children were randomly chosen for inclusion in the study. Each child had a finger prick blood sample collected for the determination of antimalarial antibodies by ELISA, malaria infection by microscopy and PCR, and for haemoglobin measurement. In addition, a simple questionnaire on socio-demographic variables and the use of insecticide-treated bed nets was completed. The cut-off for positivity for antimalarial antibodies was obtained using finite mixture models. The clustered nature of the data was taken into account in the analyses.A total of 3,277 children were included in the survey. The mean age was 10 years (SD = 2.7 [range 4-21], with males and females evenly distributed. The prevalence of malaria infection as determined by PCR was 13.6% (426/3124 [95% CI = 12.2-16.3] with marked variation between schools (range 3-25%, p<0.001, while the seroprevalence was 7.8% (234/2994 [95%CI = 6.4-9.8] for MSP119, 11.6% (364/2997 [95%CI = 9.4-14.5] for MSP2, and 20.0% (593/2973 [95% CI = 16.5-23.2 for AMA1. The prevalence of all the three antimalarial antibodies positive was 2.7% (79/2920.This survey shows that malaria prevalence and seroprevalence before the transmission season were highly heterogeneous.

The significance for epidemiological studies anti-measles antibody detection examined by enzyme immunoassay (EIA) and plaque reduction neutralization test (PRNT).

Science.gov (United States)

Siennicka, Joanna; Częścik, Agnieszka; Trzcińska, Agnieszka

2014-01-01

The paper discusses the role of anti-measles antibodies for protection and significance for epidemiological studies determination of antibodies by different serological methods. The comparison of anti-measles virus antibodies levels measured by enzyme immunoassay (EIA) and Plaque Reduction Neutralization Test (PRNT) was described. It was found that the 200 mIU/ml of anti-measles activity measured by PRNT (level protection against symp- tomatic disease) is equivalent of 636 mIU/ml measured by EIA (Enzygnost®Anti-Measles Virus/IgG, Simens).

Endemic Burkitt lymphoma is associated with strength and diversity of Plasmodium falciparum malaria stage-specific antigen antibody response.

Science.gov (United States)

Aka, Peter; Vila, Maria Candida; Jariwala, Amar; Nkrumah, Francis; Emmanuel, Benjamin; Yagi, Masanori; Palacpac, Nirianne Marie Q; Periago, Maria V; Neequaye, Janet; Kiruthu, Christine; Tougan, Takahiro; Levine, Paul H; Biggar, Robert J; Pfeiffer, Ruth M; Bhatia, Kishor; Horii, Toshihiro; Bethony, Jeffrey M; Mbulaiteye, Sam M

2013-08-01

Endemic Burkitt lymphoma (eBL) is linked to Plasmodium falciparum (Pf) infection geographically, but evidence from individual-level studies is limited. We investigated this issue among 354 childhood eBL cases and 384 age-, sex-, and location-matched controls enrolled in Ghana from 1965 to 1994. Immunoglobulin G1 (IgG1) and immunoglobulin G3 (IgG3) antibodies to antigens diagnostic of recent infection Pf histidine-rich protein-II (HRP-II) and 6NANP, Pf-vaccine candidates SE36 and 42-kDa region of the 3D7 Pf merozoite surface protein-1 (MSP-1), and tetanus toxoid were measured by indirect enzyme-linked immunoassay. Odds ratios (ORs) and 95% confidence intervals (CIs) for association with eBL were estimated using unconditional logistic regression. After adjustments, eBL was positively associated with HRP-IIIgG3 seropositivity (adjusted OR: 1.60; 95% CI 1.08-2.36) and inversely associated with SE36IgG1 seropositivity (adjusted OR: 0.37; 95% CI 0.21-0.64) and with tetanus toxoidIgG3 levels equal or higher than the mean (adjusted OR: 0.46; 95% CI 0.32-0.66). Anti-MSP-1IgG3 and anti-6NANPIgG3 were indeterminate. eBL risk was potentially 21 times higher (95% CI 5.8-74) in HRP-IIIgG3-seropositive and SE36IgG1-seronegative responders compared with HRP-IIIgG3-seronegative and SE36IgG1-seropositive responders. Our results suggest that recent malaria may be associated with risk of eBL but long-term infection may be protective.

Affinity proteomics reveals elevated muscle proteins in plasma of children with cerebral malaria.

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Julie Bachmann

2014-04-01

Full Text Available Systemic inflammation and sequestration of parasitized erythrocytes are central processes in the pathophysiology of severe Plasmodium falciparum childhood malaria. However, it is still not understood why some children are more at risks to develop malaria complications than others. To identify human proteins in plasma related to childhood malaria syndromes, multiplex antibody suspension bead arrays were employed. Out of the 1,015 proteins analyzed in plasma from more than 700 children, 41 differed between malaria infected children and community controls, whereas 13 discriminated uncomplicated malaria from severe malaria syndromes. Markers of oxidative stress were found related to severe malaria anemia while markers of endothelial activation, platelet adhesion and muscular damage were identified in relation to children with cerebral malaria. These findings suggest the presence of generalized vascular inflammation, vascular wall modulations, activation of endothelium and unbalanced glucose metabolism in severe malaria. The increased levels of specific muscle proteins in plasma implicate potential muscle damage and microvasculature lesions during the course of cerebral malaria.

Towards A Malaria Vaccine?

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B S GARG

1990-12-01

Full Text Available The last few years have seen a marked change in the understanding of malaria mmunology.We have very little knowledge on immunity of Malaria based on experiments in humanbeings due to ethical reasons. Whatsoever our knowledge exists at present is based onexperimentas in mice and monkey. However it is clear that it is sporzoite or merozoitewhich is directly exposed to our immune system in the life cycle of Malaria parasite. On thebasis of human experiments we can draw inference that immunity to malaria is species.specific (on cross immunity, stage specific and strain specific as well acquired in the response to surface antigen and relapsed antigen although the parasite also demonstrates escape machanism to immune system.So the host system kills or elimi nate the parasite by means of (a Antbody to extracell~ular form of parasite with the help of mechanism of Block invasion, Agglutination or opsonization and/or (b Cellular machanism-either by phago-cytosis of parasite or by antibody dependent cellular cytotoxicity ABCC (? or by effects of mediators like tumor necrosis fJ.ctor (TNF in cerebaral malaria or crisis forming factor as found in sudan or by possible role of lysis mechanism.However, inspite of all these theories the parasite has been able to invade the immunesystem by virtue of its intracellular development stage specificity, sequestration in capillaries and also by its unusual characteristics of antigenic diversity and antigenic variation.

Application of radioimmunoassay methods for malaria detection in two selected endemic areas in the Philippines

International Nuclear Information System (INIS)

Salazar, N.P.; Natera, E.S.; Pasay, C.J.; Tiu, W.U.

1995-01-01

Radioimmunoassay (RIA) technique was used with the synthetic peptide, (NANP)3 in detecting anti-sporozoite antibody (against Plasmodium falcifarum) in serum of persons residing in two (2) endimic areas in the Philippines. entomological surveys for sporozoite detection in mosquito vectors utilizing monoclonal antibodies (2A10 for P. falciparum and 2F2 for P. vivax) were likewise conducted in the same areas where serological surveys were performed. These two areas are located on separate islands, with varying malaria transmission seasons and levels of endemicity. Initial findings showed positive response to the CSP antigen (NANP)3 in detecting anti - P. falciparum antibodies in sera. Infection with sporozoites of P. falciparum and P. vivax in mosquito vectors were detected using monoclonal antibodies 2A10 and 2F2 respectively. The latter procedure was shown to be more sensitive than dissection of mosquito salivary glands. Initial study shows a heightened level of anti-(NANP)3 antibodies in both populations prior to the generally accepted peak of malaria season indicating that RIA with CSP antigen and specific MAbs can be a useful epidemiological tool for understanding the dynamics of malaria transmission as well as in monitoring control programmes based on reducing manvector contact. (author) 15 refs.,12 tabs

High plasma levels of soluble intercellular adhesion molecule (ICAM)-1 are associated with cerebral malaria.

Science.gov (United States)

Adukpo, Selorme; Kusi, Kwadwo A; Ofori, Michael F; Tetteh, John K A; Amoako-Sakyi, Daniel; Goka, Bamenla Q; Adjei, George O; Edoh, Dominic A; Akanmori, Bartholomew D; Gyan, Ben A; Dodoo, Daniel

2013-01-01

Cerebral malaria (CM) is responsible for most of the malaria-related deaths in children in sub-Saharan Africa. Although, not well understood, the pathogenesis of CM involves parasite and host factors which contribute to parasite sequestration through cytoadherence to the vascular endothelium. Cytoadherence to brain microvasculature is believed to involve host endothelial receptor, CD54 or intercellular adhesion molecule (ICAM)-1, while other receptors such as CD36 are generally involved in cytoadherence of parasites in other organs. We therefore investigated the contributions of host ICAM-1 expression and levels of antibodies against ICAM-1 binding variant surface antigen (VSA) on parasites to the development of CM. Paediatric malaria patients, 0.5 to 13 years were recruited and grouped into CM and uncomplicated malaria (UM) patients, based on well defined criteria. Standardized ELISA protocol was used to measure soluble ICAM-1 (sICAM-1) levels from acute plasma samples. Levels of IgG to CD36- or ICAM-1-binding VSA were measured by flow cytometry during acute and convalescent states. Wilcoxon sign rank-test analysis to compare groups revealed association between sICAM-1 levels and CM (p0.05). Median levels of antibodies to CD36-binding VSAs were also comparable between acute and convalescent samples within any patient group. Median levels of antibodies to ICAM-1-binding VSAs were however significantly lower at admission time than during recovery in both groups. High levels of sICAM-1 were associated with CM, and the sICAM-1 levels may reflect expression levels of the membrane bound form. Anti-VSA antibody levels to ICAM-binding parasites was more strongly associated with both UM and CM than antibodies to CD36 binding parasites. Thus, increasing host sICAM-1 levels were associated with CM whilst antibodies to parasite expressing non-ICAM-1-binding VSAs were not.

Detection by radioimmunoassay and enzyme-linked immunosorbent assay of coronavirus antibodies in bovine serum and lacteal secretions.

Science.gov (United States)

Rodak, L; Babiuk, L A; Acres, S D

1982-07-01

The sensitivity of a radioimmunoassay (RIA), an enzyme-linked immunosorbent assay (ELISA), and a serum neutralization assay (SN) for detecting antibodies to bovine coronavirus in serum and colostrum were compared. Although there proved to be a good correlation among all three assays (r = 0.915 and 0.964 for RIA with SN and ELISA, respectively), RIA and ELISA proved to be at least 10 times more sensitive than neutralization tests. By using these techniques, it was possible to detect a time-dependent decrease in antibody levels in bovine colostrum after parturition. Using ELISA, we demonstrated that 12 of 12 herds in Saskatchewan, and 109 of 110 animals tested, and antibody to bovine coronavirus. There was no elevated antibody response in serum or lacteal secretions of cows vaccinated once or twice with a commercially available modified live rota-coronavirus vaccine. In addition to being more sensitive than SN, ELISA and RIA proved to have other advantages for measuring antibody levels to bovine coronavirus and therefore warrant wider use as tools in diagnostic virology.

Phase 1 study in malaria naïve adults of BSAM2/Alhydrogel®+CPG 7909, a blood stage vaccine against P. falciparum malaria.

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Ruth D Ellis

Full Text Available A Phase 1 dose escalating study was conducted in malaria naïve adults to assess the safety, reactogenicity, and immunogenicity of the blood stage malaria vaccine BSAM2/Alhydrogel®+ CPG 7909. BSAM2 is a combination of the FVO and 3D7 alleles of recombinant AMA1 and MSP1(42, with equal amounts by weight of each of the four proteins mixed, bound to Alhydrogel®, and administered with the adjuvant CPG 7909. Thirty (30 volunteers were enrolled in two dose groups, with 15 volunteers receiving up to three doses of 40 µg total protein at Days 0, 56, and 180, and 15 volunteers receiving up to three doses of 160 µg protein on the same schedule. Most related adverse events were mild or moderate, but 4 volunteers experienced severe systemic reactions and two were withdrawn from vaccinations due to adverse events. Geometric mean antibody levels after two vaccinations with the high dose formulation were 136 µg/ml for AMA1 and 78 µg/ml for MSP1(42. Antibody responses were not significantly different in the high dose versus low dose groups and did not further increase after third vaccination. In vitro growth inhibition was demonstrated and was closely correlated with anti-AMA1 antibody responses. A Phase 1b trial in malaria-exposed adults is being conducted.Clinicaltrials.gov NCT00889616.

Can antibodies against flies alter malaria transmission in birds by changing vector behavior?

Science.gov (United States)

Ghosh, Suma; Waite, Jessica L; Clayton, Dale H; Adler, Frederick R

2014-10-07

Transmission of insect-borne diseases is shaped by the interactions among parasites, vectors, and hosts. Any factor that alters movement of infected vectors from infected to uninfeced hosts will in turn alter pathogen spread. In this paper, we study one such pathogen-vector-host system, avian malaria in pigeons transmitted by fly ectoparasites, where both two-way and three-way interactions play a key role in shaping disease spread. Bird immune defenses against flies can decrease malaria prevalence by reducing fly residence time on infected birds or increase disease prevalence by enhancing fly movement and thus infection transmission. We develop a mathematical model that illustrates how these changes in vector behavior influence pathogen transmission and show that malaria prevalence is maximized at an intermediate level of defense avoidance by the flies. Understanding how host immune defenses indirectly alter disease transmission by influencing vector behavior has implications for reducing the transmission of human malaria and other vectored pathogens. Published by Elsevier Ltd.

Rapid assessment of malaria transmission using age-specific sero-conversion rates.

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Laveta Stewart

2009-06-01

Full Text Available Malaria transmission intensity is a crucial determinant of malarial disease burden and its measurement can help to define health priorities. Rapid, local estimates of transmission are required to focus resources better but current entomological and parasitological methods for estimating transmission intensity are limited in this respect. An alternative is determination of antimalarial antibody age-specific sero-prevalence to estimate sero-conversion rates (SCR, which have been shown to correlate with transmission intensity. This study evaluated SCR generated from samples collected from health facility attendees as a tool for a rapid assessment of malaria transmission intensity.The study was conducted in north east Tanzania. Antibodies to Plasmodium falciparum merozoite antigens MSP-1(19 and AMA-1 were measured by indirect ELISA. Age-specific antibody prevalence was analysed using a catalytic conversion model based on maximum likelihood to generate SCR. A pilot study, conducted near Moshi, found SCRs for AMA-1 were highly comparable between samples collected from individuals in a conventional cross-sectional survey and those collected from attendees at a local health facility. For the main study, 3885 individuals attending village health facilities in Korogwe and Same districts were recruited. Both malaria parasite prevalence and sero-positivity were higher in Korogwe than in Same. MSP-1(19 and AMA-1 SCR rates for Korogwe villages ranged from 0.03 to 0.06 and 0.07 to 0.21 respectively. In Same district there was evidence of a recent reduction in transmission, with SCR among those born since 1998 [MSP-1(19 0.002 to 0.008 and AMA-1 0.005 to 0.014 ] being 5 to 10 fold lower than among individuals born prior to 1998 [MSP-1(19 0.02 to 0.04 and AMA-1 0.04 to 0.13]. Current health facility specific estimates of SCR showed good correlations with malaria incidence rates in infants in a contemporaneous clinical trial (MSP-1(19 r(2 = 0.78, p<0.01 & AMA-1 r

Detection of antibodies to the extractable nuclear antigens by enzyme linked immunosorbent assay

International Nuclear Information System (INIS)

Aziz, Khalil A.; Fzizal, Abul A.

2005-01-01

Anti-extractable nuclear antigen (ENA) antibodies are a group of autoantibodies that are directed against various components of the cell nucleus. Antibodies to these antigens are closely associated with connective tissue disease. Early diagnosis of these diseases can prove very difficult and therefore clinicians rely on the use of anti-ENA antibody testing for the exclusion. Old methods of testing are time consuming and require great skills. For these reasons clinical immunology laboratories are switching to testing for anti-ENA antibodies by enzyme linked immunosorbent assay (ELISA). The latter assays are more sensitive and require little skills. In the present study we have investigated a number of different ELISA preparations. The study was conducted at Birmingham Heartlands Hospital during the period 2003. We tested a number of ENA-positive and negative samples using 3 different commercial ELISA preparations and compared the results with traditional CCIE-assay. The present study revealed that some ELISA preparations can be more sensitive than CCIE method. Laboratories still using later method should switch to ELISA. However it is important that laboratories evaluate a long range of different ELISA preparations before selecting the most optimal one. In addition it is recommended that laboratories then audit results in order to determine true significance of such results. Finally until the true significance of ELISA generated results is known, positive ENA-results should be interpreted in conjunction with the clinical picture and this would require close liaison in between the clinical immunology laboratory and clinicians

Influenza A plasma and serum virus antibody detection comparison in dogs using blocking enzyme-linked immunosorbent assay

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H. T. Lin

2015-05-01

Full Text Available Background and Aim: The influenza A virus (IAV is an important zoonotic pathogen with infections also reported in dogs. IAV infections can be detected through the presence of antibodies using the enzyme-linked immunosorbent assay (ELISA. Serum is the only standard sample source; however, there is no information on the availability of other sample sources for IAV antibody detection in dogs. Compared with serum, plasma is more widely employed in most animal hospitals. The object of this study is to investigate whether plasma collected in ethylenediaminetetraacetic acid (EDTA tubes (EDTA plasma or heparin tubes (heparin plasma could be used in the ELISA protocol instead of serum for IAV antibody detection in dogs. Materials and Methods: Totally, 82 matched EDTA plasma and serum sample pairs and 79 matched heparin plasma and serum sample pairs were employed using blocking enzyme-linked immunosorbent assay (bELISA. The agreement and correlation between the plasma (EDTA or heparin plasma and serum were assessed using the agreement index kappa (kD calculation and Pearson correlation coefficient, respectively. Results: The agreement index kD of EDTA plasma and serum was 1.0, and that of heparin plasma and serum was 0.85. The Pearson correlation coefficient of EDTA plasma and serum was 0.87 (p<0.01, and that of heparin plasma and serum was 0.82 (p<0.01. Conclusion: The results proved that plasma, especially EDTA plasma, could be substituted for serum in the bELISA test. This might greatly expand the clinical applicability of IAV antibody detection in dogs.

High levels of antibodies to multiple domains and strains of VAR2CSA correlate with the absence of placental malaria in Cameroonian women living in an area of high Plasmodium falciparum transmission

DEFF Research Database (Denmark)

Tutterrow, Yeung L; Avril, Marion; Singh, Kavita

2012-01-01

erythrocytes and mediates binding to chondroitin sulfate A, initiating inflammation and disrupting homeostasis at the maternal-fetal interface. Although antibodies can prevent sequestration, it is unclear whether parasite clearance is due to antibodies to a single Duffy binding-like (DBL) domain...... or to an extensive repertoire of antibodies to multiple DBL domains and allelic variants. Accordingly, plasma samples collected longitudinally from pregnant women were screened for naturally acquired antibodies against an extensive panel of VAR2CSA proteins, including 2 to 3 allelic variants for each of 5 different...... DBL domains. Analyses were performed on plasma samples collected from 3 to 9 months of pregnancy from women living in areas in Cameroon with high and low malaria transmission. The results demonstrate that high antibody levels to multiple VAR2CSA domains, rather than a single domain, were associated...

Interaction of malaria with a common form of severe thalassemia in an Asian population

Science.gov (United States)

O'Donnell, A.; Premawardhena, A.; Arambepola, M.; Samaranayake, R.; Allen, S. J.; Peto, T. E. A.; Fisher, C. A.; Cook, J.; Corran, P. H.; Olivieri, Nancy F.; Weatherall, D. J.

2009-01-01

In many Asian populations, the commonest form of severe thalassemia results from the coinheritance of HbE and β thalassemia. The management of this disease is particularly difficult because of its extreme clinical diversity; although some genetic and adaptive factors have been identified as phenotypic modifiers, the reasons remain unclear. Because the role of the environment in the course of severe thalassemia has been neglected completely and because malaria due to both Plasmodium falciparum and Plasmodium vivax has been prevalent in Sri Lanka, we carried out a pilot study of patients with HbE β thalassemia that showed high frequencies of antibodies to both parasite species and that 28.6% of the children had DNA-based evidence of current infection with P. vivax. Malarial antibodies then were assessed in patients with HbE β thalassemia compared with those in age-matched controls. There was a significant increase in the frequency of antibodies in the thalassemic patients, particularly against P. vivax and in young children. There was also a higher frequency in those who had been splenectomized compared with those with intact spleens, although in the latter it was still higher than that in the controls. The thalassemic patients showed significant correlations between malaria antibody status and phenotype. Patients with HbE β thalassemia may be more prone to malaria, particularly P. vivax, which is reflected in their clinical severity. Because P. vivax malaria is widespread in Asia, further studies of its interaction with HbE β thalassemia and related diseases are required urgently as a part of ongoing thalassemia control programs. PMID:19841268

Sandwich enzyme-linked immunosorbent assay (ELISA) for measuring the concentration of, and detection of antibodies to, Aujeszky's disease virus.

Science.gov (United States)

Kardi, V; Szegletes, E; Perényi, T; Pergel, I; Smal, Z

1990-01-01

A double antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed for measuring Aujeszky's disease virus (ADV) antigen concentration and an inhibition technique based on the former was developed for detection of antibodies to ADV. The results were checked by determining the cytopathic and serum neutralization titres. The correlation was satisfactory in both cases, with correlation coefficients above 0.8. When measuring ADV antigen concentration, the lower limit of detection was 10(3) TCID 50/0.2 ml. The sensitivity of ELISA in detecting antibodies to ADV was found to be superior to that of the serum neutralization test and, thus, enabled the testing of rabbit and guinea-pig sera.

A longitudinal cohort study of malaria exposure and changing serostatus in a malaria endemic area of rural Tanzania.

Science.gov (United States)

Simmons, Ryan A; Mboera, Leonard; Miranda, Marie Lynn; Morris, Alison; Stresman, Gillian; Turner, Elizabeth L; Kramer, Randall; Drakeley, Chris; O'Meara, Wendy P

2017-08-02

Measurements of anti-malarial antibodies are increasingly used as a proxy of transmission intensity. Most serological surveys are based on the use of cross-sectional data that, when age-stratified, approximates historical patterns of transmission within a population. Comparatively few studies leverage longitudinal data to explicitly relate individual infection events with subsequent antibody responses. The occurrence of seroconversion and seroreversion events for two Plasmodium falciparum asexual stage antigens (MSP-1 and AMA-1) was examined using three annual measurements of 691 individuals from a cohort of individuals in a malaria-endemic area of rural east-central Tanzania. Mixed-effect logistic regression models were employed to determine factors associated with changes in serostatus over time. While the expected population-level relationship between seroprevalence and disease incidence was observed, on an individual level the relationship between individual infections and the antibody response was complex. MSP-1 antibody responses were more dynamic in response to the occurrence and resolution of infection events than AMA-1, while the latter was more correlated with consecutive infections. The MSP-1 antibody response to an observed infection seemed to decay faster over time than the corresponding AMA-1 response. Surprisingly, there was no evidence of an age effect on the occurrence of a conversion or reversion event. While the population-level results concur with previously published sero-epidemiological surveys, the individual-level results highlight the more complex relationship between detected infections and antibody dynamics than can be analysed using cross-sectional data. The longitudinal analysis of serological data may provide a powerful tool for teasing apart the complex relationship between infection events and the corresponding immune response, thereby improving the ability to rapidly assess the success or failure of malaria control programmes.

Improved quantification of a commercial enzyme-linked immunosorbent assay kit for measuring anti-MDA5 antibody.

Science.gov (United States)

Gono, Takahisa; Okazaki, Yuka; Murakami, Akihiro; Kuwana, Masataka

2018-04-09

To compare the quantitative performance for measuring anti-MDA5 antibody titer of two enzyme-linked immunosorbent assay (ELISA) systems: an in-house ELISA and the commercial MESACUP TM anti-MDA5 test. Anti-MDA5 antibody titer was measured in sera from 70 patients with dermatomyositis using an in-house ELISA and the MESACUP TM anti-MDA5 test side-by-side. For the commercial ELISA kit, serum samples diluted 1:101 were used according to the manufacturer's protocol, but serial dilutions of sera were also examined to identify the optimal serum dilution for quantification. The anti-MDA5 antibody titers measured by the in-house and commercial ELISAs were positively correlated with each other (r = 0.53, p = .0001), but the antibody titer measured by the commercial ELISA was less sensitive to change after medical treatment, and 37 (80%) of 46 anti-MDA5-positive sera had antibody titer exceeding the quantification range specified by the manufacturer (≥150 index). Experiments using diluted serum samples revealed that diluting the sera 1:5050 improved the quantitative performance of the MESACUP TM anti-MDA5 test, including a better correlation with the in-house ELISA results and an increased sensitivity to change. We improved the ability of the commercial ELISA kit to quantify anti-MDA5 antibody titer by altering its protocol.

Antibodies reactive to Plasmodium falciparum serine repeat antigen in children with Burkitt lymphoma from Ghana.

Science.gov (United States)

Guech-Ongey, Mercy; Yagi, Masanori; Palacpac, Nirianne Marie Q; Emmanuel, Benjamin; Talisuna, Ambrose O; Bhatia, Kishor; Stefan, D Cristina; Biggar, Robert J; Nkrumah, Francis; Neequaye, Janet; Tougan, Takahiro; Horii, Toshihiro; Mbulaiteye, Sam M

2012-04-15

The role of protective immunity to Plasmodium falciparum (Pf) malaria in Burkitt lymphoma (BL) is unknown. We investigated the association between BL and antibodies reactive to SE36 antigen, a recombinant protein based on P. falciparum serine repeat antigen 5 gene, targeted by protective malaria immune responses. Cases were children (0-14 years) enrolled at the Korle-Bu Teaching Hospital, Accra, Ghana, during 1965-1994 with BL confirmed by histology or cytology (92% of cases). Controls were apparently healthy children enrolled contemporaneous to the cases from the nearest neighbor house to the case house and were age,- sex-frequency-matched to the cases. Anti-SE36 IgG antibodies were measured using enzyme-linked absorbent immunoassays (ELISAs). SE36 titers were estimated by extrapolating ELISA optical density readings to a standard fitting curve. Anti-SE36 titers were log-transformed for analysis. Odds ratios (ORs) and two-sided 95% confidence intervals (95% CIs) were estimated using unconditional logistic regression. The mean log endpoint dilution titers were 0.63 logs lower in cases than in controls (8.26 [SD 1.68] vs. 8.89 [SD 1.75], Student's t-test, p = 0.019). Lower titers were observed in cases than controls aged 0-4 years (p = 0.05) and in those aged 5-14 years (p = 0.06). Low and medium tertiles of anti-SE36 IgG antibodies were associated with increased OR for BL ([OR 1.67, 95% CI 1.21-2.31] and [OR 1.33, 95% CI 0.96-1.86], respectively, p(trend) = 0.002) in analyses adjusting for age, sex, calendar period and test plate. Our findings suggest that compared to similarly aged children enrolled from the same community, children with BL in Ghana have lower antibodies to SE36 antigen. Copyright © 2011 UICC.

USE OF AN INDIRECT ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA TO DETECT ANTIBODIES IN AYU (Plecogiossus altivelis VACCINATED BY IMMERSION ADMINISTRATION

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. Sukenda

2007-05-01

Full Text Available ABSTRACTAn indirect enzyme-linked immunosorbent assay (ELISA was used to detect serum antibody in ayu, Plecoglossus altivelis, immunized against Pseudomonasplecoglossicida by immersion vaccination.  First, the procedure of the ELISA was optimized and the sensitivity was checked.  Secondly, the formalin-killed cells (FKC of P. plecoglossicida was administered to ayu by immersion vaccination.  Two weeks after vaccination, fish were divided into two groups, one group was given booster.  The level of specific antibody production of both boostered and vaccinated only fish were statistically higher than unvaccinated control fish at the time of each blood collection.  However, the differences between the boostered and vaccinated only fish were not statistically significant.Keywords :  immunization, Pseudomonas plecoglossicida, ayu, ELISA ABSTRAKIndirect enzyme-linked immunosorbent assay (ELISA digunakan untuk mendeteksi antibodi pada ayu, Plecoglossus altivelis, yang diimunisasi dengan cara perendaman untuk melawan infeksi Pseudomonas plecoglossicida.  Pertama, prosedur ELISA dioptimasikan dan sensitivitas dari metode ini juga diperiksa.  Kemudian, bakteri Plecoglossus altivelis yang sudah dimatikan dengan formalin diberikan ke ikan ayu dengan vaksinasi perendaman.  Dua minggu setelah vaksinasi, ikan dibagi menjadi dua kelompok, satu kelompok diberi vaksinasi kedua.  Produksi antibodi spesifik dari ikan-ikan yang divaksinasi satu kali dengan vaksinasi dua kaii secara statistik lebih tinggi dibandingkan dengan control.  Akan tetapi, tidak ada perbedaan produksi antibodi antara ikan yarig divaksanisi satu kali dengan divaksinasi dua kali.Kata kunci :  imunisasi, Pseudomonasplecoglossicida, ayu, ELISA

Role of Activins in Hepcidin Regulation during Malaria.

Science.gov (United States)

Spottiswoode, Natasha; Armitage, Andrew E; Williams, Andrew R; Fyfe, Alex J; Biswas, Sumi; Hodgson, Susanne H; Llewellyn, David; Choudhary, Prateek; Draper, Simon J; Duffy, Patrick E; Drakesmith, Hal

2017-12-01

Epidemiological observations have linked increased host iron with malaria susceptibility, and perturbed iron handling has been hypothesized to contribute to the potentially life-threatening anemia that may accompany blood-stage malaria infection. To improve our understanding of these relationships, we examined the pathways involved in regulation of the master controller of iron metabolism, the hormone hepcidin, in malaria infection. We show that hepcidin upregulation in Plasmodium berghei murine malaria infection was accompanied by changes in expression of bone morphogenetic protein (BMP)/sons of mothers against decapentaplegic (SMAD) pathway target genes, a key pathway involved in hepcidin regulation. We therefore investigated known agonists of the BMP/SMAD pathway and found that Bmp gene expression was not increased in infection. In contrast, activin B, which can signal through the BMP/SMAD pathway and has been associated with increased hepcidin during inflammation, was upregulated in the livers of Plasmodium berghei -infected mice; hepatic activin B was also upregulated at peak parasitemia during infection with Plasmodium chabaudi Concentrations of the closely related protein activin A increased in parallel with hepcidin in serum from malaria-naive volunteers infected in controlled human malaria infection (CHMI) clinical trials. However, antibody-mediated neutralization of activin activity during murine malaria infection did not affect hepcidin expression, suggesting that these proteins do not stimulate hepcidin upregulation directly. In conclusion, we present evidence that the BMP/SMAD signaling pathway is perturbed in malaria infection but that activins, although raised in malaria infection, may not have a critical role in hepcidin upregulation in this setting. Copyright © 2017 Spottiswoode et al.

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

DEFF Research Database (Denmark)

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...

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.

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

Congenital malaria with atypical presentation: A case report from low transmission area in India

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Biswas Sukla

2007-04-01

Full Text Available Abstract Background Malaria during first few months of life may be due to transplacental transfer of parasitized maternal erythrocytes. Although IgG and IgM antimalarial antibodies can be detected in maternal blood, only IgG antibodies are present in the infant's blood. These antibodies can delay and modify the onset of clinical manifestations. Case Presentation An infant is described who presented with irritability and feeding problems. Clinical examination and investigations revealed that the infant was afebrile, had jaundice, hepatosplenomegaly and haemolytic anaemia. Peripheral smear demonstrated Plasmodium vivax. While the mother had significant levels of immunoglobulin G (IgG, the infant was found negative for IgG and had low immunoglobulin M (IgM levels. The mother had a history of febrile illness during pregnancy and her peripheral smear was also positive for P. vivax. Both were successfully treated with chloroquine in the dose of 25 mg/kg/day over three days. Conclusion The case emphasizes the importance of considering the diagnosis of malaria even in infants in low transmission area, who may not present with typical symptoms of malaria, such as fever, but have other clinical manifestations like jaundice and haemolytic anaemia.

High plasma levels of soluble intercellular adhesion molecule (ICAM-1 are associated with cerebral malaria.

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Selorme Adukpo

Full Text Available BACKGROUND: Cerebral malaria (CM is responsible for most of the malaria-related deaths in children in sub-Saharan Africa. Although, not well understood, the pathogenesis of CM involves parasite and host factors which contribute to parasite sequestration through cytoadherence to the vascular endothelium. Cytoadherence to brain microvasculature is believed to involve host endothelial receptor, CD54 or intercellular adhesion molecule (ICAM-1, while other receptors such as CD36 are generally involved in cytoadherence of parasites in other organs. We therefore investigated the contributions of host ICAM-1 expression and levels of antibodies against ICAM-1 binding variant surface antigen (VSA on parasites to the development of CM. METHODOLOGY/PRINCIPAL FINDINGS: Paediatric malaria patients, 0.5 to 13 years were recruited and grouped into CM and uncomplicated malaria (UM patients, based on well defined criteria. Standardized ELISA protocol was used to measure soluble ICAM-1 (sICAM-1 levels from acute plasma samples. Levels of IgG to CD36- or ICAM-1-binding VSA were measured by flow cytometry during acute and convalescent states. Wilcoxon sign rank-test analysis to compare groups revealed association between sICAM-1 levels and CM (p0.05. Median levels of antibodies to CD36-binding VSAs were also comparable between acute and convalescent samples within any patient group. Median levels of antibodies to ICAM-1-binding VSAs were however significantly lower at admission time than during recovery in both groups. CONCLUSIONS/SIGNIFICANCE: High levels of sICAM-1 were associated with CM, and the sICAM-1 levels may reflect expression levels of the membrane bound form. Anti-VSA antibody levels to ICAM-binding parasites was more strongly associated with both UM and CM than antibodies to CD36 binding parasites. Thus, increasing host sICAM-1 levels were associated with CM whilst antibodies to parasite expressing non-ICAM-1-binding VSAs were not.

Fast conversion of scFv to Fab antibodies using type IIs restriction enzymes.

Science.gov (United States)

Sanmark, Hanna; Huovinen, Tuomas; Matikka, Tero; Pettersson, Tiina; Lahti, Maria; Lamminmäki, Urpo

2015-11-01

Single chain variable fragment (scFv) antibody libraries are widely used for developing novel bioaffinity reagents, although Fab or IgG molecules are the preferred antibody formats in many final applications. Therefore, rapid conversion methods for combining multiple DNA fragments are needed to attach constant domains to the scFv derived variable domains. In this study we describe a fast and easy cloning method for the conversion of single framework scFv fragments to Fab fragments using type IIS restriction enzymes. All cloning steps excluding plating of the Fab transformants can be done in 96 well plates and the procedure can be completed in one working day. The concept was tested by converting 69 scFv clones into Fab format on 96 well plates, which resulted in 93% success rate. The method is particularly useful as a high-throughput tool for the conversion of the chosen scFv clones into Fab molecules in order to analyze them as early as possible, as the conversion can significantly affect the binding properties of the chosen clones. Copyright © 2015 Elsevier B.V. All rights reserved.

Determinants of variant surface antigen antibody response in severe Plasmodium falciparum malaria in an area of low and unstable malaria transmission

DEFF Research Database (Denmark)

A-Elgadir, T M E; Theander, T G; Elghazali, G

2006-01-01

The variant surface antigens (VSA) of infected erythrocytes are important pathogenic markers, a set of variants (VSA(SM)), were assumed to be associated with severe malaria (SM), while SM constitutes clinically diverse forms, such as, severe malarial anemia (SMA) and cerebral malaria (CM). This s...

Enzyme linked immunosorbent assay for detecting antibody to Trichomonas vaginalis: use of whole cells and aqueous extract as antigen.

Science.gov (United States)

Alderete, J F

1984-06-01

An enzyme linked immunosorbent assay (ELISA) for detecting antibody to antigenic Trichomonas vaginalis macromolecules has been identified using whole cells or an aqueous protein extract as antigen. The test was developed under optimum conditions using serum samples from experimental animals. The sensitivity of the ELISA was equal to or greater than that obtained by radioimmunoprecipitation and electrophoresis-fluorography techniques. The ELISA was capable of assessing antibody responses during the development of lesions in animals inoculated subcutaneously and it reproducibly measured the individual classes immunoglobulins directed at T vaginalis. The colorimetric assay was also suitable for showing cross reactivity between trichomonal species as well as between different strains of T vaginalis. Conditions established for monitoring antibody to trichomanads in immunised rabbits or infected mice were equally effective for human materials, such as serum or vaginal washes. Serum from experimental animals or infected people showed high concentrations of IgG, IgA, and IgM antibody to trichomonads. Only antibodies of the IgG and IgA class were detected in vaginal washes from women with acute trichomoniasis. No IgE antibody to trichomonads was found under a variety of conditions in serum samples from patients or experimental animals.

Relation between enzyme-linked immunosorbent assay and radioimmunoassay for detection of antibodies to the capsular polysaccharide of Haemophilus influenzae type b

International Nuclear Information System (INIS)

Kristensen, K.; Weis Bentzon, M.

1992-01-01

The measurement of antibodies to the capsular polysaccharide (PRP) of Haemophilus influenzae type b (Hib) is important because vaccines inducing such antibodies are now available. We developed and evaluated an enzyme-linked immunosorbent assay (ELISA) for detection of these antibodies based on direct coating of the plates with tyraminated PRP. The assay fulfilled the requirements for parallel line assays; it was sensitive, specific, and reproducible with a coefficient of variation between days of 19%. Results from the ELISA were compared with results from radioimmunoassay and a correlation coefficient of 0.93 was found. Results obtained by the two methods were proportional and the relation was indepenedent of the antibody level. The relation between them was also unaffected by the contribution of different antibody isotypes, indicating that these were measured to the same extent by both methods. ELISA employing direct coating of the plates with tyraminated PRP represents a useful alternative for detection of antibodies when studying immunogenicity of Hib vaccines. (au)

Features of Acquired Immunity in Malaria Endemic Areas

Indian Academy of Sciences (India)

... of Acquired Immunity in Malaria Endemic Areas. Adults (>15 years) do not suffer from the disease. Concomitant presence of low levels of P. falciparum in immune persons. This immunity is lost within 6-12 months if a person moves out of endemic area. Antibodies mediate protection for the asexual stages of P. falciparum.

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.

Prevalence of malaria and typhoid co-infections in University of ...

African Journals Online (AJOL)

user

2011-03-14

Mar 14, 2011 ... screened for antibody against Salmonella species using widal test. The stool and ... The results indicated that there is no relationship between malaria and Salmonella infection, but ... vein puncture and transferred into commercially prepared sterile ..... of Salmonella vaccine that expresses circumsporozoite.

Evaluation of an egg yolk enzyme-linked immunosorbent assay antibody test and its use to assess the prevalence of Mycoplasma gallisepticum infection in laying hens in Italy

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Marco Tamba

2010-01-01

Full Text Available The prevalence of Mycoplasma gallisepticum infection in commercial layers was established by the presence of antibodies in eggs. Saline-extracted yolks were used with a commercial enzyme-linked immunosorbent assay kit. For the prevalence study, yolks from 30 eggs were obtained from each of 66 flocks coming from 36 layer farms. The prevalence of egg antibodies to Mycoplasma gallisepticum was 33.3% in single-age farms and 77.8% in multi-age farms. In 27 flocks, antibody titers were compared with results obtained from blood samples taken in the same flock and in the same period and analyzed with the same kit. This study has confirmed that egg yolk enzyme-linked immunosorbent assay antibody test is a suitable and practical approach for assessing the flock prevalence of Mycoplasma gallisepticum infection in layer hens.

Malaria parasite carbonic anhydrase: inhibition of aromatic/heterocyclic sulfonamides and its therapeutic potential

Science.gov (United States)

Krungkrai, Sudaratana R; Krungkrai, Jerapan

2011-01-01

Plasmodium falciparum (P. falciparum) is responsible for the majority of life-threatening cases of human malaria, causing 1.5-2.7 million annual deaths. The global emergence of drug-resistant malaria parasites necessitates identification and characterization of novel drug targets and their potential inhibitors. We identified the carbonic anhydrase (CA) genes in P. falciparum. The pfCA gene encodes anα-carbonic anhydrase, a Zn2+-metalloenzme, possessing catalytic properties distinct from that of the human host CA enzyme. The amino acid sequence of the pfCA enzyme is different from the analogous protozoan and human enzymes. A library of aromatic/heterocyclic sulfonamides possessing a large diversity of scaffolds were found to be very good inhibitors for the malarial enzyme at moderate-low micromolar and submicromolar inhibitions. The structure of the groups substituting the aromatic-ureido- or aromatic-azomethine fragment of the molecule and the length of the parent sulfonamide were critical parameters for the inhibitory properties of the sulfonamides. One derivative, that is, 4- (3, 4-dichlorophenylureido)thioureido-benzenesulfonamide (compound 10) was the most effective in vitro Plasmodium falciparum CA inhibitor, and was also the most effective antimalarial compound on the in vitro P. falciparum growth inhibition. The compound 10 was also effective in vivo antimalarial agent in mice infected with Plasmodium berghei, an animal model of drug testing for human malaria infection. It is therefore concluded that the sulphonamide inhibitors targeting the parasite CA may have potential for the development of novel therapies against human malaria. PMID:23569766

Enzyme immunoassay for rabies antibody in hybridoma culture fluids and its application to differentiation of street and laboratory strains of rabies virus.

OpenAIRE

Smith, J S; Sumner, J W; Roumillat, L F

1984-01-01

A rapid and sensitive enzyme immunoassay is described for detecting rabies antibody in hybridoma culture fluids. Glass fiber filter disks were used to immobilize gamma-irradiated mouse neuroblastoma cells infected with street or laboratory strains of rabies virus. Bound rabies-specific antibody was detected by reaction with horseradish peroxidase-labeled goat anti-mouse immunoglobulin G. The assay was performed in a 96-well filtration device developed by Cleveland et al. (J. Clin. Microbiol. ...

Serologic markers for detecting malaria in areas of low endemicity, Somalia, 2008.

Science.gov (United States)

Bousema, Teun; Youssef, Randa M; Cook, Jackie; Cox, Jonathan; Alegana, Victor A; Amran, Jamal; Noor, Abdisalan M; Snow, Robert W; Drakeley, Chris

2010-03-01

Areas in which malaria is not highly endemic are suitable for malaria elimination, but assessing transmission is difficult because of lack of sensitivity of commonly used methods. We evaluated serologic markers for detecting variation in malaria exposure in Somalia. Plasmodium falciparum or P. vivax was not detected by microscopy in cross-sectional surveys of samples from persons during the dry (0/1,178) and wet (0/1,128) seasons. Antibody responses against P. falciparum or P. vivax were detected in 17.9% (179/1,001) and 19.3% (202/1,044) of persons tested. Reactivity against P. falciparum was significantly different between 3 villages (p<0.001); clusters of seroreactivity were present. Distance to the nearest seasonal river was negatively associated with P. falciparum (p = 0.028) and P. vivax seroreactivity (p = 0.016). Serologic markers are a promising tool for detecting spatial variation in malaria exposure and evaluating malaria control efforts in areas where transmission has decreased to levels below the detection limit of microscopy.

Detection of antibodies to Actinobacillus pleuropneumoniae serotype 12 in pig serum using a blocking enzyme-linked immunosorbent assay

DEFF Research Database (Denmark)

Andresen, Lars Ole; Klausen, Joan; Barfod, Kristen

2002-01-01

and from herds declared free of infection with Ap. The Ap serotype 12 blocking ELISA showed a herd sensitivity of 0.77 (95% confidence interval, 0.62-0.88) and a herd specificity of 1.00 (0.95-1.00) with a cut-off value at 40% relative absorbance or 60% inhibition. The assay may be used advantageously......The objective was to develop a blocking enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to Actinobacillus pleuropneumoniae (Ap) serotype 12 in pig serum. Lipopolysaccharide (LPS) from Ap serotype 12 was purified and used as antigen in the assay. Antibodies to the LPS antigen...... in samples of pig serum were detected by inhibition of the binding of polyclonal rabbit antibodies raised against Ap serotype 12. The assay was evaluated against sera from experimentally infected pigs, from pig herds naturally infected with Ap and from herds declared free of Ap serotypc 12 infection...

Elimination of Falciparum Malaria and Emergence of Severe Dengue: An Independent or Interdependent Phenomenon?

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Ib C. Bygbjerg

2018-05-01

Full Text Available The global malaria burden, including falciparum malaria, has been reduced by 50% since 2000, though less so in Sub-Saharan Africa. Regional malaria elimination campaigns beginning in the 1940s, up-scaled in the 1950s, succeeded in the 1970s in eliminating malaria from Europe, North America, the Caribbean (except Haiti, and parts of Asia and South- and Central America. Dengue has grown dramatically throughout the pantropical regions since the 1950s, first in Southeast Asia in the form of large-scale epidemics including severe dengue, though mostly sparing Sub-Saharan Africa. Globally, the WHO estimates 50 million dengue infections every year, while others estimate almost 400 million infections, including 100 million clinical cases. Curiously, despite wide geographic overlap between malaria and dengue-endemic areas, published reports of co-infections have been scarce until recently. Superimposed acute dengue infection might be expected to result in more severe combined disease because both pathogens can induce shock and hemorrhage. However, a recent review found no reports on more severe morbidity or higher mortality associated with co-infections. Cases of severe dual infections have almost exclusively been reported from South America, and predominantly in persons infected by Plasmodium vivax. We hypothesize that malaria infection may partially protect against dengue – in particular falciparum malaria against severe dengue – and that this inter-species cross-protection may explain the near absence of severe dengue from the Sub-Saharan region and parts of South Asia until recently. We speculate that malaria infection elicits cross-reactive antibodies or other immune responses that infer cross-protection, or at least partial cross-protection, against symptomatic and severe dengue. Plasmodia have been shown to give rise to polyclonal B-cell activation and to heterophilic antibodies, while some anti-dengue IgM tests have high degree of cross

Catalytic Antibodies

Indian Academy of Sciences (India)

biological processes and is intended to catalyze a reaction for which no real enzyme is ... the reaction. In order to enhance the rates of chemical reactions, enzymes, ..... of such antibodies has already been exploited in the production of a biosensor. ..... tant to the pharmaceutical and fine chemical industries for the synthesis ...

Magnetic nanoparticle based purification and enzyme-linked immunosorbent assay using monoclonal antibody against enrofloxacin

Science.gov (United States)

Kim, Nam-Gun; Kim, Myeong-Ae; Park, Young-Il; Jung, Tae-Sung; Son, Seong-Wan; So, ByungJae

2015-01-01

Monoclonal anti-enrofloxacin antibody was prepared for a direct competitive enzyme-linked immunosorbent assay (ELISA) and purification system using monoclonal antibody (mAb) coupled magnetic nanoparticles (MNPs). The IC50 values of the developed mAb for enrofloxacin (ENR), ciprofloxacin, difloxacin, sarafloxacin, pefloxacin, and norfloxacin were 5.0, 8.3, 9.7, 21.7, 36.0, and 63.7 ng/mL, respectively. The lowest detectable level of ENR was 0.7 ng/mL in the prepared ELISA system. To validate the developed ELISA in the food matrix, known amounts of ENR were spiked in meat and egg samples at 10, 20 and 30 ng/mL. Recoveries for ENR ranged from 72.9 to 113.16% with a coefficient of variation (CV) of 2.42 to 10.11%. The applicability of the mAb-MNP system was verified by testing the recoveries for ENR residue in three different matrices. Recoveries for ENR ranged from 75.16 to 86.36%, while the CV ranged from 5.08 to 11.53%. Overall, ENR-specific monoclonal antibody was prepared and developed for use in competitive to ELISAs for the detection of ENR in animal meat samples. Furthermore, we suggest that a purification system for ENR using mAb-coupled MNPs could be useful for determination of ENR residue in food. PMID:26040610

Ethylbenzene induces microsomal oxygen free radical generation: antibody-directed characterization of the responsible cytochrome P450 enzymes.

Science.gov (United States)

Serron, S C; Dwivedi, N; Backes, W L

2000-05-01

Small aromatic hydrocarbons cause changes in oxidative metabolism by modulating the levels of cytochrome P450 enzymes, with the changes in these enzymes being responsible for qualitative changes in aromatic hydrocarbon metabolism. The goal of this study was to determine if exposure to the small alkylbenzene ethylbenzene (EB) leads to an increase in hepatic free radical production. Male F344 rats were treated with ip injections of EB (10 mmol/kg) and compared to corn oil controls. Hepatic free radical production was examined by measuring the conversion of 2',7'-dichlorofluorescin diacetate (DCFH-DA) to its fluorescent product 2',7'-dichlorofluorescein (DCF). A significant elevation of fluorescent DCF production was observed after treatment with EB, despite the lack of effect on overall cytochrome P450 levels. This process was shown to be inhibitable by metyrapone, an inhibitor of P450. DCF production was also inhibited by catalase, suggesting that hydrogen peroxide (H(2)O(2)) is one of the reactive oxygen intermediates involved in EB-mediated reactive oxygen species (ROS) formation. Interestingly, superoxide dismutase (SOD) did not inhibit DCF production in corn oil-treated rats but was an effective inhibitor in the EB-treated groups. In an effort to determine if the increase in ROS production was related to changes in specific P450 enzymes, DCF production was measured in the presence of anti-CYP2B, anti-CYP2C11, anti-CYP2E1, and anti-CYP3A2 inhibitory antibodies. Anti-CYP2B antibodies inhibited DCF production in EB-treated, but not corn oil groups, which is consistent with the low constitutive levels of this enzyme and its induction by EB. The data also demonstrate that CYP2B contributes to ROS production. Anti-CYP2C11 did not influence DCF production in either group. ROS formation in corn oil-treated rats as well as in ethylbenzene-treated rats was also inhibited with antibodies to anti-CYP2E1 and anti-CYP3A2. These results suggest that CYP2C11 does not appear to

Social and environmental malaria risk factors in urban areas of Ouagadougou, Burkina Faso

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Ouedraogo Herman

2009-01-01

Full Text Available Abstract Background Despite low endemicity, malaria remains a major health problem in urban areas where a high proportion of fevers are presumptively treated using anti-malarial drugs. Low acquired malaria immunity, behaviour of city-dwellers, access to health care and preventive interventions, and heterogenic suitability of urban ecosystems for malaria transmission contribute to the complexity of the malaria epidemiology in urban areas. Methods The study was designed to identify the determinants of malaria transmission estimated by the prevalence of anti-circumsporozoite (CSP antibodies, the prevalence and density of Plasmodium falciparum infection, and the prevalence of malarial disease in areas of Ouagadougou, Burkina-Faso. Thick blood smears, dried blood spots and clinical status have been collected from 3,354 randomly chosen children aged 6 months to 12 years using two cross-sectional surveys (during the dry and rainy seasons in eight areas from four ecological strata defined according to building density and land tenure (regular versus irregular. Demographic characteristics, socio-economic information, and sanitary and environmental data concerning the children or their households were simultaneously collected. Dependent variables were analysed using mixed multivariable models with random effects, taking into account the clustering of participants within compounds and areas. Results Overall prevalences of CSP-antibodies and P. falciparum infections were 7.7% and 16.6% during the dry season, and 12.4% and 26.1% during the rainy season, respectively, with significant differences according to ecological strata. Malaria risk was significantly higher among children who i lived in households with lower economic or education levels, iii near the hydrographic network, iv in sparsely built-up areas, v in irregularly built areas, vi who did not use a bed net, vii were sampled during the rainy season or ii had traveled outside of Ouagadougou

Iodoacetyl-functionalized pullulan: A supplemental enhancer for single-domain antibody-polyclonal antibody sandwich enzyme-linked immunosorbent assay for detection of survivin.

Science.gov (United States)

Matsushita, Takahiko; Arai, Hidenao; Koyama, Tetsuo; Hatano, Ken; Nemoto, Naoto; Matsuoka, Koji

2017-11-01

Survivin, an inhibitor of the apoptosis protein family, is a potent tumor marker for diagnosis and prognosis. The enzyme-linked immunosorbent assay (ELISA) is one of the methods that has been used for detection of survivin. However, ELISA has several disadvantages caused by the use of conventional antibodies, and we have therefore been trying to develop a novel ELISA system using camelid single-domain antibodies (VHHs) as advantageous replacements. Here we report a supplemental approach to improve the VHH-polyclonal antibody sandwich ELISA for survivin detection. Iodoacetyl-functionalized pullulan was synthesized, and its thiol reactivity was characterized by a model reaction with l-cysteine. The thiophilic pullulan was applied to an immunoassay asan additive upon coating of standard assay plates with an anti-survivin VHH fusion protein with C-terminal cysteine. The results showed that the mole ratio of the additive to VHH had a significant effect on the consequent response. Mole ratios of 0.07, 0.7, and 7 led to 90% lower, 15% higher, and 69% lower responses, respectively, than the response of a positive control in which no additive was used. The background levels observed in any additive conditions were as low as that of a negative control lacking both VHH and the additive. These results indicate the applicability of the thiol-reactive pullulan as a response enhancer to VHH-based ELISA. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of Plasmodium vivax transmission-blocking activity in low to moderate malaria transmission settings of the Colombian Pacific coast.

Science.gov (United States)

Arévalo-Herrera, Myriam; Solarte, Yezid; Rocha, Leonardo; Alvarez, Diego; Beier, John C; Herrera, Sócrates

2011-02-01

Malaria infection induces antibodies capable of suppressing the infectivity of gametocytes and gametes, however, little is known about the duration of the antibody response, the parasite specificity, and the role of complement. We report the analyses of the transmission-blocking (TB) activity of sera collected from 105 Plasmodium vivax-infected and 44 non-infected individuals from a malaria endemic region of Colombia, using a membrane feeding assay in Anopheles albimanus mosquitoes. In infected donors we found that TB activity was antibody dose dependent (35%), lasted for 2-4 months after infection, and in 70% of the cases different P. vivax wild isolates displayed differential susceptibility to blocking antibodies. Additionally, in a number of assays TB was complement-dependent. Twenty-seven percent of non-infected individuals presented TB activity that correlated with antibody titers. Studies here provide preliminary data on factors of great importance for further work on the development of TB vaccines.

Comparison of enzyme-linked immunosorbent assay, radioimmunoassay, complement fixation, anticomplement immunofluorescence and passive haemaglutination techniques for detecting cytomegalovirus IgG antibody

Energy Technology Data Exchange (ETDEWEB)

Booth, J C; Hannington, G; Bakir, T M.F.; Stern, H; Kangro, H; Griffiths, P D; Heath, R B [Saint George' s Hospital Medical School, London (UK); Saint Bartholomew' s Hospital, London (UK))

1982-12-01

The radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) techniques were found to be comparable in sensitivity and specificity for detecting cytomegalovirus IgG antibody, and 10 to 100 times more sensitive than complement-fixation (CF), anticomplement immunofluorescence (ACIF) and passive haemagglutination (PHA). In screening tests for antibody, the frequency of false-positive and -negative results was 0.6% for RIA and ELISA, 1.5% for CF, 1.6% for ACIF and 3.6% for PHA. PHA was the least satisfactory test, largely because of technical problems.

Evaluation of enzyme-linked immunosorbent assays based on monoclonal antibodies for the serology and antigen detection in canine parvovirus infections.

NARCIS (Netherlands)

G.F. Rimmelzwaan (Guus); N. Juntti; B. Klingeborn; J. Groen (Jan); F.G.C.M. Uytdehaag (Fons); A.D.M.E. Osterhaus (Albert)

1990-01-01

textabstractAn enzyme-linked immunosorbent assay (ELISA) system was developed for the detection of canine parvovirus (CPV) or CPV antigen in dog faeces and two other ELISA systems were developed for the detection of CPV-specific antibodies in dog sera. The ELISA's were based on the use of

A sandwich immunoassay for human prolyl 4-hydroxylase using monoclonal antibody

International Nuclear Information System (INIS)

Yoshida, Shinichi

1986-01-01

Monoclonal antibody was used in a sandwich enzyme immunoassay and in a radioimmunoassay for human serum immunoreactive prolyl 4-hydroxylase. The enzyme immunoassay utilized a monoclonal antibody as a solid phase and horseradish peroxidase-labeled rabbit antibody to human prolyl 4-hydroxylase as a conjugate. Sensitivity was 0.1 ng of enzyme per tube. With a conjugate purified by an enzyme-bound affinity column, sensitivity was increased to 0.01 ng per tube, and linearity was obtained between 0.01 to 30 ng per tube. The radioimmunoassay used a 125 I-labeled rabbit antibody (IgG) as the conjugate. Sensitivity of this technique was 0.4 ng of enzyme per tube. (Auth.)

Reduced antibody responses against Plasmodium falciparum vaccine candidate antigens in the presence of Trichuris trichiura

DEFF Research Database (Denmark)

Esen, Meral; Mordmüller, Benjamin; de Salazar, Pablo Martinez

2012-01-01

BACKGROUND: Helminth infections are highly prevalent in the tropics and may have an effect on immune responses to vaccines due to their immunomodulatory effect. The prevalence of helminth infections in young children, the target group for malaria and most other vaccines, is high. Therefore we...... assessed the influence of helminth infection on vaccine-induced immune responses in a phase I clinical trial of the malaria vaccine candidate GMZ2. METHODS: Twenty Gabonese preschool-age children were vaccinated with GMZ2, a blood stage malaria vaccine candidate. Humoral immune response against the vaccine...... antigens and parasitological status were assessed. Vaccine-specific antibody concentrations and memory B-cell numbers were compared in worm infected and non-infected participants. RESULTS: Antibody response to GMZ2 was 3.4-fold (95% confidence interval: 1.6, 7.4) higher in Trichuris trichiura negative...

Comparison of Bovine coronavirus-specific and Bovine respiratory syncytial virus-specific antibodies in serum versus milk samples detected by enzyme-linked immunosorbent assay.

Science.gov (United States)

Ohlson, Anna; Blanco-Penedo, Isabel; Fall, Nils

2014-01-01

Bovine coronavirus (BCV; Betacoronavirus 1) and Bovine respiratory syncytial virus (BRSV) are significant causes of enteric and respiratory disease in beef and dairy cattle throughout the world. Indirect enzyme-linked immunosorbent assays are widely used to detect serum antibodies for herd monitoring and prevalence studies. In dairy herds, milk is more readily collected than serum. Hence, in order to investigate the test agreement between serum and milk, both serum and milk samples from 105 cows in 27 dairy herds were analyzed in parallel for presence of immunoglobulin G antibodies to BCV and BRSV. The Bland-Altman analyses of data demonstrated good agreement between serum and milk antibody titers for both viruses. The results indicate milk samples are sufficient for surveillance of antibodies to BCV and BRSV.

A modified Plasmodium falciparum growth inhibition assay (GIA) to assess activity of plasma from malaria endemic areas.

Science.gov (United States)

Mlambo, Godfree; Kumar, Nirbhay

2007-02-01

Plasma samples from patients undergoing treatment in malaria endemic countries often contain anti-malaria drugs, that may overstate effects of specific antibodies in growth inhibition assays (GIA). We describe a modified assay that uses drug resistant P. falciparum parasites (W2) that circumvents the requirement for dialyzing samples that may likely contain drugs such as chloroquine and sulfadoxine/pyrimethamine (SP).

Generation of monoclonal antibodies against peptidylarginine deiminase 2 (PAD2) and development of a PAD2-specific enzyme-linked immunosorbent assay

DEFF Research Database (Denmark)

Damgaard, Dres; Palarasah, Yaseelan; Skjødt, Karsten

2014-01-01

The enzyme peptidylarginine deiminase 2 (PAD2) has been associated with inflammatory diseases, such as rheumatoid arthritis and neurodegenerative diseases including multiple sclerosis. To investigate the association of various diseases with extracellular PAD2, we raised monoclonal antibodies (m......Abs) against rabbit PAD2 and evaluated their cross-reactivity with human PAD2 by indirect enzyme-linked immunosorbent assay (ELISA), western blotting and immunohistological staining of inflamed synovial tissue. Moreover, we established a sandwich ELISA detecting human PAD2, based on two different monoclonal...... diseases....

Improvement of an enzyme immunosorbent assay for detecting antibodies against Dioctophyma renale.

Science.gov (United States)

Pedrassani, Daniela; do Nascimento, Adjair Antonio; André, Marcos Rogério; Machado, Rosangela Zacarias

2015-09-15

An available enzyme-linked immunosorbent assay (ELISA) was studied for the detection of anti-Dioctophyma renale antibodies in the sera of dogs using, detection of parasite eggs in urine sediment as a reference test. ELISA uses a soluble antigenic preparation of esophagus of D. renale and the optimal dilutions of the antigen, serum and conjugate were determined by means of checker board titration, using positive (n=13) and negative (n=27) reference serum. The specificity and sensitivity of the ELISA were 93.8% and 92.3% respectively and the kappa index was good (0.76). These results suggest that ELISA described may prove to be an effective serological test for detecting dogs infected and exposed to this parasite mainly dogs that are not eliminating parasite eggs through their urine. Copyright © 2015 Elsevier B.V. All rights reserved.

Evidence for the involvement of VAR2CSA in pregnancy-associated malaria

DEFF Research Database (Denmark)

Salanti, Ali; Dahlbäck, Madeleine; Turner, Louise

2004-01-01

In Plasmodium falciparum-endemic areas, pregnancy-associated malaria (PAM) is an important health problem. The condition is precipitated by accumulation of parasite-infected erythrocytes (IEs) in the placenta, and this process is mediated by parasite-encoded variant surface antigens (VSA) binding...... to chondroitin sulfate A (CSA). Parasites causing PAM express unique VSA types, VSAPAM, which can be serologically classified as sex specific and parity dependent. It is sex specific because men from malaria-endemic areas do not develop VSAPAM antibodies; it is parity dependent because women acquire anti...

Exploiting Unique Structural and Functional Properties of Malarial Glycolytic Enzymes for Antimalarial Drug Development

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Asrar Alam

2014-01-01

Full Text Available Metabolic enzymes have been known to carry out a variety of functions besides their normal housekeeping roles known as “moonlighting functions.” These functionalities arise from structural changes induced by posttranslational modifications and/or binding of interacting proteins. Glycolysis is the sole source of energy generation for malaria parasite Plasmodium falciparum, hence a potential pathway for therapeutic intervention. Crystal structures of several P. falciparum glycolytic enzymes have been solved, revealing that they exhibit unique structural differences from the respective host enzymes, which could be exploited for their selective targeting. In addition, these enzymes carry out many parasite-specific functions, which could be of potential interest to control parasite development and transmission. This review focuses on the moonlighting functions of P. falciparum glycolytic enzymes and unique structural differences and functional features of the parasite enzymes, which could be exploited for therapeutic and transmission blocking interventions against malaria.

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

Directory of Open Access Journals (Sweden)

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.

Surveillance of vector populations and malaria transmission during the 2009/10 El Niño event in the western Kenya highlands: opportunities for early detection of malaria hyper-transmission

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Wanjala Christine L

2011-07-01

Full Text Available Abstract Background Vector control in the highlands of western Kenya has resulted in a significant reduction of malaria transmission and a change in the vectorial system. Climate variability as a result of events such as El Niño increases the highlands suitability for malaria transmission. Surveillance and monitoring is an important component of early transmission risk identification and management. However, below certain disease transmission thresholds, traditional tools for surveillance such as entomological inoculation rates may become insensitive. A rapid diagnostic kit comprising Plasmodium falciparum circumsporozoite surface protein and merozoite surface protein antibodies in humans was tested for early detection of transmission surges in the western Kenya highlands during an El Niño event (October 2009-February 2010. Methods Indoor resting female adult malaria vectors were collected in western Kenya highlands in four selected villages categorized into two valley systems, the U-shaped (Iguhu and Emutete and the V-shaped valleys (Marani and Fort Ternan for eight months. Members of the Anopheles gambiae complex were identified by PCR. Blood samples were collected from children 6-15 years old and exposure to malaria was tested using a circum-sporozoite protein and merozoite surface protein immunchromatographic rapid diagnostic test kit. Sporozoite ELISA was conducted to detect circum-sporozoite protein, later used for estimation of entomological inoculation rates. Results Among the four villages studied, an upsurge in antibody levels was first observed in October 2009. Plasmodium falciparum sporozoites were then first observed in December 2009 at Iguhu village and February 2010 at Emutete. Despite the upsurge in Marani and Fort Ternan no sporozoites were detected throughout the eight month study period. The antibody-based assay had much earlier transmission detection ability than the sporozoite-based assay. The proportion of An. arabiensis

[Automated analyzer of enzyme immunoassay].

Science.gov (United States)

Osawa, S

1995-09-01

Automated analyzers for enzyme immunoassay can be classified by several points of view: the kind of labeled antibodies or enzymes, detection methods, the number of tests per unit time, analytical time and speed per run. In practice, it is important for us consider the several points such as detection limits, the number of tests per unit time, analytical range, and precision. Most of the automated analyzers on the market can randomly access and measure samples. I will describe the recent advance of automated analyzers reviewing their labeling antibodies and enzymes, the detection methods, the number of test per unit time and analytical time and speed per test.

Comparison of an enzyme linked immunosorbent assay (ELISA) and a radioallergosorbent test (RAST) for detection of IgE antibodies to Brugia malayi

NARCIS (Netherlands)

Wahyuni, Sitti; van Ree, Ronald; Mangali, Andarias; Supali, Taniawati; Yazdanbakhsh, Maria; Sartono, Erliyani

2003-01-01

The enzyme linked immunosorbent assay (ELISA) for specific IgE antibodies to Brugia malayi was compared with the radioallergosorbent test (RAST) for use in immunoepidemiological studies of lymphatic filariasis. Sera used were from individuals (aged 5-82 years) living in an area endemic for lymphatic

Evaluation of a commercial competitive enzyme-linked immunosorbent assay for detection of avian influenza virus subtype H5 antibodies in zoo birds

DEFF Research Database (Denmark)

Jensen, Trine Hammer; Andersen, Jannie Holmegaard; Hjulsager, Charlotte Kristiane

2017-01-01

The hemagglutination inhibition (HI) test is the current gold standard for detecting antibodies to avian influenza virus (AIV). Enzyme-linked immunosorbent assays (ELISAs) have been explored for use in poultry and certain wild bird species because of high efficiency and lower cost. This study com...

Plasma exchange to remove HIT antibodies: dissociation between enzyme-immunoassay and platelet activation test reactivities.

Science.gov (United States)

Warkentin, Theodore E; Sheppard, Jo-Ann I; Chu, F Victor; Kapoor, Anil; Crowther, Mark A; Gangji, Azim

2015-01-01

Repeated therapeutic plasma exchange (TPE) has been advocated to remove heparin-induced thrombocytopenia (HIT) IgG antibodies before cardiac/vascular surgery in patients who have serologically-confirmed acute or subacute HIT; for this situation, a negative platelet activation assay (eg, platelet serotonin-release assay [SRA]) has been recommended as the target serological end point to permit safe surgery. We compared reactivities in the SRA and an anti-PF4/heparin IgG-specific enzyme immunoassay (EIA), testing serial serum samples in a patient with recent (subacute) HIT who underwent serial TPE precardiac surgery, as well as for 15 other serially-diluted HIT sera. We observed that post-TPE/diluted HIT sera-when first testing SRA-negative-continue to test strongly positive by EIA-IgG. This dissociation between the platelet activation assay and a PF4-dependent immunoassay for HIT antibodies indicates that patients with subacute HIT undergoing repeated TPE before heparin reexposure should be tested by serial platelet activation assays even when their EIAs remain strongly positive. © 2015 by The American Society of Hematology.

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.

Multilaboratory approach to preclinical evaluation of vaccine immunogens for placental malaria

DEFF Research Database (Denmark)

Fried, Michal; Avril, Marion; Chaturvedi, Richa

2013-01-01

a vaccine targeting individual Duffy binding-like (DBL) domains. In this study, a consortium of laboratories under the Pregnancy Malaria Initiative compared the functional activity of antiadhesion antibodies elicited by different VAR2CSA domains and variants produced in prokaryotic and eukaryotic expression...... systems. Antisera were initially tested against laboratory lines of maternal parasites, and the most promising reagents were evaluated in the field against fresh placental parasite samples. Recombinant proteins expressed in Escherichia coli elicited antibody levels similar to those expressed in eukaryotic...

A sequence in subdomain 2 of DBL1α of Plasmodium falciparum erythrocyte membrane protein 1 induces strain transcending antibodies.

Directory of Open Access Journals (Sweden)

Karin Blomqvist

Full Text Available Immunity to severe malaria is the first level of immunity acquired to Plasmodium falciparum. Antibodies to the variant antigen PfEMP1 (P. falciparum erythrocyte membrane protein 1 present at the surface of the parasitized red blood cell (pRBC confer protection by blocking microvascular sequestration. Here we have generated antibodies to peptide sequences of subdomain 2 of PfEMP1-DBL1α previously identified to be associated with severe or mild malaria. A set of sera generated to the amino acid sequence KLQTLTLHQVREYWWALNRKEVWKA, containing the motif ALNRKE, stained the live pRBC. 50% of parasites tested (7/14 were positive both in flow cytometry and immunofluorescence assays with live pRBCs including both laboratory strains and in vitro adapted clinical isolates. Antibodies that reacted selectively with the sequence REYWWALNRKEVWKA in a 15-mer peptide array of DBL1α-domains were also found to react with the pRBC surface. By utilizing a peptide array to map the binding properties of the elicited anti-DBL1α antibodies, the amino acids WxxNRx were found essential for antibody binding. Complementary experiments using 135 degenerate RDSM peptide sequences obtained from 93 Ugandan patient-isolates showed that antibody binding occurred when the amino acids WxLNRKE/D were present in the peptide. The data suggests that the ALNRKE sequence motif, associated with severe malaria, induces strain-transcending antibodies that react with the pRBC surface.

[Establishment of chemiluminescent enzyme immunoassay for detecting antibodies against foot-and-mouth disease virus serotype O in swine].

Science.gov (United States)

Cui, Chen; Huang, Ligang; Li, Jing; Zou, Xingqi; Zhu, Yuanyuan; Xie, Lei; Zhao, Qizu; Yang, Limin; Liu, Wenjun

2016-11-25

Recombinant structural protein VP1 of foot-and-mouth disease virus serotype O was expressed in Escherichia coli and then purified using Nickel affinity chromatography. A chemiluminescent enzyme immunoassay (CLEIA) method was established using the purified recombinant protein as coating antigen to detect antibody of foot-and-mouth disease virus serotype O in swine. The specificity of VP1-CLEIA method is 100%. The coefficients of variation in the plate and between plates are 1.10%-6.70% and 0.66%-4.80%, respectively. Comparing with the commercial indirect ELISA kit or liquid phase block ELISA kit, the calculated coincidence rate is 93.50% or 94.00%. The high specificity and stability suggested this detection method can be used to monitor the antibody level of foot-and-mouth disease virus serotype O in swine.

Cross-sectional study defines difference in malaria morbidity in two Yanomami communities on Amazonian boundary between Brazil and Venezuela

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Teodardo José Marcano

2004-06-01

Full Text Available It is well established that immunity to malaria is short-lived and is maintained by the continuous contact with the parasite. We now show that the stable transmission of malaria in Yanomami Amerindian communities maintains a degree of immunity in the exposed population capable to reduce prevalence and morbidity of malaria. We examined 508 Yanomami Amerindians living along Orinoco (407 and Mucajaí (101 rivers, on the Venezuelan and Brazilian Amazon region, respectively. At Orinoco villages, malaria was hyperendemic and presented stable transmission, while at Mucajaí villages it was mesoendemic and showed unstable transmission. The frequency of Plasmodium vivax and P. falciparum was roughly comparable in Venezuelan and Brazilian communities. Malaria presented different profiles at Orinoco and Mucajaí villages. In the former communities, malaria showed a lower prevalence (16% x 40.6%, particularly among those over 10 years old (5.2% x 34.8%, a higher frequency of asymptomatic cases (38.5% x 4.9%, and a lower frequency of cases of severe malaria (9.2% x 36.5%. Orinoco villagers also showed a higher reactivity of the immune system, measured by the frequency of splenomegaly (72.4% x 29.7% and by the splenic index (71.4% over level 1 x 28.6, and higher prevalence (91.1% x 72.1% and mean titer (1243 x 62 of antiplasmodial IgG antibodies, as well as a higher prevalence (77.4% x 24.7% and mean titer (120 x 35 of antiplasmodial IgM antibodies. Our findings show that in isolated Yanomami communities the stability of malaria transmission, and the consequent continuous activation of the immune system of the exposed population, leads to the reduction of malaria prevalence and morbidity.

Cross-sectional study defines difference in malaria morbidity in two Yanomami communities on Amazonian boundary between Brazil and Venezuela.

Science.gov (United States)

Marcano, Teodardo José; Morgado, Anastácio; Tosta, Carlos Eduardo; Coura, José Rodrigues

2004-06-01

It is well established that immunity to malaria is short-lived and is maintained by the continuous contact with the parasite. We now show that the stable transmission of malaria in Yanomami Amerindian communities maintains a degree of immunity in the exposed population capable to reduce prevalence and morbidity of malaria. We examined 508 Yanomami Amerindians living along Orinoco (407) and Mucajaí (101) rivers, on the Venezuelan and Brazilian Amazon region, respectively. At Orinoco villages, malaria was hyperendemic and presented stable transmission, while at Mucajaí villages it was mesoendemic and showed unstable transmission. The frequency of Plasmodium vivax and P. falciparum was roughly comparable in Venezuelan and Brazilian communities. Malaria presented different profiles at Orinoco and Mucajaí villages. In the former communities, malaria showed a lower prevalence (16% x 40.6%), particularly among those over 10 years old (5.2% x 34.8%), a higher frequency of asymptomatic cases (38.5% x 4.9%), and a lower frequency of cases of severe malaria (9.2% x 36.5%). Orinoco villagers also showed a higher reactivity of the immune system, measured by the frequency of splenomegaly (72.4% x 29.7%) and by the splenic index (71.4% over level 1 x 28.6), and higher prevalence (91.1% x 72.1%) and mean titer (1243 x 62) of antiplasmodial IgG antibodies, as well as a higher prevalence (77.4% x 24.7%) and mean titer (120 x 35) of antiplasmodial IgM antibodies. Our findings show that in isolated Yanomami communities the stability of malaria transmission, and the consequent continuous activation of the immune system of the exposed population, leads to the reduction of malaria prevalence and morbidity.

Testing in mice the hypothesis that melanin is protective in malaria infections.

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Michael Waisberg

Full Text Available Malaria has had the largest impact of any infectious disease on shaping the human genome, exerting enormous selective pressure on genes that improve survival in severe malaria infections. Modern humans originated in Africa and lost skin melanization as they migrated to temperate regions of the globe. Although it is well documented that loss of melanization improved cutaneous Vitamin D synthesis, melanin plays an evolutionary ancient role in insect immunity to malaria and in some instances melanin has been implicated to play an immunoregulatory role in vertebrates. Thus, we tested the hypothesis that melanization may be protective in malaria infections using mouse models. Congenic C57BL/6 mice that differed only in the gene encoding tyrosinase, a key enzyme in the synthesis of melanin, showed no difference in the clinical course of infection by Plasmodium yoelii 17XL, that causes severe anemia, Plasmodium berghei ANKA, that causes severe cerebral malaria or Plasmodium chabaudi AS that causes uncomplicated chronic disease. Moreover, neither genetic deficiencies in vitamin D synthesis nor vitamin D supplementation had an effect on survival in cerebral malaria. Taken together, these results indicate that neither melanin nor vitamin D production improve survival in severe malaria.

Heritability of antibody isotype and subclass responses to Plasmodium falciparum antigens.

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Nancy O Duah

2009-10-01

Full Text Available It is important to understand the extent to which genetic factors regulate acquired immunity to common infections. A classical twin study design is useful to estimate the heritable component of variation in measurable immune parameters.This study assessed the relative heritability of different plasma antibody isotypes and subclasses (IgG1, IgG2, IgG3, IgG4, IgM, IgA and IgE naturally acquired to P. falciparum blood stage antigens AMA1, MSP1-19, MSP2 (two allelic types and MSP3 (two allelic types. Separate analyses were performed on plasma from 213 pairs of Gambian adult twins, 199 child twin pairs sampled in a dry season when there was little malaria transmission, and another set of 107 child twin pairs sampled at the end of the annual wet season when malaria was common. There were significantly positive heritability (h(2 estimates for 48% (20/42 of the specific antibody assays (for the seven isotypes and subclasses to the six antigens tested among the adults, 48% (20/42 among the children in the dry season and 31% (13/42 among the children in the wet season. In children, there were significant heritability estimates for IgG4 reactivity against each of the antigens, and this subclass had higher heritability than the other subclasses and isotypes. In adults, 75% (15/20 of the significantly heritable antigen-specific isotype responses were attributable to non-HLA class II genetic variation, whereas none showed a significant HLA contribution.Genome-wide approaches are now warranted to map the major genetic determinants of variable antibody isotype and subclass responses to malaria, alongside evaluation of their impact on infection and disease. Although plasma levels of IgG4 to malaria antigens are generally low, the exceptionally high heritability of levels of this subclass in children deserves particular investigation.

Dried blood spots as a source of anti-malarial antibodies for epidemiological studies

Science.gov (United States)

Corran, Patrick H; Cook, Jackie; Lynch, Caroline; Leendertse, Heleen; Manjurano, Alphaxard; Griffin, Jamie; Cox, Jonathan; Abeku, Tarekegn; Bousema, Teun; Ghani, Azra C; Drakeley, Chris; Riley, Eleanor

2008-01-01

Background Blood spots collected onto filter paper are an established and convenient source of antibodies for serological diagnosis and epidemiological surveys. Although recommendations for the storage and analysis of small molecule analytes in blood spots exist, there are no published systematic studies of the stability of antibodies under different storage conditions. Methods Blood spots, on filter paper or glass fibre mats and containing malaria-endemic plasma, were desiccated and stored at various temperatures for different times. Eluates of these spots were assayed for antibodies against two Plasmodium falciparum antigens, MSP-119 and MSP2, and calculated titres used to fit an exponential (first order kinetic) decay model. The first order rate constants (k) for each spot storage temperature were used to fit an Arrhenius equation, in order to estimate the thermal and temporal stability of antibodies in dried blood spots. The utility of blood spots for serological assays was confirmed by comparing antibodies eluted from blood spots with the equivalent plasma values in a series of samples from North Eastern Tanzania and by using blood spot-derived antibodies to estimate malaria transmission intensity in this site and for two localities in Uganda. Results Antibodies in spots on filter paper and glass fibre paper had similar stabilities but blood was more easily absorbed onto filter papers than glass fibre, spots were more regular and spot size was more closely correlated with blood volume for filter paper spots. Desiccated spots could be stored at or below 4°C for extended periods, but were stable for only very limited periods at ambient temperature. When desiccated, recoveries of antibodies that are predominantly of IgG1 or IgG3 subclasses were similar. Recoveries of antibodies from paired samples of serum and of blood spots from Tanzania which had been suitably stored showed similar recoveries of antibodies, but spots which had been stored for extended periods

Development and validation of an indirect Enzyme-linked Immunosorbent Assay for the detection of antibodies against Schmallenberg virus in blood samples from ruminants

NARCIS (Netherlands)

Heijden, van der H.M.J.F.; Bouwstra, R.J.; Mars, M.H.; Poel, van der W.H.M.; Wellenberg, G.J.; Maanen, van C.

2013-01-01

To detect Schmallenberg virus (SBV) infections in ruminants and to perform SBV epidemiological studies a cost-effective serological test is required. For these purposes an indirect whole virus Enzyme-linked Immunosorbent Assay (ELISA) for detection of SBV specific antibodies in ruminant blood

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

A simplification of the enzyme-linked immunospot technique. Increased sensitivity for cells secreting IgG antibodies to Haemophilus influenzae type b capsular polysaccharide

DEFF Research Database (Denmark)

Barington, T; Sparholt, S; Juul, L

1992-01-01

A simplified enzyme-linked immunospot (ELISPOT) technique is described for the detection of cells secreting antibodies to tetanus toxoid (TT), diphtheria toxoid (DT) or Haemophilus influenzae type b capsular polysaccharide (PRP). By combining the cell suspension with the enzyme-linked secondary...... antibodies in one incubation, the second incubation and washing procedure could be omitted from the original technique. The simplified assay had the same sensitivity for anti-TT and anti-DT spot-forming cells as the ordinary ELISPOT assay. The IgG anti-PRP spots were, however, improved both in quality...... and in quantity (median: 40% more spots), while the detection of IgM and IgA anti-PRP spot-forming cells was the same in the two techniques. This simplified technique can probably also be used to save time in other antigen systems and should be considered when designing ELISPOT assays for the detection...

Malaria in pregnant women living in areas of low transmission on the southeast Brazilian Coast: molecular diagnosis and humoural immunity profile

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Angélica Domingues Hristov

2014-12-01

Full Text Available Studies on autochthonous malaria in low-transmission areas in Brazil have acquired epidemiological relevance because they suggest continued transmission in what remains of the Atlantic Forest. In the southeastern portion of the state of São Paulo, outbreaks in the municipality of Juquitiba have been the focus of studies on the prevalence of Plasmodium, including asymptomatic cases. Data on the occurrence of the disease or the presence of antiplasmodial antibodies in pregnant women from this region have not previously been described. Although Plasmodium falciparum in pregnant women has been widely addressed in the literature, the interaction of Plasmodium vivax and Plasmodium malariae with this cohort has been poorly explored to date. We monitored the circulation of Plasmodium in pregnant women in health facilities located in Juquitiba using thick blood film and molecular protocols, as well as immunological assays, to evaluate humoural immune parameters. Through real-time and nested polymerase chain reaction, P. vivax and P. malariae were detected for the first time in pregnant women, with a positivity of 5.6%. Immunoassays revealed the presence of IgG antibodies: 44% for ELISA-Pv, 38.4% for SD-Bioline-Pv and 18.4% for indirect immunofluorescence assay-Pm. The high prevalence of antibodies showed significant exposure of this population to Plasmodium. In regions with similar profiles, testing for a malaria diagnosis might be indicated in prenatal care.

Associations between Burkitt lymphoma among children in Malawi and infection with HIV, EBV and malaria: results from a case-control study.

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Nora Mutalima

Full Text Available BACKGROUND: Burkitt lymphoma, a childhood cancer common in parts of sub-Saharan Africa, has been associated with Epstein Barr Virus (EBV and malaria, but its association with human immunodeficiency virus (HIV is not clear. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a case-control study of Burkitt lymphoma among children (aged < or = 15 years admitted to the pediatric oncology unit in Blantyre, Malawi between July 2005 and July 2006. Cases were 148 children diagnosed with Burkitt lymphoma and controls were 104 children admitted with non-malignant conditions or cancers other than hematological malignancies and Kaposi sarcoma. Interviews were conducted and serological samples tested for antibodies against HIV, EBV and malaria. Odds ratios for Burkitt lymphoma were estimated using unconditional logistic regression adjusting for sex, age, and residential district. Cases had a mean age of 7.1 years and 60% were male. Cases were more likely than controls to be HIV positive (Odds ratio (OR = 12.4, 95% Confidence Interval (CI 1.3 to 116.2, p = 0.03. ORs for Burkitt lymphoma increased with increasing antibody titers against EBV (p = 0.001 and malaria (p = 0.01. Among HIV negative participants, cases were thirteen times more likely than controls to have raised levels of both EBV and malaria antibodies (OR = 13.2; 95% CI 3.8 to 46.6; p = 0.001. Reported use of mosquito nets was associated with a lower risk of Burkitt lymphoma (OR = 0.2, 95% CI, 0.03 to 0.9, p = 0.04. CONCLUSIONS: Our findings support prior evidence that EBV and malaria act jointly in the pathogenesis of Burkitt lymphoma, suggesting that malaria prevention may decrease the risk of Burkitt lymphoma. HIV may also play a role in the etiology of this childhood tumor.

Cytokine expression in malaria-infected non-human primate placentas

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M.M. Gicheru

2012-06-01

Full Text Available Malaria parasites are known to mediate the induction of inflammatory immune responses at the maternal-foetal interface during placental malaria (PM leading to adverse consequences like pre-term deliveries and abortions. Immunological events that take place within the malaria-infected placental micro-environment leading to retarded foetal growth and disruption of pregnancies are among the critical parameters that are still in need of further elucidation. The establishment of more animal models for studying placental malaria can provide novel ways of circumventing problems experienced during placental malaria research in humans such as inaccurate estimation of gestational ages. Using the newly established olive baboon (Papio anubis-Plasmodium knowlesi (P. knowlesi H strain model of placental malaria, experiments were carried out to determine placental cytokine profiles underlying the immunopathogenesis of placental malaria. Four pregnant olive baboons were infected with blood stage P. knowlesi H strain parasites on the one fiftieth day of gestation while four other uninfected pregnant olive baboons were maintained as uninfected controls. After nine days of infection, placentas were extracted from all the eight baboons through cesarean surgery and used for the processing of placental plasma and sera samples for cytokine sandwich enzyme linked immunosorbent assays (ELISA. Results indicated that the occurrence of placental malaria was associated with elevated concentrations of tumour necrosis factor alpha (TNF-α and interleukin 12 (IL-12. Increased levels of IL-4, IL-6 and IL-10 and interferon gamma (IFN-γ levels were detected in uninfected placentas. These findings match previous reports regarding immunity during PM thereby demonstrating the reliability of the olive baboon-P. knowlesi model for use in further studies.

A central role for P48/45 in malaria parasite male gamete fertility.

NARCIS (Netherlands)

Dijk, M.R. van; Janse, C.J.; Thompson, J.; Waters, A.P.; Braks, J.A.M.; Dodemont, H.J.; Stunnenberg, H.G.; Gemert, G.J.A. van; Sauerwein, R.W.; Eling, W.M.C.

2001-01-01

Fertilization and zygote development are obligate features of the malaria parasite life cycle and occur during parasite transmission to mosquitoes. The surface protein PFS48/45 is expressed by male and female gametes of Plasmodium falciparum and PFS48/45 antibodies prevent zygote development and

Monoclonal antibodies AC-43 and AC-29 disrupt Plasmodium vivax ...

Indian Academy of Sciences (India)

Prakash

malaria vaccines that block the transmission of parasites by mosquito vectors ... A repertoire of monoclonal antibodies (mAbs) was generated against the midgut proteins of Anopheles culicifacies ... from the midgut protein extract, as indicated by western blot analysis. Similarly .... 2.2 Antigen preparation and immunization.

Targeted enzyme prodrug therapies.

Science.gov (United States)

Schellmann, N; Deckert, P M; Bachran, D; Fuchs, H; Bachran, C

2010-09-01

The cure of cancer is still a formidable challenge in medical science. Long-known modalities including surgery, chemotherapy and radiotherapy are successful in a number of cases; however, invasive, metastasized and inaccessible tumors still pose an unresolved and ongoing problem. Targeted therapies designed to locate, detect and specifically kill tumor cells have been developed in the past three decades as an alternative to treat troublesome cancers. Most of these therapies are either based on antibody-dependent cellular cytotoxicity, targeted delivery of cytotoxic drugs or tumor site-specific activation of prodrugs. The latter is a two-step procedure. In the first step, a selected enzyme is accumulated in the tumor by guiding the enzyme or its gene to the neoplastic cells. In the second step, a harmless prodrug is applied and specifically converted by this enzyme into a cytotoxic drug only at the tumor site. A number of targeting systems, enzymes and prodrugs were investigated and improved since the concept was first envisioned in 1974. This review presents a concise overview on the history and latest developments in targeted therapies for cancer treatment. We cover the relevant technologies such as antibody-directed enzyme prodrug therapy (ADEPT), gene-directed enzyme prodrug therapy (GDEPT) as well as related therapies such as clostridial- (CDEPT) and polymer-directed enzyme prodrug therapy (PDEPT) with emphasis on prodrug-converting enzymes, prodrugs and drugs.

Impact of a Plasmodium falciparum AMA1 vaccine on antibody responses in adult Malians.

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Alassane Dicko

2007-10-01

Full Text Available Apical Membrane Antigen 1 (AMA1 of Plasmodium falciparum merozoites is a leading blood-stage malaria vaccine candidate. Protection of Aotus monkeys after vaccination with AMA1 correlates with antibody responses.A randomized, controlled, double-blind phase 1 clinical trial was conducted in 54 healthy Malian adults living in an area of intense seasonal malaria transmission to assess the safety and immunogenicity of the AMA1-C1 malaria vaccine. AMA1-C1 contains an equal mixture of yeast-expressed recombinant proteins based on sequences from the FVO and 3D7 clones of P. falciparum, adsorbed on Alhydrogel. The control vaccine was the hepatitis B vaccine (Recombivax. Participants were enrolled into 1 of 3 dose cohorts (n = 18 per cohort and randomized 2:1 to receive either AMA1-C1 or Recombivax. Participants in the first, second, and third cohorts randomized to receive AMA1-C1 were vaccinated with 5, 20 and 80 microg of AMA1-C1, respectively. Vaccinations were administered on days 0, 28, and 360, and participants were followed until 6 months after the final vaccination. AMA1-C1 was well tolerated; no vaccine-related severe or serious adverse events were observed. AMA1 antibody responses to the 80 microg dose increased rapidly from baseline levels by days 14 and 28 after the first vaccination and continued to increase after the second vaccination. After a peak 14 days following the second vaccination, antibody levels decreased to baseline levels one year later at the time of the third vaccination that induced little or no increase in antibody levels.Although the AMA1-C1 vaccine candidate was well-tolerated and induced antibody responses to both vaccine and non-vaccine alleles, the antibody response after a third dose given at one year was lower than the response to the initial vaccinations. Additionally, post-vaccination increases in anti-AMA1 antibody levels were not associated with significant changes in in vitro growth inhibition of P. falciparum

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

Science.gov (United States)

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.

Sickle cell protection from malaria.

Science.gov (United States)

Eridani, Sandro

2011-10-19

A linkage between presence of Sickle Haemoglobin (HbS) and protection from malaria infection and clinical manifestations in certain areas was suspected from early observations and progressively elucidated by more recent studies. Research has confirmed the abovementioned connection, but also clarified how such protection may be abolished by coexistence of sickle cell trait (HbS trait) and alpha thalassemia, which may explain the relatively low incidence of HbS trait in the Mediterranean. The mechanisms of such protective effect are now being investigated: factors of genetic, molecular and immunological nature are prominent. As for genetic factors attention is given to the role of the red blood cell (RBC) membrane complement regulatory proteins as polymorphisms of these components seem to be associated with resistance to severe malaria; genetic ligands like the Duffy group blood antigen, necessary for erythrocytic invasion, and human protein CD36, a major receptor for P. falciparum-infected RBC's, are also under scrutiny: attention is focused also on plasmodium erythrocyte-binding antigens, which bind to RBC surface components. Genome-wide linkage and association studies are now carried out too, in order to identify genes associated with malaria resistance. Only a minor role is attributed to intravascular sickling, phagocytosis and haemolysis, while specific molecular mechanisms are the object of intensive research: among these a decisive role is played by a biochemical sequence, involving activation of haeme oxygenase (HMO-1), whose effect appears mediated by carbon monoxide (CO). A central role in protection from malaria is also played by immunological factors, which may stimulate antibody production to plasmodium antigens in the early years of life; the role of agents like pathogenic CD8 T-cells has been suggested while the effects of molecular actions on the immunity mechanism are presently investigated. It thus appears that protection from malaria can be

Detection of Francisella tularensis-Specific Antibodies in Patients with Tularemia by a Novel Competitive Enzyme-Linked Immunosorbent Assay

Science.gov (United States)

Sharma, Neekun; Hotta, Akitoyo; Yamamoto, Yoshie; Fujita, Osamu; Uda, Akihiko; Morikawa, Shigeru; Yamada, Akio

2013-01-01

A novel competitive enzyme-linked immunosorbent assay (cELISA) was developed and evaluated for detection of antibodies against Francisella tularensis in humans. The assay is based on the ability of serum antibodies to inhibit the binding of monoclonal antibodies (MAbs) directed against F. tularensis lipopolysaccharide antigens. The assay was evaluated using serum samples of tularemia patients, inactivated F. tularensis-immunized rabbits, and F. tularensis-infected mice. Antibodies against F. tularensis were successfully detected in serum samples of tularemia patients as well as the immunized and infected animals. The cELISA method was compared to indirect ELISA (iELISA) and the commonly used microagglutination test (MA) using serum samples of 19 tularemia patients and 50 healthy individuals. The sensitivity and specificity of cELISA were 93.9 and 96.1%, respectively, in comparison to the iELISA. MA was less sensitive than cELISA with a sensitivity and specificity of only 81.8 and 98.0%, respectively. A high degree of correlation (R2 = 0.8226) was observed between cELISA and iELISA results. The novel cELISA developed in this study appears to be highly sensitive and specific for serodiagnosis of human tularemia. The potential of the MAb-based cELISA to be used in both human and animal samples emphasizes its usefulness for serological survey of tularemia among multiple animal species. PMID:23114700

Multicentric Evaluation of New Commercial Enzyme Immunoassays for the Detection of Immunoglobulin M and Total Antibodies against Hepatitis A Virus▿

Science.gov (United States)

Arcangeletti, M. C.; Dussaix, E.; Ferraglia, F.; Roque-Afonso, A. M.; Graube, A.; Chezzi, C.

2011-01-01

A multicentric clinical study was conducted on representative sera from 1,738 European and U.S. subjects for the evaluation of new anti-hepatitis A virus enzyme immunoassays from Bio-Rad Laboratories. Comparison with reference DiaSorin S.p.A. tests confirmed the good performance of Bio-Rad assays (99.85% and 99.47% overall agreement in detecting total antibodies and IgM, respectively). PMID:21653739

Evaluation of an enzyme linked immunosorbent assay kit for the detection of Babesia bovis antibodies in cattle in Argentina

Energy Technology Data Exchange (ETDEWEB)

Echaide, S; Echaide, I E; Mangold, A J; Lugaresi, C I; Guglielmone, A A [Estacion Experimental Agropecuaria, Instituto Nacional de Tecnologia Agropecuaria, Rafaela, Santa Fe (Argentina); Gaido, A B [Estacion Experimental Agropecuaria Salta, Salta (Argentina)

1998-11-01

An enzyme linked immunosorbent assay (ELISA) for the detection of antibodies to Babesia bovis was evaluated by using sera of 874 cattle carrying B. bovis antibodies, 700 sera of uninfected cattle, and 357 sera from calves from 16 herds subjected to different B. bovis inoculation rates. The seropositive/ seronegative cut-off point set as double the mean percent positivity of negative cattle sera (= 16%). The sensitivity of the ELISA (four trials) ranged from 97.1% to 100% and the specificity (three trials) varied from 92.0% to 97.0%. The agreement between ELISA and immunofluorescent antibody test was {>=} 90.0% in 18 of 23 evaluations and it ranged from 86.0% to 88.0% in the remainder. The correlation coefficient between percentage of sera positive to ELISA and IFA test in 16 herds was 0.9958 (P<0.001). The ELISA has the advantages of a high sensitivity, objectivity and capacity to test large number of samples in short period of time and could replace the IFA test specially for epidemiological studies. (author) 11 refs, 1 fig., 2 tabs

Evaluation of an enzyme linked immunosorbent assay kit for the detection of Babesia bovis antibodies in cattle in Argentina

International Nuclear Information System (INIS)

Echaide, S.; Echaide, I.E.; Mangold, A.J.; Lugaresi, C.I.; Guglielmone, A.A.; Gaido, A.B.

1998-01-01

An enzyme linked immunosorbent assay (ELISA) for the detection of antibodies to Babesia bovis was evaluated by using sera of 874 cattle carrying B. bovis antibodies, 700 sera of uninfected cattle, and 357 sera from calves from 16 herds subjected to different B. bovis inoculation rates. The seropositive/ seronegative cut-off point set as double the mean percent positivity of negative cattle sera (= 16%). The sensitivity of the ELISA (four trials) ranged from 97.1% to 100% and the specificity (three trials) varied from 92.0% to 97.0%. The agreement between ELISA and immunofluorescent antibody test was ≥ 90.0% in 18 of 23 evaluations and it ranged from 86.0% to 88.0% in the remainder. The correlation coefficient between percentage of sera positive to ELISA and IFA test in 16 herds was 0.9958 (P<0.001). The ELISA has the advantages of a high sensitivity, objectivity and capacity to test large number of samples in short period of time and could replace the IFA test specially for epidemiological studies. (author)

Antibody-based enzyme-linked lectin assay (ABELLA) for the sialylated recombinant human erythropoietin present in culture supernatant.

Science.gov (United States)

Kim, Hyoung Jin; Lee, Seung Jae; Kim, Hong-Jin

2008-11-04

The terminal sialic acid of human erythropoietin (hEPO) is essential for in vivo activity. The current resorcinol and HPLC methods for analyzing alpha2,3-linked sialic acid require more than a microgram of purified rhEPO, and purification takes a great deal of time and labor. In this study, we assessed the use of an antibody-based enzyme-linked lectin assay (ABELLA) for analyzing non-purified recombinant hEPO (rhEPO). The major problem of this method was the high background due to terminal sialylation of components of the assay (antibody and bovine serum albumin) other than rhEPO. To solve this problem, we used a monoclonal antibody (Mab 287) to capture the rhEPO, and oxidized the bovine serum albumin used for blocking with meta-periodate. The sialic acid content of non-purified rhEPO measured by ABELLA was similar to that obtained by the resorcinol method on purified rhEPO. ABELLA has advantages such as adaptability and need for minimal amounts of rhEPO (40 ng/ml). Our observations suggest that ABELLA should reduce the time and labor needed to improve culture conditions so as to increase protein sialylation, and also facilitate the study of sialylation mechanisms.

Parasite enzymes as a tool to investigate immune responses

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Italo M. Cesari

1992-01-01

Full Text Available Previous evidences reported by us and by other authors revealed the presence of IgG in sera of Schistosoma mansoni-infected patients to immunodominant antigens which are enzymes. Besides their immunological interest as possible inductors of protection, several of these enzume antigens might be also intersting markers of infection in antibody-detecting immunocapture assays which use the intrinsic catalytic property of these antigens. It was thus thought important to define some enzymatic and immunological characteristics of these molecules to better exploit their use as antigens. Four different enzymes from adult worms were partially characterized in their biochemical properties and susceptibility to react with antibodies of infected patients, namely alkaline phosphatase (AKP, Mg*+, pH 9.5, type I phosphodiesterase (PDE, pH 9.5, cysteine proteinase (CP, dithiothreitol, pH 5.5 and N-acetyl-ß-D-glucosaminidase (NAG, pH 5.5. The AKP and PDE are distinct tegumental membrane-bound enzymes whereas CP and NAG are soluble acid enzymes. Antibodies in infected human sera differed in their capacity to react with and to inhibit these enzyme antigens. Possibly, the specificity of the antibodies related to the extent of homology between the parasite and the host enzyme might be in part responsible for the above differences. The results are also discussed in view of the possible functional importance of these enzymes.

Increased malaria transmission around irrigation schemes in Ethiopia and the potential of canal water management for malaria vector control.

Science.gov (United States)

Kibret, Solomon; Wilson, G Glenn; Tekie, Habte; Petros, Beyene

2014-09-13

Irrigation schemes have been blamed for the increase in malaria in many parts of sub-Saharan Africa. However, proper water management could help mitigate malaria around irrigation schemes in this region. This study investigates the link between irrigation and malaria in Central Ethiopia. Larval and adult mosquitoes were collected fortnightly between November 2009 and October 2010 from two irrigated and two non-irrigated (control) villages in the Ziway area, Central Ethiopia. Daily canal water releases were recorded during the study period and bi-weekly correlation analysis was done to determine relationships between canal water releases and larval/adult vector densities. Blood meal sources (bovine vs human) and malaria sporozoite infection were tested using enzyme-linked immunosorbent assay (ELISA). Monthly malaria data were also collected from central health centre of the study villages. Monthly malaria incidence was over six-fold higher in the irrigated villages than the non-irrigated villages. The number of anopheline breeding habitats was 3.6 times higher in the irrigated villages than the non-irrigated villages and the most common Anopheles mosquito breeding habitats were waterlogged field puddles, leakage pools from irrigation canals and poorly functioning irrigation canals. Larval and adult anopheline densities were seven- and nine-fold higher in the irrigated villages than in the non-irrigated villages, respectively, during the study period. Anopheles arabiensis was the predominant species in the study area. Plasmodium falciparum sporozoite rates of An. arabiensis and Anopheles pharoensis were significantly higher in the irrigated villages than the non-irrigated villages. The annual entomological inoculation rate (EIR) calculated for the irrigated and non-irrigated villages were 34.8 and 0.25 P. falciparum infective bites per person per year, respectively. A strong positive correlation was found between bi-weekly anopheline larval density and canal water

Comparison of two enzyme-linked immunosorbent assays and one rapid immunoblot assay for detection of herpes simplex virus type 2-specific antibodies in serum

NARCIS (Netherlands)

Groen, J; Van Dijk, G; Niesters, H G; Van Der Meijden, W I; Osterhaus, A D

The sensitivities and specificities of three immunoassays for the detection of herpes simplex virus type 2 (HSV-2)-specific immunoglobulin G antibodies in serum, including the one-strip rapid immunoblot assay (RIBA; Chiron Corporation) and two indirect enzyme immunosorbent assays (EIA; Gull

The effects of varying exposure to malaria transmission on development of antimalarial antibody responses in preschool children. XVI. Asembo Bay Cohort Project

NARCIS (Netherlands)

Singer, Lauren M.; Mirel, Lisa B.; ter Kuile, Feiko O.; Branch, OraLee H.; Vulule, John M.; Kolczak, Margarette S.; Hawley, William A.; Kariuki, Simon K.; Kaslow, David C.; Lanar, David E.; Lal, Altaf A.

2003-01-01

In areas of intense malaria transmission, malaria morbidity and mortality is highest in children 3-18 months old. Interventions that reduce malaria exposure early in life reduce morbidity but may also delay development of clinical immunity. We assessed the relationship between intensity of malaria

Rapid diagnostic tests for diagnosing uncomplicated non-falciparum or Plasmodium vivax malaria in endemic countries

Science.gov (United States)

Abba, Katharine; Kirkham, Amanda J; Olliaro, Piero L; Deeks, Jonathan J; Donegan, Sarah; Garner, Paul; Takwoingi, Yemisi

2014-01-01

Background In settings where both Plasmodium vivax and Plasmodium falciparum infection cause malaria, rapid diagnostic tests (RDTs) need to distinguish which species is causing the patients' symptoms, as different treatments are required. Older RDTs incorporated two test lines to distinguish malaria due to P. falciparum, from malaria due to any other Plasmodium species (non-falciparum). These RDTs can be classified according to which antibodies they use: Type 2 RDTs use HRP-2 (for P. falciparum) and aldolase (all species); Type 3 RDTs use HRP-2 (for P. falciparum) and pLDH (all species); Type 4 use pLDH (fromP. falciparum) and pLDH (all species). More recently, RDTs have been developed to distinguish P. vivax parasitaemia by utilizing a pLDH antibody specific to P. vivax. Objectives To assess the diagnostic accuracy of RDTs for detecting non-falciparum or P. vivax parasitaemia in people living in malaria-endemic areas who present to ambulatory healthcare facilities with symptoms suggestive of malaria, and to identify which types and brands of commercial test best detect non-falciparum and P. vivax malaria. Search methods We undertook a comprehensive search of the following databases up to 31 December 2013: Cochrane Infectious Diseases Group Specialized Register; MEDLINE; EMBASE; MEDION; Science Citation Index; Web of Knowledge; African Index Medicus; LILACS; and IndMED. Selection criteria Studies comparing RDTs with a reference standard (microscopy or polymerase chain reaction) in blood samples from a random or consecutive series of patients attending ambulatory health facilities with symptoms suggestive of malaria in non-falciparum endemic areas. Data collection and analysis For each study, two review authors independently extracted a standard set of data using a tailored data extraction form. We grouped comparisons by type of RDT (defined by the combinations of antibodies used), and combined in meta-analysis where appropriate. Average sensitivities and

Influence of intermittent preventive treatment on antibodies to VAR2CSA in pregnant Cameroonian women

DEFF Research Database (Denmark)

Babakhanyan, Anna; Tutterrow, Yeung L; Bobbili, Naveen

2016-01-01

Intermittent preventive treatment (IPT) and insecticide-treated bed nets are the standard of care for preventing malaria in pregnant women. Since these preventive measures reduce exposure to malaria, their influence on the antibody (Ab) response to the parasite antigen VAR2CSA was evaluated...... in pregnant Cameroonian women exposed to holoendemic malaria. Ab levels to full-length VAR2CSA (FV2), variants of the six Duffy binding like (DBL) domains, and proportion of high avidity Ab to FV2 were measured longitudinally in 92 women before and 147 women after IPT. As predicted, reduced exposure...

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

Science.gov (United States)

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

Nutritional anaemia and malaria in children. | Anumudu | Annals of ...

African Journals Online (AJOL)

Methods: A total of 177 children between the ages of 2 and 11 years were included in the study. Children were examined for malaria parasites by microscopy. The World Health Organization (WHO) age-adjusted cut-off for hemoglobin and hematocrit were used to classify anemia. An enzyme linked immunosorbent assay for ...

Rifampicin-dependent antibodies bind a similar or identical epitope to glycoprotein IX-specific quinine-dependent antibodies

NARCIS (Netherlands)

Burgess, Janette K.; Lopez, Jose A.; Gaudry, Leonie E.; Chong, Beng H.

2000-01-01

The drug-dependent antibody of a patient with rifampicin-induced thrombocytopenia was characterized using the antigen-capture enzyme-linked immunosorbent assay (MAIPA assay), flow cytometry, and immunoprecipitation. The antibody was found to bind glycoprotein (GP) Ib-IX but not GPIIb-IIIa because

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.

INDICES OF IMMUNE RESPONSE IN PATIENTS OF FALCIPARUM MALARIA IN REPUBLIC OF GUINEA

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M. Y. Boiro

2016-01-01

Full Text Available Malaria in the Republic of Guinea is the main cause of morbidity and lethality. It takes the first place in number of all visits in medical service (30–40% and is the main cause of hospital death. One records annually more than 8 millions malaria cases, and about 60 000 children deaths. Results of study of immune response changing on different disease phases in treatment of autochthon population and immune status of Europeans are presented. It was shown that immunity status (cellular and humoral in population of Guinea (an endemic country on falciparum malaria differs from one in Europeans living in tropics. During light forms of malaria one records an increase of T-lymphocyte and IgG number, whereas in grave cases one observed the acute decrease of these indices. The essential increase of B-lymphocyte number does not depends from gravity of disease and from malaria treatment. It was established that appearance of LSA1-41 antibodies was in a more degree in adult patients than in children. The positive correlation between IgM and IgG was established in adult patients as in children.

The association of genetic markers and malaria infection in the Brazilian Western Amazonian region

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B Beiguelman

2003-06-01

Full Text Available Almost all individuals (182 belonging to an Amazonian riverine population (Portuchuelo, RO, Brazil were investigated for ascertaining data on epidemiological aspects of malaria. Thirteen genetic blood polymorphisms were investigated (ABO, MNSs, Rh, Kell, and Duffy systems, haptoglobins, hemoglobins, and the enzymes glucose-6-phosphate dehydrogenase, glyoxalase, phosphoglucomutase, carbonic anhydrase, red cell acid phosphatase, and esterase D. The results indicated that the Duffy system is associated with susceptibility to malaria, as observed in other endemic areas. Moreover, suggestions also arose indicating that the EsD and Rh loci may be significantly associated with resistance to malaria. If statistical type II errors and sample stratification could be ruled out, hypotheses on the existence of a causal mechanism or an unknown closely linked locus involved in susceptibility to malaria infection may explain the present findings.

Variant surface antigen-specific IgG and protection against clinical consequences of pregnancy-associated Plasmodium falciparum malaria

DEFF Research Database (Denmark)

Staalsoe, Trine; Shulman, Caroline E; Bulmer, Judith N

2004-01-01

BACKGROUND: Pregnancy-associated malaria caused by Plasmodium falciparum adherence to chondroitin sulfate A in the placental intervillous space is a major cause of low birthweight and maternal anaemia in areas of endemic P falciparum transmission. Adhesion-blocking antibodies that specifically...... recognise parasite-encoded variant surface antigens (VSA) are associated with resistance to pregnancy-associated malaria. We looked for a possible relation between VSA-specific antibody concentrations, placental infection, and protection from low birthweight and maternal anaemia. METHODS: We used flow...... cytometry to measure VSA-specific IgG concentrations in plasma samples taken during child birth from 477 Kenyan women selected from a cohort of 910 women on the basis of HIV-1 status, gravidity, and placental histology. We measured VSA expressed by one placental P falciparum isolate and two isolates...

Utility of health facility-based malaria data for malaria surveillance.

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Yaw A Afrane

Full Text Available Currently, intensive malaria control programs are being implemented in Africa to reduce the malaria burden. Clinical malaria data from hospitals are valuable for monitoring trends in malaria morbidity and for evaluating the impacts of these interventions. However, the reliability of hospital-based data for true malaria incidence is often questioned because of diagnosis accuracy issues and variation in access to healthcare facilities among sub-groups of the population. This study investigated how diagnosis and treatment practices of malaria cases in hospitals affect reliability of hospital malaria data.The study was undertaken in health facilities in western Kenya. A total of 3,569 blood smears were analyzed after being collected from patients who were requested by clinicians to go to the hospital's laboratory for malaria testing. We applied several quality control measures for clinical malaria diagnosis. We compared our slide reading results with those from the hospital technicians. Among the 3,390 patients whose diagnoses were analyzed, only 36% had clinical malaria defined as presence of any level of parasitaemia and fever. Sensitivity and specificity of clinicians' diagnoses were 60.1% (95% CI: 61.1-67.5 and 75.0% (95% CI: 30.8-35.7, respectively. Among the 980 patients presumptively treated with an anti-malarial by the clinicians without laboratory diagnosis, only 47% had clinical malaria.These findings revealed substantial over-prescription of anti-malarials and misdiagnosis of clinical malaria. More than half of the febrile cases were not truly clinical malaria, but were wrongly diagnosed and treated as such. Deficiency in malaria diagnosis makes health facility data unreliable for monitoring trends in malaria morbidity and for evaluating impacts of malaria interventions. Improving malaria diagnosis should be a top priority in rural African health centers.

Double Antibody EIA of Cortisol Using Peroxidase As Label

International Nuclear Information System (INIS)

Karim, F.M.; Hamad, A.W.R.; Hashim, A.M.

1998-01-01

An enzyme immunoassay (EIA) technique for plasma cortisol was established by using cortisol-3 (carboxymethyl) oxime covalently linked to the horseradish peroxidase as the label. An antibody raised in the rabbits against cortisol-3-(carboxy-methyl) oxime-bovline serum albumin was used as the first anti-body. Sheep anti-rabbit gamma-globulin serum with 8 percent poly-ethyleneglycol were used to separate antibody-bound and free cortisol. The enzyme activity of the bound fraction was measured with ortho-phenylene diamine as substrate. The procedure performed at room temperature was evaluated by sensitivity (50 pg/ tube). The correlation coefficient between our enzyme immunoassay technique and radioimmunoassay technique for determination of plasma cortisol was 97 percent

Artemether-Lumefantrine Combination Therapy for Treatment of Uncomplicated Malaria: The Potential for Complex Interactions with Antiretroviral Drugs in HIV-Infected Individuals

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Pauline Byakika-Kibwika

2011-01-01

Full Text Available Treatment of malaria in HIV-infected individuals receiving antiretroviral therapy (ART poses significant challenges. Artemether-lumefantrine (AL is one of the artemisisnin-based combination therapies recommended for treatment of malaria. The drug combination is highly efficacious against sensitive and multidrug resistant falciparum malaria. Both artemether and lumefantrine are metabolized by hepatic cytochrome P450 (CYP450 enzymes which metabolize the protease inhibitors (PIs and nonnucleoside reverse transcriptase inhibitors (NNRTIs used for HIV treatment. Coadministration of NNRTIs and PIs with AL could potentially cause complex pharmacokinetic drug interactions. NNRTI by inducing CYP450 3A4 enzyme and PIs by inhibiting CYP450 3A4 enzymes could influence both artemether and lumefantrine concentrations and their active metabolites dihydroartemisinin and desbutyl-lumefantrine, predisposing patients to poor treatment response, toxicity, and risk for development of resistance. There are scanty data on these interactions and their consequences. Pharmacokinetic studies to evaluate these interactions in the target populations are urgently needed.

Antibodies to a recombinant glutamate-rich Plasmodium falciparum protein

DEFF Research Database (Denmark)

Hogh, B; Petersen, E; Dziegiel, Morten Hanefeld

1992-01-01

/RESA) (EENV)6 were examined in 423 individuals (age range 30 days-78 years) living in a malaria holoendemic area of Liberia. In the 5-9-year-old age group, subjects with anti-GLURP489-1271 antibody concentrations greater than the mean value of the group had lower parasite densities than those with low...

Nonobese Diabetic (NOD Mice Lack a Protective B-Cell Response against the “Nonlethal” Plasmodium yoelii 17XNL Malaria Protozoan

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Mirian Mendoza

2016-01-01

Full Text Available Background. Plasmodium yoelii 17XNL is a nonlethal malaria strain in mice of different genetic backgrounds including the C57BL/6 mice (I-Ab/I-Enull used in this study as a control strain. We have compared the trends of blood stage infection with the nonlethal murine strain of P. yoelii 17XNL malaria protozoan in immunocompetent Nonobese Diabetic (NOD mice prone to type 1 diabetes (T1D and C57BL/6 mice (control mice that are not prone to T1D and self-cure the P. yoelii 17XNL infection. Prediabetic NOD mice could not mount a protective antibody response to the P. yoelii 17XNL-infected red blood cells (iRBCs, and they all succumbed shortly after infection. Our data suggest that the lack of anti-P. yoelii 17XNL-iRBCs protective antibodies in NOD mice is a result of parasite-induced, Foxp3+ T regulatory (Treg cells able to suppress the parasite-specific antibody secretion. Conclusions. The NOD mouse model may help in identifying new mechanisms of B-cell evasion by malaria parasites. It may also serve as a more accurate tool for testing antimalaria therapeutics due to the lack of interference with a preexistent self-curing mechanism present in other mouse strains.

Inhibition of ligand exchange kinetics via active-site trapping with an antibody fragment.

Science.gov (United States)

Oyen, David; Steyaert, Jan; Barlow, John N

2014-04-01

We describe the first example of an inhibitory antibody fragment (nanobody ca1697) that binds simultaneously to an enzyme (the enzyme dihydrofolate reductase from Escherichia coli) and its bound substrate (folate). Binding of the antibody to the substrate causes a 20-fold reduction in the rate of folate exchange kinetics. This work opens up the prospect of designing new types of antibody-based inhibitors of enzymes and receptors through suitable design of immunogens.

Hari Malaria Sedunia 2013 Investasi Di Masa Depan. Taklukkan Malaria

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Hotnida Sitorus

2017-02-01

Full Text Available Abstract Malaria is still the global health problems, World Health Organization estimates that malaria causes death of approximately 660.000 in 2010, most of the age of the children in the region of sub-Saharan Africa. World Malaria Day 2013 assigned the theme “Invest in the future. Defeat malaria”. It takes political will and collective action to jointly combat malaria through malaria elimination. Needed more new donors to be involved in global partnerships against malaria. These partnerships exist, one of which is support of funding or facility for malaria endemic countries which do not have sufficient resources to control malaria. A lot of effort has been done or is still in the development stage. The use of long-lasting insecticidal nets appropriately can reduce malaria cases. The use of rapid diagnostic test, especially in remote areas and health facility with no microscopy, is very beneficial for patients to get prompt treatment. The control of malaria through integrated vector management is a rational decision making process to optimize the use of resources in the control of vector. Sterile insect technique has a promising prospect and expected to replace the role of chemical insecticides that have negative impact both on the environment and target vector (resistance. Keywords: Malaria, long-lasting insecticidal nets, rapid diagnostic test Abstrak Malaria masih menjadi masalah kesehatan dunia, Organisasi Kesehatan Dunia (WHO memperkirakan malaria menyebabkan kurang lebih 660.000 kematian pada tahun 2010, kebanyakan usia anak-anak di wilayah Sub-Sahara Afrika. Pada peringatan hari malaria dunia tahun 2013 ditetapkan tema “Investasi di masa depan. Taklukkan malaria”. Dibutuhkan kemauan politik dan tindakan kolektif untuk bersama-sama memerangi malaria melalui gerakan eliminasi malaria. Diperlukan lebih banyak donor baru untuk turut terlibat dalam kemitraan global melawan malaria. Wujud kemitraan tersebut salah satunya adalah

Enzyme-linked immunosorbent assay for total sennosides using anti-sennside A and anti-sennoside B monoclonal antibodies.

Science.gov (United States)

Morinaga, Osamu; Uto, Takuhiro; Sakamoto, Seiichi; Tanaka, Hiroyuki; Shoyama, Yukihiro

2009-01-01

Total sennosides concentration is a very important factor when rhubarb and senna will be used as crude drugs. However, one-step analytical technique for total sennosides has not been reported except HPLC. An enzyme-linked immunosorbent assay (ELISA) for total sennosides concentration by using the combination of anti-sennoside A (SA) and anti-sennoside B (SB) monoclonal antibodies (MAbs) in a single assay has been investigated. Total sennosides concentration in rhubarb and senna samples determined by newly developed assay system showed good agreement with those analyzed by ELISA using anti-SA MAb and anti-SB MAb, respectively.

The Antibody Response of Pregnant Cameroonian Women to VAR2CSA ID1-ID2a, a Small Recombinant Protein Containing the CSA-Binding Site

Science.gov (United States)

Babakhanyan, Anna; Leke, Rose G. F.; Salanti, Ali; Bobbili, Naveen; Gwanmesia, Philomina; Leke, Robert J. I.; Quakyi, Isabella A.; Chen, John J.; Taylor, Diane Wallace

2014-01-01

In pregnant women, Plasmodium falciparum-infected erythrocytes expressing the VAR2CSA antigen bind to chondroitin sulfate A in the placenta causing placental malaria. The binding site of VAR2CSA is present in the ID1-ID2a region. This study sought to determine if pregnant Cameroonian women naturally acquire antibodies to ID1-ID2a and if antibodies to ID1-ID2a correlate with absence of placental malaria at delivery. Antibody levels to full-length VAR2CSA and ID1-ID2a were measured in plasma samples from 745 pregnant Cameroonian women, 144 Cameroonian men, and 66 US subjects. IgM levels and IgG avidity to ID1-ID2a were also determined. As expected, antibodies to ID1-ID2a were absent in US controls. Although pregnant Cameroonian women developed increasing levels of antibodies to full-length VAR2CSA during pregnancy, no increase in either IgM or IgG to ID1-ID2a was observed. Surprisingly, no differences in antibody levels to ID1-ID2a were detected between Cameroonian men and pregnant women. For example, in rural settings only 8–9% of males had antibodies to full-length VAR2CSA, but 90–96% had antibodies to ID1-ID2a. In addition, no significant difference in the avidity of IgG to ID1-ID2a was found between pregnant women and Cameroonian men, and no correlation between antibody levels at delivery and absence of placental malaria was found. Thus, the response to ID1-ID2a was not pregnancy specific, but predominantly against cross-reactivity epitopes, which may have been induced by other PfEMP1 antigens, malarial antigens, or microbes. Currently, ID1-ID2a is a leading vaccine candidate, since it binds to the CSA with the same affinity as the full-length molecule and elicits binding-inhibitory antibodies in animals. Further studies are needed to determine if the presence of naturally acquired cross-reactive antibodies in women living in malaria endemic countries will alter the response to ID1-ID2a following vaccination with ID1-ID2a. PMID:24505415

The antibody response of pregnant Cameroonian women to VAR2CSA ID1-ID2a, a small recombinant protein containing the CSA-binding site.

Directory of Open Access Journals (Sweden)

Anna Babakhanyan

Full Text Available In pregnant women, Plasmodium falciparum-infected erythrocytes expressing the VAR2CSA antigen bind to chondroitin sulfate A in the placenta causing placental malaria. The binding site of VAR2CSA is present in the ID1-ID2a region. This study sought to determine if pregnant Cameroonian women naturally acquire antibodies to ID1-ID2a and if antibodies to ID1-ID2a correlate with absence of placental malaria at delivery. Antibody levels to full-length VAR2CSA and ID1-ID2a were measured in plasma samples from 745 pregnant Cameroonian women, 144 Cameroonian men, and 66 US subjects. IgM levels and IgG avidity to ID1-ID2a were also determined. As expected, antibodies to ID1-ID2a were absent in US controls. Although pregnant Cameroonian women developed increasing levels of antibodies to full-length VAR2CSA during pregnancy, no increase in either IgM or IgG to ID1-ID2a was observed. Surprisingly, no differences in antibody levels to ID1-ID2a were detected between Cameroonian men and pregnant women. For example, in rural settings only 8-9% of males had antibodies to full-length VAR2CSA, but 90-96% had antibodies to ID1-ID2a. In addition, no significant difference in the avidity of IgG to ID1-ID2a was found between pregnant women and Cameroonian men, and no correlation between antibody levels at delivery and absence of placental malaria was found. Thus, the response to ID1-ID2a was not pregnancy specific, but predominantly against cross-reactivity epitopes, which may have been induced by other PfEMP1 antigens, malarial antigens, or microbes. Currently, ID1-ID2a is a leading vaccine candidate, since it binds to the CSA with the same affinity as the full-length molecule and elicits binding-inhibitory antibodies in animals. Further studies are needed to determine if the presence of naturally acquired cross-reactive antibodies in women living in malaria endemic countries will alter the response to ID1-ID2a following vaccination with ID1-ID2a.

A double antibody radioimmunoassay specific for placental alkaline phosphatase

International Nuclear Information System (INIS)

Dass, S.; Bagshawe, K.D.

1984-01-01

Placental alkaline phosphatase (PLAP) is normally found in enzymically measurable amounts in second and third trimester pregnancy serum. Its occurrence in sera and tumours from patients with malignant disease has led to the development of methods to specifically identify and quantitate the enzyme. Recently immunological techniques have been used, employing antibodies raised to purified PLAP; these include solid phase radioimmunoassays and enzyme-immunoassay. The development of a sensitive, specific, automated double-antibody radioimmunoassay for the measurement of PLAP in serum is reported. (Auth.)

Modeling the impact of Plasmodium falciparum sexual stage immunity on the composition and dynamics of the human infectious reservoir for malaria in natural settings.

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André Lin Ouédraogo

2018-05-01

Full Text Available Malaria transmission remains high in Sub-Saharan Africa despite large-scale implementation of malaria control interventions. A comprehensive understanding of the transmissibility of infections to mosquitoes may guide the design of more effective transmission reducing strategies. The impact of P. falciparum sexual stage immunity on the infectious reservoir for malaria has never been studied in natural settings. Repeated measurements were carried out at start-wet, peak-wet and dry season, and provided data on antibody responses against gametocyte/gamete antigens Pfs48/45 and Pfs230 as anti-gametocyte immunity. Data on high and low-density infections and their infectiousness to anopheline mosquitoes were obtained using quantitative molecular methods and mosquito feeding assays, respectively. An event-driven model for P. falciparum sexual stage immunity was developed and fit to data using an agent based malaria model infrastructure. We found that Pfs48/45 and Pfs230 antibody densities increased with increasing concurrent gametocyte densities; associated with 55-70% reduction in oocyst intensity and achieved up to 44% reduction in proportions of infected mosquitoes. We showed that P. falciparum sexual stage immunity significantly reduces transmission of microscopic (p < 0.001 but not submicroscopic (p = 0.937 gametocyte infections to mosquitoes and that incorporating sexual stage immunity into mathematical models had a considerable impact on the contribution of different age groups to the infectious reservoir of malaria. Human antibody responses to gametocyte antigens are likely to be dependent on recent and concurrent high-density gametocyte exposure and have a pronounced impact on the likelihood of onward transmission of microscopic gametocyte densities compared to low density infections. Our mathematical simulations indicate that anti-gametocyte immunity is an important factor for predicting and understanding the composition and dynamics of the

Antibody reactivity to conserved linear epitopes of Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1)

DEFF Research Database (Denmark)

Staalsø, T; Khalil, E A; Elhassan, I M

1998-01-01

recognising the conserved regions of PfEMP1 arise upon exposure to the parasite, and that these may be involved in the development of protection against malaria. Antibodies to the Pfalhesin peptide of the human aniontransporter, band3, were measured by the same method. The magnitude of this antibody response...

CYP6 P450 enzymes and ACE-1 duplication produce extreme and multiple insecticide resistance in the malaria mosquito Anopheles gambiae.

Science.gov (United States)

Edi, Constant V; Djogbénou, Luc; Jenkins, Adam M; Regna, Kimberly; Muskavitch, Marc A T; Poupardin, Rodolphe; Jones, Christopher M; Essandoh, John; Kétoh, Guillaume K; Paine, Mark J I; Koudou, Benjamin G; Donnelly, Martin J; Ranson, Hilary; Weetman, David

2014-03-01

Malaria control relies heavily on pyrethroid insecticides, to which susceptibility is declining in Anopheles mosquitoes. To combat pyrethroid resistance, application of alternative insecticides is advocated for indoor residual spraying (IRS), and carbamates are increasingly important. Emergence of a very strong carbamate resistance phenotype in Anopheles gambiae from Tiassalé, Côte d'Ivoire, West Africa, is therefore a potentially major operational challenge, particularly because these malaria vectors now exhibit resistance to multiple insecticide classes. We investigated the genetic basis of resistance to the most commonly-applied carbamate, bendiocarb, in An. gambiae from Tiassalé. Geographically-replicated whole genome microarray experiments identified elevated P450 enzyme expression as associated with bendiocarb resistance, most notably genes from the CYP6 subfamily. P450s were further implicated in resistance phenotypes by induction of significantly elevated mortality to bendiocarb by the synergist piperonyl butoxide (PBO), which also enhanced the action of pyrethroids and an organophosphate. CYP6P3 and especially CYP6M2 produced bendiocarb resistance via transgenic expression in Drosophila in addition to pyrethroid resistance for both genes, and DDT resistance for CYP6M2 expression. CYP6M2 can thus cause resistance to three distinct classes of insecticide although the biochemical mechanism for carbamates is unclear because, in contrast to CYP6P3, recombinant CYP6M2 did not metabolise bendiocarb in vitro. Strongly bendiocarb resistant mosquitoes also displayed elevated expression of the acetylcholinesterase ACE-1 gene, arising at least in part from gene duplication, which confers a survival advantage to carriers of additional copies of resistant ACE-1 G119S alleles. Our results are alarming for vector-based malaria control. Extreme carbamate resistance in Tiassalé An. gambiae results from coupling of over-expressed target site allelic variants with

Isolation and functional effects of monoclonal antibodies binding to thymidylate synthase.

Science.gov (United States)

Jastreboff, M M; Todd, M B; Malech, H L; Bertino, J R

1985-01-29

Monoclonal antibodies against electrophoretically pure thymidylate synthase from HeLa cells have been produced. Antibodies (M-TS-4 and M-TS-9) from hybridoma clones were shown by enzyme-linked immunoassay to recognize thymidylate synthase from a variety of human cell lines, but they did not bind to thymidylate synthase from mouse cell lines. The strongest binding of antibodies was observed to enzyme from HeLa cells. These two monoclonal antibodies bind simultaneously to different antigenic sites on thymidylate synthase purified from HeLa cells, as reflected by a high additivity index and results of cross-linked radioimmunoassay. Both monoclonal antibodies inhibit the activity of thymidylate synthase from human cell lines. The strongest inhibition was observed with thymidylate synthase from HeLa cells. Monoclonal antibody M-TS-9 (IgM subclass) decreased the rate of binding of [3H]FdUMP to thymidylate synthase in the presence of 5,10-methylenetetrahydrofolate while M-TS-4 (IgG1) did not change the rate of ternary complex formation. These data indicate that the antibodies recognize different epitopes on the enzyme molecule.

Development of a monoclonal antibody-based sandwich-type enzyme-linked immunosorbent assay (ELISA) for detection of abrin in food samples.

Science.gov (United States)

Zhou, Yu; Tian, Xiang-Li; Li, Yan-Song; Pan, Feng-Guang; Zhang, Yuan-Yuan; Zhang, Jun-Hui; Wang, Xin-Rui; Ren, Hong-Lin; Lu, Shi-Ying; Li, Zhao-Hui; Liu, Zeng-Shan; Chen, Qi-Jun; Liu, Jing-Qiu

2012-12-15

Abrin is a plant toxin, which can be easily isolated from the seeds of Abrus precatorius. It may be used as a biological warfare agent. In order to detect abrin in food samples, a two-layer sandwich format enzyme-linked immunosorbent assay based on the monoclonal antibody (mAb) (as capture antibody) and rabbit polyclonal serum (as detecting antibody) was developed and applied for the determination of abrin in some food matrices. The linear range of the mAb was 1-100 μg L(-1) with a detection limit of 0.5 μg L(-1) for abrin in phosphate buffered saline (PBS). The recoveries of abrin from sausage, beer and milk samples ranged 97.5-98.6%, 95.8-98.4% and 94.8-9.6%, respectively, with a coefficient of variation (CV) of 3.7% or less. The newly developed sandwich ELISA using the mAb appears to be a reliable and useful method for detection of abrin in sausage, beer and milk. Copyright © 2012 Elsevier Ltd. All rights reserved.

Identification of antigen-specific human monoclonal antibodies using high-throughput sequencing of the antibody repertoire.

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Liu, Ju; Li, Ruihua; Liu, Kun; Li, Liangliang; Zai, Xiaodong; Chi, Xiangyang; Fu, Ling; Xu, Junjie; Chen, Wei

2016-04-22

High-throughput sequencing of the antibody repertoire provides a large number of antibody variable region sequences that can be used to generate human monoclonal antibodies. However, current screening methods for identifying antigen-specific antibodies are inefficient. In the present study, we developed an antibody clone screening strategy based on clone dynamics and relative frequency, and used it to identify antigen-specific human monoclonal antibodies. Enzyme-linked immunosorbent assay showed that at least 52% of putative positive immunoglobulin heavy chains composed antigen-specific antibodies. Combining information on dynamics and relative frequency improved identification of positive clones and elimination of negative clones. and increase the credibility of putative positive clones. Therefore the screening strategy could simplify the subsequent experimental screening and may facilitate the generation of antigen-specific antibodies. Copyright © 2016 Elsevier Inc. All rights reserved.

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.

Water-soluble nanoconjugates of quantum dot-chitosan-antibody for in vitro detection of cancer cells based on “enzyme-free” fluoroimmunoassay

Energy Technology Data Exchange (ETDEWEB)

Mansur, Herman S., E-mail: hmansur@demet.ufmg.br [Center of Nanoscience, Nanotechnology, and Innovation-CeNano" 2I, Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais, UFMG, Av. Presidente Antônio Carlos, 6627, Belo Horizonte, MG 31.270-901 (Brazil); Mansur, Alexandra A.P. [Center of Nanoscience, Nanotechnology, and Innovation-CeNano" 2I, Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais, UFMG, Av. Presidente Antônio Carlos, 6627, Belo Horizonte, MG 31.270-901 (Brazil); Soriano-Araújo, Amanda [Center of Nanoscience, Nanotechnology, and Innovation-CeNano" 2I, Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais, UFMG, Av. Presidente Antônio Carlos, 6627, Belo Horizonte, MG 31.270-901 (Brazil); Department of Preventive Veterinary Medicine, Veterinary School, UFMG (Brazil); Lobato, Zélia I.P. [Department of Preventive Veterinary Medicine, Veterinary School, UFMG (Brazil); Carvalho, Sandhra M. de [Center of Nanoscience, Nanotechnology, and Innovation-CeNano" 2I, Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais, UFMG, Av. Presidente Antônio Carlos, 6627, Belo Horizonte, MG 31.270-901 (Brazil); Department of Physiology and Biophysics, ICB, UFMG (Brazil); Leite, Maria de Fatima [Department of Physiology and Biophysics, ICB, UFMG (Brazil)

2015-07-01

Cancer remains one of the world's most devastating diseases with millions of fatalities and new cases every year. In this work, we attempted to develop a facile “enzyme-free” fluoroimmunoassay based on the novel nanoconjugates composed of CdS quantum dots (QDs) as the fluorescent inorganic core and an antibody-modified polysaccharide as the organic shell, modeling their possible application for the in vitro diagnosis of non-Hodgkin lymphoma (NHL) cancer. Chitosan was conjugated with an anti-CD20 polyclonal antibody (pAbCD20) by the formation of covalent amide bonds. In the sequence, these chitosan-antibody conjugates were utilized as direct ligands for the surface biofunctionalization of CdS QDs (CdS/chitosan-pAbCD20) using a single-step colloidal process in aqueous medium at room temperature. The most relevant physico-chemical properties of these nanoconjugates were assessed by morphological and spectroscopic techniques. The results indicated that CdS nanocrystals were produced with an average diameter of 2.5 nm and with cubic zinc blende crystalline nanostructure. The CdS-immunoconjugates (CdS/chitosan-pAbCD20) presented colloidal hydrodynamic diameter (H{sub D}) of 15.0 ± 1.2 nm. In addition, the results evidenced that the “enzyme-free” QD-linked immunosorbent assay (QLISA) was effective for the in vitro detection against the antigen CD20 (aCD20) based on fluorescent behavior of the CdS nanoconjugates. Moreover, the CdS-immunoconjugates were successfully used for fluorescence bioimaging of NHL cancer cells. Finally, the cell viability results using different cell cultures based on LDH, MTT and Resazurin bio-assays have demonstrated no cytotoxicity of the new CdS-chitosan bioconjugates relative to the standard controls. Thus, CdS conjugates may offer a promising platform for the future development of in vitro and in vivo applications for the detection and diagnosis of NHL cancer cells. - Highlights: • CdS quantum dots (QDs) were prepared using

[Use of monoclonal antibodies against horse immunoglobulin in an enzyme immunoassay of bacterial toxins and anatoxins].

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Burkin, M A; Gal'vidis, I A; Iakovleva, I V; Sviridov, V V

2007-01-01

Immunization of BALB/c mice by horse antiserum against diphtheria made it possible to obtain IgG1 monoclonal antibodies (MoAbs) 2B7E4 specific for light chains of horse immunoglobulin (Ig). Unlike commercial preparations of anti-horse immunoglobulin antibodies, which are specific for the whole Ig molecule or its Fc-fragment, the peroxidase (HRP) conjugate of the MoAb, 2B7E4-HRP did not interact with human, mouse, rabbit, and sheep Igs, or horse albumin. The conjugate obtained was used with MoAbs against bacterial toxins and commercial horse anatoxins, as a universal reagent in sandwich enzyme immunoassay (ELISA) for bacterial toxins and anatoxins. The detection sensitivity of diphtheria toxin/anatoxin equaled 0.0005 Lf/ml; tetanus toxin and anatoxin were detected with sensitivities of 20 LD50/ml and 0.005 UI/ml, respectively. A similar sandwich ELISA for botulinum anatoxins (group measurement) allowed types A, B, and E to be detected at 0.02, 0.002, and 0.001 UI/ml, respectively; selective measurement was only possible in the case of type E anatoxin (0.001 UI/ml).

Production and characterisation of monoclonal antibodies against native and disassembled human catalase

NARCIS (Netherlands)

Wiemer, E. A.; Ofman, R.; Middelkoop, E.; de Boer, M.; Wanders, R. J.; Tager, J. M.

1992-01-01

Catalase isolated from human erythrocytes was used to immunise mice, in order to generate hybridomas producing specific monoclonal antibodies to the enzyme. Hybridomas secreting anti-(catalase) antibodies were identified by a modified enzyme-linked immunosorbent assay (ELISA) using either

On the efficacy of malaria DNA vaccination with magnetic gene vectors.

Science.gov (United States)

Nawwab Al-Deen, Fatin; Ma, Charles; Xiang, Sue D; Selomulya, Cordelia; Plebanski, Magdalena; Coppel, Ross L

2013-05-28

We investigated the efficacy and types of immune responses from plasmid malaria DNA vaccine encoding VR1020-PyMSP119 condensed on the surface of polyethyleneimine (PEI)-coated SPIONs. In vivo mouse studies were done firstly to determine the optimum magnetic vector composition, and then to observe immune responses elicited when magnetic vectors were introduced via different administration routes. Higher serum antibody titers against PyMSP119 were observed with intraperitoneal and intramuscular injections than subcutaneous and intradermal injections. Robust IgG2a and IgG1 responses were observed for intraperitoneal administration, which could be due to the physiology of peritoneum as a major reservoir of macrophages and dendritic cells. Heterologous DNA prime followed by single protein boost vaccination regime also enhanced IgG2a, IgG1, and IgG2b responses, indicating the induction of appropriate memory immunity that can be elicited by protein on recall. These outcomes support the possibility to design superparamagnetic nanoparticle-based DNA vaccines to optimally evoke desired antibody responses, useful for a variety of diseases including malaria. Copyright © 2013 Elsevier B.V. All rights reserved.

Malaria.

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Dupasquier, Isabelle

1989-01-01

Malaria, the greatest pandemia in the world, claims an estimated one million lives each year in Africa alone. While it may still be said that for the most part malaria is found in what is known as the world's poverty belt, cases are now frequently diagnosed in western countries. Due to resistant strains of malaria which have developed because of…

Malaria and protective behaviours: is there a malaria trap?

Science.gov (United States)

Berthélemy, Jean-Claude; Thuilliez, Josselin; Doumbo, Ogobara; Gaudart, Jean

2013-06-13

In spite of massive efforts to generalize efficient prevention, such as insecticide-treated mosquito nets (ITN) or long-lasting insecticidal nets (LLINs), malaria remains prevalent in many countries and ITN/LLINs are still only used to a limited extent. This study proposes a new model for malaria economic analysis by combining economic epidemiology tools with the literature on poverty traps. A theoretical model of rational protective behaviour in response to malaria is designed, which includes endogenous externalities and disease characteristics. Survey data available for Uganda provide empirical support to the theory of prevalence-elastic protection behaviours, once endogeneity issues related to epidemiology and poverty are solved. Two important conclusions emerge from the model. First, agents increase their protective behaviour when malaria is more prevalent in a society. This is consistent with the literature on "prevalence-elastic behaviour". Second, a 'malaria trap' defined as the result of malaria reinforcing poverty while poverty reduces the ability to deal with malaria can theoretically exist and the conditions of existence of the malaria trap are identified. These results suggest the possible existence of malaria traps, which provides policy implications. Notably, providing ITN/LLINs at subsidized prices is not sufficient. To be efficient an ITN/LLINs dissemination campaigns should include incentive of the very poor for using ITN/LLINs.

Natural disaster-induced environmental migration from the Indian subcontinent resulting in malaria outbreak in Greece

Science.gov (United States)

Mavrouli, Maria; Mavroulis, Spyridon; Piperaki, Evangelia-Theofano; Hadjichristodoulou, Christos; Tsakris, Athanassios

2017-04-01

Extreme hydrometeorological disasters such as floods and hurricanes can severely damage human life, natural and built environment and economic development. Consequently, they can result in environmental migration (EM). In case of infectious disease (ID) outbreaks during the post-disaster period and subsequent EM, environmental refugees from endemic regions serve as ID carriers to their new residence sites altering the spatial ID distribution and incidence. The continuous massive influx of environmental refugees from malaria endemic regions to non-endemic ones can build up a parasite reservoir among naive host populations. Initially, serum specimens were collected in 2012 from asymptomatic individuals, 298 Greeks and 721 immigrants residing in areas of documented local malaria transmission in Laconia (Southern Peloponnese) and in Eastern Attica, Greece. Sera were tested for antibodies against Plasmodium vivax and P. falciparum using the Malaria-Ab ELISA (IBL International GMBH, Hamburg, Germany). Taking into account that Greece has been declared malaria free by the WHO since 1974, we conducted an extensive and systematic literature review related to natural disasters leading among others to increased malaria risk in Indian Subcontinent and respective forced EM in order to detect relative possible causes of reintroduction and localized outbreaks of malaria in Greece. Regarding the country of origin, information was available for 685 (95%) of the 721 immigrants. Of the 678 immigrants from Indian Subcontinent, 627 (92.5%) originated from Pakistan, 24 (3.53%) Afghanistan, 24 (3.53%) India and 3 (0.44%) Bangladesh. Of the 721 immigrants, 582 and 124 resided in Laconia and Eastern Attica respectively. Seventy-one immigrants residing in Laconia and 14 in Eastern Attica were positive for antimalarial antibodies, while none of the 298 Greeks residing in Laconia (N=248) and Attica (N=50) was found positive. Based on already published scientific data, Pakistan has been exposed

Natural Mosquito-Pathogen Hybrid IgG4 Antibodies in Vector Borne Diseases: A Hypothesis

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Berlin L. Londono-Renteria

2016-09-01

Full Text Available Chronic exposure to antigens may favor the production of IgG4 antibodies over other antibody types. Recent studies have shown that up to a 30% of normal human IgG4 is bi-specific and is able to recognize two antigens of different nature. A requirement for this specificity is the presence of both eliciting antigens in the same time and at the same place where the immune response is induced. During transmission of most vector-borne diseases, the pathogen is delivered to the vertebrate host along with the arthropod saliva during blood feeding and previous studies have shown the existence of IgG4 antibodies against mosquito salivary allergens. However, there is very little ongoing research or information available regarding IgG4 bi-specificity with regards to infectious disease, particularly during immune responses to vector-borne diseases such as malaria, filariasis or dengue virus infection. Here, we provide background information and present our hypothesis that IgG4 may not only be a useful tool to measure exposure to infected mosquito bites, but that these bi-specific antibodies may also play an important role in modulation of the immune response against malaria and other vector-borne diseases in endemic settings.

About Malaria

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... Emergency Consultations, and General Public. Contact Us About Malaria Recommend on Facebook Tweet Share Compartir Malaria is ... from sub-Saharan Africa and South Asia. About Malaria Topics FAQs Frequently Asked Question, Incubation period, uncomplicated & ...

[Prevention of post-transfusional malaria by sero-detection of latent Plasmodium carriers among blood donors].

Science.gov (United States)

Ambroise-Thomas, P

1976-06-01

The risks of post-transfusion malaria are becoming a worry and the sero-investigation of latent carriers of plasmodium, among donors, is certainly the only efficient prophylactic measure. This is the result of an investigation carried out between October 1973 and February 1975 in 18 Blood Tranfusion Centres in France. Out of 2.997 sera studied in immuno-fluorescence of malaria, 3 to 5.2% of sero-positivity have been noticed, depending on the antigen used (P. falciparum, P. malariae and P. cynomolgi bastianellii). If the presence of fluorescent antibodies -- especially at weak titers --, does not mean compulsorily that the parasitemia persists, the serologic negativity leads to a diagnosis of exclusion. In this manner, the idea of a latent malaria is eliminated and one can determine precisely which bloods will be transfused without danger. But the required condition is that the sero-diagnosis of malaria be done on homologous antigens, which is, in spite of various technical difficulties, realizable in specialized laboratories. For material reasons, these tests cannot applied to all donors who have lived overseas. In return, it would be indubitably desired that these tests be done, among these donors, on subjects belonging to rare blood groups.

Replacement of Antibodies in Pseudo-ELISAs: Molecularly Imprinted Nanoparticles for Vancomycin Detection.

Science.gov (United States)

Canfarotta, Francesco; Smolinska-Kempisty, Katarzyna; Piletsky, Sergey

2017-01-01

The enzyme-linked immunosorbent assay (ELISA) is a widely employed analytical test used to quantify a given molecule. It relies on the use of specific antibodies, linked to an enzyme, to target the desired molecule. The reaction between the enzyme and its substrate gives rise to the analytical signal that can be quantified. Thanks to their robustness and low cost, molecularly imprinted polymer nanoparticles (nanoMIPs) are a viable alternative to antibodies. Herein, we describe the synthesis of nanoMIPs imprinted for vancomycin and their subsequent application in an ELISA-like format for direct replacement of antibodies.

Direct Competitive Enzyme-Linked Immunosorbent Assay (ELISA).

Science.gov (United States)

Kohl, Thomas O; Ascoli, Carl A

2017-07-05

The competitive enzyme-linked immunosorbent assay (ELISA) (cELISA; also called an inhibition ELISA) is designed so that purified antigen competes with antigen in the test sample for binding to an antibody that has been immobilized in microtiter plate wells. The same concept works if the immobilized molecule is antigen and the competing molecules are purified labeled antibody versus antibody in a test sample. Direct cELISAs incorporate labeled antigen or antibody, whereas indirect assay configurations use reporter-labeled secondary antibodies. The cELISA is very useful for determining the concentration of small-molecule antigens in complex sample mixtures. In the direct cELISA, antigen-specific capture antibody is adsorbed onto the microtiter plate before incubation with either known standards or unknown test samples. Enzyme-linked antigen (i.e., labeled antigen) is also added, which can bind to the capture antibody only when the antibody's binding site is not occupied by either the antigen standard or antigen in the test samples. Unbound labeled and unlabeled antigens are washed away and substrate is added. The amount of antigen in the standard or the test sample determines the amount of reporter-labeled antigen bound to antibody, yielding a signal that is inversely proportional to antigen concentration within the sample. Thus, the higher the antigen concentration in the test sample, the less labeled antigen is bound to the capture antibody, and hence the weaker is the resultant signal. © 2017 Cold Spring Harbor Laboratory Press.

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].

Immunoglobulin M and G antibody responses to Plasmodium falciparum glutamate-rich protein

DEFF Research Database (Denmark)

Dziegiel, Morten Hanefeld; Rowe, P; Bennett, S

1993-01-01

were measured with a recombinant fusion protein consisting of the carboxy-terminal 783 amino acids of the GLURP. Samples for the study were obtained during a longitudinal malaria morbidity survey performed in The Gambia; cross-sectional surveys were performed at the beginning of the transmission season......The aims of the present study were to describe the age-related immunoglobulin M (IgM) and IgG response to part of a 220-kDa glutamate-rich protein (GLURP) from Plasmodium falciparum and to determine possible correlations of possession of these antibodies with malaria morbidity. IgM and IgG levels...

Development of an Indirect Competitive Enzyme-Linked Immunosorbent Assay for Glycocholic Acid Based on Chicken Single-Chain Variable Fragment Antibodies.

Science.gov (United States)

Cui, Xiping; Vasylieva, Natalia; Wu, Panpan; Barnych, Bogdan; Yang, Jun; Shen, Ding; He, Qiyi; Gee, Shirley J; Zhao, Suqing; Hammock, Bruce D

2017-10-17

Glycocholic acid (GCA) is an important metabolite of bile acids, whose urine levels are expected to be a specific diagnostic biomarker for hepatocellular carcinoma (HCC). A high-throughput immunoassay for determination of GCA would be of significant advantage and useful for primary diagnosis, surveillance, and early detection of HCC. Single-chain variable fragment (scFv) antibodies have several desirable characteristics and are an attractive alternative to traditional antibodies for the immunoassay. Because chicken antibodies possess single heavy and light variable functional domains, they are an ideal framework for simplified generation of recombinant antibodies for GCA detection. However, chicken scFvs have rarely been used to detect GCA. In this study, a scFv library was generated from chickens immunized with a GCA hapten coupled to bovine serum albumin (BSA), and anti-GCA scFvs were isolated by a phage-displayed method. Compared to the homologous coating antigen, use of a heterologous coating antigen resulted in about an 85-fold improvement in sensitivity of the immunoassay. This assay, under optimized conditions, had a linear range of 0.02-0.18 μg/mL, with an IC 50 of 0.06 μg/mL. The assay showed negligible cross-reactivity with various related bile acids, except for taurocholic acid. The detection of GCA from spiked human urine samples ranged from 86.7% to 123.3%. These results, combined with the advantages of scFv antibodies, indicated that a chicken scFv-based enzyme-linked immunosorbent assay is a suitable method for high-throughput screening of GCA in human urine.

Antibody Banding Patterns of the Enzyme-Linked Immunoelectrotransfer Blot and Brain Imaging Findings in Patients With Neurocysticercosis.

Science.gov (United States)

Arroyo, Gianfranco; Rodriguez, Silvia; Lescano, Andres G; Alroy, Karen A; Bustos, Javier A; Santivañez, Saul; Gonzales, Isidro; Saavedra, Herbert; Pretell, E Javier; Gonzalez, Armando E; Gilman, Robert H; Tsang, Victor C W; Garcia, Hector H

2018-01-06

The enzyme-linked immunoelectrotransfer blot (EITB) assay is the reference serological test for neurocysticercosis (NCC). A positive result on EITB does not always correlate with the presence of active infections in the central nervous system (CNS), and patients with a single viable brain cyst may be EITB negative. Nonetheless, EITB antibody banding patterns appears to be related with the expression of 3 protein families of Taenia solium, and in turn with the characteristics of NCC in the CNS (type, stage, and burden of viable cysts). We evaluated EITB antibody banding patterns and brain imaging findings of 548 NCC cases. Similar banding patterns were grouped into homogeneous classes using latent class analysis. The association between classes and brain imaging findings was assessed. Four classes were identified. Class 1 (patients negative or only positive to the GP50 band, related to the protein family of the same name) was associated with nonviable or single viable parenchymal cysticerci; class 2 (patients positive to bands GP42-39 and GP24, related to the T24-42 protein family, with or without anti-GP50 antibodies) was associated with intraparenchymal viable and nonviable infections; classes 3 and 4 (positive to GP50, GP42-39, and GP24 but also responding to low molecular weight bands GP21, GP18, GP14, and GP13, related to the 8 kDa protein family) were associated with extraparenchymal and intraparenchymal multiple viable cysticerci. EITB antibody banding patterns correlate with brain imaging findings and complement imaging information for the diagnosis of NCC and for staging NCC patients. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

A novel PCR-based system for the detection of four species of human malaria parasites and Plasmodium knowlesi.

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Kanako Komaki-Yasuda

Full Text Available A microscopy-based diagnosis is the gold standard for the detection and identification of malaria parasites in a patient's blood. However, the detection of cases involving a low number of parasites and the differentiation of species sometimes requires a skilled microscopist. Although PCR-based diagnostic methods are already known to be very powerful tools, the time required to apply such methods is still much longer in comparison to traditional microscopic observation. Thus, improvements to PCR systems are sought to facilitate the more rapid and accurate detection of human malaria parasites Plasmodium falciparum, P. vivax, P. ovale, and P. malariae, as well as P. knowlesi, which is a simian malaria parasite that is currently widely distributed in Southeast Asia. A nested PCR that targets the small subunit ribosomal RNA genes of malaria parasites was performed using a "fast PCR enzyme". In the first PCR, universal primers for all parasite species were used. In the second PCR, inner-specific primers, which targeted sequences from P. falciparum, P. vivax, P. ovale, P. malariae, and P. knowlesi, were used. The PCR reaction time was reduced with the use of the "fast PCR enzyme", with only 65 minutes required to perform the first and second PCRs. The specific primers only reacted with the sequences of their targeted parasite species and never cross-reacted with sequences from other species under the defined PCR conditions. The diagnoses of 36 clinical samples that were obtained using this new PCR system were highly consistent with the microscopic diagnoses.

STATUS HEMATOLOGI PENDERITA MALARIA SEREBRAL

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Nurhayati Nurhayati

2009-05-01

Full Text Available AbstrakMalaria masih merupakan masalah kesehatan masyarakat dunia. Berdasarkan klasifikasi klinis, malaria dibedakan atas malaria berat dan malaria tanpa komplikasi. Malaria serebral merupakan komplikasi terberat dari malaria falsiparum.Telah dilakukan penelitian seksi silang terhadap penderita malaria falciparum yang dirawat inap di Bangsal Penyakit Dalam RS. Perjan. Dr. M. Djamil Padang dari bulan Juni 2002 sampai Juni 2006. Pada penelitian ini didapatkan jumlah sampel sebanyak 60 orang, terdiri dari 16 orang penderita malaria serebral dan 44 orang penderita malaria tanpa komplikasi.Data penelitian menunjukan terdapat perbedaan bermakna nilai hematokrit (p<0,05 dan jumlah leukosit (p<0,05 antara penderita malaria serebral dengan penderita malaria tanpa komplikasi. Dan terdapat korelasi positif antara nilai hemoglobin dengan hematokrit (r=0,864; p<0,05 pada penderita malaria falsiparum.Kata kunci: malaria serebral, malaria tanpa komplikasi, malaria falsiparumAbstract Malaria is still a problem of health of world society. Based on the clinical classification, are distinguished on severe malaria and uncomplicated malaria. Cerebral malaria is the worst complication of falciparum malaria. Cross section of the research done at the Hospital Dr. M. Djamil Padang againts medical record of malaria patients who are hospitalized in the Internal Medicine from June 2002 until June 2004. In this study, a total sample of 60 people, consisting of 16 cerebral malaria and 44 uncomplicated malaria. Data showed there were significant differences for hematocrit values (p <0.05 and total leukocytes values (p <0.05 between cerebral malaria and uncomplicated malaria patients. There is a positive correlation between hemoglobin with hematocrit values (r = 0.864; p <0.05 of falciparum malaria patients. Keywords: cerebral malaria, uncomplicated malaria, falciparum malaria

New insight-guided approaches to detect, cure, prevent and eliminate malaria.

Science.gov (United States)

Kumar, Sushil; Kumari, Renu; Pandey, Richa

2015-05-01

New challenges posed by the development of resistance against artemisinin-based combination therapies (ACTs) as well as previous first-line therapies, and the continuing absence of vaccine, have given impetus to research in all areas of malaria control. This review portrays the ongoing progress in several directions of malaria research. The variants of RTS,S and apical membrane antigen 1 (AMA1) are being developed and test adapted as multicomponent and multistage malaria control vaccines, while many other vaccine candidates and methodologies to produce antigens are under experimentation. To track and prevent the spread of artemisinin resistance from Southeast Asia to other parts of the world, rolling circle-enhanced enzyme activity detection (REEAD), a time- and cost-effective malaria diagnosis in field conditions, and a DNA marker associated with artemisinin resistance have become available. Novel mosquito repellents and mosquito trapping and killing techniques much more effective than the prevalent ones are undergoing field testing. Mosquito lines stably infected with their symbiotic wild-type or genetically engineered bacteria that kill sympatric malaria parasites are being constructed and field tested for stopping malaria transmission. A complementary approach being pursued is the addition of ivermectin-like drug molecules to ACTs to cure malaria and kill mosquitoes. Experiments are in progress to eradicate malaria mosquito by making it genetically male sterile. High-throughput screening procedures are being developed and used to discover molecules that possess long in vivo half life and are active against liver and blood stages for the fast cure of malaria symptoms caused by simple or relapsing and drug-sensitive and drug-resistant types of varied malaria parasites, can stop gametocytogenesis and sporogony and could be given in one dose. Target-based antimalarial drug designing has begun. Some of the putative next-generation antimalarials that possess in their

Enteroparasite and vivax malaria co-infection on the Brazil-French Guiana border: Epidemiological, haematological and immunological aspects.

Directory of Open Access Journals (Sweden)

Rubens Alex de Oliveira Menezes

Full Text Available Malaria-enteroparasitic co-infections are known for their endemicity. Although they are prevalent, little is known about their epidemiology and effect on the immune response. This study evaluated the effect of enteroparasite co-infections with malaria caused by Plasmodium vivax in a border area between Brazil and French Guiana. The cross sectional study took place in Oiapoque, a municipality of Amapá, on the Amazon border. Malaria was diagnosed using thick blood smears, haemoglobin dosage by an automated method and coproparasitology by the Hoffman and Faust methods. The anti-PvMSP-119 IgG antibodies in the plasma were evaluated using ELISA and Th1 (IFN-γ, TNF-α and IL-2, and Th2 (IL-4, IL-5 and IL-10 cytokine counts were performed by flow cytometry. The participants were grouped into those that were monoinfected with vivax malaria (M, vivax malaria-enteroparasite co-infected (CI, monoinfected with enteroparasite (E and endemic controls (EC, who were negative for both diseases. 441 individuals were included and grouped according to their infection status: [M 6.9% (30/441], [Cl 26.5% (117/441], [E 32.4% (143/441] and [EC 34.2% (151/441]. Males prevailed among the (M 77% (23/30 and (CI 60% (70/117 groups. There was a difference in haemoglobin levels among the different groups under study for [EC-E], [EC-Cl], [E-M] and [Cl-M], with (p < 0.01. Anaemia was expressed as a percentage between individuals [CI-EC (p < 0.05]. In terms of parasitaemia, there were differences for the groups [CI-M (p < 0.05]. Anti-PvMSP-119 antibodies were detected in 51.2% (226/441 of the population. The level of cytokines evaluation revealed a large variation in TNF-α and IL-10 concentrations in the co-infected group. In this study we did not observe any influence of coinfection on the acquisition of IgG antibodies against PvMSP119, as well as on the profile of the cytokines that characterize the Th1 and Th2 patterns. However, co-infection increased TNF-α and IL-10

Antibody production of wild-type and enzyme V279F variants of PAF-AH as a risk factor for Cardiovascular disease

Science.gov (United States)

Ramadhani, Anggia N.; Puspitarini, Sapti; Sari, Anissa N.; Widodo

2017-11-01

Coronary artery disease (CAD) has emerged as a leading cause of death in Indonesia nowadays. WHO data in 2012 revealed that 37% of the Indonesian population died from this disease. CAD occurs because of endothelial dysfunction in the arteries. Lipoprotein-associated phospholipase A2 (Lp-PLA2), also known as platelet-activating factor acetylhydrolase (PAF-AH), is a phospholipase A2 enzyme, encoded by the PLA2G7 gene. This protein is predicted to be involved in inflammatory phospholipid metabolism so it can be used as a biomarker of CAD in the early phase. Thus, the purpose of this research is to discover the difference in antibody production between wild-type and mutant V279F. The PAF-AH enzyme was isolated from mice lymphocyte cells in order to develop this enzyme as a biomarker of cardiovascular disease. PAF-AH migrates at 55kDa according to SDS-PAGE analysis. Flow cytometry analysis showed that mutant PAF-AH (V279F) is more antigenic than wild-type PAF-AH. The missense mutation of V279F PAF-AH means this enzyme cannot catabolize the acetyl group at the sn-2 position of PAF.

P. falciparum infection and maternofetal antibody transfer in malaria-endemic settings of varying transmission.

Directory of Open Access Journals (Sweden)

Alistair R D McLean

Full Text Available During pregnancy, immunoglobulin G (IgG is transferred from the mother to the fetus, providing protection from disease in early infancy. Plasmodium falciparum infections may reduce maternofetal antibody transfer efficiency, but mechanisms remain unclear.Mother-cord paired serum samples collected at delivery from Papua New Guinea (PNG and the Thailand-Myanmar Border Area (TMBA were tested for IgG1 and IgG3 to four P. falciparum antigens and measles antigen, as well as total serum IgG. Multivariable linear regression was conducted to assess the association of peripheral P. falciparum infection during pregnancy or placental P. falciparum infection assessed at delivery with maternofetal antibody transfer efficiency. Path analysis assessed the extent to which associations between P. falciparum infection and antibody transfer were mediated by gestational age at delivery or levels of maternal total serum IgG.Maternofetal antibody transfer efficiency of IgG1 and IgG3 was lower in PNG compared to TMBA (mean difference in cord antibody levels (controlling for maternal antibody levels ranged from -0.88 to 0.09, median of -0.20 log2 units. Placental P. falciparum infections were associated with substantially lower maternofetal antibody transfer efficiency in PNG primigravid women (mean difference in cord antibody levels (controlling for maternal antibody levels ranged from -0.62 to -0.10, median of -0.36 log2 units, but not multigravid women. The lower antibody transfer efficiency amongst primigravid women with placental infection was only partially mediated by gestational age at delivery (proportion indirect effect ranged from 0% to 18%, whereas no mediation effects of maternal total serum IgG were observed.Primigravid women may be at risk of impaired maternofetal antibody transport with placental P. falciparum infection. Direct effects of P. falciparum on the placenta, rather than earlier gestational age and elevated serum IgG, are likely responsible for

New gorilla adenovirus vaccine vectors induce potent immune responses and protection in a mouse malaria model.

Science.gov (United States)

Limbach, Keith; Stefaniak, Maureen; Chen, Ping; Patterson, Noelle B; Liao, Grant; Weng, Shaojie; Krepkiy, Svetlana; Ekberg, Greg; Torano, Holly; Ettyreddy, Damodar; Gowda, Kalpana; Sonawane, Sharvari; Belmonte, Arnel; Abot, Esteban; Sedegah, Martha; Hollingdale, Michael R; Moormann, Ann; Vulule, John; Villasante, Eileen; Richie, Thomas L; Brough, Douglas E; Bruder, Joseph T

2017-07-03

A DNA-human Ad5 (HuAd5) prime-boost malaria vaccine has been shown to protect volunteers against a controlled human malaria infection. The potency of this vaccine, however, appeared to be affected by the presence of pre-existing immunity against the HuAd5 vector. Since HuAd5 seroprevalence is very high in malaria-endemic areas of the world, HuAd5 may not be the most appropriate malaria vaccine vector. This report describes the evaluation of the seroprevalence, immunogenicity and efficacy of three newly identified gorilla adenoviruses, GC44, GC45 and GC46, as potential malaria vaccine vectors. The seroprevalence of GC44, GC45 and GC46 is very low, and the three vectors are not efficiently neutralized by human sera from Kenya and Ghana, two countries where malaria is endemic. In mice, a single administration of GC44, GC45 and GC46 vectors expressing a murine malaria gene, Plasmodium yoelii circumsporozoite protein (PyCSP), induced robust PyCSP-specific T cell and antibody responses that were at least as high as a comparable HuAd5-PyCSP vector. Efficacy studies in a murine malaria model indicated that a prime-boost regimen with DNA-PyCSP and GC-PyCSP vectors can protect mice against a malaria challenge. Moreover, these studies indicated that a DNA-GC46-PyCSP vaccine regimen was significantly more efficacious than a DNA-HuAd5-PyCSP regimen. These data suggest that these gorilla-based adenovectors have key performance characteristics for an effective malaria vaccine. The superior performance of GC46 over HuAd5 highlights its potential for clinical development.

Malaria and World War II: German malaria experiments 1939-45.

Science.gov (United States)

Eckart, W U; Vondra, H

2000-06-01

The epidemiological and pharmacological fight against malaria and German malaria research during the Nazi dictatorship were completely under the spell of war. The Oberkommando des Heeres (German supreme command of the army) suffered the bitter experience of unexpected high losses caused by malaria especially at the Greek front (Metaxes line) but also in southern Russia and in the Ukraine. Hastily raised anti-malaria units tried to teach soldiers how to use the synthetic malaria drugs (Plasmochine, Atebrine) properly. Overdoses of these drugs were numerous during the first half of the war whereas in the second half it soon became clear that it would not be possible to support the army due to insufficient quantities of plasmochine and atebrine. During both running fights and troop withdrawals at all southern and southeastern fronts there was hardly any malaria prophylaxis or treatment. After war and captivity many soldiers returned home to endure heavy malaria attacks. In German industrial (Bayer, IG-Farben) and military malaria laboratories of the Heeres-Sanitäts-Akademie (Army Medical Academy) the situation was characterised by a hasty search for proper dosages of anti-malaria drugs, adequate mechanical and chemical prophylaxis (Petroleum, DDT, and other insecticides) as well as an anti-malaria vaccine. Most importantly, large scale research for proper atebrine and plasmochine dosages was conducted in German concentration camps and mental homes. In Dachau Professor Claus Schilling tested synthetic malaria drugs and injected helpless prisoners with high and sometimes lethal doses. Since the 1920s he had been furiously looking for an anti-malaria vaccine in Italian mental homes and from 1939 he continued his experiments in Dachau. Similar experiments were also performed in Buchenwald and in a psychiatric clinic in Thuringia, where Professor Gerhard Rose tested malaria drugs with mentally ill Russian prisoners of war. Schilling was put to death for his criminal

Summary of field trials using the direct and competitive enzyme immunoassays for detection of antibody to brucella abortus

International Nuclear Information System (INIS)

Nielsen, K.; Gall, D.

1998-01-01

Two indirect and two competitive enzyme immunoassays for detection of antibody to Brucella abortus, validated elsewhere, were field tested in five different Latin American laboratories. Testing was performed according to standardised protocols using sera obtained in each area. Sera from B. abortus infected herds, from vaccinated (but serologically negative in a screening test) and non-vaccinated cattle were tested in each assay and compared to the results obtained with conventional diagnostic tests used for diagnosis of brucellosis in each country. Relative sensitivity and specificity values were calculated for each country as well as a weighted summary combining the data from all the participating laboratories. The result demonstrate that all ELISAs performed as well as, or better than, the conventional aerological tests. Given the inherent errors in the use of the latter in the diagnosis of brucellosis, it is recommended that the ELISAs described here be considered as replacements for the conventional tests. The CELISA using the lipopolysaccharide antigen with the competing monoclonal antibody M84, should be considered as the most useful because of cross-species and vaccination considerations. (author)

Sickle cell protection from malaria: a review

Directory of Open Access Journals (Sweden)

Sandro Eridani

2011-11-01

Full Text Available A linkage between presence of Sickle Haemoglobin (HbS and protection from malaria infection and clinical manifestations in certain areas was suspected from early observations and progressively elucidated by more recent studies. Research has confirmed the abovementioned connection, but also clarified how such protection may be abolished by coexistence of sickle cell trait (HbS trait and alpha thalassemia, which may explain the relatively low incidence of HbS trait in the Mediterranean. The mechanisms of such protective effect are now being investigated: factors of genetic, molecular and immunological nature are prominent. As for genetic factors attention is given to the role of the red blood cell (RBC membrane complement regulatory proteins as polymorphisms of these components seem to be associated with resistance to severe malaria; genetic ligands like the Duffy group blood antigen, necessary for erythrocytic invasion, and human protein CD36, a major receptor for P. falciparum-infected RBC‘s, are also under scrutiny: attention is focused also on plasmodium erythrocyte-binding antigens, which bind to RBC surface components. Genome-wide linkage and association studies are now carried out too, in order to identify genes associated with malaria resistance. Only a minor role is attributed to intravascular sickling, phagocytosis and haemolysis, while specific molecular mechanisms are the object of intensive research: among these a decisive role is played by a biochemical sequence, involving activation of haeme oxygenase (HMO-1, whose effect appears mediated by carbon monoxide (CO. A central role in protection from malaria is also played by immunological factors, which may stimulate antibody production to plasmodium antigens in the early years of life; the role of agents like pathogenic CD8 T-cells has been suggested while the effects of molecular actions on the immunity mechanism are presently investigated. It thus appears that protection from

Age-dependent association between IgG2 and IgG3 subclasses to Pf332-C231 antigen and protection from malaria, and induction of protective antibodies by sub-patent malaria infections, in Daraweesh

DEFF Research Database (Denmark)

Giha, Hayder A; Nasr, Amre; Iriemenam, Nnaemeka C

2010-01-01

The certainty of the protective role of acquired immunity in malaria is the major drive for malaria vaccine development. In this study, we measured the levels of total IgG and IgG subclasses to four candidate malaria vaccine antigens; MSP2-3D7, MSP2-FC27, AMA-1 and Pf332-C231, in plasma obtained ...

Malaria prevalence defined by microscopy, antigen detection, DNA amplification and total nucleic acid amplification in a malaria-endemic region during the peak malaria transmission season.

Science.gov (United States)

Waitumbi, John N; Gerlach, Jay; Afonina, Irina; Anyona, Samuel B; Koros, Joseph N; Siangla, Joram; Ankoudinova, Irina; Singhal, Mitra; Watts, Kate; Polhemus, Mark E; Vermeulen, Nicolaas M; Mahoney, Walt; Steele, Matt; Domingo, Gonzalo J

2011-07-01

To determine the malaria prevalence by microscopy, antigen detection and nucleic acid detection in a defined subpopulation in a Plasmodium falciparum-endemic region during the peak transmission season. Blood specimens were collected in a cross-sectional study involving children aged 5-10 years (n = 195) presenting with acute fever to two clinics in Western Kenya. All specimens underwent microscopy, HRP2 and aldolase antigen detection by enzyme immunoassay (EIA), parasite-specific DNA and total nucleic acid (RNA and DNA) by real-time PCR (qPCR) and reverse-transcriptase PCR (qRT-PCR). Microscopy detected 65/195 cases of malaria infection [95% confidence interval (CI) 52-78]. HRP2 and aldolase EIA had similar sensitivity levels detecting antigen in 65/195 (95% CI, 52-78) and 57/195 (95% CI, 45-70) cases. Discordants in antigen detection vs. microscopy occurred at Detection of total nucleic acid allowed a 3 log lower limit of detection than just DNA detection by real-time PCR in vitro. In clinical specimens, 114/195 (95% CI, 100-127) were qPCR positive (DNA), and 187/195 (95% CI, 179-191) were qRT-PCR positive (DNA plus RNA). The prevalence of submicroscopic malaria infection was significantly higher when detecting total nucleic acid than just DNA in this outpatient population during the high transmission season. Defining standards for submicroscopic infection will be important for control programmes, diagnostics development efforts and molecular epidemiology studies. © 2011 Blackwell Publishing Ltd.

Synthesis of an oxytetracyline-tolidin-BSA immunogen and antibodies production of anti-oxytetracyline developed for oxytetracyline residue detection with enzyme-linked immunosorbent assays technique

Directory of Open Access Journals (Sweden)

Widiastuti R

2013-06-01

Full Text Available An oxytetracycline-tolidin-bovine serum albumin (OTC-tolidin-BSA-conjugate was synthezed as immunogen for producing specific antibodies in immunized rabbits that would be used as reagent for development of OTC residue detection with enzym-linked immunoassays technique. The immunogen was prepared through diazotization tolidin and subsequently reacted with OTC. The red purple immunogen of OTC-tolidin-BSA absorbed at wave lengths of 277 nm and 488 nm under UV screening absorbances and confirmation with the high performance liquid chromatography (HPLC showed the absence of peak at retention time of 3.46 minutes. Characaterized result with SDS-PAGE showed the molecular weight of the OTC-tolidin-BSA at 69.79 kDA. Subsequently, the immunogen was immunized into New Zealand rabbits in order to produce the polyclonal antibodies. The antibodies were purified using a protein A sepharose column. The OD optimum responses of 0.92 to 1.20 were obtained from the second fractionation at dilution of 1/1000 by titrating the antibodies and OTC-tolidin-BSA coating antigen at concentration of 10 µg/mL on several bleeding times.

Malaria og graviditet

DEFF Research Database (Denmark)

Hoffmann, A L; Rønn, A M; Langhoff-Roos, J

1992-01-01

In regions where malaria is endemism, the disease is a recognised cause of complications of pregnancy such as spontaneous abortion, premature delivery, intrauterine growth retardation and foetal death. Malaria is seldom seen in pregnant women in Denmark but, during the past two years, the authors...... the patients but also their practitioners were unaware that malaria can occur several years after exposure. Three out of the four patients had employed malaria prophylaxis. As resistance to malarial prophylactics in current use is increasing steadily, chemoprophylaxis should be supplemented by mechanical...... protection against malaria and insect repellents. As a rule, malaria is treated with chloroquine. In cases of Falciparum malaria in whom chloroquine resistance is suspected, treatment with mefloquine may be employed although this should only be employed in cases of dire necessity in pregnant patients during...

Rapid selection of a pyrethroid metabolic enzyme CYP9K1 by operational malaria control activities.

Science.gov (United States)

Vontas, John; Grigoraki, Linda; Morgan, John; Tsakireli, Dimitra; Fuseini, Godwin; Segura, Luis; Niemczura de Carvalho, Julie; Nguema, Raul; Weetman, David; Slotman, Michel A; Hemingway, Janet

2018-05-01

Since 2004, indoor residual spraying (IRS) and long-lasting insecticide-impregnated bednets (LLINs) have reduced the malaria parasite prevalence in children on Bioko Island, Equatorial Guinea, from 45% to 12%. After target site-based (knockdown resistance; kdr ) pyrethroid resistance was detected in 2004 in Anopheles coluzzii (formerly known as the M form of the Anopheles gambiae complex), the carbamate bendiocarb was introduced. Subsequent analysis showed that kdr alone was not operationally significant, so pyrethroid-based IRS was successfully reintroduced in 2012. In 2007 and 2014-2015, mass distribution of new pyrethroid LLINs was undertaken to increase the net coverage levels. The combined selection pressure of IRS and LLINs resulted in an increase in the frequency of pyrethroid resistance in 2015. In addition to a significant increase in kd r frequency, an additional metabolic pyrethroid resistance mechanism had been selected. Increased metabolism of the pyrethroid deltamethrin was linked with up-regulation of the cytochrome P450 CYP9K1. The increase in resistance prompted a reversion to bendiocarb IRS in 2016 to avoid a resurgence of malaria, in line with the national Malaria Control Program plan. Copyright © 2018 the Author(s). Published by PNAS.

Evaluation Of Antibody Elisa, Coproscopy And Serum Enzyme ...

African Journals Online (AJOL)

Le titrage avec immunoadsorbant lié à une enzyme (ELISA), la sédimentation fécale et les tests de l'action de l'enzyme du sérum ont été faits sur des échantillons de fèces et de sérum recueillis de 134 bovins (55 positifs et 79 négatifs pour les lésions dues à la douve du foie) lors de l'inspection de viande en Ethiopie.

Production of rabbit antibodies against purified Glucose oxidase

Directory of Open Access Journals (Sweden)

Muhammad Anjum Zia

2012-02-01

Full Text Available Glucose oxidase is an active oxygen species generating enzyme produced from Aspergillus niger grown in submerged fermentation. Disintegration of the mycelium resulted in high glucose oxidase activity that was subjected to ammonium sulfate precipitation at 60-85% saturation rates that resulted to 6.14 U mg -1 specific activity. Purification of enzyme by anion exchange column (DEAE-Cellulose resulted into 22.53 U mg-1 specific activity and 10.27 fold purification. This was applied to sephadex G-200 column for gel filtration chromatography. It was observed that enzyme achieved 59.37 U mg-1of specific activity with 27.08 fold purity and 64.36% recovery. Purified glucose oxidase was injected into rabbits through intravenous route, to raise the glucose oxidase antibodies. After 30 days incubation period, the rabbits were slaughtered and serum was separated from blood. The antibodies were isolated by ammonium sulfate precipitation and confirmed by agar gel precipitation test. This could be a convenient and low cost alternate assay for the estimation of glucose oxidase in biological fluids. Moreover, such antibodies against the said enzyme could be used in various therapeutic and diagnostic applications.

An ultra-sensitive monoclonal antibody-based enzyme-linked immunosobent assay for dibutyl phthalate in human urinary

Energy Technology Data Exchange (ETDEWEB)

Zhou, Lifang [Institute of Pharmacology, Toxicology and Biochemical Pharmaceutics, College of Pharmaceutical Science, Zhejiang University, Hangzhou 310058 (China); Lei, Yajing [Hangzhou EPIE Bio-detection Technology Limited, Hangzhou 310051 (China); Zhang, Dai; Ahmed, Shabbir [Institute of Pharmacology, Toxicology and Biochemical Pharmaceutics, College of Pharmaceutical Science, Zhejiang University, Hangzhou 310058 (China); Chen, Shuqing, E-mail: chenshuqing@zju.edu.cn [Institute of Pharmacology, Toxicology and Biochemical Pharmaceutics, College of Pharmaceutical Science, Zhejiang University, Hangzhou 310058 (China)

2016-01-15

tool to detect DBP in urinary samples. - Highlights: • DBP complete antigens (DBP–BSA and DBP–OVA) were designed and synthesized novelty. • The development of DBP monoclonal antibody with no cross-reactivity, low LOD (0.06 ng mL{sup −1}) and IC{sub 50} (7.34 ng mL{sup −1}) • Optimization and evaluation of indirect complete competitive enzyme immunoassay • Application of the method in detecting DBP of internal exposure among Chinese human urinary • Subjects were randomly recruited and system classified by ages, genders and educations.

Application of commercial enzyme linked immunosorbent assays (ELISA for the detection of antibodies for foot-and-mouth disease virus in wild boar and red deer

Directory of Open Access Journals (Sweden)

Terzić Svjetlana

2012-01-01

Full Text Available For detecting antibodies towards foot and mouth (FMD virus in sera collected from red deer hinds (Cervus elaphus and wild boars (Sus scrofa, three commercially available enzyme-linked immunosorbent assays (ELISA were used. Two ELISA kits (PrioCHECK FMDV NS and CHEKIT FMD-3ABC were used for the detection of antibodies towards non-structural proteins of FMD virus and one assay was based on the detection of antibodies for serotype O (PrioCHECK FMDV type O. All of the sera tested in our study were negative for antibodies against FMD virus. The aim of this study was to investigate the usefulness of commercially available ELISA kits given for marketing authorization in Croatia in testing the prevalence of FMD antibodies in wild boar and red deer populations. Since the producers of ELISA kits used in our study did not declare wild animals as a target species, we hypothesised that the same kits could be used for serological diagnosis of FMD in red deer and wild boars. Our study confirmed that the kits used are acceptable for detecting antibodies in both species tested, however, the investigation highlighted the problem of validating the kits due to the absence of available positive sera originating from red deer, as well as other susceptible species, especially artiodactyls.

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.

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

Science.gov (United States)

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 subset of group A-like var genes encodes the malaria parasite ligands for binding to human brain endothelial cells

DEFF Research Database (Denmark)

Claessens, Antoine; Adams, Yvonne; Ghumra, Ashfaq

2012-01-01

Cerebral malaria is the most deadly manifestation of infection with Plasmodium falciparum. The pathology of cerebral malaria is characterized by the accumulation of infected erythrocytes (IEs) in the microvasculature of the brain caused by parasite adhesins on the surface of IEs binding to human...... receptors on microvascular endothelial cells. The parasite and host molecules involved in this interaction are unknown. We selected three P. falciparum strains (HB3, 3D7, and IT/FCR3) for binding to a human brain endothelial cell line (HBEC-5i). The whole transcriptome of isogenic pairs of selected.......029) but not by antibodies from controls with uncomplicated malaria (Mann-Whitney test, P = 0.58). This work describes a binding phenotype for virulence-associated group A P. falciparum erythrocyte membrane protein 1 variants and identifies targets for interventions to treat or prevent cerebral malaria....

DARPA Antibody Technology Program Standardized Test Bed for Antibody Characterization: Characterization of an MS2 Human IgG Antibody Produced by AnaptysBio, Inc.

Science.gov (United States)

2016-02-01

Enzyme- linked immunosorbent assay (ELISA) Quality Testing MS2 coat protein (MS2CP) 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...primarily relied on the performance of an antibody in an enzyme- linked immunosorbent assay (ELISA), with little regard for quantifying the full spectrum...Protection, and Multi-Year Stabilization, in High Concentration Protein Solutions, Using Ionic Liquids. Chem. Commun. (Camb) 2007, 26, 2714–2716. 3. Bio

Structural Plasticity of Malaria Dihydroorotate Dehydrogenase Allows Selective Binding of Diverse Chemical Scaffolds

International Nuclear Information System (INIS)

Deng, Xiaoyi; Gujjar, Ramesh; El Mazouni, Farah; Kaminsky, Werner; Malmquist, Nicholas A.; Goldsmith, Elizabeth J.; Rathod, Pradipsinh K.; Phillips, Margaret A.

2009-01-01

Malaria remains a major global health burden and current drug therapies are compromised by resistance. Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) was validated as a new drug target through the identification of potent and selective triazolopyrimidine-based DHODH inhibitors with anti-malarial activity in vivo. Here we report x-ray structure determination of PfDHODH bound to three inhibitors from this series, representing the first of the enzyme bound to malaria specific inhibitors. We demonstrate that conformational flexibility results in an unexpected binding mode identifying a new hydrophobic pocket on the enzyme. Importantly this plasticity allows PfDHODH to bind inhibitors from different chemical classes and to accommodate inhibitor modifications during lead optimization, increasing the value of PfDHODH as a drug target. A second discovery, based on small molecule crystallography, is that the triazolopyrimidines populate a resonance form that promotes charge separation. These intrinsic dipoles allow formation of energetically favorable H-bond interactions with the enzyme. The importance of delocalization to binding affinity was supported by site-directed mutagenesis and the demonstration that triazolopyrimidine analogs that lack this intrinsic dipole are inactive. Finally, the PfDHODH-triazolopyrimidine bound structures provide considerable new insight into species-selective inhibitor binding in this enzyme family. Together, these studies will directly impact efforts to exploit PfDHODH for the development of anti-malarial chemotherapy.

Coexistence of Malaria and Thalassemia in Malaria Endemic Areas of Thailand

Science.gov (United States)

Kuesap, Jiraporn; Chaijaroenkul, W.; Rungsihirunrat, K.; Pongjantharasatien, K.; Na-Bangchang, Kesara

2015-01-01

Hemoglobinopathy and malaria are commonly found worldwide particularly in malaria endemic areas. Thalassemia, the alteration of globin chain synthesis, has been reported to confer resistance against malaria. The prevalence of thalassemia was investigated in 101 malaria patients with Plasmodium falciparum and Plasmodium vivax along the Thai-Myanmar border to examine protective effect of thalassemia against severe malaria. Hemoglobin typing was performed using low pressure liquid chromatography (LPLC) and α-thalassemia was confirmed by multiplex PCR. Five types of thalassemia were observed in malaria patients. The 2 major types of thalassemia were Hb E (18.8%) and α-thalassemia-2 (11.9%). There was no association between thalassemia hemoglobinopathy and malaria parasitemia, an indicator of malaria disease severity. Thalassemia had no significant association with P. vivax infection, but the parasitemia in patients with coexistence of P. vivax and thalassemia was about 2-3 times lower than those with coexistence of P. falciparum and thalassemia and malaria without thalassemia. Furthermore, the parasitemia of P. vivax in patients with coexistence of Hb E showed lower value than coexistence with other types of thalassemia and malaria without coexistence. Parasitemia, hemoglobin, and hematocrit values in patients with coexistence of thalassemia other than Hb E were significantly lower than those without coexistence of thalassemia. Furthermore, parasitemia with coexistence of Hb E were 2 times lower than those with coexistence of thalassemia other than Hb E. In conclusion, the results may, at least in part, support the protective effect of thalassemia on the development of hyperparasitemia and severe anemia in malaria patients. PMID:26174819

Detection of Antibodies to U.S. Isolates of Avian Pneumovirus by a Recombinant Nucleocapsid Protein-Based Sandwich Enzyme-Linked Immunosorbent Assay

OpenAIRE

Gulati, Baldev R.; Munir, Shirin; Patnayak, Devi P.; Goyal, Sagar M.; Kapur, Vivek

2001-01-01

The nucleocapsid (N) protein of subgroup C (United States-specific) avian pneumovirus (APV/US) was expressed in Escherichia coli, and antibodies to the recombinant N protein were shown to specifically recognize the ≈47-kDa N protein of APV/US by Western immunoblot analysis. The recombinant APV/US N protein was used in a sandwich-capture enzyme-linked immunosorbent assay (ELISA), and the resulting assay was found to be more sensitive and specific than the routine indirect ELISA for the detecti...

Survey of malaria and anti-dengue virus IgG among febrile HIV-infected patients attending a tertiary hospital in Abuja, Nigeria.

Science.gov (United States)

Mustapha, Jelili Olaide; Emeribe, Anthony Uchenna; Nasir, Idris Abdullahi

2017-01-01

Dengue and malaria are infections, of great public health concern, especially in sub-Saharan Africa where the burden of HIV infection is high. This study was conducted to determine the seroprevalence of dengue virus IgG antibodies and dengue/malaria coinfection among febrile HIV-infected patients attending the University of Abuja Teaching Hospital, Gwagwalada, Abuja. In this cross-sectional study, blood samples from 178 consenting HIV-infected patients receiving antiretroviral therapy were collected and tested for plasmodiasis and anti-Dengue virus IgG using malaria microscopy and ELISA, respectively. Interviewer-based questionnaires were used to assess subjects' sociodemographic variables and dengue risk factors. Of the 178 screened participants, 44.4% were seropositive for dengue virus IgG antibody, whereas 29.2% were positive for Plasmodium falciparum. About 44.2% were positive for both dengue virus and P. falciparum . There was a statistical association between anti-dengue IgG and occupation ( p =0.03) but not with age, residential area, educational level and patients' gender ( p >0.05). Seroprevalence of anti-dengue specific IgG was relatively higher in participants who adopted protective measures. There was a statistical association between seroprevalence of anti-dengue IgG and adoption of preventive measures ( p <0.05). The high prevalence of malaria and dengue virus IgG indicates the need to strengthen vector control and dengue surveillance programs.

Plasmodium vivax hospitalizations in a monoendemic malaria region: severe vivax malaria?

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Quispe, Antonio M; Pozo, Edwar; Guerrero, Edith; Durand, Salomón; Baldeviano, G Christian; Edgel, Kimberly A; Graf, Paul C F; Lescano, Andres G

2014-07-01

Severe malaria caused by Plasmodium vivax is no longer considered rare. To describe its clinical features, we performed a retrospective case control study in the subregion of Luciano Castillo Colonna, Piura, Peru, an area with nearly exclusive vivax malaria transmission. Severe cases and the subset of critically ill cases were compared with a random set of uncomplicated malaria cases (1:4). Between 2008 and 2009, 6,502 malaria cases were reported, including 106 hospitalized cases, 81 of which fit the World Health Organization definition for severe malaria. Of these 81 individuals, 28 individuals were critically ill (0.4%, 95% confidence interval = 0.2-0.6%) with severe anemia (57%), shock (25%), lung injury (21%), acute renal failure (14%), or cerebral malaria (11%). Two potentially malaria-related deaths occurred. Compared with uncomplicated cases, individuals critically ill were older (38 versus 26 years old, P < 0.001), but similar in other regards. Severe vivax malaria monoinfection with critical illness is more common than previously thought. © The American Society of Tropical Medicine and Hygiene.

Severe Malaria Infections Impair Germinal Center Responses by Inhibiting T Follicular Helper Cell Differentiation

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Victoria Ryg-Cornejo

2016-01-01

Full Text Available Naturally acquired immunity to malaria develops only after years of repeated exposure to Plasmodium parasites. Despite the key role antibodies play in protection, the cellular processes underlying the slow acquisition of immunity remain unknown. Using mouse models, we show that severe malaria infection inhibits the establishment of germinal centers (GCs in the spleen. We demonstrate that infection induces high frequencies of T follicular helper (Tfh cell precursors but results in impaired Tfh cell differentiation. Despite high expression of Bcl-6 and IL-21, precursor Tfh cells induced during infection displayed low levels of PD-1 and CXCR5 and co-expressed Th1-associated molecules such as T-bet and CXCR3. Blockade of the inflammatory cytokines TNF and IFN-γ or T-bet deletion restored Tfh cell differentiation and GC responses to infection. Thus, this study demonstrates that the same pro-inflammatory mediators that drive severe malaria pathology have detrimental effects on the induction of protective B cell responses.

Tamización de malaria en donantes de sangre de Cali, Colombia.

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Carmen M. Castillo

2005-06-01

Full Text Available Introducción. En Colombia existe déficit de unidades de sangre. En ciudades como Cali este déficit se agrava por el rechazo de donantes debido al riesgo de transmitir malaria; aunque en la ciudad no hay transmisión de malaria, está próxima a la Costa Pacífica, zona de alta transmisión de malaria en el país. En los bancos de sangre, la tamización de malaria está basada solamente en una entrevista. Una prueba de laboratorio para malaria podría mejorar la selección de los donantes y, así, incrementar el número de unidades de sangre disponibles. Objetivo. Evaluar las pruebas de gota gruesa, ELISA-IgG y ELISA-HRPII usando la PCR semi- anidada como prueba de referencia en la tamización de donantes de sangre en Cali. Materiales y métodos. El estudio se llevó a cabo en un banco de sangre de Cali entre febrero y mayo de 2002. Se practicaron gota gruesa, ELISA-IgG y ELISA-HRPII (Pan Malaria Antibody ELISA y Malaria Ag CELISA, Cellabs, Australia y sus resultados se compararon con la PCR semianidada. Se evaluaron 286 muestras, 115 eran donantes rechazados únicamente por tener antecedentes de haber vivido o viajado a zonas endémicas en el último año y 171 eran donantes aceptados. Resultados. Ninguna muestra tuvo resultado positivo con las pruebas realizadas. Conclusión. Los donantes rechazados basados en la entrevista podrían haber sido aceptados según las pruebas de laboratorio. Con el propósito de mejorar el proceso de tamización, sugerimos realizar una prueba de laboratorio a los donantes que son rechazados por el riesgo potencial de transmitir malaria. Se requieren estudios adicionales que permitan seleccionar la prueba más adecuada.

Study on association between genetic polymorphisms of haem oxygenase-1, tumour necrosis factor, cadmium exposure and malaria pathogenicity and severity

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Ruangweerayut Ronnatrai

2010-09-01

Full Text Available Abstract Background Malaria is the most important public health problems in tropical and sub-tropical countries. Haem oxygenase (HO enzyme and the pro-inflammatory cytokine tumour necrosis factor (TNF have been proposed as one of the factors that may play significant role in pathogenicity/severity of malaria infection. HO is the enzyme of the microsomal haem degradation pathway that yields biliverdin, carbon monoxide, and iron. In this study, the association between malaria disease pathogenicity/severity and (GTn repeat polymorphism in the promoter region of the inducible HO-1 including the effect of cadmium exposure (potent inducer of HO-1 transcription as well as polymorphism of TNF were investigated. Methods Blood samples were collected from 329 cases non-severe malaria with acute uncomplicated Plasmodium falciparum malaria (UM and 80 cases with Plasmodium vivax malaria (VM, and 77 cases with severe or cerebral malaria (SM for analysis of genetic polymorphisms of HO-1 and TNF and cadmium levels. These patients consisted of 123 (25.3% Thai, 243 (50.0% Burmese and 120 (24.7% Karen who were present at Mae Sot General Hospital, Mae Sot, Tak Province, Thailand. Results The number of (GTn repeats of the HO-1 gene in all patients varied between 16 and 39 and categorized to short (S, medium (M and long (L GTn repeats. The genotype of (GTn repeat of HO-1 was found to be significantly different among the three ethnic groups of patients. Significantly higher frequency of S/L genotype was found in Burmese compared with Thai patients, while significantly lower frequencies of S/S and M/L but higher frequency of M/M genotype was observed in Burmese compared with Karen patients. No significant association between HO-1 and TNF polymorphisms including the inducing effect of cadmium and malaria pathogenicity/severity was observed. Conclusions Difference in the expression of HO-1 genotype in different ethnic groups may contribute to different severity of malaria

Development of Antibody-Coated Magnetite Nanoparticles for Biomarker Immobilization

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Christian Chapa Gonzalez

2014-01-01

Full Text Available Magnetic nanoparticles (MNPs have great potential in biomedical applications because of their magnetic response offers the possibility to direct them to specific areas and target biological entities. Magnetic separation of biomolecules is one of the most important applications of MNPs because their versatility in detecting cancer biomarkers. However, the effectiveness of this method depends on many factors, including the type of functionalization onto MNPs. Therefore, in this study, magnetite nanoparticles have been developed in order to separate the 5′-nucleotidase enzyme (5eNT. The 5eNT is used as a bio-indicator for diagnosing diseases such as hepatic ischaemia, liver tumor, and hepatotoxic drugs damage. Magnetic nanoparticles were covered in a core/shell type with silica, aminosilane, and a double shell of silica-aminosilane. A ScFv (fragment antibody and anti-CD73 antibody were attached to the coated nanoparticles in order to separate the enzyme. The magnetic separation of this enzyme with fragment antibody was found to be 28% higher than anti-CD73 antibody and the enzyme adsorption was improved with the double shell due to the increased length of the polymeric chain. Magnetite nanoparticles with a double shell (silica-aminosilane were also found to be more sensitive than magnetite with a single shell in the detection of biomarkers.

Malaria in Brazil, Colombia, Peru and Venezuela: current challenges in malaria control and elimination.

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Recht, Judith; Siqueira, André M; Monteiro, Wuelton M; Herrera, Sonia M; Herrera, Sócrates; Lacerda, Marcus V G

2017-07-04

In spite of significant progress towards malaria control and elimination achieved in South America in the 2000s, this mosquito-transmitted tropical disease remains an important public health concern in the region. Most malaria cases in South America come from Amazon rain forest areas in northern countries, where more than half of malaria is caused by Plasmodium vivax, while Plasmodium falciparum malaria incidence has decreased in recent years. This review discusses current malaria data, policies and challenges in four South American Amazon countries: Brazil, Colombia, Peru and the Bolivarian Republic of Venezuela. Challenges to continuing efforts to further decrease malaria incidence in this region include: a significant increase in malaria cases in recent years in Venezuela, evidence of submicroscopic and asymptomatic infections, peri-urban malaria, gold mining-related malaria, malaria in pregnancy, glucose-6-phosphate dehydrogenase (G6PD) deficiency and primaquine use, and possible under-detection of Plasmodium malariae. Some of these challenges underscore the need to implement appropriate tools and procedures in specific regions, such as a field-compatible molecular malaria test, a P. malariae-specific test, malaria diagnosis and appropriate treatment as part of regular antenatal care visits, G6PD test before primaquine administration for P. vivax cases (with weekly primaquine regimen for G6PD deficient individuals), single low dose of primaquine for P. falciparum malaria in Colombia, and national and regional efforts to contain malaria spread in Venezuela urgently needed especially in mining areas. Joint efforts and commitment towards malaria control and elimination should be strategized based on examples of successful regional malaria fighting initiatives, such as PAMAFRO and RAVREDA/AMI.

Acute pancreatitis due to malaria: A case report of five patients and review of literature

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Kundavaram Paul Prabhakar Abhilash

2016-01-01

Full Text Available Malaria is endemic in large parts of India and can cause multiorgan failure and death. Acute pancreatitis as a complication is rare and is potentially fatal. This case series describes five adult patients between 2005 and 2010 who presented with a short duration febrile illness and diagnosed to have malaria with acute pancreatitis. The mean age of the five patients with acute pancreatitis was 40.4 years and four of them were males. None of them were alcohol consumers and did not have any other risk factor for acute pancreatitis. Plasmodium falciparum was responsible for all the cases. Pancreatic enzymes were significantly elevated in all the patients with a mean serum lipase level of 1795 U/L (normal value: 1.4 mg/dl, and hyperbilirubinemia were seen in all the patients. One patient died due to multiorgan failure. Acute pancreatitis is a very rare complication of malaria, and a high index of suspicion is required in patients presenting with severe malaria and abdominal pain.

Enzyme-linked immunosorbent assays for detection of equine antibodies specific to Sarcocystis neurona surface antigens.

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Hoane, Jessica S; Morrow, Jennifer K; Saville, William J; Dubey, J P; Granstrom, David E; Howe, Daniel K

2005-09-01

Sarcocystis neurona is the primary causative agent of equine protozoal myeloencephalitis (EPM), a common neurologic disease of horses in the Americas. We have developed a set of enzyme-linked immunosorbent assays (ELISAs) based on the four major surface antigens of S. neurona (SnSAGs) to analyze the equine antibody response to S. neurona. The SnSAG ELISAs were optimized and standardized with a sample set of 36 equine sera that had been characterized by Western blotting against total S. neurona parasite antigen, the current gold standard for S. neurona serology. The recombinant SnSAG2 (rSnSAG2) ELISA showed the highest sensitivity and specificity at 95.5% and 92.9%, respectively. In contrast, only 68.2% sensitivity and 71.4% specificity were achieved with the rSnSAG1 ELISA, indicating that this antigen may not be a reliable serological marker for analyzing antibodies against S. neurona in horses. Importantly, the ELISA antigens did not show cross-reactivity with antisera to Sarcocystis fayeri or Neospora hughesi, two other equine parasites. The accuracy and reliability exhibited by the SnSAG ELISAs suggest that these assays will be valuable tools for examining the equine immune response against S. neurona infection, which may help in understanding the pathobiology of this accidental parasite-host interaction. Moreover, with modification and further investigation, the SnSAG ELISAs have potential for use as immunodiagnostic tests to aid in the identification of horses affected by EPM.

Enzyme-Linked Immunosorbent Assays for Detection of Equine Antibodies Specific to Sarcocystis neurona Surface Antigens†

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Hoane, Jessica S.; Morrow, Jennifer K.; Saville, William J.; Dubey, J. P.; Granstrom, David E.; Howe, Daniel K.

2005-01-01

Sarcocystis neurona is the primary causative agent of equine protozoal myeloencephalitis (EPM), a common neurologic disease of horses in the Americas. We have developed a set of enzyme-linked immunosorbent assays (ELISAs) based on the four major surface antigens of S. neurona (SnSAGs) to analyze the equine antibody response to S. neurona. The SnSAG ELISAs were optimized and standardized with a sample set of 36 equine sera that had been characterized by Western blotting against total S. neurona parasite antigen, the current gold standard for S. neurona serology. The recombinant SnSAG2 (rSnSAG2) ELISA showed the highest sensitivity and specificity at 95.5% and 92.9%, respectively. In contrast, only 68.2% sensitivity and 71.4% specificity were achieved with the rSnSAG1 ELISA, indicating that this antigen may not be a reliable serological marker for analyzing antibodies against S. neurona in horses. Importantly, the ELISA antigens did not show cross-reactivity with antisera to Sarcocystis fayeri or Neospora hughesi, two other equine parasites. The accuracy and reliability exhibited by the SnSAG ELISAs suggest that these assays will be valuable tools for examining the equine immune response against S. neurona infection, which may help in understanding the pathobiology of this accidental parasite-host interaction. Moreover, with modification and further investigation, the SnSAG ELISAs have potential for use as immunodiagnostic tests to aid in the identification of horses affected by EPM. PMID:16148170

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

Pistachio (Pistacia vera L.) Detection and Quantification Using a Murine Monoclonal Antibody-Based Direct Sandwich Enzyme-Linked Immunosorbent Assay.

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Liu, Changqi; Chhabra, Guneet S; Sathe, Shridhar K

2015-10-21

A commercially available direct sandwich enzyme-linked immunosorbent assay (ELISA) (BioFront Technologies, Tallahassee, FL, USA) using murine anti-pistachio monoclonal antibodies (mAbs) as capture and detection antibodies was evaluated. The assay was sensitive (limit of detection = 0.09 ± 0.02 ppm full fat pistachio, linear detection range = 0.5-36 ppm, 50% maximum signal concentration = 7.9 ± 0.7 ppm), reproducible (intra- and inter-assay variability pistachio seeds subjected to autoclaving (121 °C, 15 psi, 15, 30 min), blanching (100 °C, 5, 10 min), frying (191 °C, 1 min), microwaving (500, 1000 W, 3 min), and dry roasting (140 °C, 30 min; 168 °C, 12 min). No cross-reactivity was observed in 156 food matrices, each tested at 100,000 ppm, suggesting the ELISA to be pistachio specific. The pistachio recovery ranges for spiked (10 ppm) and incurred (10-50000 ppm) food matrices were 93.1-125.6% and 35.7-112.2%, respectively. The assay did not register any false-positive or -negative results among the tested commercial and laboratory prepared samples.

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

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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.

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

NARCIS (Netherlands)

Jones, S; Grignard, L.; Nebie, I.; Chilongola, J.; Dodoo, D.; Sauerwein, R.W.; Theisen, M.; Roeffen, W.F.; Singh, S.K; Singh, R.K.; Kyei-Baafour, E.; Tetteh, K.; Drakeley, C.; Bousema, T.

2015-01-01

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 for the

Assessment of climate-driven variations in malaria incidence in Swaziland: toward malaria elimination.

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Chuang, Ting-Wu; Soble, Adam; Ntshalintshali, Nyasatu; Mkhonta, Nomcebo; Seyama, Eric; Mthethwa, Steven; Pindolia, Deepa; Kunene, Simon

2017-06-01

Swaziland aims to eliminate malaria by 2020. However, imported cases from neighbouring endemic countries continue to sustain local parasite reservoirs and initiate transmission. As certain weather and climatic conditions may trigger or intensify malaria outbreaks, identification of areas prone to these conditions may aid decision-makers in deploying targeted malaria interventions more effectively. Malaria case-surveillance data for Swaziland were provided by Swaziland's National Malaria Control Programme. Climate data were derived from local weather stations and remote sensing images. Climate parameters and malaria cases between 2001 and 2015 were then analysed using seasonal autoregressive integrated moving average models and distributed lag non-linear models (DLNM). The incidence of malaria in Swaziland increased between 2005 and 2010, especially in the Lubombo and Hhohho regions. A time-series analysis indicated that warmer temperatures and higher precipitation in the Lubombo and Hhohho administrative regions are conducive to malaria transmission. DLNM showed that the risk of malaria increased in Lubombo when the maximum temperature was above 30 °C or monthly precipitation was above 5 in. In Hhohho, the minimum temperature remaining above 15 °C or precipitation being greater than 10 in. might be associated with malaria transmission. This study provides a preliminary assessment of the impact of short-term climate variations on malaria transmission in Swaziland. The geographic separation of imported and locally acquired malaria, as well as population behaviour, highlight the varying modes of transmission, part of which may be relevant to climate conditions. Thus, the impact of changing climate conditions should be noted as Swaziland moves toward malaria elimination.

Malaria in Children.

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Cohee, Lauren M; Laufer, Miriam K

2017-08-01

Malaria is a leading cause of morbidity and mortality in endemic areas, leading to an estimated 438,000 deaths in 2015. Malaria is also an important health threat to travelers to endemic countries and should be considered in evaluation of any traveler returning from a malaria-endemic area who develops fever. Considering the diagnosis of malaria in patients with potential exposure is critical. Prompt provision of effective treatment limits the complications of malaria and can be life-saving. Understanding Plasmodium species variation, epidemiology, and drug-resistance patterns in the geographic area where infection was acquired is important for determining treatment choices. Copyright © 2017 Elsevier Inc. All rights reserved.

A rat monoclonal antibody that recognizes pro- and active MMP-7 indicates polarized expression in vivo

DEFF Research Database (Denmark)

Fingleton, Barbara; Powell, William C; Crawford, Howard C

2007-01-01

Matrix metalloproteinases (MMPs) are a family of enzymes named for their ability to degrade proteins of the extracellular matrix. Here we describe the characterization of a rat monoclonal antibody specifically recognizing one member of this enzyme family, MMP-7. This antibody has been tested...... for its use in multiple assay types and was shown to be useful for direct enzyme-linked immunosorbent assay (ELISA), Western blotting, immunocytochemistry, and immunohistochemistry of frozen or paraffin-embedded tissues. The antibody has been evaluated for its usefulness with tissues from several...

Usefulness of enzyme immunoassay (EIA) for screening of anti HIV antibodies in urinary specimens: A comparative analysis.

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Sahni, A K; Nagendra, A; Roy, Partha; Patrikar, S

2014-07-01

Standard HIV testing is done using serum or plasma. FDA approved ELISA to screen urine for IgG antibodies to HIV-1 in 1996. It is a simple, noninvasive test and is appropriate for developing countries where health care personnel may not be professionally trained or where clean needles for drawing blood may not always be available. 436 individuals with high-risk behavior and strong clinical suspicion of HIV infection were screened for IgG antibodies to HIV-1 in urine by ELISA. Urine HIV testing was performed by enzyme immunoassay, at the ongoing Voluntary Confidential Counseling and Testing Center (VCCTC) at a large tertiary care microbiology lab. The individuals enrolled for the study had high-risk exposure to the virus and majorities were from a state with a high incidence of HIV infection. In all individuals, both serum and urine were tested for IgG antibodies to HIV-1. Overall, 135 individuals (30.96%) were HIV-positive, of whom 96 (71%) had never previously tested positive; 87% of those who tested positive received their results, and most were referred for medical care. Sensitivity, specificity and predictive values of HIV-1 urine ELISA test kit were determined. Sensitivity was found to be 89.6%; 95% CI [82.9-94.0], specificity 97.3%; 95% CI [94.6-98.8], positive predictive value 93.8%; 95% CI [87.8-97.1] and negative predictive value 95.4%; 95% CI [92.3-97.4]. Efficiency, sensitivity, and specificity of the urine-based screening for HIV-1 test kits were excellent as compared to the reference test.

Safety, immunogenicity and duration of protection of the RTS,S/AS02(D malaria vaccine: one year follow-up of a randomized controlled phase I/IIb trial.

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Pedro Aide

2010-11-01

Full Text Available The RTS,S/AS02(D vaccine has been shown to have a promising safety profile, to be immunogenic and to confer protection against malaria in children and infants.We did a randomized, controlled, phase I/IIb trial of RTS,S/AS02(D given at 10, 14 and 18 weeks of age staggered with routine immunization vaccines in 214 Mozambican infants. The study was double-blind until the young child completed 6 months of follow-up over which period vaccine efficacy against new Plasmodium falciparum infections was estimated at 65.9% (95% CI 42.6-79.8, p<0.0001. We now report safety, immunogenicity and estimated efficacy against clinical malaria up to 14 months after study start. Vaccine efficacy was assessed using Cox regression models. The frequency of serious adverse events was 32.7% in the RTS,S/AS02(D and 31.8% in the control group. The geometric mean titers of anti-circumsporozoite antibodies declined from 199.9 to 7.3 EU/mL from one to 12 months post dose three of RTS,S/AS02(D, remaining 15-fold higher than in the control group. Vaccine efficacy against clinical malaria was 33% (95% CI: -4.3-56.9, p = 0.076 over 14 months of follow-up. The hazard rate of disease per 2-fold increase in anti-CS titters was reduced by 84% (95% CI 35.1-88.2, p = 0.003.The RTS,S/AS02(D malaria vaccine administered to young infants has a good safety profile and remains efficacious over 14 months. A strong association between anti-CS antibodies and risk of clinical malaria has been described for the first time. The results also suggest a decrease of both anti-CS antibodies and vaccine efficacy over time.ClinicalTrials.gov NCT00197028.

Autoimmune hemolytic anemia in a patient with Malaria

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Rajesh Sonani

2013-01-01

Full Text Available Autoimmune Hemolytic Anemia (AIHA, a very infrequent condition which represents a group of disorders in which presence of autoantibodies directed against self-antigens leads to shortened red cell survival. Till date, a very few cases of AIHA in Malaria patients are reported worldwide but still AIHA should be considered a relatively rare cause of anemia in malaria. A 20 year male presented with intermittent fever since seven days and yellowish discoloration of urine and sclera since 5 days. He was transfused three units of blood at a private clinic before one month. On examination, pallor, icterus and spelnomegaly were present. Hemoglobin (Hb was 3.2 gm% and peripheral smear revealed ring forms of both Plasmodium vivax and Plasmodium falciparum. Serum LDH and Serum billirubin (Indirect and Direct were high. This patient′s blood group was B +ve with positive autocontrol. Indirect Antiglobulin Test (IAT, antibody screening and antibody identification were pan-positive with reaction strength of +4 against each cell. Direct Antiglobulin Test was +4 positive anti IgG and negative with anti C3. He was treated with Artesunate and methylprednisone. Least incompatible, saline washed O Neg and B neg red cells were transfused on the 2 nd day of starting treatment. Hb was raised to 6.1 gm% on 4 th day. Patient was discharged on 9th day with Hb 7.0 gm% with oral tapering dose of steroids. In the above case, patient was suffering from high grade malarial parasitemia with co-existing autoimmune RBC destruction by IgG auto-antibodies which led to sudden drop in Hb and rise in serum LDH and indirect billirubin. Least incompatible packed red cells along with antimalarials and steroids led to clinical improvement. So far, one case report each from India, Korea, Canada and Germany and one case series report of three cases from India have been reported. Under-reporting or rarity of this phenomenon may be accountable for this.

Ranking malaria risk factors to guide malaria control efforts in African highlands.

Science.gov (United States)

Protopopoff, Natacha; Van Bortel, Wim; Speybroeck, Niko; Van Geertruyden, Jean-Pierre; Baza, Dismas; D'Alessandro, Umberto; Coosemans, Marc

2009-11-25

Malaria is re-emerging in most of the African highlands exposing the non immune population to deadly epidemics. A better understanding of the factors impacting transmission in the highlands is crucial to improve well targeted malaria control strategies. A conceptual model of potential malaria risk factors in the highlands was built based on the available literature. Furthermore, the relative importance of these factors on malaria can be estimated through "classification and regression trees", an unexploited statistical method in the malaria field. This CART method was used to analyse the malaria risk factors in the Burundi highlands. The results showed that Anopheles density was the best predictor for high malaria prevalence. Then lower rainfall, no vector control, higher minimum temperature and houses near breeding sites were associated by order of importance to higher Anopheles density. In Burundi highlands monitoring Anopheles densities when rainfall is low may be able to predict epidemics. The conceptual model combined with the CART analysis is a decision support tool that could provide an important contribution toward the prevention and control of malaria by identifying major risk factors.

Knowledge of malaria and practice of home management of malaria ...

African Journals Online (AJOL)

Background: Malaria is a preventable and treatable disease associated with high morbidity and mortality. It is the 3rd leading cause of death for children under five years worldwide. Home-based management of malaria may go a long way in reducing the attending morbidity and mortality associated with malaria in this group ...

Antibody recognition of Plasmodium falciparum infected red blood cells by symptomatic and asymptomatic individuals in the Brazilian Amazon

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Fratus, Alessandra Sampaio Bassi; Cabral, Fernanda Janku; Fotoran, Wesley Luzetti; Medeiros, Márcia Melo; Carlos, Bianca Cechetto; Martha, Rosimeire dalla; da Silva, Luiz Hildebrando Pereira; Lopes, Stefanie Costa Pinto; Costa, Fabio Trindade Maranhão; Wunderlich, Gerhard

2014-01-01

In the Amazon Region, there is a virtual absence of severe malaria and few fatal cases of naturally occurring Plasmodium falciparum infections; this presents an intriguing and underexplored area of research. In addition to the rapid access of infected persons to effective treatment, one cause of this phenomenon might be the recognition of cytoadherent variant proteins on the infected red blood cell (IRBC) surface, including the var gene encoded P. falciparum erythrocyte membrane protein 1. In order to establish a link between cytoadherence, IRBC surface antibody recognition and the presence or absence of malaria symptoms, we phenotype-selected four Amazonian P. falciparum isolates and the laboratory strain 3D7 for their cytoadherence to CD36 and ICAM1 expressed on CHO cells. We then mapped the dominantly expressed var transcripts and tested whether antibodies from symptomatic or asymptomatic infections showed a differential recognition of the IRBC surface. As controls, the 3D7 lineages expressing severe disease-associated phenotypes were used. We showed that there was no profound difference between the frequency and intensity of antibody recognition of the IRBC-exposed P. falciparum proteins in symptomatic vs. asymptomatic infections. The 3D7 lineages, which expressed severe malaria-associated phenotypes, were strongly recognised by most, but not all plasmas, meaning that the recognition of these phenotypes is frequent in asymptomatic carriers, but is not necessarily a prerequisite to staying free of symptoms. PMID:25099336

Avidity of anti-malarial antibodies inversely related to transmission intensity at three sites in Uganda.

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Ssewanyana, Isaac; Arinaitwe, Emmanuel; Nankabirwa, Joaniter I; Yeka, Adoke; Sullivan, Richard; Kamya, Moses R; Rosenthal, Philip J; Dorsey, Grant; Mayanja-Kizza, Harriet; Drakeley, Chris; Greenhouse, Bryan; Tetteh, Kevin K A

2017-02-10

People living in malaria endemic areas acquire protection from severe malaria quickly, but protection from clinical disease and control of parasitaemia is acquired only after many years of repeated infections. Antibodies play a central role in protection from clinical disease; however, protective antibodies are slow to develop. This study sought to investigate the influence of Plasmodium falciparum exposure on the acquisition of high-avidity antibodies to P. falciparum antigens, which may be associated with protection. Cross-sectional surveys were performed in children and adults at three sites in Uganda with varied P. falciparum transmission intensity (entomological inoculation rates; 3.8, 26.6, and 125 infectious bites per person per year). Sandwich ELISA was used to measure antibody responses to two P. falciparum merozoite surface antigens: merozoite surface protein 1-19 (MSP1-19) and apical membrane antigen 1 (AMA1). In individuals with detectable antibody levels, guanidine hydrochloride (GuHCl) was added to measure the relative avidity of antibody responses by ELISA. Within a site, there were no significant differences in median antibody levels between the three age groups. Between sites, median antibody levels were generally higher in the higher transmission sites, with differences more apparent for AMA-1 and in ≥5 year group. Similarly, median avidity index (proportion of high avidity antibodies) showed no significant increase with increasing age but was significantly lower at sites of higher transmission amongst participants ≥5 years of age. Using 5 M GuHCl, the median avidity indices in the ≥5 year group at the highest and lowest transmission sites were 19.9 and 26.8, respectively (p = 0.0002) for MSP1-19 and 12.2 and 17.2 (p = 0.0007) for AMA1. Avidity to two different P. falciparum antigens was lower in areas of high transmission intensity compared to areas with lower transmission. Appreciation of the mechanisms behind these findings as

Malaria infectivity of xanthurenic acid-deficient anopheline mosquitoes produced by TALEN-mediated targeted mutagenesis.

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Yamamoto, Daisuke S; Sumitani, Megumi; Hatakeyama, Masatsugu; Matsuoka, Hiroyuki

2018-02-01

Anopheline mosquitoes are major vectors of malaria parasites. When the gametocytes of the malaria parasite are transferred from a vertebrate to mosquitoes, they differentiate into gametes, and are fertilized in the midguts of mosquitoes. Xanthurenic acid (XA), a waste product of the ommochrome synthesis pathway, has been shown to induce exflagellation during microgametogenesis in vitro; however, it currently remains unclear whether endogenous XA affects the infectivity of anopheline mosquitoes to malaria parasites in vivo due to the lack of appropriate experimental systems such as a XA-deficient line. In the present study, we produced a XA-deficient line in Anopheles stephensi using transcription activator-like effector nuclease (TALEN)-mediated gene targeting (knockout) of the kynurenine 3-monooxygenase (kmo) gene, which encodes an enzyme that participates in the ommochrome synthesis pathway. The knockout of kmo resulted in the absence of XA, and oocyst formation was inhibited in the midguts of these XA-deficient mosquitoes, which, in turn, reduced sporozoite numbers in their salivary glands. These results suggest that endogenous XA stimulates exflagellation, and enhances the infectivity of anopheline mosquitoes to malaria parasites in vivo. The XA-deficient line of the anopheline mosquito provides a useful system for analyzing and understanding the associated factors of malaria gametogenesis in the mosquito midgut.

Pitting of malaria parasites and spherocyte formation

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Gichuki Charity W

2006-07-01

Full Text Available Abstract Background A high prevalence of spherocytes was detected in blood smears of children enrolled in a case control study conducted in the malaria holoendemic Lake Victoria basin. It was speculated that the spherocytes reflect intraerythrocytic removal of malarial parasites with a concurrent removal of RBC membrane through a process analogous to pitting of intraerythrocytic inclusion bodies. Pitting and re-circulation of RBCs devoid of malaria parasites could be a host mechanism for parasite clearance while minimizing the anaemia that would occur were the entire parasitized RBC removed. The prior demonstration of RBCs containing ring-infected erythrocyte surface antigen (pf 155 or RESA but no intracellular parasites, support the idea of pitting. Methods An in vitro model was developed to examine the phenomenon of pitting and spherocyte formation in Plasmodium falciparum infected RBCs (iRBC co-incubated with human macrophages. In vivo application of this model was evaluated using blood specimens from patients attending Kisumu Ditrict Hospital. RBCs were probed with anti-RESA monoclonal antibody and a DNA stain (propidium iodide. Flow cytometry and fluorescent microscopy was used to compare RBCs containing both the antigen and the parasites to those that were only RESA positive. Results Co-incubation of iRBC and tumor necrosis factor-alpha activated macrophages led to pitting (14% ± 1.31% macrophages with engulfed trophozoites as opposed to erythrophagocytosis (5.33% ± 0.95% (P Conclusion It is proposed that in malaria holoendemic areas where prevalence of asexual stage parasites approaches 100% in children, RBCs with pitted parasites are re-circulated and pitting may produce spherocytes.

[Congenital malaria due to Plasmodium falciparum and Plasmodium malariae].

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Zenz, W; Trop, M; Kollaritsch, H; Reinthaler, F

2000-05-19

Increasing tourism and growing numbers of immigrants from malaria-endemic countries are leading to a higher importation rate of rare tropical disorders in European countries. We describe, to the best of our knowledge, the first case of connatal malaria in Austria. The patient is the first child of a 24 year old mother who was born in Ghana and immigrated to Austria one and a half years before delivery. She did not stay in an endemic region during this period and did not show fever or any other signs of malaria. The boy was healthy for the first six weeks of his life. In the 8th week of life he was admitted to our hospital due to persistent fever of unknown origin. On physical examination he showed only mild splenomegaly. Routine laboratory testing revealed mild hemolytic anemia with a hemoglobin value of 8.3 g/l. In the blood smear Plasmodium falciparum and Plasmodium malariae were detected. Oral therapy with quinine hydrochloride was successful and blood smears became negative for Plasmodia within 6 days. This case shows that congenital malaria can occur in children of clinically healthy women who were born in malaria-endemic areas even one and a half year after they have immigrated to non-endemic regions.

Ranking malaria risk factors to guide malaria control efforts in African highlands.

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Natacha Protopopoff

Full Text Available INTRODUCTION: Malaria is re-emerging in most of the African highlands exposing the non immune population to deadly epidemics. A better understanding of the factors impacting transmission in the highlands is crucial to improve well targeted malaria control strategies. METHODS AND FINDINGS: A conceptual model of potential malaria risk factors in the highlands was built based on the available literature. Furthermore, the relative importance of these factors on malaria can be estimated through "classification and regression trees", an unexploited statistical method in the malaria field. This CART method was used to analyse the malaria risk factors in the Burundi highlands. The results showed that Anopheles density was the best predictor for high malaria prevalence. Then lower rainfall, no vector control, higher minimum temperature and houses near breeding sites were associated by order of importance to higher Anopheles density. CONCLUSIONS: In Burundi highlands monitoring Anopheles densities when rainfall is low may be able to predict epidemics. The conceptual model combined with the CART analysis is a decision support tool that could provide an important contribution toward the prevention and control of malaria by identifying major risk factors.

Malaria and mefloquine prophylaxis use among Japan Ground Self-Defense Force personnel deployed in East Timor.

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Fujii, Tatsuya; Kaku, Koki; Jelinek, Tomas; Kimura, Mikio

2007-01-01

Malaria poses a significant threat to military personnel stationed in endemic areas; therefore, it is important to examine the risks of military operations, particularly in areas where malaria-related data are scarce. The recent deployment of Japan Ground Self-Defense Force (JGSDF) for a peacekeeping operation in East Timor provided an opportunity to investigate these risks. The results of these studies may be translated into chemoprophylactic strategies for travelers. A total of 1,876 members were deployed between April 2002 and September 2003. They consisted of three battalions; each remained for 6 months and was put on mefloquine prophylaxis. Malaria infection was investigated, including exposure to Plasmodium falciparum sporozoites, assessed by seroconversion for anticircumsporozoite (anti-CS) protein antibodies. Adherence to and adverse events (AEs) of mefloquine were studied via questionnaires. Four members were evacuated: one each with optic neuritis, lung cancer with brain metastasis, IgA nephropathy, and psychotic reactions that may have been precipitated by mefloquine. Six clinical episodes of Plasmodium vivax occurred, including one relapse, but there were no clinical cases of P falciparum, yielding a crude malaria attack rate of 0.32% for the 6-month period. Overall, 3.1% of the study population seroconverted for the anti-CS protein antibodies, with some regional differences noted. About 24% of questionnaire respondents, reported AEs; however, none of the AEs was severe. The AEs tended to emerge during the initial doses of chemoprophylaxis. The implementation of mefloquine prophylaxis among JGSDF personnel in East Timor, where P falciparum constitutes a moderate risk, appears to have been a success. Mefloquine prophylaxis was generally safe for Japanese unless predisposed to neuropsychiatric illness. However, given that mefloquine is the only chemoprophylactic agent available, a risk-benefit analysis tailored to the traveler is required for visits to

Clinical Comparison of the Treponema pallidum CAPTIA Syphilis-G Enzyme Immunoassay with the Fluorescent Treponemal Antibody Absorption Immunoglobulin G Assay for Syphilis Testing

OpenAIRE

Halling, V. W.; Jones, M. F.; Bestrom, J. E.; Wold, A. D.; Rosenblatt, J. E.; Smith, T. F.; Cockerill, F. R.

1999-01-01

Recently, a treponema-specific immunoglobulin G (IgG) enzyme immunoassay (EIA), the CAPTIA Syphilis-G (Trinity Biotech, Jamestown, N.Y.), has become available as a diagnostic test for syphilis. A total of 89 stored sera previously tested by the fluorescent treponemal antibody absorption (FTA-ABS) IgG assay were evaluated by the CAPTIA EIA. The FTA-ABS IgG procedure was performed by technologists unblinded to results of rapid plasmid reagin (RPR) testing of the same specimens. Borderline CAPTI...

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.

Rapid urban malaria appraisal (RUMA I: Epidemiology of urban malaria in Ouagadougou

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Convelbo Natalie

2005-09-01

Full Text Available Abstract Background Rapid urbanization in sub-Saharan Africa has a major impact on malaria epidemiology. While much is known about malaria in rural areas in Burkina Faso, the urban situation is less well understood. Methods An assessment of urban malaria was carried out in Ouagadougou in November -December, 2002 during which a rapid urban malaria appraisal (RUMA was applied. Results The school parasitaemia prevalence was relatively high (48.3% at the cold and dry season 2002. Routine malaria statistics indicated that seasonality of malaria transmission was marked. In the health facilities, the number of clinical cases diminished quickly at the start of the cold and dry season and the prevalence of parasitaemia detected in febrile and non-febrile cases was 21.1% and 22.0%, respectively. The health facilities were likely to overestimate the malaria incidence and the age-specific fractions of malaria-attributable fevers were low (0–0.13. Peak prevalence tended to occur in older children (aged 6–15 years. Mapping of Anopheles sp. breeding sites indicated a gradient of endemicity between the urban centre and the periphery of Ouagadougou. A remarkable link was found between urban agriculture activities, seasonal availability of water supply and the occurrence of malaria infections in this semi-arid area. The study also demonstrated that the usage of insecticide-treated nets and the education level of family caretakers played a key role in reducing malaria infection rates. Conclusion These findings show that determining local endemicity and the rate of clinical malaria cases are urgently required in order to target control activities and avoid over-treatment with antimalarials. The case management needs to be tailored to the level of the prevailing endemicity.

Modulation of Malaria Phenotypes by Pyruvate Kinase (PKLR Variants in a Thai Population.

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Rebekah van Bruggen

Full Text Available Pyruvate kinase (PKLR is a critical erythrocyte enzyme that is required for glycolysis and production of ATP. We have shown that Pklr deficiency in mice reduces the severity (reduced parasitemia, increased survival of blood stage malaria induced by infection with Plasmodium chabaudi AS. Likewise, studies in human erythrocytes infected ex vivo with P. falciparum show that presence of host PK-deficiency alleles reduces infection phenotypes. We have characterized the genetic diversity of the PKLR gene, including haplotype structure and presence of rare coding variants in two populations from malaria endemic areas of Thailand and Senegal. We investigated the effect of PKLR genotypes on rich longitudinal datasets including haematological and malaria-associated phenotypes. A coding and possibly damaging variant (R41Q was identified in the Thai population with a minor allele frequency of ~4.7%. Arginine 41 (R41 is highly conserved in the pyruvate kinase family and its substitution to Glutamine (R41Q affects protein stability. Heterozygosity for R41Q is shown to be associated with a significant reduction in the number of attacks with Plasmodium falciparum, while correlating with an increased number of Plasmodium vivax infections. These results strongly suggest that PKLR protein variants may affect the frequency, and the intensity of malaria episodes induced by different Plasmodium parasites in humans living in areas of endemic malaria.

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.

Analysis of antibodies to newly described Plasmodium falciparum merozoite antigens supports MSPDBL2 as a predicted target of naturally acquired immunity.

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Tetteh, Kevin K A; Osier, Faith H A; Salanti, Ali; Kamuyu, Gathoni; Drought, Laura; Failly, Marilyne; Martin, Christophe; Marsh, Kevin; Conway, David J

2013-10-01

Prospective studies continue to identify malaria parasite genes with particular patterns of polymorphism which indicate they may be under immune selection, and the encoded proteins require investigation. Sixteen new recombinant protein reagents were designed to characterize three such polymorphic proteins expressed in Plasmodium falciparum schizonts and merozoites: MSPDBL1 (also termed MSP3.4) and MSPDBL2 (MSP3.8), which possess Duffy binding-like (DBL) domains, and SURFIN4.2, encoded by a member of the surface-associated interspersed (surf) multigene family. After testing the antigenicities of these reagents by murine immunization and parasite immunofluorescence, we analyzed naturally acquired antibody responses to the antigens in two cohorts in coastal Kenya in which the parasite was endemic (Chonyi [n = 497] and Ngerenya [n = 461]). As expected, the prevalence and levels of serum antibodies increased with age. We then investigated correlations with subsequent risk of clinical malaria among children <11 years of age during 6 months follow-up surveillance. Antibodies to the polymorphic central region of MSPDBL2 were associated with reduced risk of malaria in both cohorts, with statistical significance remaining for the 3D7 allelic type after adjustment for individuals' ages in years and antibody reactivity to whole-schizont extract (Chonyi, risk ratio, 0.51, and 95% confidence interval [CI], 0.28 to 0.93; Ngerenya, risk ratio, 0.38, and 95% CI, 0.18 to 0.82). For the MSPDBL1 Palo Alto allelic-type antigen, there was a protective association in one cohort (Ngerenya, risk ratio, 0.53, and 95% CI, 0.32 to 0.89), whereas the other antigens showed no protective associations after adjustment. These findings support the prediction that antibodies to the polymorphic region of MSPDBL2 contribute to protective immunity.

Humoral and cellular immune responses to glucose regulated protein 78 - a novel Leishmania donovani antigen

DEFF Research Database (Denmark)

Jensen, Anja T R; Ismail, Ahmed; Gaafar, Ameera

2002-01-01

The recently cloned glucose regulated protein 78 (GRP78) of Leishmania donovani has been suggested as a new and promising Leishmania vaccine candidate. We assessed antibody and T-cell reactivity to GRP78 in an enzyme-linked immunosorbent assay (ELISA) and in lymphoproliferative assays. Serological...... with a positive leishmanin skin test showed antibody reactivity to recombinant GRP78 (rGRP78). In lymphoproliferative assays, 9 of 13 isolates of peripheral blood mononuclear cells (PBMC) from individuals previously infected with L. donovani and one of three individuals previously infected with L. major showed...... in an area endemic for malaria but free of leishmaniasis and plasma from healthy Danes was negative in the assay. GRP78 antibody was detected in 10% and 5% of plasma samples from Sudanese and Ghanaian malaria patients, respectively, whereas 35% of plasma samples from otherwise healthy Sudanese individuals...

Assay for the specificity of monoclonal antibodies in crossed immunoelectrophoresis

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Skjødt, K; Schou, C; Koch, C

1984-01-01

A method is described based on crossed immunoelectrophoresis of a complex antigen mixture in agarose gel followed by incubation of the gel with the monoclonal antibody. The bound monoclonal antibody is detected by the use of a secondary enzyme-labelled antibody. Using this technique we have been ...... I molecules. In other experiments using the same technique we demonstrated the reaction of a monoclonal antibody specific for chicken Ig light chains. Udgivelsesdato: 1984-Aug-3...

Association of haptoglobin phenotypes with susceptibility to Falciparum Malaria in Sudan

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Elagib, Atif Abdel Rahman

1999-09-01

The predisposing factors for the development of serious and diverse complications caused by falciparum are not very well understood. The search for host molecular markers which the disease presentation and prognosis, is an important issue in malaria research. Along this time line, the haptoglobin phenotype of Sudanese individuals infected with falciparum malaria both complicated and non-complicated, and non-infected controls, from randomly selected individuals were determined. Anti-human Haptoglobin antibodies was radiolabelled with 125 I , using chloramine T-method.Haptoglobin phenotype determination was performed by electrophoresis separation of sera on polyacrylamide gel followed by benzidine staining, which was shown to be time and material saving, and as sensitive as Western blotting. The distribution of the haptoglobin (1-1), (2-1) among 273 uncomplicated falicparm malaria patients, was found to be 60.8%, 29.2% and 6.9%, respectively. The distribution among 208 randomly selected individuals infected with falciparm malaria both controls, from randomly selected individuals were determined. Hyptogolobin phenotype was performed by electrophoresis separation of sera on polyacrylamide gel followed by benzidine staining, which was shown to be time and material saving, and as sensitive as Western blotting. The distribution of the haptoglobin phenotypes (1-1), (2-1) and (2-2) among 273 uncomplicated facilparum malaria patients, was found to be 60.8 % , 29.7 % and 6.9 %, respectively. The distribution among 208 randomly selected healthy controls was 26.0 %, 55.8 % and 18.3 % respectively . The results show that the number of individuals with haptoglobin phentype (1-1) is significantly higher among patients with falcilparum malaria (complicated and complicated) when compared to the controls. However, the controls showed a normal distribution of the phenotypes comparable to available data obtained from similar African populations. Consequently, we suggest that the

The economic burden of malaria.

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Gallup, J L; Sachs, J D

2001-01-01

Malaria and poverty are intimately connected. Controlling for factors such as tropical location, colonial history, and geographical isolation, countries with intensive malaria had income levels in 1995 of only 33% that of countries without malaria, whether or not the countries were in Africa. The high levels of malaria in poor countries are not mainly a consequence of poverty. Malaria is geographically specific. The ecological conditions that support the more efficient malaria mosquito vectors primarily determine the distribution and intensity of the disease. Intensive efforts to eliminate malaria in the most severely affected tropical countries have been largely ineffective. Countries that have eliminated malaria in the past half century have all been either subtropical or islands. These countries' economic growth in the 5 years after eliminating malaria has usually been substantially higher than growth in the neighboring countries. Cross-country regressions for the 1965-1990 period confirm the relationship between malaria and economic growth. Taking into account initial poverty, economic policy, tropical location, and life expectancy, among other factors, countries with intensive malaria grew 1.3% less per person per year, and a 10% reduction in malaria was associated with 0.3% higher growth. Controlling for many other tropical diseases does not change the correlation of malaria with economic growth, and these diseases are not themselves significantly negatively correlated with economic growth. A second independent measure of malaria has a slightly higher correlation with economic growth in the 1980-1996 period. We speculate about the mechanisms that could cause malaria to have such a large impact on the economy, such as foreign investment and economic networks within the country.

Enzyme immunoassay for measurement of murine plasminogen activator inhibitor-1, employing a specific antibody produced by the DNA vaccine method.

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Yamada, Takayuki; Takagi, Akira; Takeshita, Kyosuke; Yamamoto, Koji; Ito, Masafumi; Matsushita, Tadashi; Murate, Takashi; Saito, Hidehiko; Kojima, Tetsuhito

2003-01-01

We developed a sensitive immunoassay to determine the concentration of mouse plasminogen activator inhibitor-1. The assay was a non-competitive sandwich enzyme-linked immunosorbent assay (ELISA) based on the production of a specific polyclonal antibody against mouse plasminogen activator inhibitor type-1 (PAI-1) used both as a trapping and detecting antibody. This antibody was raised in a rabbit by direct introduction of the expression vector plasmid DNA encoding mouse PAI-1, instead of conventional immunization with the purified protein. The standard curve was constructed with a recombinant glutathione S-transferase (GST)-mouse PAI-1 fusion protein (GST-mPAI-1) and dose-response of the assay was linear for GST-mPAI-1 between 6.25 and 100 pM. In order to assess the consistency of the assay, we measured PAI-1 antigen in normal mouse pooled plasma several times. We found that the intra-assay and inter-assay coefficients of variation (CV) were 4.8% and 9.2%, respectively, indicating that the ELISA would be sufficiently repeatable and reproducible. In this assay, lipopolysaccharide (LPS)-injected mice showed substantially higher levels (22-fold) of plasma PAI-1 antigen than did control mice (12.5+/-2.4 vs. 0.58+/-0.16 nM), similar to results reported elsewhere. Taken together, the DNA vaccine method is extremely useful for preparing specific antibodies against mouse PAI-1, which can be utilized to establish the ELISA and analyze the profile of PAI-1 distributions in mice under various conditions. This approach might also be useful for immunological investigation of other coagulation factors and related proteins.

BDA-410: a novel synthetic calpain inhibitor active against blood stage malaria.

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Li, Xuerong; Chen, Huiqing; Jeong, Jong-Jin; Chishti, Athar H

2007-09-01

Falcipains, the papain-family cysteine proteases of the Plasmodium falciparum, are potential drug targets for malaria parasite. Pharmacological inhibition of falcipains can block the hydrolysis of hemoglobin, parasite development, and egress, suggesting that falcipains play a key role at the blood stage of parasite life cycle. In the present study, we evaluated the anti-malarial effects of BDA-410, a novel cysteine protease inhibitor as a potential anti-malarial drug. Recombinant falcipain (MBP-FP-2B) and P. falciparum trophozoite extract containing native falcipains were used for enzyme inhibition studies in vitro. The effect of BDA-410 on the malaria parasite development in vitro as well as its anti-malarial activity in vivo was evaluated using the Plasmodium chabaudi infection rodent model. The 50% inhibitory concentrations of BDA-410 were determined to be 628 and 534nM for recombinant falcipain-2B and parasite extract, respectively. BDA-410 inhibited the malaria parasite growth in vitro with an IC(50) value of 173nM causing irreversible damage to the intracellular parasite. In vivo, the BDA-410 delayed the progression of malaria infection significantly using a mouse model of malaria pathogenesis. The characterization of BDA-410 as a potent inhibitor of P. falciparum cysteine proteases, and the demonstration of its efficacy in blocking parasite growth both in vitro and in vivo assays identifies BDA-410 is an important lead compound for the development of novel anti-malarial drugs.

An ELISA test for the detection of antibodies to Legionella pneumophila.

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Wreghitt, T G; Nagington, J; Gray, J

1982-01-01

An enzyme-linked immunosorbent assay (ELISA) test has been developed to detect antibodies to Legionella pneumophila serogroup 1. There is good correlation between indirect fluorescent antibody (IFA) and ELISA titres but ELISA is more sensitive.

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

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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...

Performance of “VIKIA Malaria Ag Pf/Pan” (IMACCESS®, a new malaria rapid diagnostic test for detection of symptomatic malaria infections

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Chou Monidarin

2012-08-01

Full Text Available Abstract Background Recently, IMACCESS® developed a new malaria test (VIKIA Malaria Ag Pf/Pan™, based on the detection of falciparum malaria (HRP-2 and non-falciparum malaria (aldolase. Methods The performance of this new malaria rapid diagnostic test (RDT was assessed using 1,000 febrile patients seeking malaria treatment in four health centres in Cambodia from August to December 2011. The results of the VIKIA Malaria Ag Pf/Pan were compared with those obtained by microscopy, the CareStart Malaria™ RDT (AccessBio® which is currently used in Cambodia, and real-time PCR (as “gold standard”. Results The best performances of the VIKIA Malaria Ag Pf/Pan™ test for detection of both Plasmodium falciparum and non-P. falciparum were with 20–30 min reading times (sensitivity of 93.4% for P. falciparum and 82.8% for non-P. falciparum and specificity of 98.6% for P. falciparum and 98.9% for non-P. falciparum and were similar to those for the CareStart Malaria™ test. Conclusions This new RDT performs similarly well as other commercially available tests (especially the CareStart Malaria™ test, used as comparator, and conforms to the World Health Organization’s recommendations for RDT performance. It is a good alternative tool for the diagnosis of malaria in endemic areas.

Sensitivity of some Immunoglobulin G class and subclass antibodies ...

African Journals Online (AJOL)

Indirect sandwich enzyme-linked immunosorbent assay (ELISA) was used to measure serum antibody responses in onchocerciasis patients. Apparently, IgG antibody class was more sensitive than IgG1, IgG3 and IgG4 responses to Onchocerca volvulus adult worms sodium duodecyl sulphate (SDS) extracted crude ...

Clinical malaria case definition and malaria attributable fraction in the highlands of western Kenya.

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Afrane, Yaw A; Zhou, Guofa; Githeko, Andrew K; Yan, Guiyun

2014-10-15

In African highland areas where endemicity of malaria varies greatly according to altitude and topography, parasitaemia accompanied by fever may not be sufficient to define an episode of clinical malaria in endemic areas. To evaluate the effectiveness of malaria interventions, age-specific case definitions of clinical malaria needs to be determined. Cases of clinical malaria through active case surveillance were quantified in a highland area in Kenya and defined clinical malaria for different age groups. A cohort of over 1,800 participants from all age groups was selected randomly from over 350 houses in 10 villages stratified by topography and followed for two-and-a-half years. Participants were visited every two weeks and screened for clinical malaria, defined as an individual with malaria-related symptoms (fever [axillary temperature≥37.5°C], chills, severe malaise, headache or vomiting) at the time of examination or 1-2 days prior to the examination in the presence of a Plasmodium falciparum positive blood smear. Individuals in the same cohort were screened for asymptomatic malaria infection during the low and high malaria transmission seasons. Parasite densities and temperature were used to define clinical malaria by age in the population. The proportion of fevers attributable to malaria was calculated using logistic regression models. Incidence of clinical malaria was highest in valley bottom population (5.0% cases per 1,000 population per year) compared to mid-hill (2.2% cases per 1,000 population per year) and up-hill (1.1% cases per 1,000 population per year) populations. The optimum cut-off parasite densities through the determination of the sensitivity and specificity showed that in children less than five years of age, 500 parasites per μl of blood could be used to define the malaria attributable fever cases for this age group. In children between the ages of 5-14, a parasite density of 1,000 parasites per μl of blood could be used to define the

Malaria Research

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... with facebook share with twitter share with linkedin Malaria Go to Information for Researchers ► Credit: NIAID Colorized ... for the disease. Why Is the Study of Malaria a Priority for NIAID? Roughly 3.2 billion ...

Malaria vaccines and their potential role in the elimination of malaria

Directory of Open Access Journals (Sweden)

Greenwood Brian M

2008-12-01

Full Text Available Abstract Research on malaria vaccines is currently directed primarily towards the development of vaccines that prevent clinical malaria. Malaria elimination, now being considered seriously in some epidemiological situations, requires a different vaccine strategy, since success will depend on killing all parasites in the community in order to stop transmission completely. The feature of the life-cycles of human malarias that presents the greatest challenge to an elimination programme is the persistence of parasites as asymptomatic infections. These are an important source from which transmission to mosquitoes can occur. Consequently, an elimination strategy requires a community-based approach covering all individuals and not just those who are susceptible to clinical malaria. The progress that has been made in development of candidate malaria vaccines is reviewed. It is unlikely that many of these will have the efficacy required for complete elimination of parasites, though they may have an important role to play as part of future integrated control programmes. Vaccines for elimination must have a high level of efficacy in order to stop transmission to mosquitoes. This might be achieved with some pre-erythrocytic stage candidate vaccines or by targeting the sexual stages directly with transmission-blocking vaccines. An expanded malaria vaccine programme with such objectives is now a priority.

A global model of malaria climate sensitivity: comparing malaria response to historic climate data based on simulation and officially reported malaria incidence

Directory of Open Access Journals (Sweden)

Edlund Stefan

2012-09-01

Full Text Available Abstract Background The role of the Anopheles vector in malaria transmission and the effect of climate on Anopheles populations are well established. Models of the impact of climate change on the global malaria burden now have access to high-resolution climate data, but malaria surveillance data tends to be less precise, making model calibration problematic. Measurement of malaria response to fluctuations in climate variables offers a way to address these difficulties. Given the demonstrated sensitivity of malaria transmission to vector capacity, this work tests response functions to fluctuations in land surface temperature and precipitation. Methods This study of regional sensitivity of malaria incidence to year-to-year climate variations used an extended Macdonald Ross compartmental disease model (to compute malaria incidence built on top of a global Anopheles vector capacity model (based on 10 years of satellite climate data. The predicted incidence was compared with estimates from the World Health Organization and the Malaria Atlas. The models and denominator data used are freely available through the Eclipse Foundation’s Spatiotemporal Epidemiological Modeller (STEM. Results Although the absolute scale factor relating reported malaria to absolute incidence is uncertain, there is a positive correlation between predicted and reported year-to-year variation in malaria burden with an averaged root mean square (RMS error of 25% comparing normalized incidence across 86 countries. Based on this, the proposed measure of sensitivity of malaria to variations in climate variables indicates locations where malaria is most likely to increase or decrease in response to specific climate factors. Bootstrapping measures the increased uncertainty in predicting malaria sensitivity when reporting is restricted to national level and an annual basis. Results indicate a potential 20x improvement in accuracy if data were available at the level ISO 3166–2

Immune responses during gestational malaria: a review of the current knowledge and future trend of research.

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Maestre, Amanda; Carmona-Fonseca, Jaime

2014-04-15

Women pregnant with their first child are susceptible to severe P. falciparum disease from placental malaria because they lack immunity to placenta-specific cytoadherence proteins. In subsequent pregnancies, as immunity against placental parasites is acquired, there is a reduced risk of adverse effects of malaria on the mother and fetus and asymptomatic parasitaemia is common. In the case of vivax malaria, with increasing reports of severe cases in Asia and South America, the effects of infection by this species during pregnancy remain to be elucidated. This review summarized the main aspects involved in the acquisition of specific antimalarial immune responses during pregnancy with emphasis in research carried out in America and Asia, in order to offer a framework of interpretation for studies on pregnant women with malaria which are recently being produced in these regions. The authors conclude that (1) Effective humoral responses during gestational malaria are mainly directed against variant surface antigens codified by genes of the var2Csa family of P. falciparum; (2) Acquisition of immunity against these variant antigens depends on the degree and intensity of transmission, and the chance increases with age and successive pregnancies; (3) Antibody development is guided by specific cellular immune responses in cases of placental and maternal infection, and (4) The study of the significance of acquisition of specific immunity against both P. falciparum and P. vivax in America, should be performed.

Combined measurement of soluble and cellular ICAM-1 among children with Plasmodium falciparum malaria in Uganda

Directory of Open Access Journals (Sweden)

Cserti-Gazdewich Christine M

2010-08-01

Full Text Available Abstract Background Intercellular adhesion molecule-1 (ICAM-1 is a cytoadhesion molecule implicated in the pathogenesis of Plasmodium falciparum malaria. Elevated levels of soluble ICAM-1 (sICAM-1 have previously been reported with increased malaria disease severity. However, studies have not yet examined both sICAM-1 concentrations and monocyte ICAM-1 expression in the same cohort of patients. To better understand the relationship of soluble and cellular ICAM-1 measurements in malaria, both monocyte ICAM-1 expression and sICAM-1 concentration were measured in children with P. falciparum infection exhibiting a spectrum of clinical severity. Methods Samples were analysed from 160 children, aged 0.5 to 10.8 years, with documented P. falciparum malaria in Kampala, Uganda. The patients belonged to one of three pre-study defined groups: uncomplicated malaria (UM, severe non-fatal malaria (SM-s, and fatal malaria (SM-f. Subset analysis was done on those with cerebral malaria (CM or severe malaria anaemia (SMA. Monocyte ICAM-1 was measured by flow cytometry. sICAM-1 was measured by enzyme immunoassay. Results Both sICAM-1 and monocyte cell-surface ICAM-1 followed a log-normal distribution. Median sICAM-1 concentrations increased with greater severity-of-illness: 279 ng/mL (UM, 462 ng/mL (SM-s, and 586 ng/mL (SM-f, p Conclusion In this cohort of children with P. falciparum malaria, sICAM-1 levels were associated with severity-of-illness. Patients with UM had higher monocyte ICAM-1 expression consistent with a role for monocyte ICAM-1 in immune clearance during non-severe malaria. Among the subsets of patients with either SMA or CM, monocyte ICAM-1 levels were higher in CM, consistent with the role of ICAM-1 as a marker of cytoadhesion. Categories of disease in pediatric malaria may exhibit specific combinations of soluble and cellular ICAM-1 expression.

Oligopeptide-based enzyme immunoassay for ovine lentivirus antibody detection.

OpenAIRE

Kwang, J; Torres, J V

1994-01-01

Ovine progressive pneumonia virus (OPPV) is a lentivirus which causes a progressive disease in sheep. Immunodominant epitopes have been identified in the envelope gp40 glycoprotein. Synthetic peptides representing these regions are able to detect the presence of OPPV antibodies in 96% of infected sheep.

MIGRATION AND MALARIA IN EUROPE

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Begoña Monge-Maillo

2012-03-01

Full Text Available The proportion of imported malaria cases due to immigrants in Europe has increased during the lasts decades, being the higher rates for those settled immigrants who travel to visit friends and relatives (VFRs at their country of origin. Cases are mainly due to P. falciparum and Sub-Saharan Africa is the most common origin. Clinically, malaria in immigrants is characterized by a mild clinical presentation with even asymptomatic o delayed malaria cases and low parasitemic level. These characteristics may be explained by a semi-immunity acquired after long periods of time exposed to stable transmission of malaria. Malaria cases among immigrants, even those asymptomatic patients with sub-microscopic parasitemia, could increase the risk of transmission and reintroduction of malaria in certain areas with the adequate vectors and climate conditions. Moreover imported malaria cases by immigrants can also play an important role in the non-vectorial transmission out of endemic area, by blood transfusions, organ transplantation or congenital or occupational exposures. Probably, out of endemic areas, screening of malaria among recent arrived immigrants coming from malaria endemic countries should be performed. These aim to reduce the risk of clinical malaria in the individual as well as to prevent autochthonous transmission of malaria in areas where it had been eradicated.

How well are malaria maps used to design and finance malaria control in Africa?

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Omumbo, Judy A; Noor, Abdisalan M; Fall, Ibrahima S; Snow, Robert W

2013-01-01

Rational decision making on malaria control depends on an understanding of the epidemiological risks and control measures. National Malaria Control Programmes across Africa have access to a range of state-of-the-art malaria risk mapping products that might serve their decision-making needs. The use of cartography in planning malaria control has never been methodically reviewed. An audit of the risk maps used by NMCPs in 47 malaria endemic countries in Africa was undertaken by examining the most recent national malaria strategies, monitoring and evaluation plans, malaria programme reviews and applications submitted to the Global Fund. The types of maps presented and how they have been used to define priorities for investment and control was investigated. 91% of endemic countries in Africa have defined malaria risk at sub-national levels using at least one risk map. The range of risk maps varies from maps based on suitability of climate for transmission; predicted malaria seasons and temperature/altitude limitations, to representations of clinical data and modelled parasite prevalence. The choice of maps is influenced by the source of the information. Maps developed using national data through in-country research partnerships have greater utility than more readily accessible web-based options developed without inputs from national control programmes. Although almost all countries have stratification maps, only a few use them to guide decisions on the selection of interventions allocation of resources for malaria control. The way information on the epidemiology of malaria is presented and used needs to be addressed to ensure evidence-based added value in planning control. The science on modelled impact of interventions must be integrated into new mapping products to allow a translation of risk into rational decision making for malaria control. As overseas and domestic funding diminishes, strategic planning will be necessary to guide appropriate financing for malaria

How well are malaria maps used to design and finance malaria control in Africa?

Directory of Open Access Journals (Sweden)

Judy A Omumbo

Full Text Available Rational decision making on malaria control depends on an understanding of the epidemiological risks and control measures. National Malaria Control Programmes across Africa have access to a range of state-of-the-art malaria risk mapping products that might serve their decision-making needs. The use of cartography in planning malaria control has never been methodically reviewed.An audit of the risk maps used by NMCPs in 47 malaria endemic countries in Africa was undertaken by examining the most recent national malaria strategies, monitoring and evaluation plans, malaria programme reviews and applications submitted to the Global Fund. The types of maps presented and how they have been used to define priorities for investment and control was investigated.91% of endemic countries in Africa have defined malaria risk at sub-national levels using at least one risk map. The range of risk maps varies from maps based on suitability of climate for transmission; predicted malaria seasons and temperature/altitude limitations, to representations of clinical data and modelled parasite prevalence. The choice of maps is influenced by the source of the information. Maps developed using national data through in-country research partnerships have greater utility than more readily accessible web-based options developed without inputs from national control programmes. Although almost all countries have stratification maps, only a few use them to guide decisions on the selection of interventions allocation of resources for malaria control.The way information on the epidemiology of malaria is presented and used needs to be addressed to ensure evidence-based added value in planning control. The science on modelled impact of interventions must be integrated into new mapping products to allow a translation of risk into rational decision making for malaria control. As overseas and domestic funding diminishes, strategic planning will be necessary to guide appropriate

How Well Are Malaria Maps Used to Design and Finance Malaria Control in Africa?

Science.gov (United States)

Omumbo, Judy A.; Noor, Abdisalan M.; Fall, Ibrahima S.; Snow, Robert W.

2013-01-01

Introduction Rational decision making on malaria control depends on an understanding of the epidemiological risks and control measures. National Malaria Control Programmes across Africa have access to a range of state-of-the-art malaria risk mapping products that might serve their decision-making needs. The use of cartography in planning malaria control has never been methodically reviewed. Materials and Methods An audit of the risk maps used by NMCPs in 47 malaria endemic countries in Africa was undertaken by examining the most recent national malaria strategies, monitoring and evaluation plans, malaria programme reviews and applications submitted to the Global Fund. The types of maps presented and how they have been used to define priorities for investment and control was investigated. Results 91% of endemic countries in Africa have defined malaria risk at sub-national levels using at least one risk map. The range of risk maps varies from maps based on suitability of climate for transmission; predicted malaria seasons and temperature/altitude limitations, to representations of clinical data and modelled parasite prevalence. The choice of maps is influenced by the source of the information. Maps developed using national data through in-country research partnerships have greater utility than more readily accessible web-based options developed without inputs from national control programmes. Although almost all countries have stratification maps, only a few use them to guide decisions on the selection of interventions allocation of resources for malaria control. Conclusion The way information on the epidemiology of malaria is presented and used needs to be addressed to ensure evidence-based added value in planning control. The science on modelled impact of interventions must be integrated into new mapping products to allow a translation of risk into rational decision making for malaria control. As overseas and domestic funding diminishes, strategic planning will be

Structural basis of malaria parasite lysyl-tRNA synthetase inhibition by cladosporin.

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Khan, Sameena; Sharma, Arvind; Belrhali, Hassan; Yogavel, Manickam; Sharma, Amit

2014-06-01

Malaria parasites inevitably develop drug resistance to anti-malarials over time. Hence the immediacy for discovering new chemical scaffolds to include in combination malaria drug therapy. The desirable attributes of new chemotherapeutic agents currently include activity against both liver and blood stage malaria parasites. One such recently discovered compound called cladosporin abrogates parasite growth via inhibition of Plasmodium falciparum lysyl-tRNA synthetase (PfKRS), an enzyme central to protein translation. Here, we present crystal structure of ternary PfKRS-lysine-cladosporin (PfKRS-K-C) complex that reveals cladosporin's remarkable ability to mimic the natural substrate adenosine and thereby colonize PfKRS active site. The isocoumarin fragment of cladosporin sandwiches between critical adenine-recognizing residues while its pyran ring fits snugly in the ribose-recognizing cavity. PfKRS-K-C structure highlights ample space within PfKRS active site for further chemical derivatization of cladosporin. Such derivatives may be useful against additional human pathogens that retain high conservation in cladosporin chelating residues within their lysyl-tRNA synthetase.

Seroprevalence of Marek's Disease Virus antibody in some poultry ...

African Journals Online (AJOL)

This study reports a survey of Marek's disease virus (MDV) antibody done in 21 selected poultry flocks in Lagos, Ogun and Oyo states of southwestern Nigeria. A total of 315 serum samples were examined using the Enzyme Linked Immunosorbent Assay (ELISA) technique. Marek's disease virus antibody was present in ...

Reduction in malaria prevalence and increase in malaria awareness in endemic districts of Bangladesh.

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Alam, Mohammad Shafiul; Kabir, Mohammad Moktadir; Hossain, Mohammad Sharif; Naher, Shamsun; Ferdous, Nur E Naznin; Khan, Wasif Ali; Mondal, Dinesh; Karim, Jahirul; Shamsuzzaman, A K M; Ahmed, Be-Nazir; Islam, Akramul; Haque, Rashidul

2016-11-11

Malaria is endemic in 13 districts of Bangladesh. A baseline malaria prevalence survey across the endemic districts of Bangladesh was conducted in 2007, when the prevalence was reported around 39.7 per 1000 population. After two rounds of Global Fund to Fight AIDS, Tuberculosis and Malaria (GFATM)-funded intervention by the National Malaria Control Programme (NMCP) and a BRAC-led NGO consortium, a follow-up survey was conducted across the malaria-endemic districts of Bangladesh to measure the change in prevalence rate and in people's knowledge of malaria. The survey was carried out from August to November 2013 in 70 upazilas (sub-districts) of 13 malaria-endemic districts of Bangladesh, following the same multi-stage cluster sampling design and the same number of households enrolled during the baseline prevalence survey in 2007, to collect 9750 randomly selected blood samples. For on-the-spot diagnosis of malaria, a rapid diagnostic test was used. The household head or eldest person available was interviewed using a pre-coded structured questionnaire to collect data on the knowledge and awareness of malaria in the household. Based on a weighted calculation, the overall malaria prevalence was found to be 1.41 per 1000 population. The proportion of Plasmodium falciparum mono-infection was 77.78% while both Plasmodium vivax mono-infection and mixed infection of the two species were found to be 11.11%. Bandarban had the highest prevalence (6.67 per 1000 population). Knowledge of malaria signs, symptoms and mode of transmission were higher in the follow-up survey (97.26%) than the baseline survey. Use of bed nets for prevention of malaria was found to be high (90.15%) at respondent level. People's knowledge of selected parameters increased significantly during the follow-up survey compared to the baseline survey conducted in 2007. A reduced prevalence rate of malaria and increased level of knowledge were observed in the present malaria prevalence survey in Bangladesh.

Thrombocytopenia in malaria: can platelet counts differentiate malaria from other infections

International Nuclear Information System (INIS)

Arshad, A.R.

2015-01-01

To determine the accuracy of thrombocytopenia as a diagnostic marker for malaria. Study Design: Cross-sectional study. Place and Duration of Study: Department of Medicine, 1 Mountain Medical Battalion (Bagh, Azad Kashmir) from July to September 2013. Methodology: Adult patients presenting with a short history of fever without any localizing symptoms or signs were included. Exclusion criteria included patients with fever of > 7 days duration, those in whom an underlying diagnosis could be easily confirmed on the basis of history and physical examination, those on antibiotics/ antimalarials or antiplatelet agents and patients with Dengue fever. Platelet counts in venous whole blood samples were analysed with Sysmex KX-21 Haematology analyzer. Thick and thin peripheral blood smears were then prepared and examined for malarial parasites. Diagnosis of malaria was established on the basis of smear findings. Results: There were 245 patients in total. Out of the 109 patients with thrombocytopenia, 61 had vivax malaria. Platelets count was normal in 136 patients, including 4 with vivax malaria. Falciparum malaria was not seen in any patient. All cases with malaria were uncomplicated. Various measures of accuracy thus calculated were sensitivity 93.85%, specificity 73.33%, positive predictive value 55.96%, negative predictive value 97.06%, positive likelihood ratio of 3.52, negative likelihood ratio of 0.08, diagnostic odds ratio 41.94 and diagnostic accuracy of 78.78%. Conclusion: Thrombocytopenia has an excellent sensitivity and a very good specificity for vivax malaria. Normal platelet counts provide very strong evidence against malaria as the etiology of fever without a focus. (author)

Observation of Blood Donor-Recipient Malaria Parasitaemia Patterns in a Malaria Endemic Region.

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Faruk, Jamilu Abdullahi; Ogunrinde, Gboye Olufemi; Mamman, Aisha Indo

2017-01-01

Asymptomatic malaria parasitaemia has been documented in donor blood in West Africa. However, donated blood is not routinely screened for malaria parasites (MPs). The present study therefore aimed to document the frequency of blood transfusion-induced donor-recipient malaria parasitaemia patterns, in children receiving blood transfusion in a tertiary health-centre. A cross-sectional, observational study involving 140 children receiving blood transfusion was carried out. Blood donor units and patients' blood samples were obtained, for the determination of malaria parasites (MPs). Giemsa staining technique was used to determine the presence of malaria parasitaemia. Malaria parasites were detected in 7% of donor blood and in 8.3% of the recipients' pretransfusion blood. The incidence of posttransfusion MPs was 3%, but none of these were consistent with blood transfusion-induced malaria, as no child with posttransfusion parasitaemia was transfused with parasitized donor blood. Majority of the blood transfusions (89.4%) had no MPs in either donors or recipients, while 6.8% had MPs in both donors and recipients, with the remaining 3.8% showing MPs in recipients alone. In conclusion, the incidence of posttransfusion malaria parasitaemia appears low under the prevailing circumstances.

Malaria and Tropical Travel

Centers for Disease Control (CDC) Podcasts

Malaria is a serious mosquito-borne disease that can lead to death. This podcast discusses malaria risk when traveling to tropical areas, as well as how to protect yourself and your family from malaria infection.

Knowledge, attitude, and practice about malaria: Socio-demographic implications for malaria control in rural Ghana.

Science.gov (United States)

Assan, Abraham; Takian, Amirhossein; Hanafi-Bojd, Ahmad Ali; Rahimiforoushani, Abbas; Nematolahi, Shahrzad

2017-11-01

Despite continuing international attention to malaria prevention, the disease remains a global public health problem. We investigated socio-demographic factors influencing knowledge, attitudes, and practices about malaria in rural Ghana. Our survey looked at 354 households. Mean knowledge score was higher among individuals with a history of volunteers having visited their households to educate them about malaria; families with 4-6 members; and males. Households with at least one under-five-aged child also had significantly higher knowledge scores. Households with at least one pregnant woman evinced a positive attitude towards malaria prevention. National malaria control strategies have achieved positive results in the fight against malaria. Nonetheless, multipronged community-based health strategies that integrate malaria programs and population growth control initiatives may be able to reach by 2030 the sustainable development goal of eliminating malaria.

A single point in protein trafficking by Plasmodium falciparum determines the expression of major antigens on the surface of infected erythrocytes targeted by human antibodies.

Science.gov (United States)

Chan, Jo-Anne; Howell, Katherine B; Langer, Christine; Maier, Alexander G; Hasang, Wina; Rogerson, Stephen J; Petter, Michaela; Chesson, Joanne; Stanisic, Danielle I; Duffy, Michael F; Cooke, Brian M; Siba, Peter M; Mueller, Ivo; Bull, Peter C; Marsh, Kevin; Fowkes, Freya J I; Beeson, James G

2016-11-01

Antibodies to blood-stage antigens of Plasmodium falciparum play a pivotal role in human immunity to malaria. During parasite development, multiple proteins are trafficked from the intracellular parasite to the surface of P. falciparum-infected erythrocytes (IEs). However, the relative importance of different proteins as targets of acquired antibodies, and key pathways involved in trafficking major antigens remain to be clearly defined. We quantified antibodies to surface antigens among children, adults, and pregnant women from different malaria-exposed regions. We quantified the importance of antigens as antibody targets using genetically engineered P. falciparum with modified surface antigen expression. Genetic deletion of the trafficking protein skeleton-binding protein-1 (SBP1), which is involved in trafficking the surface antigen PfEMP1, led to a dramatic reduction in antibody recognition of IEs and the ability of human antibodies to promote opsonic phagocytosis of IEs, a key mechanism of parasite clearance. The great majority of antibody epitopes on the IE surface were SBP1-dependent. This was demonstrated using parasite isolates with different genetic or phenotypic backgrounds, and among antibodies from children, adults, and pregnant women in different populations. Comparisons of antibody reactivity to parasite isolates with SBP1 deletion or inhibited PfEMP1 expression suggest that PfEMP1 is the dominant target of acquired human antibodies, and that other P. falciparum IE surface proteins are minor targets. These results establish SBP1 as part of a critical pathway for the trafficking of major surface antigens targeted by human immunity, and have key implications for vaccine development, and quantifying immunity in populations.

Application of the Ceditest FMDV type O and FMDV-NS enzyme-linked immunosorbent assays for detection of antibodies against Foot-and-mouth disease virus in selected livestock and wildlife species in Uganda

DEFF Research Database (Denmark)

Ayebazibwe, Chrisostom; Mwiine, Frank Norbert; Balinda, Sheila Nina

2012-01-01

Diagnosis and control of Foot-and-mouth disease virus (FMDV) requires rapid and sensitive diagnostic tests. Two antibody enzyme-linked immunosorbent assay (ELISA) kits, Ceditest FMDV-NS for the detection of antibodies against the nonstructural proteins of all FMDV serotypes and Ceditest FMDV type O......, and selected samples were tested not only in serotype-specific ELISAs for antibodies against primarily FMDV serotype O, but also against other serotypes. The FMDV-NS assay detected far more positive samples (93%) than the FMDV type O assay (30%) in buffalo (P ... the South African Territories (SAT) serotypes, while the seroprevalence was generally comparable in cattle with antibodies against serotype O elicited by infection and/or vaccination. However, some districts had higher seroprevalence using the FMDV type O assay indicating vaccination without infection...

Induction and maintenance of protective CD8+ T cells against malaria liver stages: implications for vaccine development

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Sze-Wah Tse

2011-08-01

Full Text Available CD8+ T cells against malaria liver stages represent a major protective immune mechanism against infection. Following induction in the peripheral lymph nodes by dendritic cells (DCs, these CD8+ T cells migrate to the liver and eliminate parasite infected hepatocytes. The processing and presentation of sporozoite antigen requires TAP mediated transport of major histocompatibility complex class I epitopes to the endoplasmic reticulum. Importantly, in DCs this process is also dependent on endosome-mediated cross presentation while this mechanism is not required for epitope presentation on hepatocytes. Protective CD8+ T cell responses are strongly dependent on the presence of CD4+ T cells and the capacity of sporozoite antigen to persist for a prolonged period of time. While human trials with subunit vaccines capable of inducing antibodies and CD4+ T cell responses have yielded encouraging results, an effective anti-malaria vaccine will likely require vaccine constructs designed to induce protective CD8+ T cells against malaria liver stages.

Droplet Microfluidics Platform for Highly Sensitive and Quantitative Detection of Malaria-Causing Plasmodium Parasites Based on Enzyme Activity Measurement

DEFF Research Database (Denmark)

Juul, Sissel; Nielsen, Christine Juul Fælled; Labouriau, Rodrigo

2012-01-01

detectable at the single-molecule level. Combined with a droplet microfluidics lab-on-a-chip platform, this design allowed for sensitive, specific, and quantitative detection of all human-malaria-causing Plasmodium species in single drops of unprocessed blood with a detection limit of less than one parasite....../μL. Moreover, the setup allowed for detection of Plasmodium parasites in noninvasive saliva samples from infected patients. During recent years malaria transmission has declined worldwide, and with this the number of patients with low-parasite density has increased. Consequently, the need for accurate...

Spectrophotometric Enzyme Assays for High-Throughput Screening

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Jean-Louis Reymond

2004-01-01

Full Text Available This paper reviews high-throughput screening enzyme assays developed in our laboratory over the last ten years. These enzyme assays were initially developed for the purpose of discovering catalytic antibodies by screening cell culture supernatants, but have proved generally useful for testing enzyme activities. Examples include TLC-based screening using acridone-labeled substrates, fluorogenic assays based on the β-elimination of umbelliferone or nitrophenol, and indirect assays such as the back-titration method with adrenaline and the copper-calcein fluorescence assay for aminoacids.

Targeting imported malaria through social networks: a potential strategy for malaria elimination in Swaziland.

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Koita, Kadiatou; Novotny, Joseph; Kunene, Simon; Zulu, Zulizile; Ntshalintshali, Nyasatu; Gandhi, Monica; Gosling, Roland

2013-06-27

Swaziland has made great progress towards its goal of malaria elimination by 2015. However, malaria importation from neighbouring high-endemic Mozambique through Swaziland's eastern border remains a major factor that could prevent elimination from being achieved. In order to reach elimination, Swaziland must rapidly identify and treat imported malaria cases before onward transmission occurs. A nationwide formative assessment was conducted over eight weeks to determine if the imported cases of malaria identified by the Swaziland National Malaria Control Programme could be linked to broader social networks and to explore methods to access these networks. Using a structured format, interviews were carried out with malaria surveillance agents (6), health providers (10), previously identified imported malaria cases (19) and people belonging to the networks identified through these interviews (25). Most imported malaria cases were Mozambicans (63%, 12/19) making a living in Swaziland and sustaining their families in Mozambique. The majority of imported cases (73%, 14/19) were labourers and self-employed contractors who travelled frequently to Mozambique to visit their families and conduct business. Social networks of imported cases with similar travel patterns were identified through these interviews. Nearly all imported cases (89%, 17/19) were willing to share contact information to enable network members to be interviewed. Interviews of network members and key informants revealed common congregation points, such as the urban market places in Manzini and Malkerns, as well as certain bus stations, where people with similar travel patterns and malaria risk behaviours could be located and tested for malaria. This study demonstrated that imported cases of malaria belonged to networks of people with similar travel patterns. This study may provide novel methods for screening high-risk groups of travellers using both snowball sampling and time-location sampling of networks to

Evaluation of an Antigen-Antibody “Combination” Enzyme Linked ...

African Journals Online (AJOL)

Conclusion: We conclude that although this assay depicts high sensitivity and specificity in detecting antibodies to HCV, it seems not to add further benefit in our study population to detect HCV infections by enhanced sensitivity due the potential contingency to trace viral capsid antigens. Keywords: Ag-Ab Combination assay ...

Malaria chemotherapy.

Science.gov (United States)

Winstanley, Peter; Ward, Stephen

2006-01-01

Most malaria control strategies today depend on safe and effective drugs, as they have done for decades. But sensitivity to chloroquine, hitherto the workhorse of malaria chemotherapy, has rapidly declined throughout the tropics since the 1980s, and this drug is now useless in many high-transmission areas. New options for resource-constrained governments are few, and there is growing evidence that the burden from malaria has been increasing, as has malaria mortality in Africa. In this chapter, we have tried to outline the main pharmacological properties of current drugs, and their therapeutic uses and limitations. We have summarised the ways in which these drugs are employed, both in the formal health sector and in self-medication. We have briefly touched on the limitations of current drug development, but have tried to pick out a few promising drugs that are under development. Given that Plasmodium falciparum is the organism that kills, and that has developed multi-drug resistance, we have tended to focus upon it. Similarly, given that around 90% of global mortality from malaria occurs in Africa, there is the tendency to dwell on this continent. We give no apology for placing our emphasis upon the use of antimalarial drugs in endemic populations rather than their use for prophylaxis in travellers.

A novel whole-bacterial enzyme linked-immunosorbant assay to quantify Chlamydia trachomatis specific antibodies reveals distinct differences between systemic and genital compartments.

Directory of Open Access Journals (Sweden)

Hannah L Albritton

Full Text Available Chlamydia trachomatis (CT is the leading sexually transmitted bacterial infection. The continued global burden of CT infection strongly predicates the need for a vaccine to supplement current chlamydial control programs. The correlates of protection against CT are currently unknown, but they must be carefully defined to guide vaccine design. The localized nature of chlamydial infection in columnar epithelial cells of the genital tract necessitates investigation of immunity at the site of infection. The purpose of this study was to develop a sensitive whole bacterial enzyme-linked immunosorbent assay (ELISA to quantify and compare CT-specific IgG and IgA in sera and genital secretions from CT-infected women. To achieve this, elementary bodies (EBs from two of the most common genital serovars (D and E were attached to poly-L-lysine-coated microtiter plates with glutaraldehyde. EB attachment and integrity were verified by the presence of outer membrane antigens and the absence of bacterial cytoplasmic antigens. EB-specific IgG and IgA standards were developed by pooling sera with high titers of CT-specific antibodies from infected women. Serum, endocervical and vaginal secretions, and endocervical cytobrush specimens from CT-infected women were used to quantify CT-specific IgG and IgA which were then normalized to total IgG and IgA, respectively. Analyses of paired serum and genital samples revealed significantly higher proportions of EB-specific antibodies in genital secretions compared to sera. Cervical and vaginal secretions and cytobrush specimens had similar proportions of EB-specific antibodies, suggesting any one of these genital sampling techniques could be used to quantify CT-specific antibodies when appropriate normalization methodologies are implemented. Overall, these results illustrate the need to investigate genital tract CT antibody responses, and our assay provides a useful quantitative tool to assess natural immunity in defined

Malaria resistance genes are associated with the levels of IgG subclasses directed against Plasmodium falciparum blood-stage antigens in Burkina Faso

Directory of Open Access Journals (Sweden)

Afridi Sarwat

2012-09-01

Full Text Available Abstract Background HBB, IL4, IL12, TNF, LTA, NCR3 and FCGR2A polymorphisms have been associated with malaria resistance in humans, whereas cytophilic immunoglobulin G (IgG antibodies are thought to play a critical role in immune protection against asexual blood stages of the parasite. Furthermore, HBB, IL4, TNF, and FCGR2A have been associated with both malaria resistance and IgG levels. This suggests that some malaria resistance genes influence the levels of IgG subclass antibodies. Methods In this study, the effect of HBB, IL4, IL12, TNF, LTA, NCR3 and FCGR2A polymorphisms on the levels of IgG responses against Plasmodium falciparum blood-stage extract was investigated in 220 individuals living in Burkina Faso. The Pearson’s correlation coefficient among IgG subclasses was determined. A family-based approach was used to assess the association of polymorphisms with anti-P. falciparum IgG, IgG1, IgG2, IgG3 and IgG4 levels. Results After applying a multiple test correction, several polymorphisms were associated with IgG subclass or IgG levels. There was an association of i haemoglobin C with IgG levels; ii the FcγRIIa H/R131 with IgG2 and IgG3 levels; iii TNF-863 with IgG3 levels; iv TNF-857 with IgG levels; and, v TNF1304 with IgG3, IgG4, and IgG levels. Conclusion Taken together, the results support the hypothesis that some polymorphisms affect malaria resistance through their effect on the acquired immune response, and pave the way towards further comprehension of genetic control of an individual’s humoral response against malaria.

Comparison of allele frequencies of Plasmodium falciparum merozoite antigens in malaria infections sampled in different years in a Kenyan population.

Science.gov (United States)

Ochola-Oyier, Lynette Isabella; Okombo, John; Wagatua, Njoroge; Ochieng, Jacob; Tetteh, Kevin K; Fegan, Greg; Bejon, Philip; Marsh, Kevin

2016-05-06

Plasmodium falciparum merozoite antigens elicit antibody responses in malaria-endemic populations, some of which are clinically protective, which is one of the reasons why merozoite antigens are the focus of malaria vaccine development efforts. Polymorphisms in several merozoite antigen-encoding genes are thought to arise as a result of selection by the human immune system. The allele frequency distribution of 15 merozoite antigens over a two-year period, 2007 and 2008, was examined in parasites obtained from children with uncomplicated malaria. In the same population, allele frequency changes pre- and post-anti-malarial treatment were also examined. Any gene which showed a significant shift in allele frequencies was also assessed longitudinally in asymptomatic and complicated malaria infections. Fluctuating allele frequencies were identified in codons 147 and 148 of reticulocyte-binding homologue (Rh) 5, with a shift from HD to YH haplotypes over the two-year period in uncomplicated malaria infections. However, in both the asymptomatic and complicated malaria infections YH was the dominant and stable haplotype over the two-year and ten-year periods, respectively. A logistic regression analysis of all three malaria infection populations between 2007 and 2009 revealed, that the chance of being infected with the HD haplotype decreased with time from 2007 to 2009 and increased in the uncomplicated and asymptomatic infections. Rh5 codons 147 and 148 showed heterogeneity at both an individual and population level and may be under some degree of immune selection.

Detection of Human Epididymis Protein 4 (HE4) in Human Serum Samples Using a Specific Monoclonal Antibody-Based Sandwich Enzyme-Linked Immunosorbent Assay (ELISA).

Science.gov (United States)

Zhou, Lijun; Lv, Zhiqiang; Shao, Jing; Xu, Ying; Luo, Xiaohong; Zhang, Yuming; Hu, Yang; Zhang, Wenji; Luo, Shuhong; Fang, Jianmin; Wang, Ying; Duan, Chaohui; Huang, Ruopan

2016-09-01

The human epididymis protein 4 (HE4) may have high specificity in the detection of malignant diseases, making the development of an immunoassay for HE4 essential. In our study, a fusion gene was constructed encoded with the HE4 protein. This protein was then produced in the bacterial cells (Escherichia coli) and used to immunize mice in order to eventually generate hybridomas specific to HE4. The hybridoma supernatants were then screened, and four positive anti-HE4 cell lines were selected. These cell lines produce monoclonal antibodies against HE4 epitopes, as demonstrated in the Western blot as well as by direct enzyme-linked immunosorbent assay (ELISA). Using the developed antibodies, we successfully identified several good antibody pairs from the hybridomas, which allowed for the development of a sandwich ELISA to measure HE4 levels. By using the HE4 ELISA, we measured HE4 levels of 60 clinical human serum samples. Compared with the Food and Drug Administration (FDA) approved kit (Roche), our results showed a strong positive correlation to those of the FDA-approved kit. In summary, highly sensitive antibody pairs were screened against HE4, and a sandwich ELISA was developed as an accurate analytical tool for the detection of HE4 in human serum, which could be especially valuable for diagnosing ovarian carcinomas. © 2015 Wiley Periodicals, Inc.

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.

Malaria Matters

Centers for Disease Control (CDC) Podcasts

2008-04-18

This podcast gives an overview of malaria, including prevention and treatment, and what CDC is doing to help control and prevent malaria globally.  Created: 4/18/2008 by National Center for Zoonotic, Vector-Borne, and Enteric Diseases (NCZVED).   Date Released: 4/18/2008.

Improving the production of the denatured recombinant N-terminal domain of rhoptry-associated protein 2 from a Plasmodium falciparum target in the pathology of anemia in falciparum malaria

Directory of Open Access Journals (Sweden)

Luis Andre Mariuba

2008-09-01

Full Text Available Rhoptry-associated protein 2 (RAP2 is known to be discharged from rhoptry onto the membrane surface of infected and uninfected erythrocytes (UEs ex vivo and in vitro and this information provides new insights into the understanding of the pathology of severe anemia in falciparum malaria. In this study, a hexahistidine-tagged recombinant protein corresponding to residues 5-190 of the N-terminal of Plasmodium falciparum RAP2 (rN-RAP2 was produced using a new method of solubilization and purification. Expression was induced with D-lactose, a less expensive alternative inducer to the more common isopropyl-²-D-thio-galactopyranosidase. The recombinant protein was purified using two types of commercially-available affinity columns, iminodiacetic and nitrilotriacetic. rN-RAP2 had immunogenic potential, since it induced high titers of anti-RAP2 antibodies in mice. These antibodies recognized full-length RAP2 prepared from Triton X-100 extracts from two strains of P. falciparum. In fact, the antibody recognized a 29-kDa product of RAP2 cleavage as well as 82 and 70-kDa products of RAP1 cleavage. These results indicate that the two antigens share sequence epitopes. Our expressed protein fragment was shown to contain a functional epitope that is also present in rhoptry-derived ring surface protein 2 which attaches to the surface of both infected and UEs and erythroid precursor cells in the bone marrow of malaria patients. Serum from malaria patients who developed anemia during infection recognized rN-RAP2, suggesting that this protein fragment may be important for epidemiological studies investigating whether immune responses to RAP2 exacerbate hemolysis in falciparum malaria patients.

Epitope mapping of monoclonal antibodies directed to aminopeptidase A and their relevance for albuminuria in mice.

Science.gov (United States)

Gerlofs-Nijland, Miriam E; Assmann, Karel J M; van Son, Jacco P H F; Dijkman, Henry B P M; te Loeke, Nathalie A J M; van der Zee, Ruurd; Wetzels, Jack F M; Groenen, Patricia J T A

2003-01-01

We have shown previously that injection of specific combinations of anti-aminopeptidase A monoclonal antibodies induces an acute massive albuminuria in mice. This albuminuria is neither dependent on systemic mediators of inflammation nor angiotensin II. In this study, we examined the contribution of two individual antibodies, the enzyme-inhibiting antibody ASD-37 and the non-enzyme-inhibiting antibody ASD-41, in the induction of albuminuria as well as the interactions between these two monoclonals. In addition, we have mapped the epitopes of both antibodies using in vitro coupled transcription/translation of specifically designed cDNA fragments followed by immunoprecipitation, and using peptide enzyme-linked immunosorbent assay in case of a continuous epitope. A single intravenous injection of 4 mg of either ASD-37 or ASD-41 did not induce albuminuria. This dose of ASD-37 did not completely inhibit enzyme activity. The combination of 4 mg ASD-37/41 (1:1 weight ratio) induced albuminuria and almost completely inhibited enzyme activity. Similar results were obtained with a combination of ASD-37/41 in a 1:39 or 39:1 weight ratio. Administration of 2 mg ASD-41 24 h before injection of 2 mg ASD-37 significantly enhanced albuminuria. The epitope of ASD-37 is located at the C-terminal end of aminopeptidase A, whereas the ASD-41 epitope is mapped near the enzyme active site. Our data suggest that ASD-41 modulates the binding of ASD-37 to its epitope and/or vice versa. As a consequence, ASD-37 and ASD-41 act synergistically, not only in inhibiting enzyme activity but also in inducing albuminuria. Copyright 2003 S. Karger AG, Basel

Study of rat kidney transamidinase structure and regulation with monoclonal antibodies and the purification and characterization of human kidney transamidinase

International Nuclear Information System (INIS)

Gross, M.D.

1985-01-01

The isolation of monoclonal antibodies to transamidinase made possible the development of an immunosorbent inhibition assay for transamidinase protein using a 125 I-labeled monoclonal antibody. This assay is a more direct measurement of transamidinase protein than the determination of the amount of polyclonal antibody required to precipitate the transamidinase activities. Rats were fed diets supplemented with creatine and/or glycine, and the amounts of transamidinase protein were determined with the assay using the monoclonal antibody. The transamidinase activities of kidneys from the rats fed the various supplemented diets ranged from 10 to 40% of the control values, whereas, the amounts of transamidinase protein were, in all instances no lower than 66% of the control values. Purified homogeneous rat kidney transamidinase and rat kidney supernatants were subjected to isoelectric focussing and four to five fractions of the enzyme were obtained. Polyclonal antibodies, but not the monoclonal antibodies were found by Western blotting experiments to recognize all the forms of the enzyme obtained by the isoelectric focussing. The author concluded that the monoclonal antibodies recognized forms of the enzyme that changed very little in amount, relative to the alterations in enzyme activities, when rats were fed a diet containing creatine

Validation of an improved enzyme-linked immunosorbent assay for the diagnosis of trypanosomal antibodies in Ghanaian cattle

International Nuclear Information System (INIS)

Doku, C.K.; Seidu, I.B.M.

2000-01-01

The validation of an enzyme-linked immunosorbent assay (Ab-ELISA) for the detection of antibodies to pathogenic trypanosomes in cattle is described. Two hundred known negative sera obtained from the tsetse-free zone of Dori (Burkina Faso) were analyzed using microtitre plates pre-coated with crude antigen lysates of Trypanosoma congolense and T. vivax. A pre-test optimization was carried out and a percent positivity (PP) of 50% was chosen (specificity: >82%) for assaying field sera. A total of 440 serum samples collected from cattle in areas of known and unknown disease prevalence were assayed. For all animals the packed red cell volume (PCV) was determined and the buffy coat technique (BCT) and blood smears were examined to detect trypanosomes at the species level. A comparison of the BCT and Ab-ELISA results showed there was a much higher prevalence of antibodies to both species than the parasite prevalence as shown by the BCT (10 fold). The rate of agreement between BCT-positive and Ab-ELISA-positive samples for both species was low (<10%). No conclusion could be drawn from this finding because of the low number of known BCT positive cases that were identified. There was a better, albeit highly variable, agreement between BCT-negative and Ab-ELISA-negative samples (30-70%). Proposals for further improvement of the Ab-ELISA and prospects for the use of the assay in the monitoring of trypanosomosis control in Ghana are discussed. (author)

Gametogenesis in malaria parasites is mediated by the cGMP-dependent protein kinase.

Directory of Open Access Journals (Sweden)

Louisa McRobert

2008-06-01

Full Text Available Malaria parasite transmission requires differentiation of male and female gametocytes into gametes within a mosquito following a blood meal. A mosquito-derived molecule, xanthurenic acid (XA, can trigger gametogenesis, but the signalling events controlling this process in the human malaria parasite Plasmodium falciparum remain unknown. A role for cGMP was revealed by our observation that zaprinast (an inhibitor of phosphodiesterases that hydrolyse cGMP stimulates gametogenesis in the absence of XA. Using cGMP-dependent protein kinase (PKG inhibitors in conjunction with transgenic parasites expressing an inhibitor-insensitive mutant PKG enzyme, we demonstrate that PKG is essential for XA- and zaprinast-induced gametogenesis. Furthermore, we show that intracellular calcium (Ca2+ is required for differentiation and acts downstream of or in parallel with PKG activation. This work defines a key role for PKG in gametogenesis, elucidates the hierarchy of signalling events governing this process in P. falciparum, and demonstrates the feasibility of selective inhibition of a crucial regulator of the malaria parasite life cycle.

Retinopathy in severe malaria in Ghanaian children - overlap between fundus changes in cerebral and non-cerebral malaria

DEFF Research Database (Denmark)

Essuman, Vera A; Ntim-Amponsah, Christine T; Astrup, Birgitte S

2010-01-01

diagnostic tool. This study was designed to determine the diagnostic usefulness of retinopathy on ophthalmoscopy in severe malaria syndromes: Cerebral malaria (CM) and non-cerebral severe malaria (non-CM), i.e. malaria with respiratory distress (RD) and malaria with severe anaemia (SA), in Ghanaian children...

Malaria resistance | Iyabo | Nigerian Medical Practitioner

African Journals Online (AJOL)

Age and puberty have been found to contribute to malaria resistance. It is expected that knowledge of natural resistance to malaria may aid in developing Vaccines against this deadly disease. Keywords: malaria resistance, puberty, malaria economy, malaria vaccine. Nigerian Medical Practitioner Vol. 49(5) 2006: 133-142 ...

The Gates Malaria Partnership: a consortium approach to malaria research and capacity development.

Science.gov (United States)

Greenwood, Brian; Bhasin, Amit; Targett, Geoffrey

2012-05-01

Recently, there has been a major increase in financial support for malaria control. Most of these funds have, appropriately, been spent on the tools needed for effective prevention and treatment of malaria such as insecticide-treated bed nets, indoor residual spraying and artemisinin combination therapy. There has been less investment in the training of the scientists from malaria-endemic countries needed to support these large and increasingly complex malaria control programmes, especially in Africa. In 2000, with support from the Bill & Melinda Gates Foundation, the Gates Malaria Partnership was established to support postgraduate training of African scientists wishing to pursue a career in malaria research. The programme had three research capacity development components: a PhD fellowship programme, a postdoctoral fellowship programme and a laboratory infrastructure programme. During an 8-year period, 36 African PhD students and six postdoctoral fellows were supported, and two research laboratories were built in Tanzania. Some of the lessons learnt during this project--such as the need to improve PhD supervision in African universities and to provide better support for postdoctoral fellows--are now being applied to a successor malaria research capacity development programme, the Malaria Capacity Development Consortium, and may be of interest to other groups involved in improving postgraduate training in health sciences in African universities. © 2012 Blackwell Publishing Ltd.

Antiphospholipid antibody: laboratory, pathogenesis and clinical manifestations

Directory of Open Access Journals (Sweden)

T. Ziglioli

2011-06-01

Full Text Available Antiphospholipid antibodies (aPL represent a heterogeneous group of antibodies that recognize various antigenic targets including beta2 glycoprotein I (β2GPI, prothrombin (PT, activated protein C, tissue plasminogen activator, plasmin and annexin A2. The most commonly used tests to detect aPL are: lupus anticoagulant (LAC, a functional coagulation assay, anticardiolipin antibody (aCL and anti-β2GPI antibody (anti-β2GPI, which are enzyme-linked immunoassay (ELISA. Clinically aPL are associated with thrombosis and/or with pregnancy morbidity. Apparently aPL alone are unable to induce thrombotic manifestations, but they increase the risk of vascular events that can occur in the presence of another thrombophilic condition; on the other hand obstetrical manifestations were shown to be associated not only to thrombosis but mainly to a direct antibody effect on the trophoblast.

Economic burden of malaria on businesses in Ghana: a case for private sector investment in malaria control.

Science.gov (United States)

Nonvignon, Justice; Aryeetey, Genevieve Cecilia; Malm, Keziah L; Agyemang, Samuel Agyei; Aubyn, Vivian N A; Peprah, Nana Yaw; Bart-Plange, Constance N; Aikins, Moses

2016-09-06

Despite the significant gains made globally in reducing the burden of malaria, the disease remains a major public health challenge, especially in sub-Saharan Africa (SSA) including Ghana. There is a significant gap in financing malaria control globally. The private sector could become a significant source of financing malaria control. To get the private sector to appreciate the need to invest in malaria control, it is important to provide evidence of the economic burden of malaria on businesses. The objective of this study, therefore, was to estimate the economic burden on malaria on businesses in Ghana, so as to stimulate the sector's investment in malaria control. Data covering 2012-2014 were collected from 62 businesses sampled from Greater Accra, Ashanti and Western Regions of Ghana, which have the highest concentration of businesses in the country. Data on the cost of businesses' spending on treatment and prevention of malaria in staff and their dependants as well as staff absenteeism due to malaria and expenditure on other health-related activities were collected. Views of business leaders on the effect of malaria on their businesses were also compiled. The analysis was extrapolated to cover 5828 businesses across the country. The results show that businesses in Ghana lost about US$6.58 million to malaria in 2014, 90 % of which were direct costs. A total of 3913 workdays were lost due to malaria in firms in the study sample during the period 2012-2014. Businesses in the study sample spent an average of 0.5 % of the annual corporate returns on treatment of malaria in employees and their dependants, 0.3 % on malaria prevention, and 0.5 % on other health-related corporate social responsibilities. Again business leaders affirmed that malaria affects their businesses' efficiency, employee attendance and productivity and expenses. Finally, about 93 % of business leaders expressed the need private sector investment in malaria control. The economic burden of

Standardization and validation of a cytometric bead assay to assess antibodies to multiple Plasmodium falciparum recombinant antigens.

Science.gov (United States)

Ondigo, Bartholomew N; Park, Gregory S; Gose, Severin O; Ho, Benjamin M; Ochola, Lyticia A; Ayodo, George O; Ofulla, Ayub V; John, Chandy C

2012-12-21

Multiplex cytometric bead assay (CBA) have a number of advantages over ELISA for antibody testing, but little information is available on standardization and validation of antibody CBA to multiple Plasmodium falciparum antigens. The present study was set to determine optimal parameters for multiplex testing of antibodies to P. falciparum antigens, and to compare results of multiplex CBA to ELISA. Antibodies to ten recombinant P. falciparum antigens were measured by CBA and ELISA in samples from 30 individuals from a malaria endemic area of Kenya and compared to known positive and negative control plasma samples. Optimal antigen amounts, monoplex vs multiplex testing, plasma dilution, optimal buffer, number of beads required were assessed for CBA testing, and results from CBA vs. ELISA testing were compared. Optimal amounts for CBA antibody testing differed according to antigen. Results for monoplex CBA testing correlated strongly with multiplex testing for all antigens (r = 0.88-0.99, P values from <0.0001 - 0.004), and antibodies to variants of the same antigen were accurately distinguished within a multiplex reaction. Plasma dilutions of 1:100 or 1:200 were optimal for all antigens for CBA testing. Plasma diluted in a buffer containing 0.05% sodium azide, 0.5% polyvinylalcohol, and 0.8% polyvinylpyrrolidone had the lowest background activity. CBA median fluorescence intensity (MFI) values with 1,000 antigen-conjugated beads/well did not differ significantly from MFI with 5,000 beads/well. CBA and ELISA results correlated well for all antigens except apical membrane antigen-1 (AMA-1). CBA testing produced a greater range of values in samples from malaria endemic areas and less background reactivity for blank samples than ELISA. With optimization, CBA may be the preferred method of testing for antibodies to P. falciparum antigens, as CBA can test for antibodies to multiple recombinant antigens from a single plasma sample and produces a greater range of values in

Households' incidence on malaria and expenditures to treat malaria ...

African Journals Online (AJOL)

CONCLUSION: The relationship between expenditure and use of different vector control depends on the geographic location of respondents. People living in the rural areas spend more to have access to malaria control tools. Location of respondent has a positive effect on expenditures and use of malaria control tools.

Malaria parasitemia among asymptomatic infants seen in a malaria ...

African Journals Online (AJOL)

In clinical settings, management of malaria cases has primarily been centred on case definition, giving minimal consideration to the asymptomatic individuals who remain a major reservoir since they do not seek care. In malaria endemic areas, infants are likely to remain asymptomatic since they have partial immunity ...

Antigen-displaying lipid-enveloped PLGA nanoparticles as delivery agents for a Plasmodium vivax malaria vaccine.

Science.gov (United States)

Moon, James J; Suh, Heikyung; Polhemus, Mark E; Ockenhouse, Christian F; Yadava, Anjali; Irvine, Darrell J

2012-01-01

The parasite Plasmodium vivax is the most frequent cause of malaria outside of sub-Saharan Africa, but efforts to develop viable vaccines against P. vivax so far have been inadequate. We recently developed pathogen-mimicking polymeric vaccine nanoparticles composed of the FDA-approved biodegradable polymer poly(lactide-co-glycolide) acid (PLGA) "enveloped" by a lipid membrane. In this study, we sought to determine whether this vaccine delivery platform could be applied to enhance the immune response against P. vivax sporozoites. A candidate malaria antigen, VMP001, was conjugated to the lipid membrane of the particles, and an immunostimulatory molecule, monophosphoryl lipid A (MPLA), was incorporated into the lipid membranes, creating pathogen-mimicking nanoparticle vaccines (VMP001-NPs). Vaccination with VMP001-NPs promoted germinal center formation and elicited durable antigen-specific antibodies with significantly higher titers and more balanced Th1/Th2 responses in vivo, compared with vaccines composed of soluble protein mixed with MPLA. Antibodies raised by NP vaccinations also exhibited enhanced avidity and affinity toward the domains within the circumsporozoite protein implicated in protection and were able to agglutinate live P. vivax sporozoites. These results demonstrate that these VMP001-NPs are promising vaccines candidates that may elicit protective immunity against P. vivax sporozoites.

Antigen-displaying lipid-enveloped PLGA nanoparticles as delivery agents for a Plasmodium vivax malaria vaccine.

Directory of Open Access Journals (Sweden)

James J Moon

Full Text Available The parasite Plasmodium vivax is the most frequent cause of malaria outside of sub-Saharan Africa, but efforts to develop viable vaccines against P. vivax so far have been inadequate. We recently developed pathogen-mimicking polymeric vaccine nanoparticles composed of the FDA-approved biodegradable polymer poly(lactide-co-glycolide acid (PLGA "enveloped" by a lipid membrane. In this study, we sought to determine whether this vaccine delivery platform could be applied to enhance the immune response against P. vivax sporozoites. A candidate malaria antigen, VMP001, was conjugated to the lipid membrane of the particles, and an immunostimulatory molecule, monophosphoryl lipid A (MPLA, was incorporated into the lipid membranes, creating pathogen-mimicking nanoparticle vaccines (VMP001-NPs. Vaccination with VMP001-NPs promoted germinal center formation and elicited durable antigen-specific antibodies with significantly higher titers and more balanced Th1/Th2 responses in vivo, compared with vaccines composed of soluble protein mixed with MPLA. Antibodies raised by NP vaccinations also exhibited enhanced avidity and affinity toward the domains within the circumsporozoite protein implicated in protection and were able to agglutinate live P. vivax sporozoites. These results demonstrate that these VMP001-NPs are promising vaccines candidates that may elicit protective immunity against P. vivax sporozoites.

Associations between maternal helminth and malaria infections in pregnancy, and clinical malaria in the offspring

DEFF Research Database (Denmark)

Ndibazza, Juliet; Webb, Emily L; Lule, Swaib

2013-01-01

Background. Helminth and malaria coinfections are common in the tropics. We investigated the hypothesis that prenatal exposure to these parasites might influence susceptibility to infections such as malaria in childhood.Methods. In a birth cohort of 2,345 mother-child pairs in Uganda, maternal...... helminth and malaria infection status was determined during pregnancy, and childhood malaria episodes recorded from birth to age five years. We examined associations between maternal infections and malaria in the offspring.Results. Common maternal infections were hookworm (45%), Mansonella perstans (21......%), Schistosoma mansoni (18%), and Plasmodium falciparum (11%). At age 5 years, 69% of the children were still under follow-up. The incidence of malaria was 34 episodes per 100 child-years, and the mean prevalence of asymptomatic malaria at annual visits was 5.4%. Maternal hookworm and M. perstans infections were...

[Current malaria situation in Turkey].

Science.gov (United States)

Gockchinar, T; Kalipsi, S

2001-01-01

Geographically, Turkey is situated in an area where malaria is very risky. The climatic conditions in the region are suitable for the malaria vector to proliferate. Due to agricultural infrastructural changes, GAP and other similar projects, insufficient environmental conditions, urbanization, national and international population moves, are a key to manage malaria control activities. It is estimated that malaria will be a potential danger for Turkey in the forthcoming years. The disease is located largely in south-eastern Anatolia. The Diyarbakir, Batman, Sanliurfa, Siirt, and Mardin districts are the most affected areas. In western districts, like Aydin and Manisa, an increase in the number of indigenous cases can be observed from time to time. This is due to workers moving from malaria districts to western parts to final work. Since these workers cannot be controlled, the population living in these regions get infected from indigenous cases. There were 84,345 malaria cases in 1994 and 82,096 in 1995, they decreased to 60,884 in 1996 and numbered 35,456 in 1997. They accounted for 36,842 and 20,963 in 1998 and 1999, respectively. In Turkey there are almost all cases of P. vivax malaria. There are also P. vivax and P. falciparum malaria cases coming from other countries: There were 321 P. vivax cases, including 2 P. falciparum ones, arriving to Turkey from Iraq in 1995. The P. vivax malaria cases accounted for 229 in 1996, and 67, cases P. vivax including 12 P. falciparum cases, in 1997, and 4 P. vivax cases in 1998 that came from that country. One P. vivax case entered Turkey from Georgia in 1998. The cause of higher incidence of P. vivax cases in 1995, it decreasing in 1999, is the lack of border controls over workers coming to Turkey. The other internationally imported cases are from Syria, Sudan, Pakistan, Afghanistan, Nigeria, India, Azerbaijan, Malaysia, Ghana, Indonesia, Yemen. Our examinations have shown that none of these internationally imported cases

Development and application of radioimmunoassays and enzyme immunoassays in microbiological and immunological diagnosis. 2. Comparative studies for the detection of toxoplasma antibodies with ELISA, RIA and other serological methods

Energy Technology Data Exchange (ETDEWEB)

Mueller, W A; Struy, H; Holzwarth, F [Medizinische Akademie, Magdeburg (German Democratic Republic)

1982-06-01

Comparative studies of indirect immunofluorescence test (IT), complement binding reaction (CBR), enzyme- and radioimmunoassay (ELISA, RIA) for the detection of toxoplasma antibodies in sera of 513 patients are reported. The precision dependent on time, showed coefficients of variation from 3% to 12% (IFT 3%, CBR 10%, ELISA 12%, RIA 7%). The correlation of IFT and ELISA as well as RIA was relatively unfavourable (coefficient of correlation IFT/ELISA r = 0.52, IFT/RIA r = 0.54, RIA/ELISA r = 0.60). The ELISA is the most sensitive method for the detection of antibodies. The specificity of the Toxo-ELISA has to be improved by application of suitable fractions of antigens.

[EIA-IgG antibody measles prevention level estimated from measles neutralizing, particle agglutination and hemagglutination-inhibition antibody titer].

Science.gov (United States)

Takayama, Naohide; Saika, Shizuko; Ichinohe, Sadato

2009-09-01

Measles hemagglutination inhibition (HI) antibody titer, widely used in clinical practice to simply and easily determine the measles immunity level has, in recent years, been increasingly replaced by measles IgG-antibody titer determined by enzyme-immunoassay (EIA). HI antibody titer appears to reflect this protective level, because HI measures the antibody against H protein required for the measles virus to adhere to host cells. EIA-IgG antibody titer does not correlate with the protective level, similar to particle agglutination (PA) titer, because EIA measures different antibodies, including those unrelated to measles protection. After determining HI, PA, neutralizing test (NT) results, and EIA-IgG antibody titer for individual specimens, we compared EIA-IgG antibody titer obtained using an EIA-Kit (Denka Seiken) to HI, PA, and NT titer with the following results: (1) Subjects with EIA-IgG titer of > or = 12.0 may be protected against measles: (2) Subjects with EIA-IgG titer of 4.0 to 8.0 appear to be protected insufficiently requiring a booster dose against measles: (3) Subjects with EIA-IgG titer of 8.0 to 12.0 may benefit from booster vaccination.

Scrub typhus masquerading as HELLP syndrome and puerperal sepsis in an asymptomatic malaria patient.

Science.gov (United States)

Karim, Habib Md Reazaul; Bhattacharyya, Prithwis; Kakati, Sonai Datta; Borah, Tridip Jyoti; Yunus, Md

2016-01-01

Scrub typhus and malaria can involve multiple organ systems and are notoriously known for varied presentations. However, clinical malaria or scrub typhus is unusual without fever. On the other hand, altered sensorium with or without fever, dehydration, hemorrhage and hemolysis may lead to low blood pressure. Presence of toxic granules and elevated band forms in such patients can even mimic sepsis. When such a patient is in the peripartum period, it creates a strong clinical dilemma for the physician especially in unbooked obstetric cases. We present such a case where a 26-year-old unbooked female presented on second postpartum day with severe anemia, altered sensorium, difficulty in breathing along with jaundice and gum bleeding without history of fever. Rapid diagnostic test for malaria was negative and no eschar was seen. These parameters suggested a diagnosis of HELLP (Hemolysis, Elevated Liver enzymes, Low Platelet) syndrome with or without puerperal sepsis. Subsequently she was diagnosed as having asymptomatic malaria and scrub typhus and responded to the treatment of it. The biochemical changes suggestive of HELLP syndrome also subsided. We present this case to emphasize the fact that mere absence of fever and eschar does not rule out scrub typhus. It should also be considered as a differential diagnosis in patients with symptoms and signs suggesting HELLP syndrome. Asymptomatic malaria can complicate case scenario towards puerperal sepsis by giving false toxic granules and band form in such situations.

Insect cells are superior to Escherichia coli in producing malaria proteins inducing IgG targeting PfEMP1 on infected erythrocytes

DEFF Research Database (Denmark)

Victor, Michala E; Bengtsson, Anja; Andersen, Gorm

2010-01-01

-exposed epitopes are unknown. An insect cell and Escherichia coli based system was used to express single and double domains encoded by the pfd1235w var gene. The resulting recombinant proteins have been evaluated for yield and purity and their ability to induce rat antibodies, which react with the native PFD1235w...... PfEMP1 antigen expressed on 3D7PFD1235w-IE. Their recognition by human anti-malaria antibodies from previously infected Tanzanian donors was also analysed....

Gammaherpesvirus Co-infection with Malaria Suppresses Anti-parasitic Humoral Immunity.

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Caline G Matar

2015-05-01

Full Text Available Immunity to non-cerebral severe malaria is estimated to occur within 1-2 infections in areas of endemic transmission for Plasmodium falciparum. Yet, nearly 20% of infected children die annually as a result of severe malaria. Multiple risk factors are postulated to exacerbate malarial disease, one being co-infections with other pathogens. Children living in Sub-Saharan Africa are seropositive for Epstein Barr Virus (EBV by the age of 6 months. This timing overlaps with the waning of protective maternal antibodies and susceptibility to primary Plasmodium infection. However, the impact of acute EBV infection on the generation of anti-malarial immunity is unknown. Using well established mouse models of infection, we show here that acute, but not latent murine gammaherpesvirus 68 (MHV68 infection suppresses the anti-malarial humoral response to a secondary malaria infection. Importantly, this resulted in the transformation of a non-lethal P. yoelii XNL infection into a lethal one; an outcome that is correlated with a defect in the maintenance of germinal center B cells and T follicular helper (Tfh cells in the spleen. Furthermore, we have identified the MHV68 M2 protein as an important virus encoded protein that can: (i suppress anti-MHV68 humoral responses during acute MHV68 infection; and (ii plays a critical role in the observed suppression of anti-malarial humoral responses in the setting of co-infection. Notably, co-infection with an M2-null mutant MHV68 eliminates lethality of P. yoelii XNL. Collectively, our data demonstrates that an acute gammaherpesvirus infection can negatively impact the development of an anti-malarial immune response. This suggests that acute infection with EBV should be investigated as a risk factor for non-cerebral severe malaria in young children living in areas endemic for Plasmodium transmission.

Frequently Asked Questions (FAQs) about Malaria

Science.gov (United States)

... Facebook Tweet Share Compartir The Disease What is Malaria? Malaria is a serious and sometimes fatal disease ... cycle of disease and poverty. How People Get Malaria (Transmission) How is malaria transmitted? Usually, people get ...

Malaria, malnutrition, and birthweight

DEFF Research Database (Denmark)

Cates, Jordan E.; Unger, Holger W.; Briand, Valerie

2017-01-01

were identified by the Maternal Malaria and Malnutrition (M3) initiative using a convenience sampling approach and were eligible for pooling given adequate ethical approval and availability of essential variables. Study-specific adjusted effect estimates were calculated using inverse probability...... be multiplicative interaction between malaria infection at enrollment and low MUAC within studies conducted in Africa; however, this finding was not consistent on the additive scale, when accounting for multiple comparisons, or when using other definitions of malaria and malnutrition. The major limitations...... of the study included availability of only 2 cross-sectional measurements of malaria and the limited availability of ultrasound-based pregnancy dating to assess impacts on preterm birth and fetal growth in all studies.  Conclusions : Pregnant women with malnutrition and malaria infection are at increased risk...

Comparative evaluation of two rapid field tests for malaria diagnosis: Partec Rapid Malaria Test® and Binax Now® Malaria Rapid Diagnostic Test.

Science.gov (United States)

Nkrumah, Bernard; Acquah, Samuel Ek; Ibrahim, Lukeman; May, Juergen; Brattig, Norbert; Tannich, Egbert; Nguah, Samuel Blay; Adu-Sarkodie, Yaw; Huenger, Frank

2011-05-23

About 90% of all malaria deaths in sub-Saharan Africa occur in children under five years. Fast and reliable diagnosis of malaria requires confirmation of the presence of malaria parasites in the blood of patients with fever or history suggestive of malaria; hence a prompt and accurate diagnosis of malaria is the key to effective disease management. Confirmation of malaria infection requires the availability of a rapid, sensitive, and specific testing at an affordable cost. We compared two recent methods (the novel Partec Rapid Malaria Test® (PT) and the Binax Now® Malaria Rapid Diagnostic Test (BN RDT) with the conventional Giemsa stain microscopy (GM) for the diagnosis of malaria among children in a clinical laboratory of a hospital in a rural endemic area of Ghana. Blood samples were collected from 263 children admitted with fever or a history of fever to the pediatric clinic of the Agogo Presbyterian Hospital. The three different test methods PT, BN RDT and GM were performed independently by well trained and competent laboratory staff to assess the presence of malaria parasites. Results were analyzed and compared using GM as the reference standard. In 107 (40.7%) of 263 study participants, Plasmodium sp. was detected by GM. PT and BN RDT showed positive results in 111 (42.2%) and 114 (43.4%), respectively. Compared to GM reference standard, the sensitivities of the PT and BN RDT were 100% (95% CI: 96.6-100) and 97.2% (95% CI: 92.0-99.4), respectively, specificities were 97.4% (95% CI: 93.6-99.3) and 93.6% (95% CI: 88.5-96.9), respectively. There was a strong agreement (kappa) between the applied test methods (GM vs PT: 0.97; p < 0.001 and GM vs BN RDT: 0.90; p < 0.001). The average turnaround time per tests was 17 minutes. In this study two rapid malaria tests, PT and BN RDT, demonstrated a good quality of their performance compared to conventional GM. Both methods require little training, have short turnaround times, are applicable as well as affordable and

Assessing ABO/Rh Blood Group Frequency and Association with Asymptomatic Malaria among Blood Donors Attending Arba Minch Blood Bank, South Ethiopia

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Getaneh Alemu

2016-01-01

Full Text Available Background. Determination of the various ABO/Rh blood group distributions and their association with malaria infection has paramount importance in the context of transfusion medicine and malaria control. Methods. Facility based cross-sectional study was conducted from February to June, 2015, to assess ABO/Rh blood groups distribution and their association with asymptomatic malaria. A structured questionnaire was used to collect data. Blood grouping was done using monoclonal antibodies. Thin and thick blood films were examined for Plasmodium parasites. Data were analyzed using SPSS version 20.0. Results. A total of 416 blood donors participated with median age of 22±0.29 (median ± standard error of the mean. Distribution of ABO phenotypes, in decreasing order, was O (175, 42.1%, A (136, 32.7%, B (87, 20.9%, and AB (18, 4.3%. Most of them were Rh+ (386, 92.8%. The overall malaria prevalence was 4.1% (17/416. ABO blood group is significantly associated with malaria infection (P=0.022. High rate of parasitemia was seen in blood group O donors (6.899, P=0.003 compared to those with other ABO blood groups. Conclusion. Blood groups O and AB phenotypes are the most and the least ABO blood groups, respectively. There is significant association between ABO blood group and asymptomatic malaria parasitemia.

Muscling out malaria

DEFF Research Database (Denmark)

Hughes, David Peter; Boomsma, Jacobus Jan

2006-01-01

) [2] highlighted the back-to-back articles in Science 3 and 4 that demonstrated the potential biocontrol of malaria by targeting mosquitoes with entomopathogenic fungi (Metarhizium and Beauveria spp.). The wide impact of the original articles and the need to find alternatives to pesticidal control...... where malaria is endemic, humanity cannot afford shortcuts, because any failures owing to poor management or premature implementation will reduce local governmental support rather than enhance it (Andrew Read, pers. commun.). Therefore, if we are to ‘muscle out malaria', well...... of key importance, and the new focus on fungal biocontrol of malaria should therefore act as a catalyst for further research on the basic biology of fungal pathogens. Understanding morphological, biochemical or immune system-based resistance to insect pathogenic fungi will be easier if we know...

Malaria Surveillance - United States, 2015.

Science.gov (United States)

Mace, Kimberly E; Arguin, Paul M; Tan, Kathrine R

2018-05-04

Malaria in humans is caused by intraerythrocytic protozoa of the genus Plasmodium. These parasites are transmitted by the bite of an infective female Anopheles species mosquito. The majority of malaria infections in the United States occur among persons who have traveled to regions with ongoing malaria transmission. However, malaria is occasionally acquired by persons who have not traveled out of the country through exposure to infected blood products, congenital transmission, laboratory exposure, or local mosquitoborne transmission. Malaria surveillance in the United States is conducted to provide information on its occurrence (e.g., temporal, geographic, and demographic), guide prevention and treatment recommendations for travelers and patients, and facilitate transmission control measures if locally acquired cases are identified. This report summarizes confirmed malaria cases in persons with onset of illness in 2015 and summarizes trends in previous years. Malaria cases diagnosed by blood film microscopy, polymerase chain reaction, or rapid diagnostic tests are reported to local and state health departments by health care providers or laboratory staff members. Case investigations are conducted by local and state health departments, and reports are transmitted to CDC through the National Malaria Surveillance System (NMSS), the National Notifiable Diseases Surveillance System (NNDSS), or direct CDC consultations. CDC reference laboratories provide diagnostic assistance and conduct antimalarial drug resistance marker testing on blood samples submitted by health care providers or local or state health departments. This report summarizes data from the integration of all NMSS and NNDSS cases, CDC reference laboratory reports, and CDC clinical consultations. CDC received reports of 1,517 confirmed malaria cases, including one congenital case, with an onset of symptoms in 2015 among persons who received their diagnoses in the United States. Although the number of

Malaria chemoprophylaxis and the serologic response to measles and diphtheria-tetanus-whole-cell pertussis vaccines

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Saliou Pierre

2005-11-01

Full Text Available Abstract Background Acute malaria has been associated with a decreased antibody response to tetanus and diphtheria toxoids, meningococcal, salmonella, and Hib vaccines. Interest in giving malaria drug therapy and prevention at the time of childhood immunizations has increased greatly following recent trials of intermittent preventive therapy during infancy (IPTi, stimulating this re-analysis of unpublished data. The effect of malaria chemoprophylaxis on vaccine response was studied following administration of measles vaccines and diphtheria-tetanus-whole cell pertussis (DTP vaccines. Methods In 1975, six villages divided into two groups of children ≤74 months of age from Burkina Faso, were assigned to receive amodiaquine hydrochloride chemoprophylaxis (CH+ every two weeks for seven months or no chemoprophylaxis (CH-. After five months, children in each group received either one dose of measles or two doses of DTP vaccines. Results For recipients of the measles vaccine, the seroconversion rates in CH+ and CH- children, respectively, were 93% and 96% (P > 0.05. The seroresponse rates in CH+ and CH- children respectively, were 73% and 86% for diphtheria (P > 0.05 and 77% and 91% for tetanus toxoid (P > 0.05. In a subset analysis, in which only children who strictly adhered to chemoprophylaxis criteria were included, there were, likewise, no significant differences in seroconversion or seroresponse for measles, diphtheria, or tetanus vaccines (P > 0.05. While analysis for pertussis showed a 43% (CH+ and 67% (CH- response (P Conclusion Malaria chemoprophylaxis prior to vaccination in malaria endemic settings did not improve or impair immunogenicity of DTP and measles vaccines. This is the first human study to look at the association between malaria chemoprophylaxis and the serologic response to whole-cell pertussis vaccine.

Agonistic Human Antibodies Binding to Lecithin-Cholesterol Acyltransferase Modulate High Density Lipoprotein Metabolism*

Science.gov (United States)

Gunawardane, Ruwanthi N.; Fordstrom, Preston; Piper, Derek E.; Masterman, Stephanie; Siu, Sophia; Liu, Dongming; Brown, Mike; Lu, Mei; Tang, Jie; Zhang, Richard; Cheng, Janet; Gates, Andrew; Meininger, David; Chan, Joyce; Carlson, Tim; Walker, Nigel; Schwarz, Margrit; Delaney, John; Zhou, Mingyue

2016-01-01

Drug discovery opportunities where loss-of-function alleles of a target gene link to a disease-relevant phenotype often require an agonism approach to up-regulate or re-establish the activity of the target gene. Antibody therapy is increasingly recognized as a favored drug modality due to multiple desirable pharmacological properties. However, agonistic antibodies that enhance the activities of the target enzymes are rarely developed because the discovery of agonistic antibodies remains elusive. Here we report an innovative scheme of discovery and characterization of human antibodies capable of binding to and agonizing a circulating enzyme lecithin cholesterol acyltransferase (LCAT). Utilizing a modified human LCAT protein with enhanced enzymatic activity as an immunogen, we generated fully human monoclonal antibodies using the XenoMouseTM platform. One of the resultant agonistic antibodies, 27C3, binds to and substantially enhances the activity of LCAT from humans and cynomolgus macaques. X-ray crystallographic analysis of the 2.45 Å LCAT-27C3 complex shows that 27C3 binding does not induce notable structural changes in LCAT. A single administration of 27C3 to cynomolgus monkeys led to a rapid increase of plasma LCAT enzymatic activity and a 35% increase of the high density lipoprotein cholesterol that was observed up to 32 days after 27C3 administration. Thus, this novel scheme of immunization in conjunction with high throughput screening may represent an effective strategy for discovering agonistic antibodies against other enzyme targets. 27C3 and other agonistic human anti-human LCAT monoclonal antibodies described herein hold potential for therapeutic development for the treatment of dyslipidemia and cardiovascular disease. PMID:26644477

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

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.

Science.gov (United States)

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

Malaria and Travelers

Science.gov (United States)

... Providers, Emergency Consultations, and General Public. Contact Us Malaria and Travelers for U.S. Residents Recommend on Facebook ... may be at risk for infection. Determine if malaria transmission occurs at the destinations Obtain a detailed ...

Using Respondent Driven Sampling to Identify Malaria Risks and Occupational Networks among Migrant Workers in Ranong, Thailand.

Directory of Open Access Journals (Sweden)

Piyaporn Wangroongsarb

Full Text Available Ranong Province in southern Thailand is one of the primary entry points for migrants entering Thailand from Myanmar, and borders Kawthaung Township in Myanmar where artemisinin resistance in malaria parasites has been detected. Areas of high population movement could increase the risk of spread of artemisinin resistance in this region and beyond.A respondent-driven sampling (RDS methodology was used to compare migrant populations coming from Myanmar in urban (Site 1 vs. rural (Site 2 settings in Ranong, Thailand. The RDS methodology collected information on knowledge, attitudes, and practices for malaria, travel and occupational histories, as well as social network size and structure. Individuals enrolled were screened for malaria by microscopy, Real Time-PCR, and serology.A total of 619 participants were recruited in Ranong City and 623 participants in Kraburi, a rural sub-district. By PCR, a total of 14 (1.1% samples were positive (2 P. falciparum in Site 1; 10 P. vivax, 1 Pf, and 1 P. malariae in Site 2. PCR analysis demonstrated an overall weighted prevalence of 0.5% (95% CI, 0-1.3% in the urban site and 1.0% (95% CI, 0.5-1.7% in the rural site for all parasite species. PCR positivity did not correlate with serological positivity; however, as expected there was a strong association between antibody prevalence and both age and exposure. Access to long-lasting insecticidal treated nets remains low despite relatively high reported traditional net use among these populations.The low malaria prevalence, relatively smaller networks among migrants in rural settings, and limited frequency of travel to and from other areas of malaria transmission in Myanmar, suggest that the risk for the spread of artemisinin resistance from this area may be limited in these networks currently but may have implications for regional malaria elimination efforts.

Malaria and Tropical Travel

Centers for Disease Control (CDC) Podcasts

2008-05-15

Malaria is a serious mosquito-borne disease that can lead to death. This podcast discusses malaria risk when traveling to tropical areas, as well as how to protect yourself and your family from malaria infection.  Created: 5/15/2008 by National Center for Zoonotic, Vector-Borne, and Enteric Diseases (NCZVED).   Date Released: 5/29/2008.

Malaria successes and challenges in Asia.

Science.gov (United States)

Bhatia, Rajesh; Rastogi, Rakesh Mani; Ortega, Leonard

2013-12-01

Asia ranks second to Africa in terms of malaria burden. In 19 countries of Asia, malaria is endemic and 2.31 billion people or 62% of the total population in these countries are at risk of malaria. In 2010, WHO estimated around 34.8 million cases and 45,600 deaths due to malaria in Asia. In 2011, 2.7 million cases and > 2000 deaths were reported. India, Indonesia, Myanmar and Pakistan are responsible for >85% of the reported cases (confirmed) and deaths in Asia. In last 10 yr, due to availability of donor's fund specially from Global fund, significant progress has been made by the countries in Asia in scaling-up malaria control interventions which were instrumental in reducing malaria morbidity and mortality significantly. There is a large heterogeneity in malaria epidemiology in Asia. As a result, the success in malaria control/elimination is also diverse. As compared to the data of the year 2000, out of 19 malaria endemic countries, 12 countries were able to reduce malaria incidence (microscopically confirmed cases only) by 75%. Two countries, namely Bangladesh and Malaysia are projected to reach 75% reduction by 2015 while India is projected to reach 50-75% only by 2015. The trend could not be assessed in four countries, namely Indonesia, Myanmar, Pakistan and Timor-Leste due to insufficient consistent data. Numerous key challenges need to be addressed to sustain the gains and eliminate malaria in most parts of Asia. Some of these are to control the spread of resistance in Plasmodium falciparum to artemisinin, control of outdoor transmission, control of vivax malaria and ensuring universal coverage of key interventions. Asia has the potential to influence the malaria epidemiology all over the world as well as to support the global efforts in controlling and eliminating malaria through production of quality-assured ACTs, RDTs and long-lasting insecticidal nets.

Human vaccination against Plasmodium vivax Duffy-binding protein induces strain-transcending antibodies

OpenAIRE

Payne, Ruth O.; Silk, Sarah E.; Elias, Sean C.; Milne, Kathryn H.; Rawlinson, Thomas A.; Llewellyn, David; Shakri, A. Rushdi; Jin, Jing; Labb?, Genevi?ve M.; Edwards, Nick J.; Poulton, Ian D.; Roberts, Rachel; Farid, Ryan; J?rgensen, Thomas; Alanine, Daniel G.W.

2017-01-01

BACKGROUND: Plasmodium vivax is the most widespread human malaria geographically; however, no effective vaccine exists. Red blood cell invasion by the P. vivax merozoite depends on an interaction between the Duffy antigen receptor for chemokines (DARC) and region II of the parasite's Duffy-binding protein (PvDBP_RII). Naturally acquired binding-inhibitory antibodies against this interaction associate with clinical immunity, but it is unknown whether these responses can be induced by human vac...

Evidence from a natural experiment that malaria parasitemia is pathogenic in retinopathy-negative cerebral malaria.

Science.gov (United States)

Small, Dylan S; Taylor, Terrie E; Postels, Douglas G; Beare, Nicholas Av; Cheng, Jing; MacCormick, Ian Jc; Seydel, Karl B

2017-06-07

Cerebral malaria (CM) can be classified as retinopathy-positive or retinopathy-negative, based on the presence or absence of characteristic retinal features. While malaria parasites are considered central to the pathogenesis of retinopathy-positive CM, their contribution to retinopathy-negative CM is largely unknown. One theory is that malaria parasites are innocent bystanders in retinopathy-negative CM and the etiology of the coma is entirely non-malarial. Because hospitals in malaria-endemic areas often lack diagnostic facilities to identify non-malarial causes of coma, it has not been possible to evaluate the contribution of malaria infection to retinopathy-negative CM. To overcome this barrier, we studied a natural experiment involving genetically inherited traits, and find evidence that malaria parasitemia does contribute to the pathogenesis of retinopathy-negative CM. A lower bound for the fraction of retinopathy-negative CM that would be prevented if malaria parasitemia were to be eliminated is estimated to be 0.93 (95% confidence interval: 0.68, 1).

Malaria infection has spatial, temporal, and spatiotemporal heterogeneity in unstable malaria transmission areas in northwest Ethiopia.

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Kassahun Alemu

Full Text Available BACKGROUND: Malaria elimination requires successful nationwide control efforts. Detecting the spatiotemporal distribution and mapping high-risk areas are useful to effectively target pockets of malaria endemic regions for interventions. OBJECTIVE: The aim of the study was to identify patterns of malaria distribution by space and time in unstable malaria transmission areas in northwest Ethiopia. METHODS: Data were retrieved from the monthly reports stored in the district malaria offices for the period between 2003 and 2012. Eighteen districts in the highland and fringe malaria areas were included and geo-coded for the purpose of this study. The spatial data were created in ArcGIS10 for each district. The Poisson model was used by applying Kulldorff methods using the SaTScan™ software to analyze the purely temporal, spatial and space-time clusters of malaria at a district levels. RESULTS: The study revealed that malaria case distribution has spatial, temporal, and spatiotemporal heterogeneity in unstable transmission areas. Most likely spatial malaria clusters were detected at Dera, Fogera, Farta, Libokemkem and Misrak Este districts (LLR =197764.1, p<0.001. Significant spatiotemporal malaria clusters were detected at Dera, Fogera, Farta, Libokemkem and Misrak Este districts (LLR=197764.1, p<0.001 between 2003/1/1 and 2012/12/31. A temporal scan statistics identified two high risk periods from 2009/1/1 to 2010/12/31 (LLR=72490.5, p<0.001 and from 2003/1/1 to 2005/12/31 (LLR=26988.7, p<0.001. CONCLUSION: In unstable malaria transmission areas, detecting and considering the spatiotemporal heterogeneity would be useful to strengthen malaria control efforts and ultimately achieve elimination.

The use of a GIS-based malaria information system for malaria research and control in South Africa.

Science.gov (United States)

Martin, Carrin; Curtis, Bronwyn; Fraser, Colleen; Sharp, Brian

2002-12-01

The paper aims to outline the innovative development and application of a Geographical Information System based Malaria Information System for malaria research and control in South Africa. This system is a product of collaboration between the Malaria Control Programmes and the Malaria Research Programme of the Medical Research Council of South Africa. The ability of such a system to process data timeously into a usable format is discussed, as well as its relevance to malaria research, appropriate malaria control measures, tourism, and social and economic development.

Severe malaria in Europe

DEFF Research Database (Denmark)

Kurth, Florian; Develoux, Michel; Mechain, Matthieu

2017-01-01

BACKGROUND: Malaria remains one of the most serious infections for travellers to tropical countries. Due to the lack of harmonized guidelines a large variety of treatment regimens is used in Europe to treat severe malaria. METHODS: The European Network for Tropical Medicine and Travel Health (Trop......Net) conducted an 8-year, multicentre, observational study to analyse epidemiology, treatment practices and outcomes of severe malaria in its member sites across Europe. Physicians at participating TropNet centres were asked to report pseudonymized retrospective data from all patients treated at their centre...... for microscopically confirmed severe Plasmodium falciparum malaria according to the 2006 WHO criteria. RESULTS: From 2006 to 2014 a total of 185 patients with severe malaria treated in 12 European countries were included. Three patients died, resulting in a 28-day survival rate of 98.4%. The majority of infections...

A nonintegrative lentiviral vector-based vaccine provides long-term sterile protection against malaria.

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