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

DEFF Research Database (Denmark)

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

2011-01-01

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

Malaria vaccines: the case for a whole-organism approach.

Science.gov (United States)

Pinzon-Charry, Alberto; Good, Michael F

2008-04-01

Malaria is a significant health problem causing morbidity and mortality worldwide. Vaccine development has been an imperative for decades. However, the intricacy of the parasite's lifecycle coupled with the lack of evidence for robust infection-induced immunity has made vaccine development exceptionally difficult. To review some of the key advances in the field and discuss potential ways forward for a whole-organism vaccine. The authors searched PubMed using the words 'malaria and vaccine'. We searched for manuscripts detailing antigen characterisation and vaccine strategies with emphasis on subunit versus whole-parasite approaches. Abstracts were selected and relevant articles are discussed. The searches were not restricted by language or date. The early cloning of malaria antigens has fuelled rapid development of subunit vaccines. However, the disappointing results of clinical trials have resulted in reappraisal of current strategies. Whole-parasite approaches have re-emerged as an alternative strategy. Immunization using radiation or genetically attenuated sporozoites has been shown to result in sterile immunity and immunization with blood-stage parasites curtailed by antimalarials has demonstrated delayed parasitemia in rodent models as well as in human malaria.

randomised trial of alternative malaria chemoprophylaxis strategies

African Journals Online (AJOL)

hi-tech

2000-02-02

Feb 2, 2000 ... randomisation produced comparable intervention and comparison groups with balanced characteristics. Specific results of the baseline studies are presented in the companion paper. ... strategies for protecting pregnant women against malaria. ..... from malaria vaccine trial conducted among Tanzanian.

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.

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

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

2013-01-01

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

Insights into long-lasting protection induced by RTS,S/AS02A malaria vaccine: further results from a phase IIb trial in Mozambican children.

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Caterina Guinovart

Full Text Available The pre-erythrocytic malaria vaccine RTS,S/AS02A has shown to confer protection against clinical malaria for at least 21 months in a trial in Mozambican children. Efficacy varied between different endpoints, such as parasitaemia or clinical malaria; however the underlying mechanisms that determine efficacy and its duration remain unknown. We performed a new, exploratory analysis to explore differences in the duration of protection among participants to better understand the protection afforded by RTS,S.The study was a Phase IIb double-blind, randomized controlled trial in 2022 children aged 1 to 4 years. The trial was designed with two cohorts to estimate vaccine efficacy against two different endpoints: clinical malaria (cohort 1 and infection (cohort 2. Participants were randomly allocated to receive three doses of RTS,S/AS02A or control vaccines. We did a retrospective, unplanned sub-analysis of cohort 2 data using information collected for safety through the health facility-based passive case detection system. Vaccine efficacy against clinical malaria was estimated over the first six-month surveillance period (double-blind phase and over the following 12 months (single-blind phase, and analysis was per-protocol. Adjusted vaccine efficacy against first clinical malaria episodes in cohort 2 was of 35.4% (95% CI 4.5-56.3; p = 0.029 over the double-blind phase and of 9.0% (-30.6-36.6; p = 0.609 during the single-blind phase.Contrary to observations in cohort 1, where efficacy against clinical malaria did not wane over time, in cohort 2 the efficacy decreases with time. We hypothesize that this reduced duration of protection is a result of the early diagnosis and treatment of infections in cohort 2 participants, preventing sufficient exposure to asexual-stage antigens. On the other hand, the long-term protection against clinical disease observed in cohort 1 may be a consequence of a prolonged exposure to low-dose blood-stage asexual parasitaemia.ClinicalTrials

Comparison of clinical and parasitological data from controlled human malaria infection trials.

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Meta Roestenberg

Full Text Available Exposing healthy human volunteers to Plasmodium falciparum-infected mosquitoes is an accepted tool to evaluate preliminary efficacy of malaria vaccines. To accommodate the demand of the malaria vaccine pipeline, controlled infections are carried out in an increasing number of centers worldwide. We assessed their safety and reproducibility.We reviewed safety and parasitological data from 128 malaria-naïve subjects participating in controlled malaria infection trials conducted at the University of Oxford, UK, and the Radboud University Nijmegen Medical Center, The Netherlands. Results were compared to a report from the US Military Malaria Vaccine Program.We show that controlled human malaria infection trials are safe and demonstrate a consistent safety profile with minor differences in the frequencies of arthralgia, fatigue, chills and fever between institutions. But prepatent periods show significant variation. Detailed analysis of Q-PCR data reveals highly synchronous blood stage parasite growth and multiplication rates.Procedural differences can lead to some variation in safety profile and parasite kinetics between institutions. Further harmonization and standardization of protocols will be useful for wider adoption of these cost-effective small-scale efficacy trials. Nevertheless, parasite growth rates are highly reproducible, illustrating the robustness of controlled infections as a valid tool for malaria vaccine development.

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

Science.gov (United States)

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

2015-12-23

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

Important advances in malaria vaccine research

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Priyanka Jadhav

2012-01-01

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

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

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Matthew B Laurens

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

Steady progress toward a malaria vaccine.

Science.gov (United States)

Lyke, Kirsten E

2017-10-01

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

Safety and immunogenicity of GMZ2 - a MSP3-GLURP fusion protein malaria vaccine candidate

DEFF Research Database (Denmark)

Esen, Meral; Kremsner, Peter G; Schleucher, Regina

2009-01-01

Malaria is a major public health problem in Sub-Saharan Africa. In highly endemic regions infants, children and pregnant women are mostly affected. An effective malaria vaccine would complement existing malaria control strategies because it can be integrated in existing immunization programs easily....... Here we present the results of the first phase Ia clinical trial of GMZ2 adjuvanted in aluminium hydroxide. GMZ2 is a malaria vaccine candidate, designed upon the rationale to induce immune responses against asexual blood stages of Plasmodium falciparum similar to those encountered in semi...... is a safe and immunogenic malaria vaccine candidate suitable for further clinical development....

Malaria vaccines and their potential role in the elimination of malaria

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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.

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.

The evolutionary consequences of blood-stage vaccination on the rodent malaria Plasmodium chabaudi.

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Victoria C Barclay

Full Text Available Malaria vaccine developers are concerned that antigenic escape will erode vaccine efficacy. Evolutionary theorists have raised the possibility that some types of vaccine could also create conditions favoring the evolution of more virulent pathogens. Such evolution would put unvaccinated people at greater risk of severe disease. Here we test the impact of vaccination with a single highly purified antigen on the malaria parasite Plasmodium chabaudi evolving in laboratory mice. The antigen we used, AMA-1, is a component of several candidate malaria vaccines currently in various stages of trials in humans. We first found that a more virulent clone was less readily controlled by AMA-1-induced immunity than its less virulent progenitor. Replicated parasites were then serially passaged through control or AMA-1 vaccinated mice and evaluated after 10 and 21 rounds of selection. We found no evidence of evolution at the ama-1 locus. Instead, virulence evolved; AMA-1-selected parasites induced greater anemia in naïve mice than both control and ancestral parasites. Our data suggest that recombinant blood stage malaria vaccines can drive the evolution of more virulent malaria parasites.

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

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.

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

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Yimin Wu

2008-07-01

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

Optimal control for Malaria disease through vaccination

Science.gov (United States)

Munzir, Said; Nasir, Muhammad; Ramli, Marwan

2018-01-01

Malaria is a disease caused by an amoeba (single-celled animal) type of plasmodium where anopheles mosquito serves as the carrier. This study examines the optimal control problem of malaria disease spread based on Aron and May (1982) SIR type models and seeks the optimal solution by minimizing the prevention of the spreading of malaria by vaccine. The aim is to investigate optimal control strategies on preventing the spread of malaria by vaccination. The problem in this research is solved using analytical approach. The analytical method uses the Pontryagin Minimum Principle with the symbolic help of MATLAB software to obtain optimal control result and to analyse the spread of malaria with vaccination control.

Overview of Plant-Made Vaccine Antigens against Malaria

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Marina Clemente

2012-01-01

Full Text Available This paper is an overview of vaccine antigens against malaria produced in plants. Plant-based expression systems represent an interesting production platform due to their reduced manufacturing costs and high scalability. At present, different Plasmodium antigens and expression strategies have been optimized in plants. Furthermore, malaria antigens are one of the few examples of eukaryotic proteins with vaccine value expressed in plants, making plant-derived malaria antigens an interesting model to analyze. Up to now, malaria antigen expression in plants has allowed the complete synthesis of these vaccine antigens, which have been able to induce an active immune response in mice. Therefore, plant production platforms offer wonderful prospects for improving the access to malaria vaccines.

MALARIA VACCINE: MYTH OR REALITY?

African Journals Online (AJOL)

Femi Olaleye

Malaria currently remains the highest killer disease nationwide despite existing control measures. Malaria vaccine ... that malaria could be eliminated or at least controlled. However, because of changes in vector behaviour, drug resistance, manpower constraints for public ..... Although animal host models are different from ...

First results of phase 3 trial of RTS,S/AS01 malaria vaccine in African children

DEFF Research Database (Denmark)

Agnandji, Selidji Todagbe; Lell, Bertrand; Soulanoudjingar, Solange Solmeheim

2011-01-01

An ongoing phase 3 study of the efficacy, safety, and immunogenicity of candidate malaria vaccine RTS,S/AS01 is being conducted in seven African countries.......An ongoing phase 3 study of the efficacy, safety, and immunogenicity of candidate malaria vaccine RTS,S/AS01 is being conducted in seven African countries....

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

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Patrick Georges Cech

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

WHO policy development processes for a new vaccine: case study of malaria vaccines

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Cheyne James

2010-06-01

Full Text Available Abstract Background Recommendations from the World Health Organization (WHO are crucial to inform developing country decisions to use, or not, a new intervention. This article analysed the WHO policy development process to predict its course for a malaria vaccine. Methods The decision-making processes for one malaria intervention and four vaccines were classified through (1 consultations with staff and expert advisors to WHO's Global Malaria Programme (GMP and Immunization, Vaccines and Biologicals Department (IVB; (2 analysis of the procedures and recommendations of the major policy-making bodies of these groups; (3 interviews with staff of partnerships working toward new vaccine availability; and (4 review and analyses of evidence informing key policy decisions. Case description WHO policy formulation related to use of intermittent preventive treatment in infancy (IPTi and the following vaccine interventions: Haemophilus influenzae type b conjugate vaccine (Hib, pneumococcal conjugate vaccine (PCV, rotavirus vaccine (RV, and human papillomavirus vaccine (HPV, five interventions which had relatively recently been through systematic WHO policy development processes as currently constituted, was analysed. Required information was categorized in three areas defined by a recent WHO publication on development of guidelines: safety and efficacy in relevant populations, implications for costs and population health, and localization of data to specific epidemiological situations. Discussion and evaluation Data needs for a malaria vaccine include safety; the demonstration of efficacy in a range of epidemiological settings in the context of other malaria prevention interventions; and information on potential rebound in which disease increases subsequent to the intervention. In addition, a malaria vaccine would require attention to additional factors, such as costs and cost-effectiveness, supply and demand, impact of use on other interventions, and

A research agenda for malaria eradication: vaccines.

NARCIS (Netherlands)

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

2011-01-01

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

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.

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...

Novel approaches to identify protective malaria vaccine candidates

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Wan Ni eChia

2014-11-01

Full Text Available Efforts to develop vaccines against malaria have been the focus of substantial research activities for decades. Several categories of candidate vaccines are currently being developed for protection against malaria, based on antigens corresponding to the pre-erythrocytic, blood-stage or sexual stages of the parasite. Long lasting sterile protection from Plasmodium falciparum sporozoite challenge has been observed in human following vaccination with whole parasite formulations, clearly demonstrating that a protective immune response targeting predominantly the pre-erythrocytic stages can develop against malaria. However, most of vaccine candidates currently being investigated, which are mostly subunits vaccines, have not been able to induce substantial (>50% protection thus far. This is due to the fact that the antigens responsible for protection against the different parasite stages are still yet to be known and relevant correlates of protection have remained elusive. For a vaccine to be developed in a timely manner, novel approaches are required. In this article, we review the novel approaches that have been developed to identify the antigens for the development of an effective malaria vaccine.

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.

Malaria transmission dynamics at a site in northern Ghana proposed for testing malaria vaccines.

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Appawu, Maxwell; Owusu-Agyei, Seth; Dadzie, Samuel; Asoala, Victor; Anto, Francis; Koram, Kwadwo; Rogers, William; Nkrumah, Francis; Hoffman, Stephen L; Fryauff, David J

2004-01-01

We studied the malaria transmission dynamics in Kassena Nankana district (KND), a site in northern Ghana proposed for testing malaria vaccines. Intensive mosquito sampling for 1 year using human landing catches in three micro-ecological sites (irrigated, lowland and rocky highland) yielded 18 228 mosquitoes. Anopheles gambiae s.l. and Anopheles funestus constituted 94.3% of the total collection with 76.8% captured from the irrigated communities. Other species collected but in relatively few numbers were Anopheles pharoensis (5.4%) and Anopheles rufipes (0.3%). Molecular analysis of 728 An. gambiae.s.l. identified Anopheles gambiae s.s. as the most dominant sibling species (97.7%) of the An. gambiae complex from the three ecological sites. Biting rates of the vectors (36.7 bites per man per night) were significantly higher (P<0.05) in the irrigated area than in the non-irrigated lowland (5.2) and rocky highlands (5.9). Plasmodium falciparum sporozoite rates of 7.2% (295/4075) and 7.1% (269/3773) were estimated for An. gambiae s.s. and An. funestus, respectively. Transmission was highly seasonal, and the heaviest transmission occurred from June to October. The intensity of transmission was higher for people in the irrigated communities than the non-irrigated ones. An overall annual entomological inoculation rate (EIR) of 418 infective bites was estimated in KND. There were micro-ecological variations in the EIRs, with values of 228 infective bites in the rocky highlands, 360 in the lowlands and 630 in the irrigated area. Approximately 60% of malaria transmission in KND occurred indoors during the second half of the night, peaking at daybreak between 04.00 and 06.00 hours. Vaccine trials could be conducted in this district, with timing dependent on the seasonal patterns and intensity of transmission taking into consideration the micro-geographical differences and vaccine trial objectives.

Efficacy and Safety of the RTS,S/AS01 Malaria Vaccine during 18 Months after Vaccination

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Theander, Thor Grundtvig; Lusingu, John Peter Andrea

2014-01-01

BACKGROUND: A malaria vaccine could be an important addition to current control strategies. We report the safety and vaccine efficacy (VE) of the RTS,S/AS01 vaccine during 18 mo following vaccination at 11 African sites with varying malaria transmission. METHODS AND FINDINGS: 6,537 infants aged 6......-12 wk and 8,923 children aged 5-17 mo were randomized to receive three doses of RTS,S/AS01 or comparator vaccine. VE against clinical malaria in children during the 18 mo after vaccine dose 3 (per protocol) was 46% (95% CI 42% to 50%) (range 40% to 77%; VE, p... after vaccine dose 1 (intention to treat [ITT]) was 45% (95% CI 41% to 49%). VE against severe malaria, malaria hospitalization, and all-cause hospitalization was 34% (95% CI 15% to 48%), 41% (95% CI 30% to 50%), and 19% (95% CI 11% to 27%), respectively (ITT). VE against clinical malaria in infants...

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....

External quality assurance of malaria nucleic acid testing for clinical trials and eradication surveillance

NARCIS (Netherlands)

Murphy, S.C.; Hermsen, C.C.; Douglas, A.D.; Edwards, N.J.; Petersen, I.; Fahle, G.A.; Adams, M.; Berry, A.A.; Billman, Z.P.; Gilbert, S.C.; Laurens, M.B.; Leroy, O.; Lyke, K.E.; Plowe, C.V.; Seilie, A.M.; Strauss, K.A.; Teelen, K.; Hill, A.V.; Sauerwein, R.W.

2014-01-01

Nucleic acid testing (NAT) for malaria parasites is an increasingly recommended diagnostic endpoint in clinical trials of vaccine and drug candidates and is also important in surveillance of malaria control and elimination efforts. A variety of reported NAT assays have been described, yet no formal

Comparative decline in funding of European Commission malaria vaccine projects: what next for the European scientists working in this field?

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Imoukhuede Egeruan B

2011-09-01

Full Text Available Abstract Since 2000, under the Fifth and subsequent Framework Programmes, the European Commission has funded research to spur the development of a malaria vaccine. This funding has contributed to the promotion of an integrated infrastructure consisting of European basic, applied and clinical scientists in academia and small and medium enterprises, together with partners in Africa. Research has added basic understanding of what is required of a malaria vaccine, allowing selected candidates to be prioritized and some to be moved forward into clinical trials. To end the health burden of malaria, and its economic and social impact on development, the international community has now essentially committed itself to the eventual eradication of malaria. Given the current tentative advances towards elimination or eradication of malaria in many endemic areas, malaria vaccines constitute an additional and almost certainly essential component of any strategic plan to interrupt transmission of malaria. However, funding for malaria vaccines has been substantially reduced in the Seventh Framework Programme compared with earlier Framework Programmes, and without further support the gains made by earlier European investment will be lost.

RTS,S malaria vaccine development: progress and considerations for postapproval introduction

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Asante KP

2016-06-01

Full Text Available Kwaku Poku Asante, George Adjei, Yeetey Enuameh, Seth Owusu-Agyei Kintampo Health Research Centre, Kintampo, Brong Ahafo Region, Ghana Abstract: Though the burden of malaria has decreased in the last decade in some sub-Saharan African countries, it is still high in others, and there is no malaria vaccine in use. The development of malaria vaccines in combination with current control programs could be effective in reducing the malaria burden. In this paper, we review and discuss the progress made in the RTS,S malaria vaccine development and considerations for its postapproval process. We conclude that the development of malaria vaccines has been a long process confronted with challenges of funding, difficulty in identifying malaria antigens that correlate with protection, and development of adjuvant systems among others. The scientific approval of the vaccine by the European Medicines Agency in July 2015 and subsequent recommendations for pilot implementation studies by the World Health Organization made history as the first human parasite vaccine. It is also a major public health achievement as the vaccine has the potential to prevent thousands of malaria cases. However, there are implementation challenges such as cold chain systems, community acceptance, and monitoring of adverse events post-licensure that need to be carefully addressed. Keywords: malaria, vaccines, challenges, introduction, Africa, implementation considerations 

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...

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

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

2009-01-01

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

Extended follow-up following a phase 2b randomized trial of the candidate malaria vaccines FP9 ME-TRAP and MVA ME-TRAP among children in Kenya.

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Philip Bejon

2007-08-01

Full Text Available "FFM ME-TRAP" is sequential immunisation with two attenuated poxvirus vectors (FP9 and modified vaccinia virus Ankara delivering the pre-erythrocytic malaria antigen ME-TRAP. Over nine months follow-up in our original study, there was no evidence that FFM ME-TRAP provided protection against malaria. The incidence of malaria was slightly higher in children who received FFM ME-TRAP, but this was not statistically significant (hazard ratio 1.5, 95% CI 1.0-2.3. Although the study was unblinded, another nine months follow-up was planned to monitor the incidence of malaria and other serious adverse events.405 children aged 1-6 yrs were initially randomized to vaccination with either FFM ME-TRAP or control (rabies vaccine. 380 children were still available for follow-up after the first nine months. Children were seen weekly and whenever they were unwell for nine months monitoring. The axillary temperature was measured, and blood films taken when febrile. The primary analysis was time to parasitaemia >2,500/microl. During the second nine months monitoring, 49 events met the primary endpoint (febrile malaria with parasites >2,500/microl in the Intention To Treat (ITT group. 23 events occurred among the 189 children in the FFM ME-TRAP group, and 26 among the 194 children in the control group. In the full 18 months of monitoring, there were 63 events in the FFM ME-TRAP group and 60 in the control group (HR = 1.2, CI 0.84-1.73, p = 0.35. There was no evidence that the HR changed over the 18 months (test for interaction between time and vaccination p = 0.11.Vaccination with FFM ME-TRAP was not protective against malaria in this study. Malaria incidence during 18 months of surveillance was similar in both vaccine groups.Controlled-Trials.com ISRCTN88335123.

Shape of Key Malaria Protein Could Help Improve Vaccine Efficacy

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... Featured Diseases & Conditions Food Allergy HIV/AIDS Influenza Malaria Respiratory Syncytial Virus (RSV) Tuberculosis Zika Virus Find ... To Volunteer for Vaccine Research Studies Volunteer for Malaria Vaccine Research Volunteer Profiles Q&A: Vaccine Clinical ...

A malaria vaccine that elicits in humans antibodies able to kill Plasmodium falciparum.

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Pierre Druilhe

2005-11-01

Full Text Available Plasmodium falciparum merozoite surface protein 3 is a malaria vaccine candidate that was identified, characterised, and developed based on a unique immuno-clinical approach. The vaccine construct was derived from regions fully conserved among various strains and containing B cell epitopes targeted by human antibodies (from malaria-immune adults that are able to mediate a monocyte-dependent parasite killing effect. The corresponding long synthetic peptide was administered to 36 volunteers, with either alum or Montanide ISA720 as adjuvant.Both formulations induced cellular and humoral immune responses. With alum, the responses lasted up to 12 mo. The vaccine-induced antibodies were predominantly of cytophilic classes, i.e., able to cooperate with effector cells. In vitro, the antibodies induced an inhibition of the P. falciparum erythrocytic growth in a monocyte-dependent manner, which was in most instances as high as or greater than that induced by natural antibodies from immune African adults. In vivo transfer of the volunteers' sera into P. falciparum-infected humanized SCID mice profoundly reduced or abrogated parasitaemia. These inhibitory effects were related to the antibody reactivity with the parasite native protein, which was seen in 60% of the volunteers, and remained in samples taken 12 mo postimmunisation.This is the first malaria vaccine clinical trial to clearly demonstrate antiparasitic activity by vaccine-induced antibodies by both in vitro and in vivo methods. The results, showing the induction of long-lasting antibodies directed to a fully conserved polypeptide, also challenge current concepts about malaria vaccines, such as unavoidable polymorphism, low antigenicity, and poor induction of immune memory.

Stakeholders' opinions and questions regarding the anticipated malaria vaccine in Tanzania.

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Mtenga, Sally; Kimweri, Angela; Romore, Idda; Ali, Ali; Exavery, Amon; Sicuri, Elisa; Tanner, Marcel; Abdulla, Salim; Lusingu, John; Kafuruki, Shubi

2016-04-05

Within the context of combined interventions, malaria vaccine may provide additional value in malaria prevention. Stakeholders' perspectives are thus critical for informed recommendation of the vaccine in Tanzania. This paper presents the views of stakeholders with regards to malaria vaccine in 12 Tanzanian districts. Quantitative and qualitative methods were employed. A structured questionnaire was administered to 2123 mothers of under five children. Forty-six in-depth interviews and 12 focus group discussions were conducted with teachers, religious leaders, community health workers, health care professionals, and scientists. Quantitative data analysis involved frequency distributions and cross tabulations using Chi square test to determine the association between malaria vaccine acceptability and independent variables. Qualitative data were analysed thematically. Overall, 84.2% of the mothers had perfect acceptance of malaria vaccine. Acceptance varied significantly according to religion, occupation, tribe and region (p Stakeholders had high acceptance and positive opinions towards the combined use of the anticipated malaria vaccine and ITNs, and that their acceptance remains high even when the vaccine may not provide full protection, this is a crucial finding for malaria vaccine policy decisions in Tanzania. An inclusive communication strategy should be designed to address the stakeholders' questions through a process that should engage and be implemented by communities and health care professionals. Social cultural aspects associated with vaccine acceptance should be integrated in the communication strategy.

A nonintegrative lentiviral vector-based vaccine provides long-term sterile protection against malaria.

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Frédéric Coutant

Full Text Available Trials testing the RTS,S candidate malaria vaccine and radiation-attenuated sporozoites (RAS have shown that protective immunity against malaria can be induced and that an effective vaccine is not out of reach. However, longer-term protection and higher protection rates are required to eradicate malaria from the endemic regions. It implies that there is still a need to explore new vaccine strategies. Lentiviral vectors are very potent at inducing strong immunological memory. However their integrative status challenges their safety profile. Eliminating the integration step obviates the risk of insertional oncogenesis. Providing they confer sterile immunity, nonintegrative lentiviral vectors (NILV hold promise as mass pediatric vaccine by meeting high safety standards. In this study, we have assessed the protective efficacy of NILV against malaria in a robust pre-clinical model. Mice were immunized with NILV encoding Plasmodium yoelii Circumsporozoite Protein (Py CSP and challenged with sporozoites one month later. In two independent protective efficacy studies, 50% (37.5-62.5 of the animals were fully protected (p = 0.0072 and p = 0.0008 respectively when compared to naive mice. The remaining mice with detectable parasitized red blood cells exhibited a prolonged patency and reduced parasitemia. Moreover, protection was long-lasting with 42.8% sterile protection six months after the last immunization (p = 0.0042. Post-challenge CD8+ T cells to CSP, in contrast to anti-CSP antibodies, were associated with protection (r = -0.6615 and p = 0.0004 between the frequency of IFN-g secreting specific T cells in spleen and parasitemia. However, while NILV and RAS immunizations elicited comparable immunity to CSP, only RAS conferred 100% of sterile protection. Given that a better protection can be anticipated from a multi-antigen vaccine and an optimized vector design, NILV appear as a promising malaria vaccine.

Review Article: Vaccine for Malaria – How Far? | Oyeyinka | African ...

African Journals Online (AJOL)

This is a review of the progress made so far in the effort to produce a malaria vaccine. The problems that have made it impossible to get an effective vaccine for malaria are discussed. Also examined are the current efforts to produce the vaccine and the prospects for an effective vaccine in the future. Key words: Vaccine ...

External quality assurance of malaria nucleic acid testing for clinical trials and eradication surveillance.

Science.gov (United States)

Murphy, Sean C; Hermsen, Cornelus C; Douglas, Alexander D; Edwards, Nick J; Petersen, Ines; Fahle, Gary A; Adams, Matthew; Berry, Andrea A; Billman, Zachary P; Gilbert, Sarah C; Laurens, Matthew B; Leroy, Odile; Lyke, Kristen E; Plowe, Christopher V; Seilie, Annette M; Strauss, Kathleen A; Teelen, Karina; Hill, Adrian V S; Sauerwein, Robert W

2014-01-01

Nucleic acid testing (NAT) for malaria parasites is an increasingly recommended diagnostic endpoint in clinical trials of vaccine and drug candidates and is also important in surveillance of malaria control and elimination efforts. A variety of reported NAT assays have been described, yet no formal external quality assurance (EQA) program provides validation for the assays in use. Here, we report results of an EQA exercise for malaria NAT assays. Among five centers conducting controlled human malaria infection trials, all centers achieved 100% specificity and demonstrated limits of detection consistent with each laboratory's pre-stated expectations. Quantitative bias of reported results compared to expected results was generally Quality Assessment program that fulfills the need for EQA of malaria NAT assays worldwide.

Potency assay design for adjuvanted recombinant proteins as malaria vaccines.

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Giersing, Birgitte K; Dubovsky, Filip; Saul, Allan; Denamur, Francoise; Minor, Philip; Meade, Bruce

2006-05-15

Many licensed vaccines are composed of live, attenuated or inactivated whole-cell microorganisms, or they comprise purified components from whole-cell extracts or culture supernatants. For some diseases, pathology is fairly well understood, and there may be known correlates of protection that provide obvious parameters for assessment of vaccine potency. However, this is not always the case, and some effective vaccines are routinely used even though the mechanisms or correlates of protection are unknown. Some more modern vaccine approaches employ purified recombinant proteins, based on molecules that appear on the surface of the pathogen. This is one of the strategies that has been adopted in the quest to develop a malaria vaccine. Use of these parasite antigens as vaccine candidates is supported by substantial epidemiological data, and some have demonstrated the ability to elicit protective responses in animal models of malaria infection. However, there is as yet no immunological correlate of protection and no functional assays or animal models that have demonstrated the ability to predict efficacy in humans. There is little precedence for the most appropriate and practical method for assessing potency of vaccines based on these recombinant molecules for malaria vaccines. This is likely because the majority of malaria vaccine candidates have only recently entered clinical evaluation. The PATH Malaria Vaccine Initiative (MVI) convened a panel with expertise in potency assay design from industry, governmental institutions, and regulatory bodies to discuss and review the rationale, available methods, and best approaches for assessing the potency of recombinant proteins, specifically for their use as malarial vaccines. The aim of this meeting was to produce a discussion document on the practical potency assessment of recombinant protein malaria vaccines, focusing on early phase potency assay development.

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

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Segeja Method D

2009-07-01

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

A malaria vaccine that elicits in humans antibodies able to kill Plasmodium falciparum.

Directory of Open Access Journals (Sweden)

2005-11-01

Full Text Available BACKGROUND: Plasmodium falciparum merozoite surface protein 3 is a malaria vaccine candidate that was identified, characterised, and developed based on a unique immuno-clinical approach. The vaccine construct was derived from regions fully conserved among various strains and containing B cell epitopes targeted by human antibodies (from malaria-immune adults that are able to mediate a monocyte-dependent parasite killing effect. The corresponding long synthetic peptide was administered to 36 volunteers, with either alum or Montanide ISA720 as adjuvant. METHODS AND FINDINGS: Both formulations induced cellular and humoral immune responses. With alum, the responses lasted up to 12 mo. The vaccine-induced antibodies were predominantly of cytophilic classes, i.e., able to cooperate with effector cells. In vitro, the antibodies induced an inhibition of the P. falciparum erythrocytic growth in a monocyte-dependent manner, which was in most instances as high as or greater than that induced by natural antibodies from immune African adults. In vivo transfer of the volunteers' sera into P. falciparum-infected humanized SCID mice profoundly reduced or abrogated parasitaemia. These inhibitory effects were related to the antibody reactivity with the parasite native protein, which was seen in 60% of the volunteers, and remained in samples taken 12 mo postimmunisation. CONCLUSION: This is the first malaria vaccine clinical trial to clearly demonstrate antiparasitic activity by vaccine-induced antibodies by both in vitro and in vivo methods. The results, showing the induction of long-lasting antibodies directed to a fully conserved polypeptide, also challenge current concepts about malaria vaccines, such as unavoidable polymorphism, low antigenicity, and poor induction of immune memory.

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

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Régine Audran

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

Willingness to pay for three hypothetical malaria vaccines in Nigeria.

Science.gov (United States)

Udezi, Waka Anthony; Usifoh, Cyril Odianose; Ihimekpen, Omoyeme Oluwatosin

2010-08-01

Unlike some African countries that have reported a approximately 50% reduction in malaria deaths in recent years, Nigeria has shown no evidence of a systematic decline in malaria burden. An important and sustainable reduction in malaria burden cannot be achieved unless an effective and inexpensive malaria vaccine becomes available. The goals of this study were to determine the willingness to pay (WTP) for 3 hypothetical malaria vaccines with different levels of protection (in years), effectiveness, and adverse effects; and to identify factors that influence the price that people are willing to pay in Nigeria. With the aid of a questionnaire, a contingent valuation method using payment cards was used to elicit WTP values for 3 hypothetical malaria vaccines. Payment cards contained both a description of the features of the vaccine being evaluated and price options. The 3 hypothetical vaccines had the following characteristics: vaccine A was 75% effective, protected for 3 years, and was well tolerated; vaccine B was 85% effective, protected for 6 years, and was less well tolerated than vaccine A; and vaccine C was 95% effective and protected for 12 years, but was the least well tolerated. Participants consisted of a convenience sample of individuals who were at the pharmacy waiting area of the state-owned hospitals located in Benin City and Warri, Nigeria. Every third patient or caregiver who was in the pharmacy to fill a prescription was asked to take part in the study as they waited to see the pharmacist. If consent was not granted, the next person in line was approached to be interviewed. Linear multiple regression analysis and nonparametric Kruskal-Wallis, Mann-Whitney, or chi(2) test was applied in inferential analysis, where necessary, to investigate the effects of sociodemographic factors on WTP. Prices on payment cards were expressed in Nigerian naira (NGN 150.00 approximately US $1.00), but study results were expressed in US dollars. A total of 359

Community perceptions of malaria and vaccines in two districts of Mozambique

Directory of Open Access Journals (Sweden)

Bingham Allison

2012-11-01

Full Text Available Abstract Background Malaria is a leading cause of mortality and morbidity in Mozambique, with nearly three-quarters of the country’s malaria-related deaths occurring in children younger than five years. A malaria vaccine is not yet available, but planning is underway for a possible introduction, as soon as one becomes available. In an effort to inform the planning process, this study explored sociocultural and health communications issues among individuals at the community level who are both responsible for decisions about vaccine use and who are likely to influence decisions about vaccine use. Methods Researchers conducted a qualitative study in two malaria-endemic districts in southern Mozambique. Using criterion-based sampling, they conducted 23 focus group discussions and 26 in-depth interviews. Implementation was guided by the engagement of community stakeholders. Results Community members recognize that malaria contributes to high death rates and affects the workforce, school attendance, and the economy. Vaccines are seen as a means to reduce the threat of childhood illnesses and to keep children and the rest of the community healthy. Perceived constraints to accessing vaccine services include long queues, staff shortages, and a lack of resources at health care facilities. Local leaders play a significant role in motivating caregivers to have their children vaccinated. Participants generally felt that a vaccine could help to prevent malaria, although some voiced concern that the focus was only on young children and not on older children, pregnant women, and the elderly. Probed on their understanding of vaccine efficacy, participants voiced various views, including the perception that while some vaccines did not fully prevent disease they still had important benefits. Overall, it would be essential for local leaders to be involved in the design of specific messages for a future malaria vaccine communications strategy, and for those

Immunoinformatics of Placental Malaria Vaccine Development

DEFF Research Database (Denmark)

Jessen, Leon Eyrich

Malaria is an infectious disease caused by a protozoan parasite of the genus Plasmodium, which is transferred by female Anopheles mosquitos. WHO estimates that in 2012 there were 207 million cases of malaria, of which 627,000 were fatal. People living in malaria-endemic areas, gradually acquire...... immunity with multiple infections. Placental malaria (PM) is caused by P. falciparum sequestering in the placenta of pregnant women due to the presence of novel receptors in the placenta. An estimated 200,000 infants die a year as a result of PM. In 2004 the specific protein responsible...... and development in the field of placental malaria vaccine development....

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

Directory of Open Access Journals (Sweden)

Jedidah Mwacharo

2009-12-01

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

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

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Christopher J A Duncan

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

Simulation of the cost-effectiveness of malaria vaccines

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Tediosi Fabrizio

2009-06-01

Full Text Available Abstract Background A wide range of possible malaria vaccines is being considered and there is a need to identify which vaccines should be prioritized for clinical development. An important element of the information needed for this prioritization is a prediction of the cost-effectiveness of potential vaccines in the transmission settings in which they are likely to be deployed. This analysis needs to consider a range of delivery modalities to ensure that clinical development plans can be aligned with the most appropriate deployment strategies. Methods The simulations are based on a previously published individual-based stochastic model for the natural history and epidemiology of Plasmodium falciparum malaria. Three different vaccine types: pre-erythrocytic vaccines (PEV, blood stage vaccines (BSV, mosquito-stage transmission-blocking vaccines (MSTBV, and combinations of these, are considered each delivered via a range of delivery modalities (Expanded Programme of Immunization – EPI-, EPI with booster, and mass vaccination combined with EPI. The cost-effectiveness ratios presented are calculated for four health outcomes, for assumed vaccine prices of US$ 2 or US$ 10 per dose, projected over a 10-year period. Results The simulations suggest that PEV will be more cost-effective in low transmission settings, while BSV at higher transmission settings. Combinations of BSV and PEV are more efficient than PEV, especially in moderate to high transmission settings, while compared to BSV they are more cost-effective in moderate to low transmission settings. Combinations of MSTBV and PEV or PEV and BSV improve the effectiveness and the cost-effectiveness compared to PEV and BSV alone only when applied with EPI and mass vaccinations. Adding booster doses to the EPI is unlikely to be a cost-effective alternative to delivering vaccines via the EPI for any vaccine, while mass vaccination improves effectiveness, especially in low transmission settings, and is

Comparative decline in funding of European Commission malaria vaccine projects: what next for the European scientists working in this field?

DEFF Research Database (Denmark)

Thøgersen, Regitze L; Holder, Anthony A; Hill, Adrian Vs

2011-01-01

scientists in academia and small and medium enterprises, together with partners in Africa. Research has added basic understanding of what is required of a malaria vaccine, allowing selected candidates to be prioritized and some to be moved forward into clinical trials. To end the health burden of malaria...

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

DEFF Research Database (Denmark)

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

2015-01-01

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

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.

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

DEFF Research Database (Denmark)

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

2013-01-01

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

[Vaccinations and malaria prophylaxis for international travelers].

Science.gov (United States)

Alberer, Martin; Löscher, Thomas

2015-05-01

The prevention of infectious diseases by vaccination and by counselling about malaria prophylaxis is a central aspect of travel medicine. Besides mandatory vaccinations required for entry to certain countries various vaccinations may be indicated depending on destination and type of travel as well as on individual risks of the traveler. In addition, pre-travel counselling should always include a check-up of standard vaccinations. Protection against mosquito bites is the basis of malaria prophylaxis. The addition of chemoprophylaxis is warranted in high risk areas. When regular chemoprophylaxis is not applied it is recommended to carry an appropriate antimalarial drug which can be used for emergency stand-by treatment in case of unexplained fever and when medical attention is not available within 24 hours. Travelers should realize that self-treatment is a first-aid measure and that they should still seek medical advice as soon as possible. © Georg Thieme Verlag KG Stuttgart · New York.

External quality assurance of malaria nucleic acid testing for clinical trials and eradication surveillance.

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Sean C Murphy

Full Text Available Nucleic acid testing (NAT for malaria parasites is an increasingly recommended diagnostic endpoint in clinical trials of vaccine and drug candidates and is also important in surveillance of malaria control and elimination efforts. A variety of reported NAT assays have been described, yet no formal external quality assurance (EQA program provides validation for the assays in use. Here, we report results of an EQA exercise for malaria NAT assays. Among five centers conducting controlled human malaria infection trials, all centers achieved 100% specificity and demonstrated limits of detection consistent with each laboratory's pre-stated expectations. Quantitative bias of reported results compared to expected results was generally <0.5 log10 parasites/mL except for one laboratory where the EQA effort identified likely reasons for a general quantitative shift. The within-laboratory variation for all assays was low at <10% coefficient of variation across a range of parasite densities. Based on this study, we propose to create a Molecular Malaria Quality Assessment program that fulfills the need for EQA of malaria NAT assays worldwide.

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.

Update on the Clinical Development of Candidate Malaria Vaccines

National Research Council Canada - National Science Library

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

2004-01-01

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

Safety and immunogenicity of RTS,S/AS01 malaria vaccine in infants and children with WHO stage 1 or 2 HIV disease: a randomised, double-blind, controlled trial.

Science.gov (United States)

Otieno, Lucas; Oneko, Martina; Otieno, Walter; Abuodha, Joseph; Owino, Emmanuel; Odero, Chris; Mendoza, Yolanda Guerra; Andagalu, Ben; Awino, Norbert; Ivinson, Karen; Heerwegh, Dirk; Otsyula, Nekoye; Oziemkowska, Maria; Usuf, Effua Abigail; Otieno, Allan; Otieno, Kephas; Leboulleux, Didier; Leach, Amanda; Oyieko, Janet; Slutsker, Laurence; Lievens, Marc; Cowden, Jessica; Lapierre, Didier; Kariuki, Simon; Ogutu, Bernhards; Vekemans, Johan; Hamel, Mary J

2016-10-01

Malaria remains a major global public health concern, especially in sub-Saharan Africa. The RTS,S/AS01 malaria candidate vaccine was reviewed by the European Medicines Agency and received a positive scientific opinion; WHO subsequently recommended pilot implementation in sub-Saharan African countries. Because malaria and HIV overlap geographically, HIV-infected children should be considered for RTS,S/AS01 vaccination. We therefore aimed to assess the safety of RTS,S/AS01 in HIV-infected children at two sites in western Kenya. We did a randomised, double-blind, controlled trial at the clinical trial sites of the Kenya Medical Research Institute (KEMRI)-Walter Reed Army Institute of research in Kisumu and the KEMRI/US Centers for Disease Control and Prevention in Siaya. Eligible participants were infants and children aged from 6 weeks to 17 months with WHO stage 1 or 2 HIV disease (documented positive by DNA PCR), whether or not they were receiving antiretroviral therapy (ART). We randomly assigned participants (1:1) to receive three doses of either RTS,S/AS01 or rabies vaccine (both 0·5 mL per dose by intramuscular injection), given once per month at 0, 1, and 2 months. We did the treatment allocation using a web-based central randomisation system stratified by age (6 weeks-4 months, 5-17 months), and by baseline CD4% (vaccine recipient, their parent or carer, the funder, and investigators responsible for the assessment of endpoints were all masked to treatment allocation (only staff responsible for the preparation and administration of the vaccines were aware of the assignment and these individuals played no other role in the study). We provided ART, even if the participants were not receiving ART before the study, and daily co-trimoxazole for prevention of opportunistic infections. The primary outcome was the occurrence of serious adverse events until 14 months after dose 1 of the vaccine, assessed in the intention-to-treat population. This trial was registered

Secreted HSP Vaccine for Malaria Prophylaxis

Science.gov (United States)

2017-10-01

burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing...thereby stimulating an avid, antigen specific, cytotoxic CD8 T cell response. Here we developed malaria vaccine that relies on secreted gp96-Ig... stimulating multi-epitope specific cytotoxic T cells. In the proposed studies, we will adapt this vaccine approach to stimulate cytotoxic T cells

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

Science.gov (United States)

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

2016-01-01

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

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

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Kwadwo A Koram

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

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

Science.gov (United States)

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

2017-10-06

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

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

The Feasibility of Gamma Irradiation for Developing Malaria Vaccine

International Nuclear Information System (INIS)

Syaifudin, M.; Tetriana, D.; Darlina; Nurhayati, S.

2011-01-01

Malaria, a plasmodial disease, causes more than one million deaths per year and has a significant public health impact. Improved access to prompt treatment with effective antimalarial drugs need to be conducted for prevention of infection in high risk groups. However, the parasite as causal agent has exhibited a potential danger of wide-spread resistances. This warning has directed attention to the study of alternative methods of protection against the disease, among them is to do the immunization. A deeper understanding of the nature and regulation of protective immune mechanisms against this parasite will facilitate the development of much needed vaccines. Developing a malaria vaccine remains an enormous scientific, technical, and financial challenge. Currently a vaccine is not fully available. Among the practical applications of radiobiological techniques that may be of considerable interest for public health is the use of ionizing radiation in the preparation of vaccines. Convincing data were reported that sporozoites of Plasmodium berghei irradiated with X- or gamma-rays, provide an antigenic stimulus effective to induce a protective immune response in mice and rats against subsequent sporozoite infection. Irradiated parasites are better immunogens than killed ones and although non-infective they are still metabolically active, as shown by continued protein and nucleic acid synthesis. There is a substantial number of data from human studies demonstrating that sporozoites attenuated by radiation are potent inducer of protective immunity and that they are safe and do not give rise to the asexual erythrocytic infections that cause malaria. This vaccine is relatively inexpensive to produce, easy to store, and transportable without refrigeration. A long-term effort and commitment to providing resources must be maintained and increased to achieve the goal of a malaria vaccine candidate where ionizing radiation as a tool to prepare is seemingly feasible. (author)

A randomized placebo-controlled phase Ia malaria vaccine trial of two virosome-formulated synthetic peptides in healthy adult volunteers.

Directory of Open Access Journals (Sweden)

Blaise Genton

2007-10-01

-specific antibody response in all volunteers immunized with the appropriate dose. In the case of PEV301 the 50 microg antigen dose was associated with a higher mean antibody titer and seroconversion rate than the 10 microg dose. In contrast, for PEV302 mean titer and seroconversion rate were higher with the lower dose. Combined delivery of PEV301 and PEV302 did not interfere with the development of an antibody response to either of the two antigens. No relevant antibody responses against the two malaria antigens were observed in the control group receiving unmodified virosomes.The present study demonstrates that three immunizations with the virosomal malaria vaccine components PEV301 or/and PEV302 (containing 10 microg or 50 microg of antigen are safe and well tolerated. At appropriate antigen doses seroconversion rates of 100% were achieved. Two injections may be sufficient for eliciting an appropriate immune response, at least in individuals with pre-existing anti-malarial immunity. These results justify further development of a final multi-stage virosomal vaccine formulation incorporating additional malaria antigens.ClinicalTrials.gov NCT00400101.

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

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John Lusingu

2010-11-01

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

RTS,S/AS01E Malaria Vaccine Induces Memory and Polyfunctional T Cell Responses in a Pediatric African Phase III Trial

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Gemma Moncunill

2017-08-01

Full Text Available Comprehensive assessment of cellular responses to the RTS,S/AS01E vaccine is needed to understand potential correlates and ultimately mechanisms of protection against malaria disease. Cellular responses recognizing the RTS,S/AS01E-containing circumsporozoite protein (CSP and Hepatitis B surface antigen (HBsAg were assessed before and 1 month after primary vaccination by intracellular cytokine staining and 16-color flow cytometry in 105 RTS,S/AS01-vaccinated and 74 rabies-vaccinated participants (controls in a pediatric phase III trial in Africa. RTS,S/AS01E-vaccinated children had significantly higher frequencies of CSP- and HBsAg-specific CD4+ T cells producing IL-2, TNF-α, and CD40L and HBsAg-specific CD4+ T producing IFN-γ and IL-17 than baseline and the control group. Vaccine-induced responses were identified in both central and effector memory (EM compartments. EM CD4+ T cells expressing IL-4 and IL-21 were detected recognizing both vaccine antigens. Consistently higher response rates to both antigens in RTS,S/AS01E-vaccinated than comparator-vaccinated children were observed. RTS,S/AS01E induced polyfunctional CSP- and HBsAg-specific CD4+ T cells, with a greater degree of polyfunctionality in HBsAg responses. In conclusion, RTS,S/AS01E vaccine induces T cells of higher functional heterogeneity and polyfunctionality than previously characterized. Responses detected in memory CD4+ T cell compartments may provide correlates of RTS,S/AS01-induced immunity and duration of protection in future correlates of immunity studies.

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

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

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Ilin Chuang

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

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

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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.

Efficacy of RTS,S/AS01E vaccine against malaria in children 5 to 17 months of age

DEFF Research Database (Denmark)

Bejon, Philip; Lusingu, John; Olotu, Ally

2008-01-01

. We evaluated the efficacy of RTS,S given with a more immunogenic adjuvant system (AS01E) in children 5 to 17 months of age, a target population for vaccine licensure. METHODS: We conducted a double-blind, randomized trial of RTS,S/AS01E vaccine as compared with rabies vaccine in children in Kilifi...... vaccine or the control (rabies) vaccine. Among the 809 children who completed the study procedures according to the protocol, the cumulative number in whom clinical malaria developed was 32 of 402 assigned to receive RTS,S/AS01E and 66 of 407 assigned to receive the rabies vaccine; the adjusted efficacy...... rate for RTS,S/AS01E was 53% (95% confidence interval [CI], 28 to 69; Prabies vaccine, with an adjusted rate of efficacy...

Polymorphism in liver-stage malaria vaccine candidate proteins: immune evasion and implications for vaccine design.

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Flanagan, Katie L; Wilson, Kirsty L; Plebanski, Magdalena

2016-01-01

The pre-erythrocytic stage of infection by malaria parasites represents a key target for vaccines that aim to eradicate malaria. Two important broad immune evasion strategies that can interfere with vaccine efficacy include the induction of dendritic cell (DC) dysfunction and regulatory T cells (Tregs) by blood-stage malaria parasites, leading to inefficient priming of T cells targeting liver-stage infections. The parasite also uses 'surgical strike' strategies, whereby polymorphism in pre-erythrocytic antigens can interfere with host immunity. Specifically, we review how even single amino acid changes in T cell epitopes can lead to loss of binding to major histocompatibility complex (MHC), lack of cross-reactivity, or antagonism and immune interference, where simultaneous or sequential stimulation with related variants of the same T cell epitope can cause T cell anergy or the conversion of effector to immunosuppressive T cell phenotypes.

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

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

2013-01-01

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

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

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Neal N Padte

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

Perception and acceptability of malaria vaccine among maternal ...

African Journals Online (AJOL)

Perception and acceptability of malaria vaccine among maternal and child health clinic ... Journal of Community Medicine and Primary Health Care ... used for data collection from maternal and child health clinic attendees in Calabar, Nigeria.

Phase 1 trial of the Plasmodium falciparum blood stage vaccine MSP1(42-C1/Alhydrogel with and without CPG 7909 in malaria naïve adults.

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Ruth D Ellis

2010-01-01

Full Text Available Merozoite surface protein 1(42 (MSP1(42 is a leading blood stage malaria vaccine candidate. In order to induce immune responses that cover the major antigenic polymorphisms, FVO and 3D7 recombinant proteins of MSP1(42 were mixed (MSP1(42-C1. To improve the level of antibody response, MSP1(42-C1 was formulated with Alhydrogel plus the novel adjuvant CPG 7909.A Phase 1 clinical trial was conducted in healthy malaria-naïve adults at the Center for Immunization Research in Washington, D.C., to evaluate the safety and immunogenicity of MSP1(42-C1/Alhydrogel +/- CPG 7909. Sixty volunteers were enrolled in dose escalating cohorts and randomized to receive three vaccinations of either 40 or 160 microg protein adsorbed to Alhydrogel +/- 560 microg CPG 7909 at 0, 1 and 2 months.Vaccinations were well tolerated, with only one related adverse event graded as severe (Grade 3 injection site erythema and all other vaccine related adverse events graded as either mild or moderate. Local adverse events were more frequent and severe in the groups receiving CPG. The addition of CPG enhanced anti-MSP1(42 antibody responses following vaccination by up to 49-fold two weeks after second immunization and 8-fold two weeks after the third immunization when compared to MSP1(42-C1/Alhydrogel alone (p<0.0001. After the third immunization, functionality of the antibody was tested by an in vitro growth inhibition assay. Inhibition was a function of antibody titer, with an average of 3% (range -2 to 10% in the non CPG groups versus 14% (3 to 32% in the CPG groups.The favorable safety profile and high antibody responses induced with MSP1(42-C1/Alhydrogel + CPG 7909 are encouraging. MSP1(42-C1/Alhydrogel is being combined with other blood stage antigens and will be taken forward in a formulation adjuvanted with CPG 7909.ClinicalTrials.gov Identifier: NCT00320658.

Evaluation of two formulations of adjuvanted RTS, S malaria vaccine in children aged 3 to 5 years living in a malaria-endemic region of Mozambique: a Phase I/IIb randomized double-blind bridging trial

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Mandomando Inacio

2007-03-01

Full Text Available Abstract Background Previous trials of the RTS, S malaria candidate vaccine have shown that this vaccine is safe, tolerated and immunogenic. The development plan for this vaccine aims at administering it in the first year of life through the Expanded Program on Immunization (EPI. The objective was to evaluate the safety and reactogenicity of RTS, S/AS02D (0.5 ml dose, a pediatric formulation of GlaxoSmithKline Biologicals' current malaria candidate vaccine RTS, S/AS02A (0.25 ml dose. A 0.5 ml dose of AS02D is composed of the same active ingredients in the same quantities as in a 0.25 ml dose of AS02A and has been developed to be easily introduced into routine EPI practices. Methods We performed a phase I/IIb randomized double-blind bridging study in a malaria-endemic region of Mozambique, to compare the safety and immunogenicity of both candidate vaccines with the aim of replacing RTS, S/AS02A with RTS, S/AS02D as the candidate pediatric vaccine. 200 Mozambican children aged 3 to 5 years were randomized 1:1 to receive one of the 2 vaccines according to a 0, 1, 2 month schedule. Results Both vaccines were safe and had similar reactogenicity profiles. All subjects with paired pre and post-vaccination samples showed a vaccine response with respect to anti-circumsporozoite (CS antibodies irrespective of initial anti-CS serostatus. Geometric mean titers (GMTs were 191 EU/ml (95% CI 150–242 in recipients of RTS, S/AS02D compared to 180 EU/ml (95% CI 146–221 in recipients of RTS, S/AS02A. For the anti-hepatitis B surface antigen (HBsAg, all subjects were seroprotected at day 90, and the GMTs were 23978 mIU/ml (95% CI 17896–32127 in RTS, S/AS02D recipients and 17410 mIU/ml (95% CI 13322–22752 in RTS, S/AS02A recipients. There was a decrease in anti-CS GMTs between months 3 and 14 in both groups (191 vs 22 EU/mL in RTS, S/AS02D group and 180 vs 29 EU/mL in RTS, S/AS02A group. Conclusion Our data show that the RTS, S/AS02D is safe, well tolerated

Towards a vaccine against pregnancy-associated malaria

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Tuikue Ndam N.

2008-09-01

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

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

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Bertrand Lell

2009-10-01

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

Immunogenicity of a virosomally-formulated Plasmodium falciparum GLURP-MSP3 chimeric protein-based malaria vaccine candidate in comparison to adjuvanted formulations

DEFF Research Database (Denmark)

Tamborrini, Marco; Stoffel, Sabine A; Westerfeld, Nicole

2011-01-01

In clinical trials, immunopotentiating reconstituted influenza virosomes (IRIVs) have shown great potential as a versatile antigen delivery platform for synthetic peptides derived from Plasmodium falciparum antigens. This study describes the immunogenicity of a virosomally-formulated recombinant ...... fusion protein comprising domains of the two malaria vaccine candidate antigens MSP3 and GLURP....

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.

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

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Seth Owusu-Agyei

2009-10-01

malaria vaccines were well tolerated. Anti-circumsporozoite responses were greater with RTS,S/AS01(E than RTS,S/AS02(D and when 3 rather than 2 doses were given. This study supports the selection of RTS,S/AS01(E and a 3 dose schedule for further development in children and infants.ClinicalTrials.gov NCT00360230.

A full-length Plasmodium falciparum recombinant circumsporozoite protein expressed by Pseudomonas fluorescens platform as a malaria vaccine candidate.

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Amy R Noe

Full Text Available The circumsporozoite protein (CSP of Plasmodium falciparum is a major surface protein, which forms a dense coat on the sporozoite's surface. Preclinical research on CSP and clinical evaluation of a CSP fragment-based RTS, S/AS01 vaccine have demonstrated a modest degree of protection against P. falciparum, mediated in part by humoral immunity and in part by cell-mediated immunity. Given the partial protective efficacy of the RTS, S/AS01 vaccine in a recent Phase 3 trial, further improvement of CSP-based vaccines is crucial. In this report, we describe the preclinical development of a full-length, recombinant CSP (rCSP-based vaccine candidate against P. falciparum malaria suitable for current Good Manufacturing Practice (cGMP production. Utilizing a novel high-throughput Pseudomonas fluorescens expression platform, we demonstrated greater efficacy of full-length rCSP as compared to N-terminally truncated versions, rapidly down-selected a promising lead vaccine candidate, and developed a high-yield purification process to express immunologically active, intact antigen for clinical trial material production. The rCSP, when formulated with various adjuvants, induced antigen-specific antibody responses as measured by enzyme-linked immunosorbent assay (ELISA and immunofluorescence assay (IFA, as well as CD4+ T-cell responses as determined by ELISpot. The adjuvanted rCSP vaccine conferred protection in mice when challenged with transgenic P. berghei sporozoites containing the P. falciparum repeat region of CSP. Furthermore, heterologous prime/boost regimens with adjuvanted rCSP and an adenovirus type 35-vectored CSP (Ad35CS showed modest improvements in eliciting CSP-specific T-cell responses and anti-malarial protection, depending on the order of vaccine delivery. Collectively, these data support the importance of further clinical development of adjuvanted rCSP, either as a stand-alone product or as one of the components in a heterologous prime

Development of malaria transmission-blocking vaccines: from concept to product.

Science.gov (United States)

Wu, Yimin; Sinden, Robert E; Churcher, Thomas S; Tsuboi, Takafumi; Yusibov, Vidadi

2015-06-01

Despite decades of effort battling against malaria, the disease is still a major cause of morbidity and mortality. Transmission-blocking vaccines (TBVs) that target sexual stage parasite development could be an integral part of measures for malaria elimination. In the 1950s, Huff et al. first demonstrated the induction of transmission-blocking immunity in chickens by repeated immunizations with Plasmodium gallinaceum-infected red blood cells. Since then, significant progress has been made in identification of parasite antigens responsible for transmission-blocking activity. Recombinant technologies accelerated evaluation of these antigens as vaccine candidates, and it is possible to induce effective transmission-blocking immunity in humans both by natural infection and now by immunization with recombinant vaccines. This chapter reviews the efforts to produce TBVs, summarizes the current status and advances and discusses the remaining challenges and approaches. Copyright © 2015 Elsevier Ltd. All rights reserved.

Factors likely to affect community acceptance of a malaria vaccine in two districts of Ghana: a qualitative study.

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Arantza Meñaca

Full Text Available Malaria is a leading cause of morbidity and mortality among children in Ghana. As part of the effort to inform local and national decision-making in preparation for possible malaria vaccine introduction, this qualitative study explored community-level factors that could affect vaccine acceptance in Ghana and provides recommendations for a health communications strategy. The study was conducted in two purposively selected districts: the Ashanti and Upper East Regions. A total of 25 focus group discussions, 107 in-depth interviews, and 21 semi-structured observations at Child Welfare Clinics were conducted. Malaria was acknowledged to be one of the most common health problems among children. While mosquitoes were linked to the cause and bed nets were considered to be the main preventive method, participants acknowledged that no single measure prevented malaria. The communities highly valued vaccines and cited vaccination as the main motivation for taking children to Child Welfare Clinics. Nevertheless, knowledge of specific vaccines and what they do was limited. While communities accepted the idea of minor vaccine side effects, other side effects perceived to be more serious could deter families from taking children for vaccination, especially during vaccination campaigns. Attendance at Child Welfare Clinics after age nine months was limited. Observations at clinics revealed that while two different opportunities for counseling were offered, little attention was given to addressing mothers' specific concerns and to answering questions related to child immunization. Positive community attitudes toward vaccines and the understanding that malaria prevention requires a comprehensive approach would support the introduction of a malaria vaccine. These attitudes are bolstered by a well-established child welfare program and the availability in Ghana of active, flexible structures for conveying health information to communities. At the same time, it would

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

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Edmond J Remarque

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

An open source business model for malaria.

Science.gov (United States)

Årdal, Christine; Røttingen, John-Arne

2015-01-01

Greater investment is required in developing new drugs and vaccines against malaria in order to eradicate malaria. These precious funds must be carefully managed to achieve the greatest impact. We evaluate existing efforts to discover and develop new drugs and vaccines for malaria to determine how best malaria R&D can benefit from an enhanced open source approach and how such a business model may operate. We assess research articles, patents, clinical trials and conducted a smaller survey among malaria researchers. Our results demonstrate that the public and philanthropic sectors are financing and performing the majority of malaria drug/vaccine discovery and development, but are then restricting access through patents, 'closed' publications and hidden away physical specimens. This makes little sense since it is also the public and philanthropic sector that purchases the drugs and vaccines. We recommend that a more "open source" approach is taken by making the entire value chain more efficient through greater transparency which may lead to more extensive collaborations. This can, for example, be achieved by empowering an existing organization like the Medicines for Malaria Venture (MMV) to act as a clearing house for malaria-related data. The malaria researchers that we surveyed indicated that they would utilize such registry data to increase collaboration. Finally, we question the utility of publicly or philanthropically funded patents for malaria medicines, where little to no profits are available. Malaria R&D benefits from a publicly and philanthropically funded architecture, which starts with academic research institutions, product development partnerships, commercialization assistance through UNITAID and finally procurement through mechanisms like The Global Fund to Fight AIDS, Tuberculosis and Malaria and the U.S.' President's Malaria Initiative. We believe that a fresh look should be taken at the cost/benefit of patents particularly related to new malaria

An open source business model for malaria.

Directory of Open Access Journals (Sweden)

Christine Årdal

Full Text Available Greater investment is required in developing new drugs and vaccines against malaria in order to eradicate malaria. These precious funds must be carefully managed to achieve the greatest impact. We evaluate existing efforts to discover and develop new drugs and vaccines for malaria to determine how best malaria R&D can benefit from an enhanced open source approach and how such a business model may operate. We assess research articles, patents, clinical trials and conducted a smaller survey among malaria researchers. Our results demonstrate that the public and philanthropic sectors are financing and performing the majority of malaria drug/vaccine discovery and development, but are then restricting access through patents, 'closed' publications and hidden away physical specimens. This makes little sense since it is also the public and philanthropic sector that purchases the drugs and vaccines. We recommend that a more "open source" approach is taken by making the entire value chain more efficient through greater transparency which may lead to more extensive collaborations. This can, for example, be achieved by empowering an existing organization like the Medicines for Malaria Venture (MMV to act as a clearing house for malaria-related data. The malaria researchers that we surveyed indicated that they would utilize such registry data to increase collaboration. Finally, we question the utility of publicly or philanthropically funded patents for malaria medicines, where little to no profits are available. Malaria R&D benefits from a publicly and philanthropically funded architecture, which starts with academic research institutions, product development partnerships, commercialization assistance through UNITAID and finally procurement through mechanisms like The Global Fund to Fight AIDS, Tuberculosis and Malaria and the U.S.' President's Malaria Initiative. We believe that a fresh look should be taken at the cost/benefit of patents particularly related

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

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Jinhong Hu

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

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

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

1994-05-01

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

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

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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.

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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

N-Terminal Plasmodium vivax Merozoite Surface Protein-1, a Potential Subunit for Malaria Vivax Vaccine

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Fernanda G. Versiani

2013-01-01

Full Text Available The human malaria is widely distributed in the Middle East, Asia, the western Pacific, and Central and South America. Plasmodium vivax started to have the attention of many researchers since it is causing diseases to millions of people and several reports of severe malaria cases have been noticed in the last few years. The lack of in vitro cultures for P. vivax represents a major delay in developing a functional malaria vaccine. One of the major candidates to antimalarial vaccine is the merozoite surface protein-1 (MSP1, which is expressed abundantly on the merozoite surface and capable of activating the host protective immunity. Studies have shown that MSP-1 possesses highly immunogenic fragments, capable of generating immune response and protection in natural infection in endemic regions. This paper shows humoral immune response to different proteins of PvMSP1 and the statement of N-terminal to be added to the list of potential candidates for malaria vivax vaccine.

Using simulation to aid trial design: Ring-vaccination trials.

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Matt David Thomas Hitchings

2017-03-01

Full Text Available The 2014-6 West African Ebola epidemic highlights the need for rigorous, rapid clinical trial methods for vaccines. A challenge for trial design is making sample size calculations based on incidence within the trial, total vaccine effect, and intracluster correlation, when these parameters are uncertain in the presence of indirect effects of vaccination.We present a stochastic, compartmental model for a ring vaccination trial. After identification of an index case, a ring of contacts is recruited and either vaccinated immediately or after 21 days. The primary outcome of the trial is total vaccine effect, counting cases only from a pre-specified window in which the immediate arm is assumed to be fully protected and the delayed arm is not protected. Simulation results are used to calculate necessary sample size and estimated vaccine effect. Under baseline assumptions about vaccine properties, monthly incidence in unvaccinated rings and trial design, a standard sample-size calculation neglecting dynamic effects estimated that 7,100 participants would be needed to achieve 80% power to detect a difference in attack rate between arms, while incorporating dynamic considerations in the model increased the estimate to 8,900. This approach replaces assumptions about parameters at the ring level with assumptions about disease dynamics and vaccine characteristics at the individual level, so within this framework we were able to describe the sensitivity of the trial power and estimated effect to various parameters. We found that both of these quantities are sensitive to properties of the vaccine, to setting-specific parameters over which investigators have little control, and to parameters that are determined by the study design.Incorporating simulation into the trial design process can improve robustness of sample size calculations. For this specific trial design, vaccine effectiveness depends on properties of the ring vaccination design and on the

The Ethics of Health Care Delivery in a Pediatric Malaria Vaccine Trial: The Perspectives of Stakeholders From Ghana and Tanzania.

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Ward, Claire Leonie; Shaw, David; Anane-Sarpong, Evelyn; Sankoh, Osman; Tanner, Marcel; Elger, Bernice

2018-02-01

This study explores ethical issues raised in providing medical care to participants and communities of low-resource settings involved in a Phase II/III pediatric malaria vaccine trial (PMVT). We conducted 52 key informant interviews with major stakeholders of an international multi-center PMVT (GSK/PATH-MVI RTS,S) (NCT00866619) in Ghana and Tanzania. Based on their stakeholder experiences, the responses fell into three main themes: (a) undue inducement, (b) community disparities, and (c) broad therapeutic misconceptions. The study identified the critical ethical aspects, from the perspectives of stakeholders, of delivering health care during a PMVT. The study showed that integrating research into health care services needs to be addressed in a manner that upholds the favorable risk-benefit ratio of research and attends to the health needs of local populations. The implementation of research should aim to improve local standards of care through building a collaborative agenda with local institutions and systems of health.

Stable malaria incidence despite scaling up control strategies in a malaria vaccine-testing site in Mali.

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Coulibaly, Drissa; Travassos, Mark A; Kone, Abdoulaye K; Tolo, Youssouf; Laurens, Matthew B; Traore, Karim; Diarra, Issa; Niangaly, Amadou; Daou, Modibo; Dembele, Ahmadou; Sissoko, Mody; Guindo, Bouréima; Douyon, Raymond; Guindo, Aldiouma; Kouriba, Bourema; Sissoko, Mahamadou S; Sagara, Issaka; Plowe, Christopher V; Doumbo, Ogobara K; Thera, Mahamadou A

2014-09-19

The recent decline in malaria incidence in many African countries has been attributed to the provision of prompt and effective anti-malarial treatment using artemisinin-based combination therapy (ACT) and to the widespread distribution of long-lasting, insecticide-treated bed nets (LLINs). At a malaria vaccine-testing site in Bandiagara, Mali, ACT was introduced in 2004, and LLINs have been distributed free of charge since 2007 to infants after they complete the Expanded Programme of Immunization (EPI) schedule and to pregnant women receiving antenatal care. These strategies may have an impact on malaria incidence. To document malaria incidence, a cohort of 400 children aged 0 to 14 years was followed for three to four years up to July 2013. Monthly cross-sectional surveys were done to measure the prevalence of malaria infection and anaemia. Clinical disease was measured both actively and passively through continuous availability of primary medical care. Measured outcomes included asymptomatic Plasmodium infection, anaemia and clinical malaria episodes. The incidence rate of clinical malaria varied significantly from June 2009 to July 2013 without a clear downward trend. A sharp seasonality in malaria illness incidence was observed with higher clinical malaria incidence rates during the rainy season. Parasite and anaemia point prevalence also showed seasonal variation with much higher prevalence rates during rainy seasons compared to dry seasons. Despite the scaling up of malaria prevention and treatment, including the widespread use of bed nets, better diagnosis and wider availability of ACT, malaria incidence did not decrease in Bandiagara during the study period.

Transcutaneous delivery of T Cell-inducing viral vector Malaria vaccines by microneedle patches

OpenAIRE

2011-01-01

There is an urgent need for improvements to existing vaccine delivery technologies to run parallel with the development of new-generation vaccines. The burdens of needle-based immunisation strategies are exacerbated by poor resource provision in such areas as sub-Saharan Africa, where annual malaria mortality stands at 860,000. Needle-free delivery of vaccine to the skin holds promise for improved immunogenicity with lower doses of vaccine, in addition to significant logistical advantages. Va...

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

DEFF Research Database (Denmark)

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

2017-01-01

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

Strategies & recent development of transmission-blocking vaccines against Plasmodium falciparum

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Neha Chaturvedi

2016-01-01

Full Text Available Transmission blocking malaria vaccines are aimed to block the development and maturity of sexual stages of parasite within mosquitoes. The vaccine candidate antigens (Pfs25, Pfs48/45, Pfs230 that have shown transmission blocking immunity in model systems are in different stages of development. These antigens are immunogenic with limited genetic diversity. Pfs25 is a leading candidate and currently in phase I clinical trial. Efforts are now focused on the cost-effective production of potent antigens using safe adjuvants and optimization of vaccine delivery system that are capable of inducing strong immune responses. This review addresses the potential usefulness, development strategies, challenges, clinical trials and current status of Plasmodium falciparum sexual stage malaria vaccine candidate antigens for the development of transmission-blocking vaccines.

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

DEFF Research Database (Denmark)

Olotu, Ally; Lusingu, John; Leach, Amanda

2011-01-01

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

Increased immunogenicity of recombinant Ad35-based malaria vaccine through formulation with aluminium phosphate adjuvant

NARCIS (Netherlands)

Ophorst, Olga J. A. E.; Radosevic, Katarina; Klap, Jaco M.; Sijtsma, Jeroen; Gillissen, Gert; Mintardjo, Ratna; van Ooij, Mark J. M.; Holterman, Lennart; Companjen, Arjen; Goudsmit, Jaap; Havenga, Menzo J. E.

2007-01-01

Previously, we have shown the potency of recombinant Adenovirus serotype 35 viral vaccines (rAd35) to induce strong immune response against the circumsporozoite protein (CS) of the plasmodium parasite. To further optimize immunogenicity of Ad35-based malaria vaccines we formulated rAd35.CS vaccine

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

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Lázara Rojas Rivero

2005-02-01

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

Effect of schistosoma infection on malaria immune response: A systematic review.

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Yesuf, Elias Ali; Dejene, Tariku

2011-01-01

Background Worldwide an estimated 225 million cases and about 800, 000 deaths due to malaria were documented in 2009. Malaria vaccines have been developed as a malaria control strategy. Immune response to these vaccines might be affected by the blood fluke schistosoma which is often co-endemic with malaria in Sub-Saharan Africa where most of phase II and Phase III malaria vaccine trials were conducted.Objectives To systematically search, appraise and synthesize the best available evidence on the effect of schistosoma infection on the immune response to malaria antigens and provide direction to future malaria vaccination trials.Types of participants The review considered studies with above 5 year old individuals as participants.Phenomenon of interest The phenomenon of interest was the presence of schistosoma infectionTypes of outcomes Blood serum levels of Th1 and Th2 specific to Merozoite Surface Proteins 1, 2, and 3 of malaria were considered as primary outcomes. While blood serum levels of IgG1, IgG2, IgG3, IFN-γ, IL-10 and TGF-β directed against Merozoite Surface Proteins were considered as secondary outcomes.Types of studies Studies with any quantitative study designs were considered for inclusion.Search Strategy Any quantitative English language articles published between 1994 and April 2011 were sought using a comprehensive search strategy.Assessment of methodological quality It was done using Joanna Briggs Institutes' Meta Analysis of Statistical Assessment and Review Instrument critical appraisal tools.Data extraction Data extraction was carried out using the Joanna Briggs Institute Meta Analysis of Statistical Assessment and Review Instrument data extraction tool.Data synthesis Meta- analysis was conducted using random effects model with an inverse variance method with RevMan5 software. Heterogeneity between the studies was assessed using ξ test at a p-value of SMD (95% CI), 0.15 (-2.00, 2.31), p=0.89.Similarly a small and statistically not significant

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

DEFF Research Database (Denmark)

Hviid, Lars

2007-01-01

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

Assessing the economic benefits of vaccines based on the health investment life course framework: a review of a broader approach to evaluate malaria vaccination.

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Constenla, Dagna

2015-03-24

Economic evaluations have routinely understated the net benefits of vaccination by not including the full range of economic benefits that accrue over the lifetime of a vaccinated person. Broader approaches for evaluating benefits of vaccination can be used to more accurately calculate the value of vaccination. This paper reflects on the methodology of one such approach - the health investment life course approach - that looks at the impact of vaccine investment on lifetime returns. The role of this approach on vaccine decision-making will be assessed using the malaria health investment life course model example. We describe a framework that measures the impact of a health policy decision on government accounts over many generations. The methodological issues emerging from this approach are illustrated with an example from a recently completed health investment life course analysis of malaria vaccination in Ghana. Beyond the results, various conceptual and practical challenges of applying this framework to Ghana are discussed in this paper. The current framework seeks to understand how disease and available technologies can impact a range of economic parameters such as labour force participation, education, healthcare consumption, productivity, wages or economic growth, and taxation following their introduction. The framework is unique amongst previous economic models in malaria because it considers future tax revenue for governments. The framework is complementary to cost-effectiveness and budget impact analysis. The intent of this paper is to stimulate discussion on how existing and new methodology can add to knowledge regarding the benefits from investing in new and underutilized vaccines. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

DEFF Research Database (Denmark)

Hviid, Lars

2011-01-01

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

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

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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.

Efficacy and safety of RTS,S/AS01 malaria vaccine with or without a booster dose in infants and children in Africa

DEFF Research Database (Denmark)

Theander, Thor Grundtvig; Lusingu, John Peter Andrea

2015-01-01

and a booster dose at month 20 (R3R group); three doses of RTS,S/AS01 and a dose of comparator vaccine at month 20 (R3C group); or a comparator vaccine at months 0, 1, 2, and 20 (C3C [control group]). Participants were followed up until Jan 31, 2014. Cases of clinical and severe malaria were captured through......, the vaccine has the potential to make a substantial contribution to malaria control when used in combination with other effective control measures, especially in areas of high transmission. FUNDING: GlaxoSmithKline Biologicals SA and the PATH Malaria Vaccine Initiative....

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

Antigen-displaying lipid-enveloped PLGA nanoparticles as delivery agents for a Plasmodium vivax malaria vaccine.

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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.

Sterile protection against Plasmodium knowlesi in rhesus monkeys from a malaria vaccine: comparison of heterologous prime boost strategies.

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George Jiang

Full Text Available Using newer vaccine platforms which have been effective against malaria in rodent models, we tested five immunization regimens against Plasmodium knowlesi in rhesus monkeys. All vaccines included the same four P. knowlesi antigens: the pre-erythrocytic antigens CSP, SSP2, and erythrocytic antigens AMA1, MSP1. We used four vaccine platforms for prime or boost vaccinations: plasmids (DNA, alphavirus replicons (VRP, attenuated adenovirus serotype 5 (Ad, or attenuated poxvirus (Pox. These four platforms combined to produce five different prime/boost vaccine regimens: Pox alone, VRP/Pox, VRP/Ad, Ad/Pox, and DNA/Pox. Five rhesus monkeys were immunized with each regimen, and five Control monkeys received a mock vaccination. The time to complete vaccinations was 420 days. All monkeys were challenged twice with 100 P. knowlesi sporozoites given IV. The first challenge was given 12 days after the last vaccination, and the monkeys receiving the DNA/Pox vaccine were the best protected, with 3/5 monkeys sterilely protected and 1/5 monkeys that self-cured its parasitemia. There was no protection in monkeys that received Pox malaria vaccine alone without previous priming. The second sporozoite challenge was given 4 months after the first. All 4 monkeys that were protected in the first challenge developed malaria in the second challenge. DNA, VRP and Ad5 vaccines all primed monkeys for strong immune responses after the Pox boost. We discuss the high level but short duration of protection in this experiment and the possible benefits of the long interval between prime and boost.

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.

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...

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

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Holger eSpiegel

2015-12-01

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

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 ...

Severe falciparum malaria in young children of the Kassena-Nankana district of northern Ghana.

Science.gov (United States)

Oduro, Abraham R; Koram, Kwadwo A; Rogers, William; Atuguba, Frank; Ansah, Patrick; Anyorigiya, Thomas; Ansah, Akosua; Anto, Francis; Mensah, Nathan; Hodgson, Abraham; Nkrumah, Francis

2007-07-27

Severe falciparum malaria in children was studied as part of the characterization of the Kassena-Nankana District Ghana for future malaria vaccine trials. Children aged 6-59 months with diagnosis suggestive of acute disease were characterized using the standard WHO definition for severe malaria. Of the total children screened, 45.2% (868/1921) satisfied the criteria for severe malaria. Estimated incidence of severe malaria was 3.4% (range: 0.4-8.3%) cases per year. The disease incidence was seasonal: 560 cases per year, of which 70.4% occurred during the wet season (June-October). The main manifestations were severe anaemia (36.5%); prolonged or multiple convulsions (21.6%); respiratory distress (24.4%) and cerebral malaria (5.4%). Others were hyperpyrexia (11.1%); hyperparasitaemia (18.5%); hyperlactaemia (33.4%); and hypoglycaemia (3.2%). The frequency of severe anaemia was 39.8% in children of six to 24 months of age and 25.9% in children of 25-60 months of age. More children (8.7%) in the 25-60 months age group had cerebral malaria compared with 4.4% in the 6-24 months age group. The overall case fatality ratio was 3.5%. Cerebral malaria and hyperlactataemia were the significant risk factors associated with death. Severe anaemia, though a major presentation, was not significantly associated with risk of death. Severe malaria is a frequent and seasonal childhood disease in northern Ghana and maybe an adequate endpoint for future malaria vaccine trials.

Development of standardized laboratory methods and quality processes for a phase III study of the RTS, S/AS01 candidate malaria vaccine

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Carter Terrell

2011-08-01

Full Text Available Abstract Background A pivotal phase III study of the RTS,S/AS01 malaria candidate vaccine is ongoing in several research centres across Africa. The development and establishment of quality systems was a requirement for trial conduct to meet international regulatory standards, as well as providing an important capacity strengthening opportunity for study centres. Methods Standardized laboratory methods and quality assurance processes were implemented at each of the study centres, facilitated by funding partners. Results A robust protocol for determination of parasite density based on actual blood cell counts was set up in accordance with World Health Organization recommendations. Automated equipment including haematology and biochemistry analyzers were put in place with standard methods for bedside testing of glycaemia, base excess and lactacidaemia. Facilities for X-rays and basic microbiology testing were also provided or upgraded alongside health care infrastructure in some centres. External quality assurance assessment of all major laboratory methods was established and method qualification by each laboratory demonstrated. The resulting capacity strengthening has ensured laboratory evaluations are conducted locally to the high standards required in clinical trials. Conclusion Major efforts by study centres, together with support from collaborating parties, have allowed standardized methods and robust quality assurance processes to be put in place for the phase III evaluation of the RTS, S/AS01 malaria candidate vaccine. Extensive training programmes, coupled with continuous commitment from research centre staff, have been the key elements behind the successful implementation of quality processes. It is expected these activities will culminate in healthcare benefits for the subjects and communities participating in these trials. Trial registration Clinicaltrials.gov NCT00866619

Identification of pre-erythrocytic malaria antigens that target hepatocytes for killing in vivo and contribute to protection elicited by whole-parasite vaccination.

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Lin Chen

Full Text Available Pre-erythrocytic malaria vaccines, including those based on whole-parasite approaches, have shown protective efficacy in animal and human studies. However few pre-erythocytic antigens other than the immunodominant circumsporozoite protein (CSP have been studied in depth with the goal of developing potent subunit malaria vaccines that are suited for use in endemic areas. Here we describe a novel technique to identify pre-erythrocytic malaria antigens that contribute to protection elicited by whole-parasite vaccination in the mouse model. Our approach combines immunization with genetically attenuated parasites and challenge with DNA plasmids encoding for potential protective pre-erythrocytic malaria antigens as luciferase fusions by hydrodynamic tail vein injection. After optimizing the technique, we first showed that immunization with Pyfabb/f-, a P. yoelii genetically attenuated parasite, induces killing of CSP-presenting hepatocytes. Depletion of CD8+ but not CD4+ T cells diminished the killing of CSP-expressing hepatocytes, indicating that killing is CD8+ T cell-dependent. Finally we showed that the use of heterologous prime/boost immunization strategies that use genetically attenuated parasites and DNA vaccines enabled the characterization of a novel pre-erythrocytic antigen, Tmp21, as a contributor to Pyfabb/f- induced protection. This technique will be valuable for identification of potentially protective liver stage antigens and has the potential to contribute to the understanding of immunity elicited by whole parasite vaccination, as well as the development of effective subunit malaria vaccines.

Sieve analysis in HIV-1 vaccine efficacy trials.

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Edlefsen, Paul T; Gilbert, Peter B; Rolland, Morgane

2013-09-01

The genetic characterization of HIV-1 breakthrough infections in vaccine and placebo recipients offers new ways to assess vaccine efficacy trials. Statistical and sequence analysis methods provide opportunities to mine the mechanisms behind the effect of an HIV vaccine. The release of results from two HIV-1 vaccine efficacy trials, Step/HVTN-502 (HIV Vaccine Trials Network-502) and RV144, led to numerous studies in the last 5 years, including efforts to sequence HIV-1 breakthrough infections and compare viral characteristics between the vaccine and placebo groups. Novel genetic and statistical analysis methods uncovered features that distinguished founder viruses isolated from vaccinees from those isolated from placebo recipients, and identified HIV-1 genetic targets of vaccine-induced immune responses. Studies of HIV-1 breakthrough infections in vaccine efficacy trials can provide an independent confirmation to correlates of risk studies, as they take advantage of vaccine/placebo comparisons, whereas correlates of risk analyses are limited to vaccine recipients. Through the identification of viral determinants impacted by vaccine-mediated host immune responses, sieve analyses can shed light on potential mechanisms of vaccine protection.

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...

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

Science.gov (United States)

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

2012-12-01

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

Clinical development of a VAR2CSA-based placental malaria vaccine PAMVAC

DEFF Research Database (Denmark)

Gbédandé, Komi; Fievet, Nadine; Viwami, Firmine

2017-01-01

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

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

DEFF Research Database (Denmark)

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

2008-01-01

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

Generation of genetically attenuated blood-stage malaria parasites; characterizing growth and virulence in a rodent model of malaria

NARCIS (Netherlands)

Lin, Jingwen

2013-01-01

Despite intense efforts over the past 50 years to develop a vaccine, there is currently no licensed malaria vaccine available. The limited success in inducing sufficient protection against malaria with subunit-vaccines has renewed an interest in whole-parasite vaccination strategies. While

Probability of Transmission of Malaria from Mosquito to Human Is Regulated by Mosquito Parasite Density in Naïve and Vaccinated Hosts.

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Thomas S Churcher

2017-01-01

Full Text Available Over a century since Ronald Ross discovered that malaria is caused by the bite of an infectious mosquito it is still unclear how the number of parasites injected influences disease transmission. Currently it is assumed that all mosquitoes with salivary gland sporozoites are equally infectious irrespective of the number of parasites they harbour, though this has never been rigorously tested. Here we analyse >1000 experimental infections of humans and mice and demonstrate a dose-dependency for probability of infection and the length of the host pre-patent period. Mosquitoes with a higher numbers of sporozoites in their salivary glands following blood-feeding are more likely to have caused infection (and have done so quicker than mosquitoes with fewer parasites. A similar dose response for the probability of infection was seen for humans given a pre-erythrocytic vaccine candidate targeting circumsporozoite protein (CSP, and in mice with and without transfusion of anti-CSP antibodies. These interventions prevented infection more efficiently from bites made by mosquitoes with fewer parasites. The importance of parasite number has widespread implications across malariology, ranging from our basic understanding of the parasite, how vaccines are evaluated and the way in which transmission should be measured in the field. It also provides direct evidence for why the only registered malaria vaccine RTS,S was partially effective in recent clinical trials.

Vaccine Containing the Three Allelic Variants of the Plasmodium vivax Circumsporozoite Antigen Induces Protection in Mice after Challenge with a Transgenic Rodent Malaria Parasite

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Alba Marina Gimenez

2017-10-01

Full Text Available Plasmodium vivax is the most common species that cause malaria outside of the African continent. The development of an efficacious vaccine would contribute greatly to control malaria. Recently, using bacterial and adenoviral recombinant proteins based on the P. vivax circumsporozoite protein (CSP, we demonstrated the possibility of eliciting strong antibody-mediated immune responses to each of the three allelic forms of P. vivax CSP (PvCSP. In the present study, recombinant proteins representing the PvCSP alleles (VK210, VK247, and P. vivax-like, as well as a hybrid polypeptide, named PvCSP-All epitopes, were generated. This hybrid containing the conserved C-terminal of the PvCSP and the three variant repeat domains in tandem were successfully produced in the yeast Pichia pastoris. After purification and biochemical characterization, they were used for the experimental immunization of C57BL/6 mice in a vaccine formulation containing the adjuvant Poly(I:C. Immunization with a recombinant protein expressing all three different allelic forms in fusion elicited high IgG antibody titers reacting with all three different allelic variants of PvCSP. The antibodies targeted both the C-terminal and repeat domains of PvCSP and recognized the native protein on the surface of P. vivax sporozoites. More importantly, mice that received the vaccine formulation were protected after challenge with chimeric Plasmodium berghei sporozoites expressing CSP repeats of P. vivax sporozoites (Pb/PvVK210. Our results suggest that it is possible to elicit protective immunity against one of the most common PvCSP alleles using soluble recombinant proteins expressed by P. pastoris. These recombinant proteins are promising candidates for clinical trials aiming to develop a multiallele vaccine against P. vivax malaria.

Epidemiology of malaria in the forest-savanna transitional zone of Ghana

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Newton Sam

2009-09-01

Full Text Available Abstract Background Information on the epidemiology of malaria is essential for designing and interpreting results of clinical trials of drugs, vaccines and other interventions. As a background to the establishment of a site for anti-malarial drugs and vaccine trials, the epidemiology of malaria in a rural site in central Ghana was investigated. Methods Active surveillance of clinical malaria was carried out in a cohort of children below five years of age (n = 335 and the prevalence of malaria was estimated in a cohort of subjects of all ages (n = 1484 over a 12-month period. Participants were sampled from clusters drawn around sixteen index houses randomly selected from a total of about 22,000 houses within the study area. The child cohort was visited thrice weekly to screen for any illness and a blood slide was taken if a child had a history of fever or a temperature greater than or equal to 37.5 degree Celsius. The all-age cohort was screened for malaria once every eight weeks over a 12-month period. Estimation of Entomological Inoculation Rate (EIR and characterization of Anopheline malaria vectors in the study area were also carried out. Results The average parasite prevalence in the all age cohort was 58% (95% CI: 56.9, 59.4. In children below five years of age, the average prevalence was 64% (95% CI: 61.9, 66.0. Geometric mean parasite densities decreased significantly with increasing age. More than 50% of all children less than 10 years of age were anaemic. Children less than 5 years of age had as many as seven malaria attacks per child per year. The attack rates decreased significantly with increasing cut-offs of parasite density. The average Multiplicity of Infection (MOI was of 6.1. All three pyrimethamine resistance mutant alleles of the Plasmodium falciparum dhfr gene were prevalent in this population and 25% of infections had a fourth mutant of pfdhps-A437G. The main vectors were Anopheles funestus and Anopheles gambiae and the EIR

Motivators of enrolment in HIV vaccine trials: a review of HIV vaccine preparedness studies.

Science.gov (United States)

Dhalla, Shayesta; Poole, Gary

2011-11-01

HIV vaccine preparedness studies (VPS) are important precursors to HIV vaccine trials. As well, they contribute to an understanding of motivators and barriers for participation in hypothetical HIV vaccine trials. Motivators can take the form of altruism and a desire for social benefits. Perceived personal benefits, including psychological, personal, and financial well-being, may also motivate participation. The authors performed a systematic review of HIV VPS using the Cochrane Database for Systematic Reviews, Medline, PubMed, Embase, and Google Scholar. The authors independently searched the literature for individual HIV VPS that examined motivators of participation in a hypothetical HIV vaccine trial, using the same search strategy. As the denominators employed in the literature varied across studies, the denominators were standardized to the number of respondents per survey item, regardless of their willingness to participate (WTP) in an HIV vaccine trial. The authors retrieved eight studies on social benefits (i.e., altruism) and 11 studies on personal benefits conducted in the Organization for Economic Co-operation and Development (OECD) countries, as well as 19 studies on social benefits and 20 studies on personal benefits in the non-OECD countries. Various different forms of altruism were found to be the major motivators for participation in an HIV vaccine trial in both the OECD and the non-OECD countries. In a large number of studies, protection from HIV was cited as a personal motivator for participation in a hypothetical HIV vaccine trial in the OECD and the non-OECD countries. Knowledge of motivators can inform and target recruitment for HIV vaccine trials, although it must be remembered that hypothetical motivators may not always translate into motivators in an actual vaccine trial.

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

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Denise L. Doolan

1992-01-01

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

A Glycolipid Adjuvant, 7DW8-5, Enhances CD8+ T Cell Responses Induced by an Adenovirus-Vectored Malaria Vaccine in Non-Human Primates

OpenAIRE

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

2013-01-01

A key strategy to a successful vaccine against malaria is to identify and develop new adjuvants that can enhance T-cell responses and improve protective immunity. Upon co-administration with a rodent malaria vaccine in mice, 7DW8-5, a recently identified novel analog of α-galactosylceramide (α-GalCer), enhances the level of malaria-specific protective immune responses more strongly than the parent compound. In this study, we sought to determine whether 7DW8-5 could provide a similar potent ad...

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

DEFF Research Database (Denmark)

Lusingu, John; Olotu, Ally; Leach, Amanda

2010-01-01

) recipient and nine episodes among eight rabies vaccine recipients met the criteria for severe malaria. Unsolicited AEs were reported in 78% of subjects in the RTS,S/AS01(E) group and 74% of subjects in the rabies vaccine group. In both vaccine groups, gastroenteritis and pneumonia were the most frequently...

Effect of race/ethnicity on participation in HIV vaccine trials and comparison to other trials of biomedical prevention.

Science.gov (United States)

Dhalla, Shayesta; Poole, Gary

2014-01-01

Racial/ethnic minorities are underrepresented in actual HIV vaccine trials in North America, and willingness to participate (WTP) and retention in an HIV vaccine trial may differ from that in Whites. In this review, the authors identified HIV vaccine preparedness studies (VPS) in North America in high-risk populations that examined the relationship between race/ethnicity and WTP in a preventive phase 3 HIV vaccine trial, and the relationship to retention. Studies were categorized by risk group, and comparison group (Whites vs. non-Whites). Other types of trials of biomedical prevention were also identified, and WTP and retention rates were compared and contrasted to actual HIV vaccine trials. In the studies identified, WTP in a hypothetical trial HIV vaccine trial did not differ by race/ethnicity. In contrast, actual HIV vaccine trials, an HIV acquisition trial, and a phase 2B preexposure prophylaxis (PrEP) trial have enrolled a large percentage of White men. Human papilloma virus (HPV) privately-funded trials have also enrolled a large number of Whites, due to convenience sampling. Retention in the HIV acquisition trial was lower in African-Americans compared with Whites. Strategies to increase WTP and enhanced retention (ER) strategies may help in recruiting and retaining minority participants in actual HIV vaccine trials and other trials of biomedical prevention.

Detection of Malaria parasite species based on 18S rRNA and assessment of its resistance to the drug for DHPS gene to support the development of irradiation Malaria vaccine

International Nuclear Information System (INIS)

Mukh Syaifudin; Darlina; Siti Nurhayati

2016-01-01

Malaria remains a major public health problem because it causes 1-2 million mortality per year. Therefore the development of its vaccine, including vaccine created by ionizing radiation, is urgently needed to control the disease. Aim of this research was to determine the species of malaria parasite infecting the blood of malaria suspected patients and its resistance to sulfadoxine-pyrimethamine (SP). The number of samples used were 10 blood specimens that obtained from Dok II Hospital in Jayapura. Microscopic examination on thin blood smear was done according to standard procedure, followed by Polymerase Chain Reaction (PCR) based diagnosis to further confirm the parasite using 18S rRNA gene on deoxyribonucleic acid extract. The presence of mutation in the dhps (dihydropteroate synthetase) gene related to SP drugs was examined using restriction fragment length polymorphism (RFLP) method. Results showed that 9 samples were infected with Plasmodium falciparum and 1 infected with P. vivax. Allelic mutants of dhps gene at codon K540E were detected in 3 (33.3%) samples. Even though only in very limited number of samples analyzed, the information obtained will be a great value in additional knowledge for vaccine development with irradiation. (author)

Participants' perceptions and understanding of a malaria clinical trial in Bangladesh.

Science.gov (United States)

Das, Debashish; Cheah, Phaik Yeong; Akter, Fateha; Paul, Dulal; Islam, Akhterul; Sayeed, Abdullah A; Samad, Rasheda; Rahman, Ridwanur; Hossain, Amir; Dondorp, Arjen; Day, Nicholas P; White, Nicholas J; Hasan, Mahtabuddin; Ghose, Aniruddha; Ashley, Elizabeth A; Faiz, Abul

2014-06-04

Existing evidence suggests that there is often limited understanding among participants in clinical trials about the informed consent process, resulting in their providing consent without really understanding the purpose of the study, specific procedures, and their rights. The objective of the study was to determine the subjects' understanding of research, perceptions of voluntariness and motivations for participation in a malaria clinical trial. In this study semi-structured interviews of adult clinical trial participants with uncomplicated falciparum malaria were conducted in Ramu Upazila Health Complex, in Bangladesh. Of 16 participants, the vast majority (81%) were illiterate. All subjects had a 'therapeutic misconception' i.e. the trial was perceived to be conducted primarily for the benefit of individual patients when in fact the main objective was to provide information to inform public health policy. From the patients' perspective, getting well from their illness was their major concern. Poor actual understanding of trial specific procedures was reported despite participants' satisfaction with treatment and nursing care. There is frequently a degree of overlap between research and provision of clinical care in malaria research studies. Patients may be motivated to participate to research without a good understanding of the principal objectives of the study despite a lengthy consent process. The findings suggest that use of a standard consent form following the current ICH-GCP guidelines does not result in achieving fully informed consent and the process should be revised, simplified and adapted to individual trial settings.

Protection of Rhesus Monkeys by a DNA Prime/Poxvirus Boost Malaria Vaccine Depends on Optimal DNA Priming and Inclusion of Blood Stage Antigens

Science.gov (United States)

Weiss, Walter R.; Kumar, Anita; Jiang, George; Williams, Jackie; Bostick, Anthony; Conteh, Solomon; Fryauff, David; Aguiar, Joao; Singh, Manmohan; O'Hagan, Derek T.; Ulmer, Jeffery B.; Richie, Thomas L.

2007-01-01

Background We have previously described a four antigen malaria vaccine consisting of DNA plasmids boosted by recombinant poxviruses which protects a high percentage of rhesus monkeys against Plasmodium knowlesi (Pk) malaria. This is a multi-stage vaccine that includes two pre-erythrocytic antigens, PkCSP and PkSSP2(TRAP), and two erythrocytic antigens, PkAMA-1 and PkMSP-1(42kD). The present study reports three further experiments where we investigate the effects of DNA dose, timing, and formulation. We also compare vaccines utilizing only the pre-erythrocytic antigens with the four antigen vaccine. Methodology In three experiments, rhesus monkeys were immunized with malaria vaccines using DNA plasmid injections followed by boosting with poxvirus vaccine. A variety of parameters were tested, including formulation of DNA on poly-lactic co-glycolide (PLG) particles, varying the number of DNA injections and the amount of DNA, varying the interval between the last DNA injection to the poxvirus boost from 7 to 21 weeks, and using vaccines with from one to four malaria antigens. Monkeys were challenged with Pk sporozoites given iv 2 to 4 weeks after the poxvirus injection, and parasitemia was measured by daily Giemsa stained blood films. Immune responses in venous blood samples taken after each vaccine injection were measured by ELIspot production of interferon-γ, and by ELISA. Conclusions 1) the number of DNA injections, the formulation of the DNA plasmids, and the interval between the last DNA injection and the poxvirus injection are critical to vaccine efficacy. However, the total dose used for DNA priming is not as important; 2) the blood stage antigens PkAMA-1 and PkMSP-1 were able to protect against high parasitemias as part of a genetic vaccine where antigen folding is not well defined; 3) immunization with PkSSP2 DNA inhibited immune responses to PkCSP DNA even when vaccinations were given into separate legs; and 4) in a counter-intuitive result, higher

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

Directory of Open Access Journals (Sweden)

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.ClinicalTrials

Plasmodium falciparum malaria challenge by the bite of aseptic Anopheles stephensi mosquitoes: results of a randomized infectivity trial.

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Kirsten E Lyke

2010-10-01

Full Text Available Experimental infection of malaria-naïve volunteers by the bite of Plasmodium falciparum-infected mosquitoes is a preferred means to test the protective effect of malaria vaccines and drugs. The standard model relies on the bite of five infected mosquitoes to induce malaria. We examined the efficacy of malaria transmission using mosquitoes raised aseptically in compliance with current Good Manufacturing Practices (cGMPs.Eighteen adults aged 18-40 years were randomized to receive 1, 3 or 5 bites of Anopheles stephensi mosquitoes infected with the chloroquine-sensitive NF54 strain of P. falciparum. Seventeen participants developed malaria; fourteen occurring on Day 11. The mean prepatent period was 10.9 days (9-12 days. The geometric mean parasitemia was 15.7 parasites/µL (range: 4-70 by microscopy. Polymerase chain reaction (PCR detected parasites 3.1 (range: 0-4 days prior to microscopy. The geometric mean sporozoite load was 16,753 sporozoites per infected mosquito (range: 1,000-57,500. A 1-bite participant withdrew from the study on Day 13 post-challenge and was PCR and smear negative.The use of aseptic, cGMP-compliant P. falciparum-infected mosquitoes is safe, is associated with a precise prepatent period compared to the standard model and appears more efficient than the standard approach, as it led to infection in 100% (6/6 of volunteers exposed to three mosquito bites and 83% (5/6 of volunteers exposed to one mosquito bite.ClinicalTrials.gov NCT00744133.

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

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Susan Thrane

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

Microneedle array design determines the induction of protective memory CD8+ T cell responses induced by a recombinant live malaria vaccine in mice.

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John B Carey

Full Text Available Vaccine delivery into the skin has received renewed interest due to ease of access to the immune system and microvasculature, however the stratum corneum (SC, must be breached for successful vaccination. This has been achieved by removing the SC by abrasion or scarification or by delivering the vaccine intradermally (ID with traditional needle-and-syringes or with long microneedle devices. Microneedle patch-based transdermal vaccine studies have predominantly focused on antibody induction by inactivated or subunit vaccines. Here, our principal aim is to determine if the design of a microneedle patch affects the CD8(+ T cell responses to a malaria antigen induced by a live vaccine.Recombinant modified vaccinia virus Ankara (MVA expressing a malaria antigen was percutaneously administered to mice using a range of silicon microneedle patches, termed ImmuPatch, that differed in microneedle height, density, patch area and total pore volume. We demonstrate that microneedle arrays that have small total pore volumes induce a significantly greater proportion of central memory T cells that vigorously expand to secondary immunization. Microneedle-mediated vaccine priming induced significantly greater T cell immunity post-boost and equivalent protection against malaria challenge compared to ID vaccination. Notably, unlike ID administration, ImmuPatch-mediated vaccination did not induce inflammatory responses at the site of immunization or in draining lymph nodes.This study demonstrates that the design of microneedle patches significantly influences the magnitude and memory of vaccine-induced CD8(+ T cell responses and can be optimised for the induction of desired immune responses. Furthermore, ImmuPatch-mediated delivery may be of benefit to reducing unwanted vaccine reactogenicity. In addition to the advantages of low cost and lack of pain, the development of optimised microneedle array designs for the induction of T cell responses by live vaccines aids

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.

T-cell responses in malaria

DEFF Research Database (Denmark)

Hviid, L; Jakobsen, P H; Abu-Zeid, Y A

1992-01-01

Malaria is caused by infection with protozoan parasites of the genus Plasmodium. It remains one of the most severe health problems in tropical regions of the world, and the rapid spread of resistance to drugs and insecticides has stimulated intensive research aimed at the development of a malaria...... vaccine. Despite this, no efficient operative vaccine is currently available. A large amount of information on T-cell responses to malaria antigens has been accumulated, concerning antigens derived from all stages of the parasite life cycle. The present review summarizes some of that information......, and discusses factors affecting the responses of T cells to malaria antigens....

Recombinant and epitope-based vaccines on the road to the market and implications for vaccine design and production.

Science.gov (United States)

Oyarzún, Patricio; Kobe, Bostjan

2016-03-03

Novel vaccination approaches based on rational design of B- and T-cell epitopes - epitope-based vaccines - are making progress in the clinical trial pipeline. The epitope-focused recombinant protein-based malaria vaccine (termed RTS,S) is a next-generation approach that successfully reached phase-III trials, and will potentially become the first commercial vaccine against a human parasitic disease. Progress made on methods such as recombinant DNA technology, advanced cell-culture techniques, immunoinformatics and rational design of immunogens are driving the development of these novel concepts. Synthetic recombinant proteins comprising both B- and T-cell epitopes can be efficiently produced through modern biotechnology and bioprocessing methods, and can enable the induction of large repertoires of immune specificities. In particular, the inclusion of appropriate CD4+ T-cell epitopes is increasingly considered a key vaccine component to elicit robust immune responses, as suggested by results coming from HIV-1 clinical trials. In silico strategies for vaccine design are under active development to address genetic variation in pathogens and several broadly protective "universal" influenza and HIV-1 vaccines are currently at different stages of clinical trials. Other methods focus on improving population coverage in target populations by rationally considering specificity and prevalence of the HLA proteins, though a proof-of-concept in humans has not been demonstrated yet. Overall, we expect immunoinformatics and bioprocessing methods to become a central part of the next-generation epitope-based vaccine development and production process.

Randomized Trials Comparing Inactivated Vaccine after Medium- or High-titer Measles Vaccine with Standard Titer Measles Vaccine after Inactivated Vaccine

DEFF Research Database (Denmark)

Aaby, Peter; Ravn, Henrik; Benn, Christine S.

2016-01-01

Background: Observational studies have suggested that girls have higher mortality if their most recent immunization is an inactivated vaccine rather than a live vaccine. We therefore reanalyzed 5 randomized trials of early measles vaccine (MV) in which it was possible to compare an inactivated va...

Design of clinical trials for therapeutic cancer vaccines development.

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Mackiewicz, Jacek; Mackiewicz, Andrzej

2009-12-25

Advances in molecular and cellular biology as well as biotechnology led to definition of a group of drugs referred to as medicinal products of advanced technologies. It includes gene therapy products, somatic cell therapeutics and tissue engineering. Therapeutic cancer vaccines including whole cell tumor cells vaccines or gene modified whole cells belong to somatic therapeutics and/or gene therapy products category. The drug development is a multistep complex process. It comprises of two phases: preclinical and clinical. Guidelines on preclinical testing of cell based immunotherapy medicinal products have been defined by regulatory agencies and are available. However, clinical testing of therapeutic cancer vaccines is still under debate. It presents a serious problem since recently clinical efficacy of the number of cancer vaccines has been demonstrated that focused a lot of public attention. In general clinical testing in the current form is very expensive, time consuming and poorly designed what may lead to overlooking of products clinically beneficial for patients. Accordingly regulatory authorities and researches including Cancer Vaccine Clinical Trial Working Group proposed three regulatory solutions to facilitate clinical development of cancer vaccines: cost-recovery program, conditional marketing authorization, and a new development paradigm. Paradigm includes a model in which cancer vaccines are investigated in two types of clinical trials: proof-of-principle and efficacy. The proof-of-principle trial objectives are: safety; dose selection and schedule of vaccination; and demonstration of proof-of-principle. Efficacy trials are randomized clinical trials with objectives of demonstrating clinical benefit either directly or through a surrogate. The clinical end points are still under debate.

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...

Comparative testing of six antigen-based malaria vaccine candidates directed toward merozoite-stage Plasmodium falciparum

DEFF Research Database (Denmark)

Arnot, David E; Cavanagh, David R; Remarque, Edmond J

2008-01-01

Immunogenicity testing of Plasmodium falciparum antigens being considered as malaria vaccine candidates was undertaken in rabbits. The antigens compared were recombinant baculovirus MSP-1(19) and five Pichia pastoris candidates, including two versions of MSP-1(19), AMA-1 (domains I and II), AMA-1......G concentrations. The two P. pastoris-produced MSP-1(19)-induced IgGs conferred the lowest growth inhibition. Comparative analysis of immunogenicity of vaccine antigens can be used to prioritize candidates before moving to expensive GMP production and clinical testing. The assays used have given discriminating...

Pneumococcal Conjugate Vaccines and Otitis Media: An Appraisal of the Clinical Trials

Science.gov (United States)

Fletcher, Mark A.; Fritzell, Bernard

2012-01-01

Streptococcus pneumoniae is the predominant otitis media pathogen and its prevention through effective vaccination could diminish childhood illness and antibiotic use. This paper reviews 5 pneumococcal conjugate vaccine (PCV) trials that used otitis media as an endpoint: Northern California Kaiser Permanente (NCKP; vaccine, 7-valent PCV [PCV7]-CRM); Finnish Otitis Media (FinOM; vaccines, PCV7-CRM or PCV7-OMPC); Native American Trial (vaccine, PCV7-CRM); Pneumococcal Otitis Efficacy Trial (POET; vaccine, 11-valent PCV [PCV11]-PD). For the microbiological endpoint, vaccine efficacy against vaccine-serotype pneumococcal otitis media was about 60% across trials. Against the clinical endpoint of all episodes, vaccine efficacy was 7% (PCV7-CRM/NCKP), 6% (PCV7-CRM/FinOM), −1% (PCV7-OMPC/FinOM), and −0.4% (PCV7-CRM/Native American Trial); 34% against first episodes of ear, nose, and throat specialist-referral cases (PCV11-PD/POET). Both follow-up through 2 years of age, for the 5 trials, and long-term follow-up, for PCV7-CRM/NCKP and PCV7-CRM/FinOM, demonstrated greater vaccine efficacy against recurrent AOM and tympanostomy-tube placement, suggesting that vaccination against early episodes of AOM may prevent subsequent episodes of complicated otitis media. Although study designs varied by primary endpoint measured, age at follow-up, source of middle-ear fluid for culture, case ascertainment, and type of randomization, each clinical trial demonstrated vaccine efficacy against microbiological and/or clinical otitis media. PMID:22701486

Intranasal vaccine trial for canine infectious tracheobronchitis (kennel cough).

Science.gov (United States)

Glickman, L T; Appel, M J

1981-08-01

Two field trials were conducted during periods of endemic (summer) and epizootic (winter) canine infectious tracheobronchitis activity to evaluate the efficacy of three intranasal vaccines in a closed commercial beagle breeding kennel. A trivalent vaccine containing Bordetella bronchiseptica, canine parainfluenza, and canine adenovirus-2 was administered at 3 weeks of age. The vaccine was 71.2% and 81.8% effective in decreasing the incidence of coughing during the winter and summer trials, respectively. The number of deaths was lower in each of the vaccine groups than in the placebo groups. No adverse reactions were observed with any of the intranasal vaccines.

Recruitment barriers for prophylactic vaccine trials: A study in Belgium.

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Harrington, Lauriane; Van Damme, Pierre; Vandermeulen, Corinne; Mali, Stéphanie

2017-12-04

Recruitment of volunteers is one of the main challenges in clinical trial management, and there is little information about recruitment barriers for preventative vaccine trials. We investigated both the recruitment barriers and recruitment strategies for preventive vaccine trials in Belgium. A 10 min survey was used as well as interviews of staff at all clinical trial sites in Belgium that regularly perform vaccine trials. We observed that there are successful recruitment strategies and few recruitment issues for trials involving healthy adults and those over 65 years old. However, challenges face the recruitment of paediatric populations, pregnant women, patients and the very elderly (over 85 years old). From these results, we identified three priority areas to increase recruitment for prophylactic vaccine trials in Belgium. These are: the lack of public knowledge about infectious diseases; the lack of resources of healthcare professionals to take part in clinical trials; and the burden to potential volunteers to take part in a trial. These were discussed with stakeholders and solutions were proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

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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

Adolescent decision making about participation in a hypothetical HIV vaccine trial.

Science.gov (United States)

Alexander, Andreia B; Ott, Mary A; Lally, Michelle A; Sniecinski, Kevin; Baker, Alyne; Zimet, Gregory D

2015-03-10

The purpose of this study was to examine the process of adolescent decision-making about participation in an HIV vaccine clinical trial, comparing it to adult models of informed consent with attention to developmental differences. As part of a larger study of preventive misconception in adolescent HIV vaccine trials, we interviewed 33 male and female 16-19-year-olds who have sex with men. Participants underwent a simulated HIV vaccine trial consent process, and then completed a semistructured interview about their decision making process when deciding whether or not to enroll in and HIV vaccine trial. An ethnographic content analysis approach was utilized. Twelve concepts related to adolescents' decision-making about participation in an HIV vaccine trial were identified and mapped onto Appelbaum and Grisso's four components of decision making capacity including understanding of vaccines and how they work, the purpose of the study, trial procedures, and perceived trial risks and benefits, an appreciation of their own situation, the discussion and weighing of risks and benefits, discussing the need to consult with others about participation, motivations for participation, and their choice to participate. The results of this study suggest that most adolescents at high risk for HIV demonstrate the key abilities needed to make meaningful decisions about HIV vaccine clinical trial participation. Published by Elsevier Ltd.

HIV vaccine trials: critical issues in informed consent.

Science.gov (United States)

Lindegger, G; Richter, L M

2000-06-01

Informed consent (IC), a fundamental principle of ethics in medical research, is recognized as a vital component of HIV vaccine trials. There are different notions of IC, some legally based and others based on ethics. It is argued that, though legal indemnity is necessary, vaccine trials should be founded on fully ethical considerations. Various contentious aspects of IC are examined, especially the problem of social desirability and of adequate comprehension. The need for sensitivity to cultural norms in implementing IC procedures is critically reviewed, and some of the potential conflict between ethos and ethics is considered. The transmission of information is examined as a particular aspect of IC in HIV vaccine trials.

A systematic review and meta-analysis on the safety of newly adjuvanted vaccines among children.

Science.gov (United States)

Stassijns, Jorgen; Bollaerts, Kaatje; Baay, Marc; Verstraeten, Thomas

2016-02-03

New adjuvants such as the AS- or the MF59-adjuvants improve vaccine efficacy and facilitate dose-sparing. Their use in influenza and malaria vaccines has resulted in a large body of evidence on their clinical safety in children. We carried out a systematic search for safety data from published clinical trials on newly adjuvanted vaccines in children ≤10 years of age. Serious adverse events (SAEs), solicited AEs, unsolicited AEs and AEs of special interest were evaluated for four new adjuvants: the immuno-stimulants containing adjuvant systems AS01 and AS02, and the squalene containing oil-in-water emulsions AS03 and MF59. Relative risks (RR) were calculated, comparing children receiving newly adjuvanted vaccines to children receiving other vaccines with a variety of antigens, both adjuvanted and unadjuvanted. Twenty-nine trials were included in the meta-analysis, encompassing 25,056 children who received at least one dose of the newly adjuvanted vaccines. SAEs did not occur more frequently in adjuvanted groups (RR 0.85, 95%CI 0.75-0.96). Our meta-analyses showed higher reactogenicity following administration of newly adjuvanted vaccines, however, no consistent pattern of solicited AEs was observed across adjuvant systems. Pain was the most prevalent AE, but often mild and of short duration. No increased risks were found for unsolicited AEs, febrile convulsions, potential immune mediated diseases and new onset of chronic diseases. Our meta-analysis did not show any safety concerns in clinical trials of the newly adjuvanted vaccines in children ≤10 years of age. An unexplained increase of meningitis in one Phase III AS01-adjuvanted malaria trial and the link between narcolepsy and the AS03-adjuvanted pandemic vaccine illustrate that continued safety monitoring is warranted. Copyright © 2015 Elsevier Ltd. All rights reserved.

Using Hematology Data from Malaria Vaccine Research Trials in Humans and Rhesus Macaques (Macaca mulatta) To Guide Volume Limits for Blood Withdrawal.

Science.gov (United States)

Hegge, Sara R; Hickey, Bradley W; Mcgrath, Shannon M; Stewart, V Ann

2016-12-01

Guidelines on safe volume limits for blood collection from research participants in both humans and laboratory animals vary widely between institutions. The main adverse event that may be encountered in large blood volume withdrawal is iron-deficiency anemia. Monitoring various parameters in a standard blood panel may help to prevent this outcome. To this end, we analyzed the Hgb and MCV values from 43 humans and 46 macaques in malaria vaccine research trials. Although the percentage of blood volume removed was greater for macaques than humans, macaques demonstrated an overall increase of MCV over time, indicating the ability to respond appropriately to frequent volume withdrawals. In contrast, humans showed a consistent declining trend in MCV. These declines in human MCV and Hgb were significant from the beginning to end of the study despite withdrawals that were smaller than recommended volume limits. Limiting the volume withdrawn to no more than 12.5% seemed to be sufficient for macaques, and at 14% or more individual animals tended to fail to respond appropriately to large-volume blood loss, as demonstrated by a decrease in MCV. The overall positive erythropoietic response seen in macaques was likely due to the controlled, iron-fortified diet they received. The lack of erythropoietic response in the human subjects may warrant iron supplementation or reconsideration of current blood volume withdrawal guidelines.

Microneedle Array Design Determines the Induction of Protective Memory CD8+ T Cell Responses Induced by a Recombinant Live Malaria Vaccine in Mice

Science.gov (United States)

Carey, John B.; Pearson, Frances E.; Vrdoljak, Anto; McGrath, Marie G.; Crean, Abina M.; Walsh, Patrick T.; Doody, Timothy; O'Mahony, Conor; Hill, Adrian V. S.; Moore, Anne C.

2011-01-01

Background Vaccine delivery into the skin has received renewed interest due to ease of access to the immune system and microvasculature, however the stratum corneum (SC), must be breached for successful vaccination. This has been achieved by removing the SC by abrasion or scarification or by delivering the vaccine intradermally (ID) with traditional needle-and-syringes or with long microneedle devices. Microneedle patch-based transdermal vaccine studies have predominantly focused on antibody induction by inactivated or subunit vaccines. Here, our principal aim is to determine if the design of a microneedle patch affects the CD8+ T cell responses to a malaria antigen induced by a live vaccine. Methodology and Findings Recombinant modified vaccinia virus Ankara (MVA) expressing a malaria antigen was percutaneously administered to mice using a range of silicon microneedle patches, termed ImmuPatch, that differed in microneedle height, density, patch area and total pore volume. We demonstrate that microneedle arrays that have small total pore volumes induce a significantly greater proportion of central memory T cells that vigorously expand to secondary immunization. Microneedle-mediated vaccine priming induced significantly greater T cell immunity post-boost and equivalent protection against malaria challenge compared to ID vaccination. Notably, unlike ID administration, ImmuPatch-mediated vaccination did not induce inflammatory responses at the site of immunization or in draining lymph nodes. Conclusions/Significance This study demonstrates that the design of microneedle patches significantly influences the magnitude and memory of vaccine-induced CD8+ T cell responses and can be optimised for the induction of desired immune responses. Furthermore, ImmuPatch-mediated delivery may be of benefit to reducing unwanted vaccine reactogenicity. In addition to the advantages of low cost and lack of pain, the development of optimised microneedle array designs for the induction

malERA: An updated research agenda for diagnostics, drugs, vaccines, and vector control in malaria elimination and eradication.

Science.gov (United States)

2017-11-01

Since the turn of the century, a remarkable expansion has been achieved in the range and effectiveness of products and strategies available to prevent, treat, and control malaria, including advances in diagnostics, drugs, vaccines, and vector control. These advances have once again put malaria elimination on the agenda. However, it is clear that even with the means available today, malaria control and elimination pose a formidable challenge in many settings. Thus, currently available resources must be used more effectively, and new products and approaches likely to achieve these goals must be developed. This paper considers tools (both those available and others that may be required) to achieve and maintain malaria elimination. New diagnostics are needed to direct treatment and detect transmission potential; new drugs and vaccines to overcome existing resistance and protect against clinical and severe disease, as well as block transmission and prevent relapses; and new vector control measures to overcome insecticide resistance and more powerfully interrupt transmission. It is also essential that strategies for combining new and existing approaches are developed for different settings to maximise their longevity and effectiveness in areas with continuing transmission and receptivity. For areas where local elimination has been recently achieved, understanding which measures are needed to maintain elimination is necessary to prevent rebound and the reestablishment of transmission. This becomes increasingly important as more countries move towards elimination.

Mother-Newborn Pairs in Malawi Have Similar Antibody Repertoires to Diverse Malaria Antigens.

Science.gov (United States)

Boudová, Sarah; Walldorf, Jenny A; Bailey, Jason A; Divala, Titus; Mungwira, Randy; Mawindo, Patricia; Pablo, Jozelyn; Jasinskas, Algis; Nakajima, Rie; Ouattara, Amed; Adams, Matthew; Felgner, Philip L; Plowe, Christopher V; Travassos, Mark A; Laufer, Miriam K

2017-10-01

Maternal antibodies may play a role in protecting newborns against malaria disease. Plasmodium falciparum parasite surface antigens are diverse, and protection from infection requires allele-specific immunity. Although malaria-specific antibodies have been shown to cross the placenta, the extent to which antibodies that respond to the full repertoire of diverse antigens are transferred from the mother to the infant has not been explored. Understanding the breadth of maternal antibody responses and to what extent these antibodies are transferred to the child can inform vaccine design and evaluation. We probed plasma from cord blood and serum from mothers at delivery using a customized protein microarray that included variants of malaria vaccine target antigens to assess the intensity and breadth of seroreactivity to three malaria vaccine candidate antigens in mother-newborn pairs in Malawi. Among the 33 paired specimens that were assessed, mothers and newborns had similar intensity and repertoire of seroreactivity. Maternal antibody levels against vaccine candidate antigens were the strongest predictors of infant antibody levels. Placental malaria did not significantly impair transplacental antibody transfer. However, mothers with placental malaria had significantly higher antibody levels against these blood-stage antigens than mothers without placental malaria. The repertoire and levels of infant antibodies against a wide range of malaria vaccine candidate antigen variants closely mirror maternal levels in breadth and magnitude regardless of evidence of placental malaria. Vaccinating mothers with an effective malaria vaccine during pregnancy may induce high and potentially protective antibody repertoires in newborns. Copyright © 2017 American Society for Microbiology.

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

Directory of Open Access Journals (Sweden)

Elizabeth G. Kane

2011-01-01

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

Cardiac complication after experimental human malaria infection: a case report

Directory of Open Access Journals (Sweden)

Druilhe Pierre

2009-12-01

Full Text Available Abstract A 20 year-old healthy female volunteer participated in a clinical Phase I and IIa safety and efficacy trial with candidate malaria vaccine PfLSA-3-rec adjuvanted with aluminium hydroxide. Eleven weeks after the third and last immunization she was experimentally infected by bites of Plasmodium falciparum-infected mosquitoes. When the thick blood smear became positive, at day 11, she was treated with artemether/lumefantrine according to protocol. On day 16 post-infection i.e. two days after completion of treatment, she woke up with retrosternal chest pain. She was diagnosed as acute coronary syndrome and treated accordingly. She recovered quickly and her follow-up was uneventful. Whether the event was related to the study procedures such as the preceding vaccinations, malaria infection or antimalarial drugs remains elusive. However, the relation in time with the experimental malaria infection and apparent absence of an underlying condition makes the infection the most probable trigger. This is in striking contrast, however, with the millions of malaria cases each year and the fact that such complication has never been reported in the literature. The rare occurrence of cardiac events with any of the preceding study procedures may even support a coincidental finding. Apart from acute coronary syndrome, myocarditis can be considered as a final diagnosis, but the true nature and patho-physiological explanation of the event remain unclear.

Population genomics diversity of Plasmodium falciparum in malaria ...

African Journals Online (AJOL)

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

Clinical Trials of an Experimental Ebola Vaccine: A Canadian ...

International Development Research Centre (IDRC) Digital Library (Canada)

This initiative supports phases 2 and 3 clinical trials of an experimental Ebola vaccine. The experimental vaccine is based on an attenuated recombinant Vesicular Stomatitis Virus vector (VSV-EBOV). The Public Health Agency of Canada developed the vaccine and licensed it to NewLink Genetics and Merck. Early vaccine ...

Defining childhood severe falciparum malaria for intervention studies.

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Philip Bejon

2007-08-01

Full Text Available Clinical trials of interventions designed to prevent severe falciparum malaria in children require a clear endpoint. The internationally accepted definition of severe malaria is sensitive, and appropriate for clinical purposes. However, this definition includes individuals with severe nonmalarial disease and coincident parasitaemia, so may lack specificity in vaccine trials. Although there is no "gold standard" individual test for severe malaria, malaria-attributable fractions (MAFs can be estimated among groups of children using a logistic model, which we use to test the suitability of various case definitions as trial endpoints.A total of 4,583 blood samples were taken from well children in cross-sectional surveys and from 1,361 children admitted to a Kenyan District hospital with severe disease. Among children under 2 y old with severe disease and over 2,500 parasites per microliter of blood, the MAFs were above 85% in moderate- and low-transmission areas, but only 61% in a high-transmission area. HIV and malnutrition were not associated with reduced MAFs, but gastroenteritis with severe dehydration (defined by reduced skin turgor, lower respiratory tract infection (clinician's final diagnosis, meningitis (on cerebrospinal fluid [CSF] examination, and bacteraemia were associated with reduced MAFs. The overall MAF was 85% (95% confidence interval [CI] 83.8%-86.1% without excluding these conditions, 89% (95% CI 88.4%-90.2% after exclusions, and 95% (95% CI 94.0%-95.5% when a threshold of 2,500 parasites/mul was also applied. Applying a threshold and exclusion criteria reduced sensitivity to 80% (95% CI 77%-83%.The specificity of a case definition for severe malaria is improved by applying a parasite density threshold and by excluding children with meningitis, lower respiratory tract infection (clinician's diagnosis, bacteraemia, and gastroenteritis with severe dehydration, but not by excluding children with HIV or malnutrition.

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.

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.

Community response to intermittent preventive treatment of malaria in infants (IPTi in Papua New Guinea

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Senn Nicolas

2010-12-01

Full Text Available Abstract Background Building on previous acceptability research undertaken in sub-Saharan Africa this article aims to investigate the acceptability of intermittent preventive treatment of malaria in infants (IPTi in Papua New Guinea (PNG. Methods A questionnaire was administered to mothers whose infants participated in the randomised placebo controlled trial of IPTi. Mothers whose infants participated and who refused to participate in the trial, health workers, community reporters and opinion leaders were interviewed. Men and women from the local community also participated in focus group discussions. Results Respondents viewed IPTi as acceptable in light of wider concern for infant health and the advantages of trial participation. Mothers reported complying with at-home administration of IPTi due to perceived benefits of IPTi and pressure from health workers. In spite of patchy knowledge, respondents also demonstrated a demand for infant vaccinations and considered non-vaccination to be neglect. There is little evidence that IPTi has negative impacts on attitudes to EPI, EPI adherence or existing malaria prevention practices. Conclusion The degree of similarity between findings from the acceptability studies undertaken in sub-Saharan Africa and PNG allows some generalization relating to the implementation of IPTi outside of Africa: IPTi fits well with local health cultures, appears to be accepted easily and has little impact on attitudes towards EPI or malaria prevention. The study adds to the evidence indicating that IPTi could be rolled out in a range of social and cultural contexts.

Comparison of Current Regulatory Status for Gene-Based Vaccines in the U.S., Europe and Japan

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Yoshikazu Nakayama

2015-03-01

Full Text Available Gene-based vaccines as typified by plasmid DNA vaccines and recombinant viral-vectored vaccines are expected as promising solutions against infectious diseases for which no effective prophylactic vaccines exist such as HIV, dengue virus, Ebola virus and malaria, and for which more improved vaccines are needed such as tuberculosis and influenza virus. Although many preclinical and clinical trials have been conducted to date, no DNA vaccines or recombinant viral-vectored vaccines expressing heterologous antigens for human use have yet been licensed in the U.S., Europe or Japan. In this research, we describe the current regulatory context for gene-based prophylactic vaccines against infectious disease in the U.S., Europe, and Japan. We identify the important considerations, in particular, on the preclinical assessments that would allow these vaccines to proceed to clinical trials, and the differences on the regulatory pathway for the marketing authorization in each region.

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

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

2017-11-01

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

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

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José Manuel Lozano

2017-11-01

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

Vaccines for the 21st century

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Delany, Isabel; Rappuoli, Rino; De Gregorio, Ennio

2014-01-01

In the last century, vaccination has been the most effective medical intervention to reduce death and morbidity caused by infectious diseases. It is believed that vaccines save at least 2–3 million lives per year worldwide. Smallpox has been eradicated and polio has almost disappeared worldwide through global vaccine campaigns. Most of the viral and bacterial infections that traditionally affected children have been drastically reduced thanks to national immunization programs in developed countries. However, many diseases are not yet preventable by vaccination, and vaccines have not been fully exploited for target populations such as elderly and pregnant women. This review focuses on the state of the art of recent clinical trials of vaccines for major unmet medical needs such as HIV, malaria, TB, and cancer. In addition, we describe the innovative technologies currently used in vaccine research and development including adjuvants, vectors, nucleic acid vaccines, and structure-based antigen design. The hope is that thanks to these technologies, more diseases will be addressed in the 21st century by novel preventative and therapeutic vaccines. PMID:24803000

Development of behaviour change communication strategy for a vaccination-linked malaria control tool in southern Tanzania

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Mshinda Hassan

2008-09-01

Full Text Available Abstract Background Intermittent preventive treatment of malaria in infants (IPTi using sulphadoxine-pyrimethamine and linked to the expanded programme on immunization (EPI is a promising strategy for malaria control in young children. As evidence grows on the efficacy of IPTi as public health strategy, information is needed so that this novel control tool can be put into practice promptly, once a policy recommendation is made to implement it. This paper describes the development of a behaviour change communication strategy to support implementation of IPTi by the routine health services in southern Tanzania, in the context of a five-year research programme evaluating the community effectiveness of IPTi. Methods Mixed methods including a rapid qualitative assessment and quantitative health facility survey were used to investigate communities' and providers' knowledge and practices relating to malaria, EPI, sulphadoxine-pyrimethamine and existing health posters. Results were applied to develop an appropriate behaviour change communication strategy for IPTi involving personal communication between mothers and health staff, supported by a brand name and two posters. Results Malaria in young children was considered to be a nuisance because it causes sleepless nights. Vaccination services were well accepted and their use was considered the mother's responsibility. Babies were generally taken for vaccination despite complaints about fevers and swellings after the injections. Sulphadoxine-pyrimethamine was widely used for malaria treatment and intermittent preventive treatment of malaria in pregnancy, despite widespread rumours of adverse reactions based on hearsay and newspaper reports. Almost all health providers said that they or their spouse were ready to take SP in pregnancy (96%, 223/242. A brand name, key messages and images were developed and pre-tested as behaviour change communication materials. The posters contained public health messages

Inhaled nitric oxide for the adjunctive therapy of severe malaria: Protocol for a randomized controlled trial

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Lavery James V

2011-07-01

Full Text Available Abstract Background Severe malaria remains a major cause of global morbidity and mortality. Despite the use of potent anti-parasitic agents, the mortality rate in severe malaria remains high. Adjunctive therapies that target the underlying pathophysiology of severe malaria may further reduce morbidity and mortality. Endothelial activation plays a central role in the pathogenesis of severe malaria, of which angiopoietin-2 (Ang-2 has recently been shown to function as a key regulator. Nitric oxide (NO is a major inhibitor of Ang-2 release from endothelium and has been shown to decrease endothelial inflammation and reduce the adhesion of parasitized erythrocytes. Low-flow inhaled nitric oxide (iNO gas is a US FDA-approved treatment for hypoxic respiratory failure in neonates. Methods/Design This prospective, parallel arm, randomized, placebo-controlled, blinded clinical trial compares adjunctive continuous inhaled nitric oxide at 80 ppm to placebo (both arms receiving standard anti-malarial therapy, among Ugandan children aged 1-10 years of age with severe malaria. The primary endpoint is the longitudinal change in Ang-2, an objective and quantitative biomarker of malaria severity, which will be analysed using a mixed-effects linear model. Secondary endpoints include mortality, recovery time, parasite clearance and neurocognitive sequelae. Discussion Noteworthy aspects of this trial design include its efficient sample size supported by a computer simulation study to evaluate statistical power, meticulous attention to complex ethical issues in a cross-cultural setting, and innovative strategies for safety monitoring and blinding to treatment allocation in a resource-constrained setting in sub-Saharan Africa. Trial Registration ClinicalTrials.gov Identifier: NCT01255215

Chloroplast-derived vaccine antigens confer dual immunity against cholera and malaria by oral or injectable delivery.

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Davoodi-Semiromi, Abdoreza; Schreiber, Melissa; Nalapalli, Samson; Verma, Dheeraj; Singh, Nameirakpam D; Banks, Robert K; Chakrabarti, Debopam; Daniell, Henry

2010-02-01

Cholera and malaria are major diseases causing high mortality. The only licensed cholera vaccine is expensive; immunity is lost in children within 3 years and adults are not fully protected. No vaccine is yet available for malaria. Therefore, in this study, the cholera toxin-B subunit (CTB) of Vibrio cholerae fused to malarial vaccine antigens apical membrane antigen-1 (AMA1) and merozoite surface protein-1 (MSP1) was expressed in lettuce and tobacco chloroplasts. Southern blot analysis confirmed homoplasmy and stable integration of transgenes. CTB-AMA1 and CTB-MSP1 fusion proteins accumulated up to 13.17% and 10.11% (total soluble protein, TSP) in tobacco and up to 7.3% and 6.1% (TSP) in lettuce, respectively. Nine groups of mice (n = 10/group) were immunized subcutaneously (SQV) or orally (ORV) with purified antigens or transplastomic tobacco leaves. Significant levels of antigen-specific antibody titres of immunized mice completely inhibited proliferation of the malarial parasite and cross-reacted with the native parasite proteins in immunoblots and immunofluorescence studies. Protection against cholera toxin challenge in both ORV (100%) and SQV (89%) mice correlated with CTB-specific titres of intestinal, serum IgA and IgG1 in ORV and only IgG1 in SQV mice, but no other immunoglobulin. Increasing numbers of interleukin-10(+) T cell but not Foxp3(+) regulatory T cells, suppression of interferon-gamma and absence of interleukin-17 were observed in protected mice, suggesting that immunity is conferred via the Tr1/Th2 immune response. Dual immunity against two major infectious diseases provided by chloroplast-derived vaccine antigens for long-term (>300 days, 50% of mouse life span) offers a realistic platform for low cost vaccines and insight into mucosal and systemic immunity.

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

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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

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

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Jin Changwen

2010-03-01

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

Examination on the protein profiles of salivary glands of P. berghei infected anopheles Sp. post gamma irradiation using SDS-PAGE technique for developing malaria vaccine

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Tetriana, D.; Syaifudin, M.

2014-01-01

Sporozoite is a step of malaria parasitic live cycle that is most invasive and appropriate vaccine candidate. Result of experiments showed that malaria vaccine created by attenuating Plasmodium sp sporozoites with gamma rays was proven more effective. Study on the effects of irradiation to the profiles of protein in vaccine development is also important. The aim of this research was to examine the protein profile of salivary glands in sporozoite infected Anopheles sp post gamma irradiation using Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) technique. Examination covered the infection of Anopheles sp with Plasmodium sp, maintenance of infected mosquitoes for 14-16 days to obtain sporozoites, in vivo - in vitro irradiation of mosquitoes, preparation of salivary glands, electrophoresis on 10% SDS-PAGE, and Commassie blue staining. Results showed a different protein profile of infected and non infected salivary glands of Anopheles sp. There was additional protein band numbers at higher dose of irradiation (200 Gy) from sporozoite protein of P. berghei (MW 62 kDa). However, no difference of the profiles of circumsporozoite protein (CSP) observed among gamma irradiation doses of 150, 175 and 200 Gy. These results provide basic information that would lead to further study on the role of sporozoite proteins in malaria vaccine development. (author)

Vaccines today, vaccines tomorrow: a perspective.

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Loucq, Christian

2013-01-01

Vaccines are considered as one of the major contributions of the 20th century and one of the most cost effective public health interventions. The International Vaccine Institute has as a mission to discover, develop and deliver new and improved vaccines against infectious diseases that affects developing nations. If Louis Pasteur is known across the globe, vaccinologists like Maurice Hilleman, Jonas Salk and Charles Mérieux are known among experts only despite their contribution to global health. Thanks to a vaccine, smallpox has been eradicated, polio has nearly disappeared, Haemophilus influenzae B, measles and more recently meningitis A are controlled in many countries. While a malaria vaccine is undergoing phase 3, International Vaccine Institute, in collaboration with an Indian manufacturer has brought an oral inactivated cholera vaccine to pre-qualification. The field of vaccinology has undergone major changes thanks to philanthropists such as Bill and Melinda Gates, initiatives like the Decade of Vaccines and public private partnerships. Current researches on vaccines have more challenging targets like the dengue viruses, malaria, human immunodeficiency virus, the respiratory syncytial virus and nosocomial diseases. Exciting research is taking place on new adjuvants, nanoparticles, virus like particles and new route of administration. An overcrowded infant immunization program, anti-vaccine groups, immunizing a growing number of elderlies and delivering vaccines to difficult places are among challenges faced by vaccinologists and global health experts.

77 FR 40322 - Oral Rabies Vaccine Trial; Availability of an Environmental Assessment

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2012-07-09

...] Oral Rabies Vaccine Trial; Availability of an Environmental Assessment AGENCY: Animal and Plant Health... assessment relative to an oral rabies vaccination field trial in New Hampshire, New York, Ohio, Vermont, and West Virginia. The environmental assessment analyzes the use of an experimental rabies vaccine in field...

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

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

2010-01-01

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

Likelihood-based methods for evaluating principal surrogacy in augmented vaccine trials.

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Liu, Wei; Zhang, Bo; Zhang, Hui; Zhang, Zhiwei

2017-04-01

There is growing interest in assessing immune biomarkers, which are quick to measure and potentially predictive of long-term efficacy, as surrogate endpoints in randomized, placebo-controlled vaccine trials. This can be done under a principal stratification approach, with principal strata defined using a subject's potential immune responses to vaccine and placebo (the latter may be assumed to be zero). In this context, principal surrogacy refers to the extent to which vaccine efficacy varies across principal strata. Because a placebo recipient's potential immune response to vaccine is unobserved in a standard vaccine trial, augmented vaccine trials have been proposed to produce the information needed to evaluate principal surrogacy. This article reviews existing methods based on an estimated likelihood and a pseudo-score (PS) and proposes two new methods based on a semiparametric likelihood (SL) and a pseudo-likelihood (PL), for analyzing augmented vaccine trials. Unlike the PS method, the SL method does not require a model for missingness, which can be advantageous when immune response data are missing by happenstance. The SL method is shown to be asymptotically efficient, and it performs similarly to the PS and PL methods in simulation experiments. The PL method appears to have a computational advantage over the PS and SL methods.

Comprehension of a simplified assent form in a vaccine trial for adolescents.

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Lee, Sonia; Kapogiannis, Bill G; Flynn, Patricia M; Rudy, Bret J; Bethel, James; Ahmad, Sushma; Tucker, Diane; Abdalian, Sue Ellen; Hoffman, Dannie; Wilson, Craig M; Cunningham, Coleen K

2013-06-01

Future HIV vaccine efficacy trials with adolescents will need to ensure that participants comprehend study concepts in order to confer true informed assent. A Hepatitis B vaccine trial with adolescents offers valuable opportunity to test youth understanding of vaccine trial requirements in general. Youth reviewed a simplified assent form with study investigators and then completed a comprehension questionnaire. Once enrolled, all youth were tested for HIV and confirmed to be HIV-negative. 123 youth completed the questionnaire (mean age=15 years; 63% male; 70% Hispanic). Overall, only 69 (56%) youth answered all six questions correctly. Youth enrolled in a Hepatitis B vaccine trial demonstrated variable comprehension of the study design and various methodological concepts, such as treatment group masking.

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

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

2009-06-29

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

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

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Narum David L

2009-06-01

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

Motivators to participation in actual HIV vaccine trials.

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Dhalla, Shayesta; Poole, Gary

2014-02-01

An examination of actual HIV vaccine trials can contribute to an understanding of motivators for participation in these studies. Analysis of these motivators reveals that they can be categorized as social and personal benefits. Social benefits are generally altruistic, whereas personal benefits are psychological, physical, and financial. In this systematic review, the authors performed a literature search for actual preventive HIV vaccine trials reporting motivators to participation. Of studies conducted in the Organization for Economic Co-operation and Development (OECD) countries, the authors retrieved 12 studies reporting on social benefits and seven reporting on personal benefits. From the non-OECD countries, nine studies reported on social benefits and eight studies on personal benefits. Social benefits were most frequently described on macroscopic, altruistic levels. Personal benefits were most frequently psychological in nature. Rates of participation were compared between the OECD and the non-OECD countries. Knowledge of actual motivators in specific countries and regions can help target recruitment in various types of actual HIV vaccine trials.

Participants’ perceptions and understanding of a malaria clinical trial in Bangladesh

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Das, Debashish; Cheah, Phaik Yeong; Akter, Fateha; Paul, Dulal; Islam, Akhterul; Sayeed, Abdullah A; Samad, Rasheda; Rahman, Ridwanur; Hossain, Amir; Dondorp, Arjen; Day, Nicholas P; White, Nicholas J; Hasan, Mahtabuddin; Ghose, Aniruddha; Ashley, Elizabeth A

2014-01-01

Background Existing evidence suggests that there is often limited understanding among participants in clinical trials about the informed consent process, resulting in their providing consent without really understanding the purpose of the study, specific procedures, and their rights. The objective of the study was to determine the subjects’ understanding of research, perceptions of voluntariness and motivations for participation in a malaria clinical trial. Methods In this study semi-structur...

Insecticide-treated nets for the prevention of malaria in pregnancy: a systematic review of randomised controlled trials.

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Carol Gamble

2007-03-01

Full Text Available BACKGROUND: Protection from malaria with insecticide-treated bednets (ITNs during pregnancy is widely advocated, but evidence of benefit has been inconsistent. We undertook a systematic review of randomised trials. METHODS AND FINDINGS: Three cluster-randomised and two individually randomised trials met the inclusion criteria; four from Africa (n = 6,418 and one from Thailand (n = 223. In Africa, ITNs compared to no nets increased mean birth weight by 55 g (95% confidence interval [CI] 21-88, reduced low birth weight by 23% (relative risk [RR] 0.77, 95% CI 0.61-0.98, and reduced miscarriages/stillbirths by 33% (RR 0.67, 0.47-0.97 in the first few pregnancies. Placental parasitaemia was reduced by 23% in all gravidae (RR 0.77, 0.66-0.90. The effects were apparent in the cluster-randomised trials and the one individually randomised trial in Africa. The trial in Thailand, which randomised individuals to ITNs or untreated nets, showed reductions in anaemia and fetal loss in all gravidae, but not reductions in clinical malaria or low birth weight. CONCLUSIONS: ITNs used throughout pregnancy or from mid-pregnancy onwards have a beneficial impact on pregnancy outcome in malaria-endemic Africa in the first few pregnancies. The potential impact of ITNs in pregnant women and their newborns in malaria regions outside Africa requires further research.

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

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Caroline Kulangara

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

Tools and Strategies for Malaria Control and Elimination: What Do We Need to Achieve a Grand Convergence in Malaria?

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Janet Hemingway

2016-03-01

Full Text Available Progress made in malaria control during the past decade has prompted increasing global dialogue on malaria elimination and eradication. The product development pipeline for malaria has never been stronger, with promising new tools to detect, treat, and prevent malaria, including innovative diagnostics, medicines, vaccines, vector control products, and improved mechanisms for surveillance and response. There are at least 25 projects in the global malaria vaccine pipeline, as well as 47 medicines and 13 vector control products. In addition, there are several next-generation diagnostic tools and reference methods currently in development, with many expected to be introduced in the next decade. The development and adoption of these tools, bolstered by strategies that ensure rapid uptake in target populations, intensified mechanisms for information management, surveillance, and response, and continued financial and political commitment are all essential to achieving global eradication.

Immunogenicity of a virosomally-formulated Plasmodium falciparum GLURP-MSP3 chimeric protein-based malaria vaccine candidate in comparison to adjuvanted formulations

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Tamborrini Marco

2011-12-01

Full Text Available Abstract Background In clinical trials, immunopotentiating reconstituted influenza virosomes (IRIVs have shown great potential as a versatile antigen delivery platform for synthetic peptides derived from Plasmodium falciparum antigens. This study describes the immunogenicity of a virosomally-formulated recombinant fusion protein comprising domains of the two malaria vaccine candidate antigens MSP3 and GLURP. Methods The highly purified recombinant protein GMZ2 was coupled to phosphatidylethanolamine and the conjugates incorporated into the membrane of IRIVs. The immunogenicity of this adjuvant-free virosomal formulation was compared to GMZ2 formulated with the adjuvants Montanide ISA 720 and Alum in three mouse strains with different genetic backgrounds. Results Intramuscular injections of all three candidate vaccine formulations induced GMZ2-specific antibody responses in all mice tested. In general, the humoral immune response in outbred NMRI mice was stronger than that in inbred BALB/c and C57BL/6 mice. ELISA with the recombinant antigens demonstrated immunodominance of the GLURP component over the MSP3 component. However, compared to the Al(OH3-adjuvanted formulation the two other formulations elicited in NMRI mice a larger proportion of anti-MSP3 antibodies. Analyses of the induced GMZ2-specific IgG subclass profiles showed for all three formulations a predominance of the IgG1 isotype. Immune sera against all three formulations exhibited cross-reactivity with in vitro cultivated blood-stage parasites. Immunofluorescence and immunoblot competition experiments showed that both components of the hybrid protein induced IgG cross-reactive with the corresponding native proteins. Conclusion A virosomal formulation of the chimeric protein GMZ2 induced P. falciparum blood stage parasite cross-reactive IgG responses specific for both MSP3 and GLURP. GMZ2 thus represents a candidate component suitable for inclusion into a multi-valent virosomal

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

DEFF Research Database (Denmark)

Ajua, Anthony; Engleitner, Thomas; Esen, Meral

2012-01-01

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

Spatial and environmental connectivity analysis in a cholera vaccine trial.

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Emch, Michael; Ali, Mohammad; Root, Elisabeth D; Yunus, Mohammad

2009-02-01

This paper develops theory and methods for vaccine trials that utilize spatial and environmental information. Satellite imagery is used to identify whether households are connected to one another via water bodies in a study area in rural Bangladesh. Then relationships between neighborhood-level cholera vaccine coverage and placebo incidence and neighborhood-level spatial variables are measured. The study hypothesis is that unvaccinated people who are environmentally connected to people who have been vaccinated will be at lower risk compared to unvaccinated people who are environmentally connected to people who have not been vaccinated. We use four datasets including: a cholera vaccine trial database, a longitudinal demographic database of the rural population from which the vaccine trial participants were selected, a household-level geographic information system (GIS) database of the same study area, and high resolution Quickbird satellite imagery. An environmental connectivity metric was constructed by integrating the satellite imagery with the vaccine and demographic databases linked with GIS. The results show that there is a relationship between neighborhood rates of cholera vaccination and placebo incidence. Thus, people are indirectly protected when more people in their environmentally connected neighborhood are vaccinated. This result is similar to our previous work that used a simpler Euclidean distance neighborhood to measure neighborhood vaccine coverage [Ali, M., Emch, M., von Seidlein, L., Yunus, M., Sack, D. A., Holmgren, J., et al. (2005). Herd immunity conferred by killed oral cholera vaccines in Bangladesh. Lancet, 366(9479), 44-49]. Our new method of measuring environmental connectivity is more precise since it takes into account the transmission mode of cholera and therefore this study validates our assertion that the oral cholera vaccine provides indirect protection in addition to direct protection.

A Plasmodium Promiscuous T Cell Epitope Delivered within the Ad5 Hexon Protein Enhances the Protective Efficacy of a Protein Based Malaria Vaccine.

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Jairo Andres Fonseca

Full Text Available A malaria vaccine is a public health priority. In order to produce an effective vaccine, a multistage approach targeting both the blood and the liver stage infection is desirable. The vaccine candidates also need to induce balanced immune responses including antibodies, CD4+ and CD8+ T cells. Protein-based subunit vaccines like RTS,S are able to induce strong antibody response but poor cellular reactivity. Adenoviral vectors have been effective inducing protective CD8+ T cell responses in several models including malaria; nonetheless this vaccine platform exhibits a limited induction of humoral immune responses. Two approaches have been used to improve the humoral immunogenicity of recombinant adenovirus vectors, the use of heterologous prime-boost regimens with recombinant proteins or the genetic modification of the hypervariable regions (HVR of the capsid protein hexon to express B cell epitopes of interest. In this study, we describe the development of capsid modified Ad5 vectors that express a promiscuous Plasmodium yoelii T helper epitope denominated PyT53 within the hexon HVR2 region. Several regimens were tested in mice to determine the relevance of the hexon modification in enhancing protective immune responses induced by the previously described protein-based multi-stage experimental vaccine PyCMP. A heterologous prime-boost immunization regime that combines a hexon modified vector with transgenic expression of PyCMP followed by protein immunizations resulted in the induction of robust antibody and cellular immune responses in comparison to a similar regimen that includes a vector with unmodified hexon. These differences in immunogenicity translated into a better protective efficacy against both the hepatic and red blood cell stages of P. yoelii. To our knowledge, this is the first time that a hexon modification is used to deliver a promiscuous T cell epitope. Our data support the use of such modification to enhance the immunogenicity

malaria

African Journals Online (AJOL)

children who presented with malaria symptoms at the same clinic and tested positive or ... phagocytes immunity and induce anti-inflammatory immune response ...... treatment gap, Malawi will be ready to submit a validation request for virtual .... Conclusions. Vaccination and quarantine are the important disease preventive.

The elderly, the young and the pregnant traveler -- A retrospective data analysis from a large Swiss Travel Center with a special focus on malaria prophylaxis and yellow fever vaccination.

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Jaeger, Veronika K; Tschudi, Nadine; Rüegg, Rolanda; Hatz, Christoph; Bühler, Silja

2015-01-01

Vulnerable individuals such as elderly, children/adolescents and pregnant/breastfeeding women increasingly travel overseas. We describe the travel and vaccination patterns of these groups at the largest Travel Clinic in Switzerland especially focusing on travel to yellow fever and malaria-endemic countries, and yellow fever vaccination (YFV) and malaria medications. An analysis of pre-travel visits between 2010 and 2012 at the Travel Clinic of the University of Zurich, was performed assessing differences between the elderly, young and middle-aged travelers as well as between pregnant/breastfeeding and other female travelers. Overall, the vulnerable groups did not differ from other travelers regarding their travel patterns. YFV was the most often administered vaccine to elderly travelers; half of them received it for the first time. More than 30% of children/adolescents received YFV, but no child below six months was vaccinated. 80% of young travelers and a similar percentage of pregnant women went to malaria-endemic regions. Twenty-five pregnant/breastfeeding women traveled to YF endemic areas. Travel patterns of vulnerable travelers are comparable to those of other travelers. In view of the limited data on malaria medications and precautions against YFV during pregnancy and at the extreme ages of life, giving travel advice to these groups is challenging. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

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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

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

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Michele D Spring

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

76 FR 48119 - Oral Rabies Vaccine Trial; Availability of a Risk Assessment and an Environmental Assessment

Science.gov (United States)

2011-08-08

...] Oral Rabies Vaccine Trial; Availability of a Risk Assessment and an Environmental Assessment AGENCY... environmental assessment relative to an oral rabies vaccination field trial in West Virginia. The environmental... rabies vaccine, analyzes the use of that vaccine in field safety and efficacy trials in West Virginia...

Volunteer motivators for participating in HIV vaccine clinical trials in Nairobi, Kenya.

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Nyaoke, Borna A; Mutua, Gaudensia N; Sajabi, Rose; Nyasani, Delvin; Mureithi, Marianne W; Anzala, Omu A

2017-01-01

1.5 million Kenyans are living with HIV/AIDS as per 2015 estimates. Though there is a notable decline in new HIV infections, continued effort is still needed to develop an efficacious, accessible and affordable HIV vaccine. HIV vaccine clinical trials bear risks, hence a need to understand volunteer motivators for enrolment, retention and follow-up. Understanding the factors that motivate volunteers to participate in a clinical trial can help to strategize, refine targeting and thus increase enrolment of volunteers in future HIV vaccine clinical trials. The health belief model classifies motivators into social benefits such as 'advancing research' and collaboration with science, and personal benefits such as health benefits and financial interests. A thematic analysis was carried out on data obtained from four HIV clinical trials conducted at KAVI-Institute of Clinical Research in Nairobi Kenya from 2009 to 2015. Responses were obtained from a Questionnaire administered to the volunteers during their screening visit at the research site. Of the 281 healthy, HIV-uninfected volunteers participating in this study; 38% were motivated by personal benefits including, 31% motivated by health benefits and 7% motivated by possible financial gains. In addition, 62% of the volunteers were motivated by social benefits with 20% of who were seeking to help their family/society/world while 42% were interested in advancing research. The majority of volunteers in the HIV vaccine trials at our site were motivated by social benefits, suggesting that altruism can be a major contributor to participation in HIV vaccine studies. Personal benefits were a secondary motivator for the volunteers. The motivators to volunteer in HIV clinical trials were similar across ages, education level and gender. Education on what is needed (including volunteer participation) to develop an efficacious vaccine could be the key to greater volunteer motivation to participate in HIV vaccine clinical trials.

Volunteer motivators for participating in HIV vaccine clinical trials in Nairobi, Kenya.

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Borna A Nyaoke

Full Text Available 1.5 million Kenyans are living with HIV/AIDS as per 2015 estimates. Though there is a notable decline in new HIV infections, continued effort is still needed to develop an efficacious, accessible and affordable HIV vaccine. HIV vaccine clinical trials bear risks, hence a need to understand volunteer motivators for enrolment, retention and follow-up. Understanding the factors that motivate volunteers to participate in a clinical trial can help to strategize, refine targeting and thus increase enrolment of volunteers in future HIV vaccine clinical trials. The health belief model classifies motivators into social benefits such as 'advancing research' and collaboration with science, and personal benefits such as health benefits and financial interests.A thematic analysis was carried out on data obtained from four HIV clinical trials conducted at KAVI-Institute of Clinical Research in Nairobi Kenya from 2009 to 2015. Responses were obtained from a Questionnaire administered to the volunteers during their screening visit at the research site.Of the 281 healthy, HIV-uninfected volunteers participating in this study; 38% were motivated by personal benefits including, 31% motivated by health benefits and 7% motivated by possible financial gains. In addition, 62% of the volunteers were motivated by social benefits with 20% of who were seeking to help their family/society/world while 42% were interested in advancing research.The majority of volunteers in the HIV vaccine trials at our site were motivated by social benefits, suggesting that altruism can be a major contributor to participation in HIV vaccine studies. Personal benefits were a secondary motivator for the volunteers. The motivators to volunteer in HIV clinical trials were similar across ages, education level and gender. Education on what is needed (including volunteer participation to develop an efficacious vaccine could be the key to greater volunteer motivation to participate in HIV vaccine

The Malaria Season Is Upon Us

African Journals Online (AJOL)

imported or Odyssean malaria from countries such as Swaziland,. Mozambique ... can be administered.⁵ The only .... Treatment. With the introduction of an effective vaccine for Southern Africa .... Being prepared for a malaria infection by packing ... sulfadoxine-pyrimethamine against Plasmodium falciparum in Yemen and.

Controlled Human Malaria Infection: Applications, Advances, and Challenges.

Science.gov (United States)

Stanisic, Danielle I; McCarthy, James S; Good, Michael F

2018-01-01

Controlled human malaria infection (CHMI) entails deliberate infection with malaria parasites either by mosquito bite or by direct injection of sporozoites or parasitized erythrocytes. When required, the resulting blood-stage infection is curtailed by the administration of antimalarial drugs. Inducing a malaria infection via inoculation with infected blood was first used as a treatment (malariotherapy) for neurosyphilis in Europe and the United States in the early 1900s. More recently, CHMI has been applied to the fields of malaria vaccine and drug development, where it is used to evaluate products in well-controlled early-phase proof-of-concept clinical studies, thus facilitating progression of only the most promising candidates for further evaluation in areas where malaria is endemic. Controlled infections have also been used to immunize against malaria infection. Historically, CHMI studies have been restricted by the need for access to insectaries housing infected mosquitoes or suitable malaria-infected individuals. Evaluation of vaccine and drug candidates has been constrained in these studies by the availability of a limited number of Plasmodium falciparum isolates. Recent advances have included cryopreservation of sporozoites, the manufacture of well-characterized and genetically distinct cultured malaria cell banks for blood-stage infection, and the availability of Plasmodium vivax -specific reagents. These advances will help to accelerate malaria vaccine and drug development by making the reagents for CHMI more widely accessible and also enabling a more rigorous evaluation with multiple parasite strains and species. Here we discuss the different applications of CHMI, recent advances in the use of CHMI, and ongoing challenges for consideration. Copyright © 2017 American Society for Microbiology.

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

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Thomas Smith

2012-01-01

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

Vaccines licensed and in clinical trials for the prevention of dengue.

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Torresi, J; Ebert, G; Pellegrini, M

2017-05-04

Dengue has become a major global public health threat with almost half of the world's population living in at-risk areas. Vaccination would likely represent an effective strategy for the management of dengue disease in endemic regions, however to date there is only one licensed preventative vaccine for dengue infection. The development of a vaccine against dengue virus (DENV) has been hampered by an incomplete understanding of protective immune responses against DENV. The most clinically advanced dengue vaccine is the chimeric yellow fever-dengue vaccine (CYD) that employs the yellow fever virus 17D strain as the replication backbone (Chimerivax-DEN; CYD-TDV). This vaccine had an overall pooled protective efficacy of 65.6% but was substantially more effective against severe dengue and dengue hemorrhagic fever. Several other vaccine approaches have been developed including live attenuated chimeric dengue vaccines (DENVax and LAV Delta 30), DEN protein subunit V180 vaccine (DEN1-80E) and DENV DNA vaccines. These vaccines have been shown to be immunogenic in animals and also safe and immunogenic in humans. However, these vaccines are yet to progress to phase III trials to determine their protective efficacy against dengue. This review will summarize the details of vaccines that have progressed to clinical trials in humans.

Clinical trials for vaccine development in registry of Korea Food and Drug Administration.

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Kang, Seog-Youn

2013-01-01

Based on the action plan "Ensuring a stable supply of National Immunization Program vaccines and sovereignty of biopharmaceutical products," Korea Food and Drug Administration (KFDA) has made efforts to develop vaccines in the context of self reliance and to protect public health. Along with the recognized infrastructures for clinical trials, clinical trials for vaccines have also gradually been conducted at multinational sites as well as at local sites. KFDA will support to expand six to eleven kinds of vaccines by 2017. In accordance with integrated regulatory system, KFDA has promoted clinical trials, established national lot release procedure, and strengthened good manufacturing practices inspection and post marketing surveillance. Against this backdrop, KFDA will support the vaccine development and promote excellent public health protection.

Community perspectives on the ethical issues surrounding adolescent HIV vaccine trials in South Africa.

Science.gov (United States)

Jaspan, Heather B; Soka, Nosiphiwo F; Strode, Ann E; Mathews, Catherine; Mark, Daniella; Flisher, Alan J; Wood, Robin; Bekker, Linda-Gail

2008-10-23

Adolescents globally are at high risk for HIV acquisition and are the targets of HIV prevention interventions such as HIV vaccines. In order to understand stakeholders' attitudes towards the ethical issues of adolescent involvement in HIV vaccine trials, we conducted focus group discussions with key members of a semi-urban, informal Cape Town community with high HIV prevalence in which HIV vaccine trials are taking place. Themes were identified from focus group transcripts by four researchers, and included necessity of guardian consent, age of independent consent, and confidentiality of in-trial medical results. In general, ethical adolescent HIV vaccine trials will be feasible in this community.

Evidence for single-dose protection by the bivalent HPV vaccine-Review of the Costa Rica HPV vaccine trial and future research studies.

Science.gov (United States)

Kreimer, Aimée R; Herrero, Rolando; Sampson, Joshua N; Porras, Carolina; Lowy, Douglas R; Schiller, John T; Schiffman, Mark; Rodriguez, Ana Cecilia; Chanock, Stephen; Jimenez, Silvia; Schussler, John; Gail, Mitchell H; Safaeian, Mahboobeh; Kemp, Troy J; Cortes, Bernal; Pinto, Ligia A; Hildesheim, Allan; Gonzalez, Paula

2018-01-20

The Costa Rica Vaccine Trial (CVT), a phase III randomized clinical trial, provided the initial data that one dose of the HPV vaccine could provide durable protection against HPV infection. Although the study design was to administer all participants three doses of HPV or control vaccine, 20% of women did not receive the three-dose regimens, mostly due to involuntary reasons unrelated to vaccination. In 2011, we reported that a single dose of the bivalent HPV vaccine could be as efficacious as three doses of the vaccine using the endpoint of persistent HPV infection accumulated over the first four years of the trial; findings independently confirmed in the GSK-sponsored PATRICIA trial. Antibody levels after one dose, although lower than levels elicited by three doses, were 9-times higher than levels elicited by natural infection. Importantly, levels remained essentially constant over at least seven years, suggesting that the observed protection provided by a single dose might be durable. Much work has been done to assure these non-randomized findings are valid. Yet, the group of recipients who received one dose of the bivalent HPV vaccine in the CVT and PATRICIA trials was small and not randomly selected nor blinded to the number of doses received. The next phase of research is to conduct a formal randomized, controlled trial to evaluate the protection afforded by a single dose of HPV vaccine. Complementary studies are in progress to bridge our findings to other populations, and to further document the long-term durability of antibody response following a single dose. Published by Elsevier Ltd.

Cost-effectiveness analysis of vaccinating children in Malawi with RTS,S vaccines in comparison with long-lasting insecticide-treated nets.

Science.gov (United States)

Seo, Mikyung Kelly; Baker, Peter; Ngo, Karen Ngoc-Lan

2014-02-24

New RTS,S malaria vaccines may soon be licensed, yet its cost-effectiveness is unknown. Before the widespread introduction of RTS,S vaccines, cost-effectiveness studies are needed to help inform governments in resource-poor settings about how best to prioritize between the new vaccine and existing malaria interventions. A Markov model simulated malaria progression in a hypothetical Malawian birth cohort. Parameters were based on published data. Three strategies were compared: no intervention, vaccination at one year, and long-lasting, insecticide-treated nets (LLINs) at birth. Both health service and societal perspectives were explored. Health outcomes were measured in disability-adjusted life years (DALYs) averted and costed in 2012 US$. Incremental cost-effectiveness ratios (ICERs) were calculated and extensive sensitivity analyses were conducted. Three times GDP per capita ($1,095) per DALY averted was used for a cost-effectiveness threshold, whilst one times GDP ($365) was considered 'very cost-effective'. From a societal perspective the vaccine strategy was dominant. It averted 0.11 more DALYs than LLINs and 0.372 more DALYs than the no intervention strategy per person, while costing $10.04 less than LLINs and $59.74 less than no intervention. From a health service perspective the vaccine's ICER was $145.03 per DALY averted, and thus can be considered very cost-effective. The results were robust to changes in all variables except the vaccine and LLINs' duration of efficacy. Vaccines remained cost-effective even at the lowest assumed efficacy levels of 49.6% (mild malaria) and 14.2% (severe malaria), and the highest price of $15. However, from a societal perspective, if the vaccine duration efficacy was set below 2.69 years or the LLIN duration of efficacy was greater than 4.24 years then LLINs became the more cost-effective strategy. The results showed that vaccinating Malawian children with RTS,S vaccines was very cost-effective from both a societal and a

Vaccines and immunization

African Journals Online (AJOL)

Prof Ezechukwu

vaccines for malaria and HIV infection. Despite the ... decades, effective vaccines against the major causes of ... challenge antibodies, specific helper and effector T lymphocytes ... materials to produced immunity to a disease. It was originally ...

Key feasibility considerations when conducting vaccine clinical trials in Asia–Pacific countries

Directory of Open Access Journals (Sweden)

Lansang EZ

2013-03-01

Full Text Available Elvira Zenaida Lansang,1 Kenneth Tan,2 Saumya Nayak,1 Ken J Lee,1 Karen Wai1 1Feasibility and Site Identification – Asia, Quintiles East Asia Pte Ltd, Singapore; 2National University of Singapore, Singapore Introduction: Conducting clinical trial feasibility is an important first step in initiating a clinical trial. A robust feasibility process ensures that a realistic capability assessment is made before conducting a trial. A retrospective analysis of vaccine clinical trials was performed to understand changes which could affect feasibility recommendations. Methods: Feasibilities conducted by Quintiles between January 2011 and August 2012 were reviewed. Vaccine studies only involving Asia–Pacific countries were selected, and common study parameters were identified. Information from Quintiles’ database was retrieved to examine changes in parameters over time. Results: A total of six vaccine studies were identified within the 1.7-year period. Two studies were excluded because they did not contain feasibility information or had involved sites that were sponsor selected. Four studies were analyzed. Three cases required healthy volunteers, while one case involved a specific patient population. Age requirement and seasonality of disease mainly influenced recommendations for Study 1. Sponsor’s marketing strategy influenced the recommendations for Study 2. Study 3 showed the effect of a country’s immunization program and reimbursement of vaccines on a study’s success. In contrast to the other studies, Study 4 demonstrated the impact of eligibility criteria in recruitment recommendations for a vaccine trial requiring specific patient pools. Conclusion: Feasibility recommendations for vaccine trials are largely based on (1 eligibility criteria; (2 cultural beliefs; (3 country’s past recruitment performance; (4 use of advertising; (5 site’s access to subject populations; (6 cooperation with local health professionals and government; (7

Macromolecular systems for vaccine delivery.

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MuŽíková, G; Laga, R

2016-10-20

Vaccines have helped considerably in eliminating some life-threatening infectious diseases in past two hundred years. Recently, human medicine has focused on vaccination against some of the world's most common infectious diseases (AIDS, malaria, tuberculosis, etc.), and vaccination is also gaining popularity in the treatment of cancer or autoimmune diseases. The major limitation of current vaccines lies in their poor ability to generate a sufficient level of protective antibodies and T cell responses against diseases such as HIV, malaria, tuberculosis and cancers. Among the promising vaccination systems that could improve the potency of weakly immunogenic vaccines belong macromolecular carriers (water soluble polymers, polymer particels, micelles, gels etc.) conjugated with antigens and immunistumulatory molecules. The size, architecture, and the composition of the high molecular-weight carrier can significantly improve the vaccine efficiency. This review includes the most recently developed (bio)polymer-based vaccines reported in the literature.

Malaria drives T cells to exhaustion

Directory of Open Access Journals (Sweden)

Michelle N Wykes

2014-05-01

Full Text Available Malaria is a significant global burden but after >30 years of effort there is no vaccine on the market. While the complex life cycle of the parasite presents several challenges, many years of research have also identified several mechanisms of immune evasion by Plasmodium spp.. Recent research on malaria, has investigated the Programmed cell death-1 (PD-1 pathway which mediates exhaustion of T cells, characterized by poor effector functions and recall responses and in some cases loss of the cells by apoptosis. Such studies have shown exhaustion of CD4+ T cells and an unappreciated role for CD8+ T cells in promoting sterile immunity against blood stage malaria. This is because PD-1 mediates up to a 95% reduction in numbers and functional capacity of parasite-specific CD8+ T cells, thus masking their role in protection. The role of T cell exhaustion during malaria provides an explanation for the absence of sterile immunity following the clearance of acute disease which will be relevant to future malaria-vaccine design and suggests the need for novel therapeutic solutions. This review will thus examine the role of PD-1-mediated T cell exhaustion in preventing lasting immunity against malaria.

Using simulation to estimate the power of a badger vaccine trial

NARCIS (Netherlands)

Aznar, I.; More, S.J.; Frankena, K.; Jong, de M.C.M.

2011-01-01

The aim of this study was to estimate the power of a badger vaccine field trial using simulation techniques. The effects of sample size, sensitivity and specificity of the diagnostic test, transmission rate between unvaccinated badgers, Vaccine Efficacy for Susceptibility (VES) and Vaccine Efficacy

A New Decade of Vaccines

LENUS (Irish Health Repository)

Murphy, JFA

2011-09-01

The call for a new decade of vaccines was made in December 2010. The aims are to secure the further discovery, development and delivery of vaccination. The first challenge is the acquisition of funds for the research and development of 20 new vaccines1. The Gates Foundation has pledged $10 billion for this venture. The other major players are WHO, UNICEF and the US National Institute of Allergy and Infectious Diseases. The top priorities are TB, AIDS and Malaria. It is hoped that a Malaria vaccine will available in 3 years. The ambitious target of saving the lives of over 7 million children has been set. The programme must also address the need for vaccines in insulin dependent diabetes, cancers and degenerative diseases2.

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 ...

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

Directory of Open Access Journals (Sweden)

K Singh

2016-01-01

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

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

-comparisons of results of vaccine trials performed in different centres/with different products; (2) to facilitate standardization and harmonization of immunological assays used in epidemiology research; and (3) to allow optimization and validation of immunological assays used in malaria vaccine development.

Geographic analysis of vaccine uptake in a cluster-randomized controlled trial in Hue, Vietnam.

Science.gov (United States)

Ali, Mohammad; Thiem, Vu Dinh; Park, Jin-Kyung; Ochiai, Rion Leon; Canh, Do Gia; Danovaro-Holliday, M Carolina; Kaljee, Linda M; Clemens, John D; Acosta, Camilo J

2007-09-01

This paper identifies spatial patterns and predictors of vaccine uptake in a cluster-randomized controlled trial in Hue, Vietnam. Data for this study result from the integration of demographic surveillance, vaccine record, and geographic data of the study area. A multi-level cross-classified (non-hierarchical) model was used for analyzing the non-nested nature of individual's ecological data. Vaccine uptake was unevenly distributed in space and there was spatial variability among predictors of vaccine uptake. Vaccine uptake was higher among students with younger, male, or not literate family heads. Students from households with higher per-capita income were less likely to participate in the trial. Residency south of the river or further from a hospital/polyclinic was associated with higher vaccine uptake. Younger students were more likely to be vaccinated than older students in high- or low-risk areas, but not in the entire study area. The findings are important for the management of vaccine campaigns during a trial and for interpretation of disease patterns during vaccine-efficacy evaluation.

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.

Uganda gets set for vaccine trials, but the ethical debate continues.

Science.gov (United States)

1997-04-01

An HIV vaccine trial scheduled for 1997 involves 2000 male and female members of the Uganda People's Defence Force. The volunteers are 18-40 years old and have been evaluated for 18 months. The trial of Alvac-HIV vaccine developed by Pasteur Manieux Connaught will be conducted by the Joint Clinical Research Council, a joint venture of Makerere University and the Ministries of Health and Defence, in collaboration with the Johns Hopkins University. The vaccine has already been tested on 300 volunteers in France and the US. The initial stage of testing will involve a randomized, placebo-controlled, double-blind trial comparing the safety and immunogenicity of four successive injections in 20 HIV-negative and 20 HIV-positive volunteers. Follow-up will continue for a year. While volunteers will get free medical attention if they develop a severe reaction to the vaccine and will receive a full explanation about the experimental nature of the vaccine, it has not been determined how volunteers will be compensated if something unforeseen goes wrong. Additional concerns revolve around Uganda's readiness to institute proper legal controls and ethical standards in cases of biomedical research.

A study protocol for a randomised open-label clinical trial of artesunate-mefloquine versus chloroquine in patients with non-severe Plasmodium knowlesi malaria in Sabah, Malaysia (ACT KNOW trial)

Science.gov (United States)

Grigg, M J; William, T; Dhanaraj, P; Menon, J; Barber, B E; von Seidlein, L; Rajahram, G; Price, R N; Anstey, N M; Yeo, T W

2014-01-01

Introduction Malaria due to Plasmodium knowlesi is reported throughout South-East Asia, and is the commonest cause of it in Malaysia. P. knowlesi replicates every 24 h and can cause severe disease and death. Current 2010 WHO Malaria Treatment Guidelines have no recommendations for the optimal treatment of non-severe knowlesi malaria. Artemisinin-combination therapies (ACT) and chloroquine have each been successfully used to treat knowlesi malaria; however, the rapidity of parasite clearance has not been prospectively compared. Malaysia's national policy for malaria pre-elimination involves mandatory hospital admission for confirmed malaria cases with discharge only after two negative blood films; use of a more rapidly acting antimalarial agent would have health cost benefits. P. knowlesi is commonly microscopically misreported as P. malariae, P. falciparum or P. vivax, with a high proportion of the latter two species being chloroquine-resistant in Malaysia. A unified ACT-treatment protocol would provide effective blood stage malaria treatment for all Plasmodium species. Methods and analysis ACT KNOW, the first randomised controlled trial ever performed in knowlesi malaria, is a two-arm open-label trial with enrolments over a 2-year period at three district sites in Sabah, powered to show a difference in proportion of patients negative for malaria by microscopy at 24 h between treatment arms (clinicaltrials.gov #NCT01708876). Enrolments started in December 2012, with completion expected by September 2014. A total sample size of 228 is required to give 90% power (α 0.05) to determine the primary end point using intention-to-treat analysis. Secondary end points include parasite clearance time, rates of recurrent infection/treatment failure to day 42, gametocyte carriage throughout follow-up and rates of anaemia at day 28, as determined by survival analysis. Ethics and dissemination This study has been approved by relevant institutional ethics committees in

The costs and effectiveness of large Phase III pre-licensure vaccine clinical trials.

Science.gov (United States)

Black, Steven

2015-01-01

Prior to the 1980s, most vaccines were licensed based upon safety and effectiveness studies in several hundred individuals. Beginning with the evaluation of Haemophilus influenzae type b conjugate vaccines, much larger pre-licensure trials became common. The pre-licensure trial for Haemophilus influenzae oligosaccharide conjugate vaccine had more than 60,000 children and that of the seven-valent pneumococcal conjugate vaccine included almost 38,000 children. Although trial sizes for both of these studies were driven by the sample size required to demonstrate efficacy, the sample size requirements for safety evaluations of other vaccines have subsequently increased. With the demonstration of an increased risk of intussusception following the Rotashield brand rotavirus vaccine, this trend has continued. However, routinely requiring safety studies of 20,000-50,000 or more participants has two major downsides. First, the cost of performing large safety trials routinely prior to licensure of a vaccine is very large, with some estimates as high at US$200 million euros for one vaccine. This high financial cost engenders an opportunity cost whereby the number of vaccines that a company is willing or able to develop to meet public health needs becomes limited by this financial barrier. The second downside is that in the pre-licensure setting, such studies are very time consuming and delay the availability of a beneficial vaccine substantially. One might argue that in some situations, this financial commitment is warranted such as for evaluations of the risk of intussusception following newer rotavirus vaccines. However, it must be noted that while an increased risk of intussusception was not identified in large pre-licensure studies, in post marketing evaluations an increased risk of this outcome has been identified. Thus, even the extensive pre-licensure evaluations conducted did not identify an associated risk. The limitations of large Phase III trials have also been

Conquering the intolerable burden of malaria: what's new, what's needed: a summary.

Science.gov (United States)

Breman, Joel G; Alilio, Martin S; Mills, Anne

2004-08-01

approach for countering the spread and intensity of Plasmodium falciparum resistance to chloroquine, sulfadoxine/pyrimethamine, and other antimalarial drugs. Although costly, ACT ($1.20-2.50 per adult treatment) becomes more cost-effective as resistance to alternative drugs increases; early use of ACT may delay development of resistance to these drugs and prevent the medical toll associated with use of ineffective drugs. The burden of malaria in one district in Tanzania has not decreased since the primary health care approach replaced the vertical malaria control efforts of the 1960s. Despite decentralization, this situation resulted, in part, from weak district management capacity, poor coordination, inadequate monitoring, and lack of training of key staff. Experience in the Solomon Islands showed that spraying with DDT, use of insecticide-treated bed nets (ITNs), and health education were all associated with disease reduction. The use of nets permitted a reduction in DDT spraying, but could not replace it without an increased malaria incidence. Baseline data and reliable monitoring of key outcome indicators are needed to measure whether the ambitious goals for the control of malaria and other diseases has occurred. Such systems are being used for evidence-based decision making in Tanzania and several other countries. Baseline cluster sampling surveys in several countries across Africa indicate that only 53% of the children with febrile illness in malarious areas are being treated; chloroquine (CQ) is used 84% of the time, even where the drug may be ineffective. Insecticide-treated bed nets were used only 2% of the time by children less than five years of age. Progress in malaria vaccine research has been substantial over the past five years; 35 candidate malaria vaccines are in development, many of which are in clinical trials. Development of new vaccines and drugs has been the result of increased investments and formation of public-private partnerships. Before malaria

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...

Correlates of protection for rotavirus vaccines: Possible alternative trial endpoints, opportunities, and challenges.

Science.gov (United States)

Angel, Juana; Steele, A Duncan; Franco, Manuel A

2014-01-01

Rotavirus (RV) is a major vaccine-preventable killer of young children worldwide. Two RV vaccines are globally commercially available and other vaccines are in different stages of development. Due to the absence of a suitable correlate of protection (CoP), all RV vaccine efficacy trials have had clinical endpoints. These trials represent an important challenge since RV vaccines have to be introduced in many different settings, placebo-controlled studies are unethical due to the availability of licensed vaccines, and comparator assessments for new vaccines with clinical endpoints are very large, complex, and expensive to conduct. A CoP as a surrogate endpoint would allow predictions of vaccine efficacy for new RV vaccines and enable a regulatory pathway, contributing to the more rapid development of new RV vaccines. The goal of this review is to summarize experiences from RV natural infection and vaccine studies to evaluate potential CoP for use as surrogate endpoints for assessment of new RV vaccines, and to explore challenges and opportunities in the field.

78 FR 33798 - Oral Rabies Vaccine Trial; Availability of a Supplemental Environmental Assessment

Science.gov (United States)

2013-06-05

... Inspection Service [Docket No. APHIS-2013-0046] Oral Rabies Vaccine Trial; Availability of a Supplemental... Inspection Service has prepared a supplemental environmental assessment (EA) relative to an oral rabies... analyzes expanding the field trial for an experimental oral rabies vaccine for wildlife to additional areas...

Newer Vaccines against Mosquito-borne Diseases.

Science.gov (United States)

Aggarwal, Anju; Garg, Neha

2018-02-01

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

Is maternal education a social vaccine for childhood malaria infection? A cross-sectional study from war-torn Democratic Republic of Congo.

Science.gov (United States)

Ma, Cary; Claude, Kasereka Masumbuko; Kibendelwa, Zacharie Tsongo; Brooks, Hannah; Zheng, Xiaonan; Hawkes, Michael

2017-03-01

In zones of violent conflict in the tropics, social disruption leads to elevated child mortality, of which malaria is the leading cause. Understanding the social determinants of malaria transmission may be helpful to optimize malaria control efforts. We conducted a cross-sectional study of healthy children aged 2 months to 5 years attending well-child and/or immunization visits in the Democratic Republic of Congo (DRC). Six hundred and forty-seven children were tested for malaria antigenemia by rapid diagnostic test and the accompanying parent or legal guardian simultaneously completed a survey questionnaire related to demographics, socioeconomic status, maternal education, as well as bednet use and recent febrile illness. We examined the associations between variables using multivariable logistic regression analysis, chi-squared statistic, Fisher's exact test, and Spearman's rank correlation, as appropriate. One hundred and twenty-three out of the 647 (19%) children in the study tested positive for malaria. Higher levels of maternal education were associated with a lower risk of malaria in their children. The prevalence of malaria in children of mothers with no education, primary school, and beyond primary was 41/138 (30%), 41/241 (17%), and 39/262 (15%), respectively (p = 0.001). In a multivariable logistic regression model adjusting for the effect of a child's age and study site, the following remained significant predictors of malaria antigenemia: maternal education, number of children under five per household, and HIV serostatus. Higher maternal education, through several putative causal pathways, was associated with lower malaria prevalence among children in the DRC. Our findings suggest that maternal education might be an effective 'social vaccine' against malaria in the DRC and globally.

Serious adverse events after HPV vaccination: a critical review of randomized trials and post-marketing case series.

Science.gov (United States)

Martínez-Lavín, Manuel; Amezcua-Guerra, Luis

2017-10-01

This article critically reviews HPV vaccine serious adverse events described in pre-licensure randomized trials and in post-marketing case series. HPV vaccine randomized trials were identified in PubMed. Safety data were extracted. Post-marketing case series describing HPV immunization adverse events were reviewed. Most HPV vaccine randomized trials did not use inert placebo in the control group. Two of the largest randomized trials found significantly more severe adverse events in the tested HPV vaccine arm of the study. Compared to 2871 women receiving aluminum placebo, the group of 2881 women injected with the bivalent HPV vaccine had more deaths on follow-up (14 vs. 3, p = 0.012). Compared to 7078 girls injected with the 4-valent HPV vaccine, 7071 girls receiving the 9-valent dose had more serious systemic adverse events (3.3 vs. 2.6%, p = 0.01). For the 9-valent dose, our calculated number needed to seriously harm is 140 (95% CI, 79–653) [DOSAGE ERROR CORRECTED] . The number needed to vaccinate is 1757 (95% CI, 131 to infinity). Practically, none of the serious adverse events occurring in any arm of both studies were judged to be vaccine-related. Pre-clinical trials, post-marketing case series, and the global drug adverse reaction database (VigiBase) describe similar post-HPV immunization symptom clusters. Two of the largest randomized HPV vaccine trials unveiled more severe adverse events in the tested HPV vaccine arm of the study. Nine-valent HPV vaccine has a worrisome number needed to vaccinate/number needed to harm quotient. Pre-clinical trials and post-marketing case series describe similar post-HPV immunization symptoms.

The role of vitamin D in malaria.

Science.gov (United States)

Lương, Khanh Vinh Quốc; Nguyễn, Lan Thi Hoàng

2015-01-15

An abnormal calcium-parathyroid hormone (PTH)-vitamin D axis has been reported in patients with malaria infection. A role for vitamin D in malaria has been suggested by many studies. Genetic studies have identified numerous factors that link vitamin D to malaria, including human leukocyte antigen genes, toll-like receptors, heme oxygenase-1, angiopoietin-2, cytotoxic T lymphocyte antigen-4, nucleotide-binding oligomerization domain-like receptors, and Bcl-2. Vitamin D has also been implicated in malaria via its effects on the Bacillus Calmette-Guerin (BCG) vaccine, matrix metalloproteinases, mitogen-activated protein kinase pathways, prostaglandins, reactive oxidative species, and nitric oxide synthase. Vitamin D may be important in malaria; therefore, additional research on its role in malaria is needed.

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...

Process and effects of a community intervention on malaria in rural Burkina Faso: randomized controlled trial

Directory of Open Access Journals (Sweden)

Gustafsson Lars

2008-03-01

Full Text Available Abstract Background In the rural areas of sub-Saharan Africa, the majority of young children affected by malaria have no access to formal health services. Home treatment through mothers of febrile children supported by mother groups and local health workers has the potential to reduce malaria morbidity and mortality. Methods A cluster-randomized controlled effectiveness trial was implemented from 2002–2004 in a malaria endemic area of rural Burkina Faso. Six and seven villages were randomly assigned to the intervention and control arms respectively. Febrile children from intervention villages were treated with chloroquine (CQ by their mothers, supported by local women group leaders. CQ was regularly supplied through a revolving fund from local health centres. The trial was evaluated through two cross-sectional surveys at baseline and after two years of intervention. The primary endpoint of the study was the proportion of moderate to severe anaemia in children aged 6–59 months. For assessment of the development of drug efficacy over time, an in vivo CQ efficacy study was nested into the trial. The study is registered under http://www.controlled-trials.com (ISRCTN 34104704. Results The intervention was shown to be feasible under program conditions and a total of 1.076 children and 999 children were evaluated at baseline and follow-up time points respectively. Self-reported CQ treatment of fever episodes at home as well as referrals to health centres increased over the study period. At follow-up, CQ was detected in the blood of high proportions of intervention and control children. Compared to baseline findings, the prevalence of anaemia (29% vs 16%, p P. falciparum parasitaemia, fever and palpable spleens was lower at follow-up but there were no differences between the intervention and control group. CQ efficacy decreased over the study period but this was not associated with the intervention. Discussion The decreasing prevalence of malaria

'He is now like a brother, I can even give him some blood'--relational ethics and material exchanges in a malaria vaccine 'trial community' in The Gambia.

Science.gov (United States)

Geissler, P Wenzel; Kelly, Ann; Imoukhuede, Babatunde; Pool, Robert

2008-09-01

This paper explores social relations within the 'trial community' (staff and volunteers) of a Malaria Vaccine Trial (MVT), implemented by the Medical Research Council (MRC) in The Gambia between 2001 and 2004. It situates ethical concerns with medical research within the everyday life of scientific fieldwork. Based upon discussions with volunteers and staff, we explore processes of mediation between scientific project and study population, and between formal ethics, local ethical debates and everyday practice. We observe that material contact and substantial transactions, notably of blood and medicine, are central to the construction of the MVT. These transactions are guided by a concrete and relational form of ethics, which contrasts with the abstract and vertical formal ethical principles underwriting the scientific study protocol. The success of the MVT owed much to these kinship-like ethics. One possible conclusion from these observations is that research ethics should be understood, not just as a quasi-legal frame but also as an open, searching movement, much in the same way that kinship is not merely a juridical institution and a prescriptive frame of rules, but a network made through relational work. However, this conclusion raises new problems: by contrasting formal, abstract principles to intimate, immediate relations, and economic justice to personal morality, we accept that the order of medical research is moved further out of the public and political, and into the domains of either quasi-legal claims or of private morality. Irrespective of the undeniable importance of clear-cut rules and of good face-to-face relations, a third essential foundation of medical research ethics is the democratically constituted public sphere, including equitable health services, and transparent institutions to facilitate open debate and regulate particular interests. Ultimately, the ethics of global science can rely neither on principles nor trust but requires citizenship

Reasons for ineligibility in phase 1 and 2A HIV vaccine clinical trials at Kenya AIDS vaccine initiative (KAVI, Kenya.

Directory of Open Access Journals (Sweden)

Gloria S Omosa-Manyonyi

2011-01-01

Full Text Available With the persistent challenges towards controlling the HIV epidemic, there is an ongoing need for research into HIV vaccines and drugs. Sub-Saharan African countries--worst affected by the HIV pandemic--have participated in the conduct of clinical trials for HIV vaccines. In Kenya, the Kenya AIDS Vaccine Initiative (KAVI at the University of Nairobi has conducted HIV vaccine clinical trials since 2001.Participants were recruited after an extensive informed consent process followed by screening to determine eligibility. Screening included an assessment of risk behavior, medical history and physical examination, and if clinically healthy, laboratory testing. In the absence of locally derived laboratory reference ranges, the ranges used in these trials were derived from populations in the West.Two hundred eighty-one participants were screened between 2003 and 2006 for two clinical trials. Of these, 167 (59.4% met the inclusion/exclusion criteria. Overall, laboratory abnormalities based on the non-indigenous laboratory references used were the most frequent reasons (61.4% for ineligibility. Medical abnormalities contributed 30.7% of the total reasons for ineligibility. Based on the laboratory reference intervals now developed from East and Southern Africa, those ineligible due to laboratory abnormalities would have been 46.3%. Of the eligible participants, 18.6% declined enrollment.Participant recruitment for HIV vaccine clinical trials is a rigorous and time-consuming exercise. Over 61% of the screening exclusions in clinically healthy people were due to laboratory abnormalities. It is essential that laboratory reference ranges generated from local populations for laboratory values be used in the conduct of clinical trials to avoid unnecessary exclusion of willing participants and to avoid over-reporting of adverse events for enrolled participants.Protocol IAVI VRC V001 [1]. ClinicalTrials.gov NCT00124007 Protocol IAVI 010 [2](registration with

Challenges in conducting a community-based influenza vaccine trial in a rural community in northern India.

Science.gov (United States)

Kumar, Rakesh; Amarchand, Ritvik; Narayan, Venkatesh Vinayak; Saha, Siddhartha; Lafond, Kathryn E; Kapoor, Suresh K; Dar, Lalit; Jain, Seema; Krishnan, Anand

2018-04-04

Evidence on influenza vaccine effectiveness from low and middle countries (LMICs) is limited due to limited institutional capacities; lack of adequate resources; and lack of interest by ministries of health for influenza vaccine introduction. There are concerns that the highest ethical standards will be compromised during trials in LMICs leading to mistrust of clinical trials. These factors pose regulatory and operational challenges to researchers in these countries. We conducted a community-based vaccine trial to assess the efficacy of live attenuated influenza vaccine and inactivated influenza vaccine in rural north India. Key regulatory challenges included obtaining regulatory approvals, reporting of adverse events, and compensating subjects for trial-related injuries; all of which were required to be completed in a timely fashion. Key operational challenges included obtaining audio-visual consent; maintaining a low attrition rate; and administering vaccines during a narrow time period before the influenza season, and under extreme heat. We overcame these challenges through advanced planning, and sustaining community engagement. We adapted the trial procedures to cope with field conditions by conducting mock vaccine camps; and planned for early morning vaccination to mitigate threats to the cold chain. These lessons may help investigators to confront similar challenges in other LMICs.

A trial of intermittent preventive treatment and home-based management of malaria in a rural area of The Gambia

Directory of Open Access Journals (Sweden)

Webb Emily L

2011-01-01

Full Text Available Abstract Background Individual malaria interventions provide only partial protection in most epidemiological situations. Thus, there is a need to investigate whether combining interventions provides added benefit in reducing mortality and morbidity from malaria. The potential benefits of combining IPT in children (IPTc with home management of malaria (HMM was investigated. Methods During the 2008 malaria transmission season, 1,277 children under five years of age resident in villages within the rural Farafenni demographic surveillance system (DSS in North Bank Region, The Gambia were randomized to receive monthly IPTc with a single dose of sulphadoxine/pyrimethamine (SP plus three doses of amodiaquine (AQ or SP and AQ placebos given by village health workers (VHWs on three occasions during the months of September, October and November, in a double-blind trial. Children in all study villages who developed an acute febrile illness suggestive of malaria were treated by VHWs who had been taught how to manage malaria with artemether-lumefantrine (Coartem™. The primary aims of the project were to determine whether IPTc added significant benefit to HMM and whether VHWs could effectively combine the delivery of both interventions. Results The incidence of clinical attacks of malaria was very low in both study groups. The incidence rate of malaria in children who received IPTc was 0.44 clinical attacks per 1,000 child months at risk while that for control children was 1.32 per 1,000 child months at risk, a protective efficacy of 66% (95% CI -23% to 96%; p = 0.35. The mean (standard deviation haemoglobin concentration at the end of the malaria transmission season was similar in the two treatment groups: 10.2 (1.6 g/dL in the IPTc group compared to 10.3 (1.5 g/dL in the placebo group. Coverage with IPTc was high, with 94% of children receiving all three treatments during the study period. Conclusion Due to the very low incidence of malaria, no firm

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.

Malaria infection and socioeconomic status of some residents of Port ...

African Journals Online (AJOL)

ADOWIE PERE

public health interventions against malaria, such as insecticide spraying or ... prepared, air dried, stained and examined ... Port Harcourt metropolis is presented in Table 1. It showed that more ..... of effective vaccine for malaria prevention and.

SieveSifter: a web-based tool for visualizing the sieve analyses of HIV-1 vaccine efficacy trials.

Science.gov (United States)

Fiore-Gartland, Andrew; Kullman, Nicholas; deCamp, Allan C; Clenaghan, Graham; Yang, Wayne; Magaret, Craig A; Edlefsen, Paul T; Gilbert, Peter B

2017-08-01

Analysis of HIV-1 virions from participants infected in a randomized controlled preventive HIV-1 vaccine efficacy trial can help elucidate mechanisms of partial protection. By comparing the genetic sequence of viruses from vaccine and placebo recipients to the sequence of the vaccine itself, a technique called 'sieve analysis', one can identify functional specificities of vaccine-induced immune responses. We have created an interactive web-based visualization and data access tool for exploring the results of sieve analyses performed on four major preventive HIV-1 vaccine efficacy trials: (i) the HIV Vaccine Trial Network (HVTN) 502/Step trial, (ii) the RV144/Thai trial, (iii) the HVTN 503/Phambili trial and (iv) the HVTN 505 trial. The tool acts simultaneously as a platform for rapid reinterpretation of sieve effects and as a portal for organizing and sharing the viral sequence data. Access to these valuable datasets also enables the development of novel methodology for future sieve analyses. Visualization: http://sieve.fredhutch.org/viz . Source code: https://github.com/nkullman/SIEVE . Data API: http://sieve.fredhutch.org/data . agartlan@fredhutch.org. © The Author(s) 2017. Published by Oxford University Press.

Military Infectious Diseases Update on Vaccine Development

Science.gov (United States)

2011-01-24

Licensed live vaccines (polio, MMR) - Radiation- attenuated sporozoites - Genetically- attenuated sporozoites 2011 MHS Conference Whole Organism...Not sufficiently attenuated Seattle Biomedical , Gates Foundation, WEHI and USMMVP 2011 MHS Conference Subunit approach- RTS,S Vaccine RTS,S is...Ad Boost  DNA plasmids [Prime] – Encoding malaria proteins CSP and AMA1  Adenovirus 5 ( attenuated )[Boost] – Encoding malaria proteins CSP and AMA1

3D analysis of the TCR/pMHCII complex formation in monkeys vaccinated with the first peptide inducing sterilizing immunity against human malaria.

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Manuel A Patarroyo

Full Text Available T-cell receptor gene rearrangements were studied in Aotus monkeys developing high antibody titers and sterilizing immunity against the Plasmodium falciparum malaria parasite upon vaccination with the modified synthetic peptide 24112, which was identified in the Merozoite Surface Protein 2 (MSP-2 and is known to bind to HLA-DRbeta1*0403 molecules with high capacity. Spectratyping analysis showed a preferential usage of Vbeta12 and Vbeta6 TCR gene families in 67% of HLA-DRbeta1*0403-like genotyped monkeys. Docking of peptide 24112 into the HLA-DRbeta1*0401-HA peptide-HA1.7TCR complex containing the VDJ rearrangements identified in fully protected monkeys showed a different structural signature compared to nonprotected monkeys. These striking results show the exquisite specificity of the TCR/pMHCII complex formation needed for inducing sterilizing immunity and provide important hints for a logical and rational methodology to develop multiepitopic, minimal subunit-based synthetic vaccines against infectious diseases, among them malaria.

Use of malaria rapid diagnostic tests by community health workers in Afghanistan: cluster randomised trial.

Science.gov (United States)

Leslie, Toby; Rowland, Mark; Mikhail, Amy; Cundill, Bonnie; Willey, Barbara; Alokozai, Asif; Mayan, Ismail; Hasanzai, Anwar; Baktash, Sayed Habibullah; Mohammed, Nader; Wood, Molly; Rahimi, Habib-U-Rahman; Laurent, Baptiste; Buhler, Cyril; Whitty, Christopher J M

2017-07-07

The World Health Organisation (WHO) recommends parasitological diagnosis of malaria before treatment, but use of malaria rapid diagnostic tests (mRDTs) by community health workers (CHWs) has not been fully tested within health services in south and central Asia. mRDTs could allow CHWs to diagnose malaria accurately, improving treatment of febrile illness. A cluster randomised trial in community health services was undertaken in Afghanistan. The primary outcome was the proportion of suspected malaria cases correctly treated for polymerase chain reaction (PCR)-confirmed malaria and PCR negative cases receiving no antimalarial drugs measured at the level of the patient. CHWs from 22 clusters (clinics) received standard training on clinical diagnosis and treatment of malaria; 11 clusters randomised to the intervention arm received additional training and were provided with mRDTs. CHWs enrolled cases of suspected malaria, and the mRDT results and treatments were compared to blind-read PCR diagnosis. In total, 256 CHWs enrolled 2400 patients with 2154 (89.8%) evaluated. In the intervention arm, 75.3% (828/1099) were treated appropriately vs. 17.5% (185/1055) in the control arm (cluster adjusted risk ratio: 3.72, 95% confidence interval 2.40-5.77; p < 0.001). In the control arm, 85.9% (164/191) with confirmed Plasmodium vivax received chloroquine compared to 45.1% (70/155) in the intervention arm (p < 0.001). Overuse of chloroquine in the control arm resulted in 87.6% (813/928) of those with no malaria (PCR negative) being treated vs. 10.0% (95/947) in the intervention arm, p < 0.001. In the intervention arm, 71.4% (30/42) of patients with P. falciparum did not receive artemisinin-based combination therapy, partly because operational sensitivity of the RDTs was low (53.2%, 38.1-67.9). There was high concordance between recorded RDT result and CHW prescription decisions: 826/950 (87.0%) with a negative test were not prescribed an antimalarial. Co

Impact of intermittent screening and treatment for malaria among school children in Kenya: a cluster randomised trial.

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Katherine E Halliday

2014-01-01

Full Text Available Improving the health of school-aged children can yield substantial benefits for cognitive development and educational achievement. However, there is limited experimental evidence of the benefits of alternative school-based malaria interventions or how the impacts of interventions vary according to intensity of malaria transmission. We investigated the effect of intermittent screening and treatment (IST for malaria on the health and education of school children in an area of low to moderate malaria transmission.A cluster randomised trial was implemented with 5,233 children in 101 government primary schools on the south coast of Kenya in 2010-2012. The intervention was delivered to children randomly selected from classes 1 and 5 who were followed up for 24 months. Once a school term, children were screened by public health workers using malaria rapid diagnostic tests (RDTs, and children (with or without malaria symptoms found to be RDT-positive were treated with a six dose regimen of artemether-lumefantrine (AL. Given the nature of the intervention, the trial was not blinded. The primary outcomes were anaemia and sustained attention. Secondary outcomes were malaria parasitaemia and educational achievement. Data were analysed on an intention-to-treat basis. During the intervention period, an average of 88.3% children in intervention schools were screened at each round, of whom 17.5% were RDT-positive. 80.3% of children in the control and 80.2% in the intervention group were followed-up at 24 months. No impact of the malaria IST intervention was observed for prevalence of anaemia at either 12 or 24 months (adjusted risk ratio [Adj.RR]: 1.03, 95% CI 0.93-1.13, p = 0.621 and Adj.RR: 1.00, 95% CI 0.90-1.11, p = 0.953 respectively, or on prevalence of P. falciparum infection or scores of classroom attention. No effect of IST was observed on educational achievement in the older class, but an apparent negative effect was seen on spelling scores in

Oral iron supplements for children in malaria-endemic areas

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Neuberger, Ami; Okebe, Joseph; Yahav, Dafna; Paul, Mical

2016-01-01

Background Iron-deficiency anaemia is common during childhood. Iron administration has been claimed to increase the risk of malaria. Objectives To evaluate the effects and safety of iron supplementation, with or without folic acid, in children living in areas with hyperendemic or holoendemic malaria transmission. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library, MEDLINE (up to August 2015) and LILACS (up to February 2015). We also checked the metaRegister of Controlled Trials (mRCT) and World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) up to February 2015. We contacted the primary investigators of all included trials, ongoing trials, and those awaiting assessment to ask for unpublished data and further trials. We scanned references of included trials, pertinent reviews, and previous meta-analyses for additional references. Selection criteria We included individually randomized controlled trials (RCTs) and cluster RCTs conducted in hyperendemic and holoendemic malaria regions or that reported on any malaria-related outcomes that included children younger than 18 years of age. We included trials that compared orally administered iron, iron with folic acid, and iron with antimalarial treatment versus placebo or no treatment. We included trials of iron supplementation or fortification interventions if they provided at least 80% of the Recommended Dietary Allowance (RDA) for prevention of anaemia by age. Antihelminthics could be administered to either group, and micronutrients had to be administered equally to both groups. Data collection and analysis The primary outcomes were clinical malaria, severe malaria, and death from any cause. We assessed the risk of bias in included trials with domain-based evaluation and assessed the quality of the evidence using the Grading of Recommendations Assessment

Novel use Of Hydroxyurea in an African Region with Malaria (NOHARM): a trial for children with sickle cell anemia.

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Opoka, Robert O; Ndugwa, Christopher M; Latham, Teresa S; Lane, Adam; Hume, Heather A; Kasirye, Phillip; Hodges, James S; Ware, Russell E; John, Chandy C

2017-12-14

Hydroxyurea treatment is recommended for children with sickle cell anemia (SCA) living in high-resource malaria-free regions, but its safety and efficacy in malaria-endemic sub-Saharan Africa, where the greatest sickle-cell burden exists, remain unknown. In vitro studies suggest hydroxyurea could increase malaria severity, and hydroxyurea-associated neutropenia could worsen infections. NOHARM (Novel use Of Hydroxyurea in an African Region with Malaria) was a randomized, double-blinded, placebo-controlled trial conducted in malaria-endemic Uganda, comparing hydroxyurea to placebo at 20 ± 2.5 mg/kg per day for 12 months. The primary outcome was incidence of clinical malaria. Secondary outcomes included SCA-related adverse events (AEs), clinical and laboratory effects, and hematological toxicities. Children received either hydroxyurea (N = 104) or placebo (N = 103). Malaria incidence did not differ between children on hydroxyurea (0.05 episodes per child per year; 95% confidence interval [0.02, 0.13]) vs placebo (0.07 episodes per child per year [0.03, 0.16]); the hydroxyurea/placebo malaria incidence rate ratio was 0.7 ([0.2, 2.7]; P = .61). Time to infection also did not differ significantly between treatment arms. A composite SCA-related clinical outcome (vaso-occlusive painful crisis, dactylitis, acute chest syndrome, splenic sequestration, or blood transfusion) was less frequent with hydroxyurea (45%) than placebo (69%; P = .001). Children receiving hydroxyurea had significantly increased hemoglobin concentration and fetal hemoglobin, with decreased leukocytes and reticulocytes. Serious AEs, sepsis episodes, and dose-limiting toxicities were similar between treatment arms. Three deaths occurred (2 hydroxyurea, 1 placebo, and none from malaria). Hydroxyurea treatment appears safe for children with SCA living in malaria-endemic sub-Saharan Africa, without increased severe malaria, infections, or AEs. Hydroxyurea provides SCA-related laboratory and clinical

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.

Atovaquone and proguanil hydrochloride for treatment of malaria.

Science.gov (United States)

Kremsner, P G; Looareesuwan, S; Chulay, J D

1999-05-01

Safe and effective new drugs are needed for treatment of malaria. Atovaquone and proguanil hydrochloride is a new antimalarial combination that has recently become available in many countries. Data from clinical trials evaluating atovaquone/proguanil for treatment of malaria were reviewed. In 10 open-label clinical trials, treatment of uncomplicated falciparum malaria with 1000 mg atovaquone and 400 mg proguanil hydrochloride (or the equivalent based on body weight in patients proguanil has been used to provide radical cure of asymptomatic Plasmodium falciparum infections prior to initiation of placebo-controlled trials of malaria prophylaxis. Recurrent parasitemia occurred within 28 days in 0 of 99 subjects who subsequently received prophylaxis with atovaquone/proguanil and 1 of 81 subjects who subsequently received placebo. Atovaquone/proguanil is also effective for treatment of malaria caused by the other three Plasmodium species that cause malaria in humans. For treatment of vivax malaria, therapy with primaquine in addition to atovaquone/proguanil is needed to prevent relapse from latent hepatic hypnozoites. Atovaquone and proguanil hydrochloride is a safe and effective combination for treatment of malaria.

A Cluster Randomised Trial Introducing Rapid Diagnostic Tests into Registered Drug Shops in Uganda: Impact on Appropriate Treatment of Malaria

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Mbonye, Anthony K.; Magnussen, Pascal; Lal, Sham; Hansen, Kristian S.; Cundill, Bonnie; Chandler, Clare; Clarke, Siân E.

2015-01-01

Background Inappropriate treatment of malaria is widely reported particularly in areas where there is poor access to health facilities and self-treatment of fevers with anti-malarial drugs bought in shops is the most common form of care-seeking. The main objective of the study was to examine the impact of introducing rapid diagnostic tests for malaria (mRDTs) in registered drug shops in Uganda, with the aim to increase appropriate treatment of malaria with artemisinin-based combination therapy (ACT) in patients seeking treatment for fever in drug shops. Methods A cluster-randomized trial of introducing mRDTs in registered drug shops was implemented in 20 geographical clusters of drug shops in Mukono district, central Uganda. Ten clusters were randomly allocated to the intervention (diagnostic confirmation of malaria by mRDT followed by ACT) and ten clusters to the control arm (presumptive treatment of fevers with ACT). Treatment decisions by providers were validated by microscopy on a reference blood slide collected at the time of consultation. The primary outcome was the proportion of febrile patients receiving appropriate treatment with ACT defined as: malaria patients with microscopically-confirmed presence of parasites in a peripheral blood smear receiving ACT or rectal artesunate, and patients with no malaria parasites not given ACT. Findings A total of 15,517 eligible patients (8672 intervention and 6845 control) received treatment for fever between January-December 2011. The proportion of febrile patients who received appropriate ACT treatment was 72·9% versus 33·7% in the control arm; a difference of 36·1% (95% CI: 21·3 – 50·9), pshop vendors adhered to the mRDT results, reducing over-treatment of malaria by 72·6% (95% CI: 46·7– 98·4), pshop vendors using presumptive diagnosis (control arm). Conclusion Diagnostic testing with mRDTs compared to presumptive treatment of fevers implemented in registered drug shops substantially improved appropriate

Trials of Edmonston-Zagreb measles vaccine in Guinea-Bissau

DEFF Research Database (Denmark)

Jensen, T G; Whittle, H; Mordhorst, Camilla

1994-01-01

In two trials of measles vaccination in Guinea-Bissau, children were randomized to receive either the Edmonston-Zagreb (EZ) virus at age 4-8 months or, as a control group, a standard dose (5000 p.f.u.) of the Schwarz (SW) virus at 9-12 months. In the first trial a medium dose of EZ virus (40,000 p...

Randomized controlled trial on promoting influenza vaccination in general practice waiting rooms.

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Christophe Berkhout

Full Text Available Most of general practitioners (GPs use advertising in their waiting rooms for patient's education purposes. Patients vaccinated against seasonal influenza have been gradually lessening. The objective of this trial was to assess the effect of an advertising campaign for influenza vaccination using posters and pamphlets in GPs' waiting rooms.Registry based 2/1 cluster randomized controlled trial, a cluster gathering the enlisted patients of 75 GPs aged over 16 years. The trial, run during the 2014-2015 influenza vaccination campaign, compared patient's awareness from being in 50 GPs' standard waiting rooms (control group versus that of waiting in 25 rooms from GPs who had received and exposed pamphlets and one poster on influenza vaccine (intervention group, in addition to standard mandatory information. The main outcome was the number of vaccination units delivered in pharmacies. Data were extracted from the SIAM-ERASME claim database of the Health Insurance Fund of Lille-Douai (France. The association between the intervention (yes/no and the main outcome was assessed through a generalized estimating equation. Seventy-five GPs enrolled 10,597 patients over 65 years or suffering from long lasting diseases (intervention/control as of 3781/6816 patients from October 15, 2014 to February 28, 2015. No difference was found regarding the number of influenza vaccination units delivered (Relative Risk (RR = 1.01; 95% Confidence interval: 0.97 to 1.05; p = 0.561.Effects of the monothematic campaign promoting vaccination against influenza using a poster and pamphlets exposed in GPs' waiting rooms could not be demonstrated.

Malarone (atovaquone and proguanil hydrochloride): a review of its clinical development for treatment of malaria. Malarone Clinical Trials Study Group.

Science.gov (United States)

Looareesuwan, S; Chulay, J D; Canfield, C J; Hutchinson, D B

1999-04-01

The continuing spread of drug-resistant malaria emphasizes the need for new antimalarial drugs. Atovaquone is a broad-spectrum antiprotozoal drug with a novel mechanism of action, via inhibition of parasite mitochondrial electron transport, and a favorable safety profile. Early studies with atovaquone alone for treatment of malaria demonstrated good initial control of parasitemia but an unacceptable rate of recrudescent parasitemia. Parasites isolated during recrudescence after treatment with atovaquone alone were resistant to atovaquone in vitro. The combination of atovaquone and proguanil is synergistic in vitro, and clinical studies demonstrated enhanced efficacy of the combination compared to either drug alone for treatment of malaria. Malarone, a fixed-dose combination of 250 mg of atovaquone and 100 mg of proguanil hydrochloride, is available in many countries for treatment of acute, uncomplicated malaria caused by Plasmodium falciparum. At the recommended dose (in adults, four tablets once a day for three days), the overall cure rate was > 98% in more than 500 patients with falciparum malaria. In four randomized, controlled clinical trials, treatment with atovaquone and proguanil hydrochloride was significantly more effective than mefloquine (Thailand), amodiaquine (Gabon), chloroquine (Peru and the Philippines) or chloroquine plus pyrimethamine/sulfadoxine (Philippines). In clinical trials where the comparator drug was highly effective, treatment with atovaquone and proguanil hydrochloride was equally effective. Parasites isolated during recrudescence after treatment with the combination of atovaquone and proguanil were not resistant to atovaquone in vitro. The most commonly reported adverse events in clinical trials (abdominal pain, anorexia, nausea, vomiting, diarrhea and coughing) occurred with similar frequency in patients treated with a comparator drug. Malarone is a safe and effective new agent for treatment of malaria.

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....

Randomized trial of piperaquine with sulfadoxine-pyrimethamine or dihydroartemisinin for malaria intermittent preventive treatment in children.

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Badara Cisse

Full Text Available BACKGROUND: The long terminal half life of piperaquine makes it suitable for intermittent preventive treatment for malaria but no studies of its use for prevention have been done in Africa. We did a cluster randomized trial to determine whether piperaquine in combination with either dihydroartemisin (DHA or sulfadoxine-pyrimethamine (SP is as effective, and better tolerated, than SP plus amodiaquine (AQ, when used for intermittent preventive treatment in children delivered by community health workers in a rural area of Senegal. METHODS: Treatments were delivered to children 3-59 months of age in their homes once per month during the transmission season by community health workers. 33 health workers, each covering about 60 children, were randomized to deliver either SP+AQ, DHA+PQ or SP+PQ. Primary endpoints were the incidence of attacks of clinical malaria, and the incidence of adverse events. RESULTS: 1893 children were enrolled. Coverage of monthly rounds and compliance with daily doses was similar in all groups; 90% of children received at least 2 monthly doses. Piperaquine combinations were better tolerated than SP+AQ with a significantly lower risk of common, mild adverse events. 103 episodes of clinical malaria were recorded during the course of the trial. 68 children had malaria with parasitaemia >3000/microL, 29/671 (4.3% in the SP+AQ group, compared with 22/604 (3.6% in the DHA+PQ group (risk difference 0.47%, 95%CI -2.3%,+3.3%, and 17/618 (2.8% in the SP+PQ group (risk difference 1.2%, 95%CI -1.3%,+3.6%. Prevalences of parasitaemia and the proportion of children carrying Pfdhfr and Pfdhps mutations associated with resistance to SP were very low in all groups at the end of the transmission season. CONCLUSIONS: Seasonal IPT with SP+PQ in children is highly effective and well tolerated; the combination of two long-acting drugs is likely to impede the emergence of resistant parasites. TRIAL REGISTRATION: ClinicalTrials.gov NCT00529620.

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

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Simone C de Cassan

2015-07-01

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

Artemisinin derivatives for treating severe malaria.

Science.gov (United States)

McIntosh, H M; Olliaro, P

2000-01-01

Artemisinin derivatives may have advantages over quinoline drugs for treating severe malaria since they are fast acting and effective against quinine resistant malaria parasites. The objective of this review was to assess the effects of artemisinin drugs for severe and complicated falciparum malaria in adults and children. We searched the Cochrane Infectious Diseases Group trials register, Cochrane Controlled Trials Register, Medline, Embase, Science Citation Index, Lilacs, African Index Medicus, conference abstracts and reference lists of articles. We contacted organisations, researchers in the field and drug companies. Randomised and pseudo-randomised trials comparing artemisinin drugs (rectal, intramuscular or intravenous) with standard treatment, or comparisons between artemisinin derivatives in adults or children with severe or complicated falciparum malaria. Eligibility, trial quality assessment and data extraction were done independently by two reviewers. Study authors were contacted for additional information. Twenty three trials are included, allocation concealment was adequate in nine. Sixteen trials compared artemisinin drugs with quinine in 2653 patients. Artemisinin drugs were associated with better survival (mortality odds ratio 0.61, 95% confidence interval 0.46 to 0.82, random effects model). In trials where concealment of allocation was adequate (2261 patients), this was barely statistically significant (odds ratio 0.72, 95% CI 0.54 to 0.96, random effects model). In 1939 patients with cerebral malaria, mortality was also lower with artemisinin drugs overall (odds ratio 0.63, 95% CI 0.44 to 0.88, random effects model). The difference was not significant however when only trials reporting adequate concealment of allocation were analysed (odds ratio 0.78, 95% CI 0.55 to 1.10, random effects model) based on 1607 patients. No difference in neurological sequelae was shown. Compared with quinine, artemisinin drugs showed faster parasite clearance from

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

DEFF Research Database (Denmark)

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

2017-01-01

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

On modeling HIV and T cells in vivo: assessing causal estimators in vaccine trials.

Directory of Open Access Journals (Sweden)

W David Wick

2006-06-01

Full Text Available The first efficacy trials--named STEP--of a T cell vaccine against HIV/AIDS began in 2004. The unprecedented structure of these trials raised new modeling and statistical challenges. Is it plausible that memory T cells, as opposed to antibodies, can actually prevent infection? If they fail at prevention, to what extent can they ameliorate disease? And how do we estimate efficacy in a vaccine trial with two primary endpoints, one traditional, one entirely novel (viral load after infection, and where the latter may be influenced by selection bias due to the former? In preparation for the STEP trials, biostatisticians developed novel techniques for estimating a causal effect of a vaccine on viral load, while accounting for post-randomization selection bias. But these techniques have not been tested in biologically plausible scenarios. We introduce new stochastic models of T cell and HIV kinetics, making use of new estimates of the rate that cytotoxic T lymphocytes--CTLs; the so-called killer T cells--can kill HIV-infected cells. Based on these models, we make the surprising discovery that it is not entirely implausible that HIV-specific CTLs might prevent infection--as the designers explicitly acknowledged when they chose the endpoints of the STEP trials. By simulating thousands of trials, we demonstrate that the new statistical methods can correctly identify an efficacious vaccine, while protecting against a false conclusion that the vaccine exacerbates disease. In addition to uncovering a surprising immunological scenario, our results illustrate the utility of mechanistic modeling in biostatistics.

Comparative analysis of pentavalent rotavirus vaccine strains and G8 rotaviruses identified during vaccine trial in Africa.

Science.gov (United States)

Heylen, Elisabeth; Zeller, Mark; Ciarlet, Max; Lawrence, Jody; Steele, Duncan; Van Ranst, Marc; Matthijnssens, Jelle

2015-10-06

RotaTeqTM is a pentavalent rotavirus vaccine based on a bovine rotavirus genetic backbone in vitro reassorted with human outer capsid genes. During clinical trials of RotaTeqTM in Sub-Saharan Africa, the vaccine efficacy over a 2-year follow-up was lower against the genotypes contained in the vaccine than against the heterotypic G8P[6] and G8P[1] rotavirus strains of which the former is highly prevalent in Africa. Complete genome analyses of 43 complete rotavirus genomes collected during phase III clinical trials of RotaTeqTM in Sub-Saharan Africa, were conducted to gain insight into the high level of cross-protection afforded by RotaTeqTM against these G8 strains. Phylogenetic analysis revealed the presence of a high number of bovine rotavirus gene segments in these human G8 strains. In addition, we performed an in depth analysis on the individual amino acid level which showed that G8 rotaviruses were more similar to the RotaTeqTM vaccine than non-G8 strains. Because RotaTeqTM possesses a bovine genetic backbone, the high vaccine efficacy against G8 strains might be partially explained by the fact that all these strains contain a complete or partial bovine-like backbone. Altogether, this study supports the hypothesis that gene segments other than VP7 and VP4 play a role in vaccine-induced immunity.

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.

Harnessing naturally occurring tumor immunity: a clinical vaccine trial in prostate cancer.

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Mayu O Frank

2010-09-01

Full Text Available Studies of patients with paraneoplastic neurologic disorders (PND have revealed that apoptotic tumor serves as a potential potent trigger for the initiation of naturally occurring tumor immunity. The purpose of this study was to assess the feasibility, safety, and immunogenicity of an apoptotic tumor-autologous dendritic cell (DC vaccine.We have modeled PND tumor immunity in a clinical trial in which apoptotic allogeneic prostate tumor cells were used to generate an apoptotic tumor-autologous dendritic cell vaccine. Twenty-four prostate cancer patients were immunized in a Phase I, randomized, single-blind, placebo-controlled study to assess the safety and immunogenicity of this vaccine. Vaccinations were safe and well tolerated. Importantly, we also found that the vaccine was immunogenic, inducing delayed type hypersensitivity (DTH responses and CD4+ and CD8+ T cell proliferation, with no effect on FoxP3+ regulatory T cells. A statistically significant increase in T cell proliferation responses to prostate tumor cells in vitro (p = 0.002, decrease in prostate specific antigen (PSA slope (p = 0.016, and a two-fold increase in PSA doubling time (p = 0.003 were identified when we compared data before and after vaccination.An apoptotic cancer cell vaccine modeled on naturally occurring tumor immune responses in PND patients provides a safe and immunogenic tumor vaccine.ClinicalTrials.gov NCT00289341.

Community-randomized trial of lambdacyhalothrin-treated hammock nets for malaria control in Yanomami communities in the Amazon region of Venezuela.

Science.gov (United States)

Magris, M; Rubio-Palis, Y; Alexander, N; Ruiz, B; Galván, N; Frias, D; Blanco, M; Lines, J

2007-03-01

We conducted a community-randomized controlled trial in an area of moderate malaria transmission in the Amazon region, southern Venezuela, home of the Yanomami indigenous ethnic group. The aim was to compare the malaria incidence rate in villages with lambdacyhalothrin-treated hammock nets (ITHN) or with placebo-treated hammock nets (PTHN). In both arms of the study, intensive surveillance for early case detection was maintained and prompt malaria treatment was administered. Baseline data were collected before the intervention and a population of around 924 Yanomami was followed for 2 years. Despite the recent introduction of nets in the Yanomami villages and the adverse natural conditions in the area, the nets were accepted enthusiastically by the study population, used conscientiously and looked after carefully. The malaria incidence rate per thousand person-years at risk was 114.6 in the IHTN group and 186.8 in the PTHN group. The adjusted rate ratios indicated that ITHN prevent 56% [IRR: 0.44, 95% confidence interval (CI): 52-59%] of new malaria cases. ITHN reduced the prevalence of parasitaemia by 83% [relative risks (RR): 0.17, 95% CI: 47-100%], according to a cross-sectional survey carried out during the high transmission season. The prevalence of splenomegaly and anaemia was too low to detect any possible reduction as a result of ITHN. The main conclusion of the present study is that ITHN can reduce malaria incidence in the area and it is the most feasible method for malaria control in a forested area where indigenous villages are scattered over a large territory. This is the first community-level epidemiological trial to show that ITHN are highly effective against malaria transmitted by Anopheles darlingi.

Dengue vaccination during pregnancy - An overview of clinical trials data.

Science.gov (United States)

Skipetrova, Anna; Wartel, Tram Anh; Gailhardou, Sophia

2018-04-28

The live, attenuated, tetravalent dengue vaccine (CYD-TDV) is licensed in several endemic countries and contraindicated during pregnancy. Inadvertent vaccination during pregnancy may occur during clinical trials that include women of childbearing age. The potential risk associated with dengue vaccination in pregnancy remains unknown. We describe pregnancy outcomes following inadvertent dengue vaccination in pregnancy from CYD-TDV trial data. Data were collected from trials conducted as part of the CYD-TDV clinical development. Women who received CYD-TDV or placebo during the pre-specified pregnancy risk window (from 30 days before the date of their last menstrual period to end of pregnancy) were considered as exposed; pregnancies occurring in non-risk periods during the trials were considered to be non-exposed. Pregnancy losses were defined as abortion (spontaneous or unspecified), death in utero, and stillbirth. 615 pregnancies were reported from 19 CYD-TDV trials: 404 in the CYD-TDV arm, and 211 in the placebo arm. Exposure could not be determined for 7 pregnancies (5, CYD-TDV; 2, placebo). In the CYD-TDV arm, 58 pregnancies were considered as exposed. Most of these (n = 47, 81%) had healthy live births; 6 (10.3%) had pregnancy losses; 3 underwent elective termination and 2 had unknown outcome. In the placebo group, 30 pregnancies were considered exposed. Most of these (n = 25, 83%) had healthy births; 4 (13.3%) had pregnancy losses; and 1 had elective termination. Among non-exposed pregnancies, most resulted in healthy live births; 23/341 (6.7%) in the CYD-TDV group and 17/179 (9.5%) in the placebo group had pregnancy losses. Most reported pregnancy losses were in women considered high-risk for adverse pregnancy outcome, primarily due to young age. In the small dataset assessed, no evidence of increased adverse pregnancy outcomes has been identified from inadvertent immunization of women in early pregnancy with CYD-TDV compared with the control group

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...

Long-Lasting Insecticidal Hammocks for controlling forest malaria: a community-based trial in a rural area of central Vietnam.

Directory of Open Access Journals (Sweden)

Ngo Duc Thang

2009-10-01

Full Text Available In Vietnam, malaria remains a problem in some remote areas located along its international borders and in the central highlands, partly due to the bionomics of the local vector, mainly found in forested areas and less vulnerable to standard control measures. Long Lasting Insecticidal Hammocks (LLIH, a tailored and user-friendly tool for forest workers, may further contribute in reducing the malaria burden. Their effectiveness was tested in a large community-based intervention trial carried out in Ninh Thuan province in Central Vietnam.Thirty villages (population 18,646 were assembled in 20 clusters (1,000 individuals per cluster that were randomly allocated to either the intervention or control group (no LLIH after stratification according to the pre-intervention P. falciparum antibody prevalence ( or =30%. LLIH were distributed to the intervention group in December 2004. For the following 2 years, the incidence of clinical malaria and the prevalence of infection were determined by passive case detection at community level and by bi-annual malariometric surveys. A 2-fold larger effect on malaria incidence in the intervention as compared to the control group was observed. Similarly, malaria prevalence decreased more substantially in the intervention (1.6-fold greater reduction than in the control group. Both for incidence and prevalence, a stronger and earlier effect of the intervention was observed in the high endemicity stratum. The number of malaria cases and infections averted by the intervention overall was estimated at 10.5 per 1,000 persons and 5.6/100 individuals, respectively, for the last half of 2006. In the high endemicity stratum, the impact was much higher, i.e. 29/1000 malaria cases and 15.7 infections/100 individuals averted.LLIH reduced malaria incidence and prevalence in this remote and forested area of Central Vietnam. As the targets of the newly-launched Global Malaria Action Plan include the 75% reduction of the global

Exploring barriers and facilitators to participation of male-to-female transgender persons in preventive HIV vaccine clinical trials.

Science.gov (United States)

Andrasik, Michele Peake; Yoon, Ro; Mooney, Jessica; Broder, Gail; Bolton, Marcus; Votto, Teress; Davis-Vogel, Annet

2014-06-01

Observed seroincidence and prevalence rates in male-to-female (MTF) transgender individuals highlight the need for effective targeted HIV prevention strategies for this community. In order to develop an effective vaccine that can be used by transgender women, researchers must understand and address existing structural issues that present barriers to this group's participation in HIV vaccine clinical trials. Overcoming barriers to participation is important for ensuring HIV vaccine acceptability and efficacy for the MTF transgender community. To explore barriers and facilitators to MTF transgender participation in preventive HIV vaccine clinical trials, the HIV Vaccine Trials Network conducted focus groups among transgender women in four urban areas (Atlanta, Boston, Philadelphia, and San Francisco). Barriers and facilitators to engagement of transgender women in preventive HIV vaccine clinical trials led to the following recommendations: (a) transgender cultural competency training, (b) creating trans-friendly environments, (c) true partnerships with local trans-friendly organizations and health care providers, (d) protocols that focus on transgender specific issues, and (e) data collection and tracking of transgender individuals. These results have implications for the conduct of HIV vaccine trials, as well as engagement of transgender women in research programs in general.

Consensus Statement on Diagnostic End Points for Infant Tuberculosis Vaccine Trials

NARCIS (Netherlands)

Hatherill, Mark; Verver, Suzanne; Mahomed, Hassan; Barker, Lew; Behr, Marcel; Cardenas, Vicky; Eisele, Bernd; Douoguih, Macaya; Evans, Thomas G.; Eskola, Juhani; Fourie, Bernard; Grewal, Harleen; Grode, Leander; Hawkridge, Tony; Hesseling, Anneke; Hussey, Gregory; Kiringa, Grace; Landry, Bernard; Lockhart, Stephen; Marais, Ben; Måseide, Kårstein; Mayanja, Harriet; McClain, Bruce; McShane, Helen; Moyo, Sizulu; Ofori, Opokua; Parida, Shreemanta K.; Ryall, Robert P.; Sacarlal, Jahit; Sadoff, Jerry; Shea, Jacqui; Tameris, Michele; van Rie, Annelies; von Reyn, C. Fordham; Wajja, Anne; Walker, Bob; Walzl, Gerhard; Wilkinson, Robert J.

2012-01-01

Background. Definition of clinical trial end points for childhood tuberculosis is hindered by lack of a standard case definition. We aimed to identify areas of consensus or debate on potential end points for tuberculosis vaccine trials among human immunodeficiency virus-uninfected children. Methods.

Motivations and concerns about adolescent tuberculosis vaccine trial participation in rural Uganda: a qualitative study.

Science.gov (United States)

Buregyeya, Esther; Kulane, Asli; Kiguli, Juliet; Musoke, Phillipa; Mayanja, Harriet; Mitchell, Ellen Maeve Hanlon

2015-01-01

Research is being carried out to develop and test new potentially more effective tuberculosis vaccines. Among the vaccines being developed are those that target adolescents. This study explored the stakeholders' perceptions about adolescent participation in a hypothetical tuberculosis vaccine trial in Ugandan adolescents. Focus group discussions with adolescents, parents of infants and adolescents, and key informant interviews with community leaders and traditional healers were conducted. The majority of the respondents expressed potential willingness to allow their children participate in a tuberculosis vaccine trial. Main motivations for potential participation would be being able to learn about health-related issues. Hesitations included the notion that trial participation would distract the youths from their studies, fear of possible side effects of an investigational product, and potential for being sexually exploited by researchers. In addition, bad experiences from participation in previous research and doubts about the importance of research were mentioned. Suggested ways to motivate participation included: improved clarity on study purpose, risks, benefits and better scheduling of study procedures to minimize disruption to participants' academic schedules. Findings from this study suggest that the community is open to potential participation of adolescents in a tuberculosis vaccine trial. However, there is a need to communicate more effectively with the community about the purpose of the trial and its effects, including safety data, in a low-literacy, readily understood format. This raises a challenge to researchers, who cannot know all the potential effects of a trial product before it is tested.

Mosquito larval source management for controlling malaria

Science.gov (United States)

Tusting, Lucy S; Thwing, Julie; Sinclair, David; Fillinger, Ulrike; Gimnig, John; Bonner, Kimberly E; Bottomley, Christian; Lindsay, Steven W

2015-01-01

Background Malaria is an important cause of illness and death in people living in many parts of the world, especially sub-Saharan Africa. Long-lasting insecticide treated bed nets (LLINs) and indoor residual spraying (IRS) reduce malaria transmission by targeting the adult mosquito vector and are key components of malaria control programmes. However, mosquito numbers may also be reduced by larval source management (LSM), which targets mosquito larvae as they mature in aquatic habitats. This is conducted by permanently or temporarily reducing the availability of larval habitats (habitat modification and habitat manipulation), or by adding substances to standing water that either kill or inhibit the development of larvae (larviciding). Objectives To evaluate the effectiveness of mosquito LSM for preventing malaria. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; EMBASE; CABS Abstracts; and LILACS up to 24 October 2012. We handsearched the Tropical Diseases Bulletin from 1900 to 2010, the archives of the World Health Organization (up to 11 February 2011), and the literature database of the Armed Forces Pest Management Board (up to 2 March 2011). We also contacted colleagues in the field for relevant articles. Selection criteria We included cluster randomized controlled trials (cluster-RCTs), controlled before-and-after trials with at least one year of baseline data, and randomized cross-over trials that compared LSM with no LSM for malaria control. We excluded trials that evaluated biological control of anopheline mosquitoes with larvivorous fish. Data collection and analysis At least two authors assessed each trial for eligibility. We extracted data and at least two authors independently determined the risk of bias in the included studies. We resolved all disagreements through discussion with a third author. We analyzed the data using Review Manager 5 software

Influence of malaria on the serum levels of vitamin A, zinc and ...

African Journals Online (AJOL)

GREGO

2007-04-02

Apr 2, 2007 ... to usual anti-malaria drugs and insecticides (Müller and. Garenne, 1999). ... METHOD. Collection and preparation of sera ... consultation (for malaria) or vaccination (control) in the catholic medical .... are presented in Table 1.

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

Directory of Open Access Journals (Sweden)

Susanne Helena Hodgson

2014-12-01

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

77 FR 49409 - Oral Rabies Vaccine Trial; Availability of an Environmental Assessment and Finding of No...

Science.gov (United States)

2012-08-16

...] Oral Rabies Vaccine Trial; Availability of an Environmental Assessment and Finding of No Significant... assessment and finding of no significant impact relative to an oral rabies vaccination field trial in New... be prepared. FOR FURTHER INFORMATION CONTACT: Mr. Richard Chipman, Rabies Program Coordinator...

Beyond the checklist: assessing understanding for HIV vaccine trial participation in South Africa.

Science.gov (United States)

Lindegger, Graham; Milford, Cecilia; Slack, Catherine; Quayle, Michael; Xaba, Xolani; Vardas, Eftyhia

2006-12-15

Informed consent and understanding are essential ethical requirements for clinical trial participation. Traditional binary measures of understanding may be limited and not be the best measures of level of understanding. This study designed and compared 4 measures of understanding for potential participants being prepared for enrollment in South African HIV vaccine trials, using detailed operational scoring criteria. Assessment of understanding of 7 key trial components was compared via self-report, checklist, vignettes, and narrative measures. Fifty-nine participants, including members of vaccine preparedness groups and 1 HIV vaccine trial, took part. There were significant differences across the measures for understanding of 5 components and for overall understanding. Highest scores were obtained on self-report and checklist measures, and lowest scores were obtained for vignettes and narrative descriptions. The findings suggest that levels of measured understanding are dependent on the tools used. Forced-choice measures like checklists tend to yield higher scores than open-ended measures like narratives or vignettes. Consideration should be given to complementing checklists and self-reports with open-ended measures, particularly for critical trial concepts, where the consequences of misunderstanding are potentially severe.

Contraceptive use in women enrolled into preventive HIV vaccine trials: experience from a phase I/II trial in East Africa.

Directory of Open Access Journals (Sweden)

Hannah Kibuuka

Full Text Available HIV vaccine trials generally require that pregnant women are excluded from participation, and contraceptive methods must be used to prevent pregnancy during the trial. However, access to quality services and misconceptions associated with contraceptive methods may impact on their effective use in developing countries. We describe the pattern of contraceptive use in a multi-site phase I/IIa HIV Vaccine trial in East Africa (Uganda, Kenya and Tanzania and factors that may have influenced their use during the trial.Pregnancy prevention counseling was provided to female participants during informed consent process and at each study visit. Participants' methods of contraception used were documented. Methods of contraceptives were provided on site. Pregnancy testing was done at designated visits during the trial. Obstacles to contraceptive use were identified and addressed at each visit.Overall, 103 (31.8% of a total of 324 enrolled volunteers were females. Female participants were generally young with a mean age of 29(+/-7.2, married (49.5% and had less than high school education (62.1%. Hormonal contraceptives were the most common method of contraception (58.3% followed by condom use (22.3%. The distribution of methods of contraception among the three sites was similar except for more condom use and less abstinence in Uganda. The majority of women (85.4% reported to contraceptive use prior to screening. The reasons for not using contraception included access to quality services, insufficient knowledge of certain methods, and misconceptions.Although hormonal contraceptives were frequently used by females participating in the vaccine trial, misconceptions and their incorrect use might have led to inconsistent use resulting in undesired pregnancies. The study underscores the need for an integrated approach to pregnancy prevention counseling during HIV vaccine trials.ClinicalTrials.gov NCT00123968.

Multiple-level stakeholder engagement in malaria clinical trials: addressing the challenges of conducting clinical research in resource-limited settings.

Science.gov (United States)

Mtove, George; Kimani, Joshua; Kisinza, William; Makenga, Geofrey; Mangesho, Peter; Duparc, Stephan; Nakalembe, Miriam; Phiri, Kamija S; Orrico, Russell; Rojo, Ricardo; Vandenbroucke, Pol

2018-03-22

Multinational clinical trials are logistically complex and require close coordination between various stakeholders. They must comply with global clinical standards and are accountable to multiple regulatory and ethical bodies. In resource-limited settings, it is challenging to understand how to apply global clinical standards to international, national, and local factors in clinical trials, making multiple-level stakeholder engagement an important element in the successful conduct of these clinical trials. During the planning and implementation of a large multinational clinical trial for intermittent preventive treatment of malaria in pregnancy in resource-limited areas of sub-Saharan Africa, we encountered numerous challenges, which required implementation of a range of engagement measures to ensure compliance with global clinical and regulatory standards. These challenges included coordination with ongoing global malaria efforts, heterogeneity in national regulatory structures, sub-optimal healthcare infrastructure, local practices and beliefs, and perspectives that view healthcare providers with undue trust or suspicion. In addition to engagement with international bodies, such as the World Health Organization, the Malaria in Pregnancy Consortium, the Steve Biko Centre for Bioethics, and the London School of Hygiene and Tropical Medicine, in order to address the challenges just described, Pfizer Inc. and Medicines for Malaria Venture (the "Sponsoring Entities" for these studies) and investigators liaised with national- and district-level stakeholders such as health ministers and regional/local community health workers. Community engagement measures undertaken by investigators included local meetings with community leaders to explain the research aims and answer questions and concerns voiced by the community. The investigators also engaged with family members of prospective trial participants in order to be sensitive to local practices and beliefs. Engagement

Clinical Development of a Cytomegalovirus DNA Vaccine: From Product Concept to Pivotal Phase 3 Trial.

Science.gov (United States)

Smith, Larry R; Wloch, Mary K; Chaplin, Jennifer A; Gerber, Michele; Rolland, Alain P

2013-09-25

2013 marks a milestone year for plasmid DNA vaccine development as a first-in-class cytomegalovirus (CMV) DNA vaccine enters pivotal phase 3 testing. This vaccine consists of two plasmids expressing CMV antigens glycoprotein B (gB) and phosphoprotein 65 (pp65) formulated with a CRL1005 poloxamer and benzalkonium chloride (BAK) delivery system designed to enhance plasmid expression. The vaccine's planned initial indication under investigation is for prevention of CMV reactivation in CMV-seropositive (CMV⁺) recipients of an allogeneic hematopoietic stem cell transplant (HCT). A randomized, double-blind placebo-controlled phase 2 proof-of-concept study provided initial evidence of the safety of this product in CMV⁺ HCT recipients who underwent immune ablation conditioning regimens. This study revealed a significant reduction in viral load endpoints and increased frequencies of pp65-specific interferon-γ-producing T cells in vaccine recipients compared to placebo recipients. The results of this endpoint-defining trial provided the basis for defining the primary and secondary endpoints of a global phase 3 trial in HCT recipients. A case study is presented here describing the development history of this vaccine from product concept to initiation of the phase 3 trial.

76 FR 56731 - Oral Rabies Vaccine Trial; Availability of an Environmental Assessment and Finding of No...

Science.gov (United States)

2011-09-14

...] Oral Rabies Vaccine Trial; Availability of an Environmental Assessment and Finding of No Significant... the Animal and Plant Health Inspection Service relative to an oral rabies vaccination field trial in... INFORMATION CONTACT: Dr. Dennis Slate, Rabies Program Coordinator, Wildlife Services, APHIS, 59 Chennell Drive...

Operational trial of ParaSight-F (dipstick) in the diagnosis of falciparum malaria at the primary health care level.

Science.gov (United States)

Banchongaksorn, T; Prajakwong, S; Rooney, W; Vickers, P

1997-06-01

The rapid manual ParaSight-F test of Plasmodium falciparum malaria, an antigen capture test for detecting trophozoite-derived histidine rich protein-2 (PF HRP-2), is simple to perform and provides a definite diagnosis within 10 minutes. During an operational trial at health centers and mobile malaria units where microscopical diagnosis is not available and using defined symptom screening criteria, 3,361 subjects were tested yielding 618 positives (18.4%) for PF-HRP-2 by ParaSight-F. Microscopic examination of the same subjects by thick blood film examined 7 days later at a malaria clinic showed 578 falciparum, and 349 vivax and mixed infection (F+V) 41. The technology proved highly effective in detecting falciparum malaria at the peripheral levels where access to malaria laboratory services are difficult, thus allowing immediate administration of a complete course of treatment in the absence of a microscopic examination.

Long-term survival in trial of medium-titre Edmonston-Zagreb measles vaccine in Guinea-Bissau

DEFF Research Database (Denmark)

Aaby, Peter; Lisse, Ida; Whittle, H

1994-01-01

A trial of protective efficacy which compared medium-titre Edmonston-Zagreb (EZ) measles vaccine (10(4.6) p.f.u.) from the age of 4 months with the standard Schwarz (SW) measles vaccine given from the age of 9 months was started in an urban community in Guinea-Bissau in 1985. Because trials of high...

Cognition, behaviour and academic skills after cognitive rehabilitation in Ugandan children surviving severe malaria: a randomised trial

Directory of Open Access Journals (Sweden)

John Chandy C

2011-08-01

Full Text Available Abstract Background Infection with severe malaria in African children is associated with not only a high mortality but also a high risk of cognitive deficits. There is evidence that interventions done a few years after the illness are effective but nothing is known about those done immediately after the illness. We designed a study in which children who had suffered from severe malaria three months earlier were enrolled into a cognitive intervention program and assessed for the immediate benefit in cognitive, academic and behavioral outcomes. Methods This parallel group randomised study was carried out in Kampala City, Uganda between February 2008 and October 2010. Sixty-one Ugandan children aged 5 to 12 years with severe malaria were assessed for cognition (using the Kaufman Assessment Battery for Children, second edition and the Test of Variables of Attention, academic skills (Wide Range Achievement Test, third edition and psychopathologic behaviour (Child Behaviour Checklist three months after an episode of severe malaria. Twenty-eight were randomised to sixteen sessions of computerised cognitive rehabilitation training lasting eight weeks and 33 to a non-treatment group. Post-intervention assessments were done a month after conclusion of the intervention. Analysis of covariance was used to detect any differences between the two groups after post-intervention assessment, adjusting for age, sex, weight for age z score, quality of the home environment, time between admission and post-intervention testing and pre-intervention score. The primary outcome was improvement in attention scores for the intervention group. This trial is registered with Current Controlled Trials, number ISRCTN53183087. Results Significant intervention effects were observed in the intervention group for learning mean score (SE, [93.89 (4.00 vs 106.38 (4.32, P = 0.04] but for working memory the intervention group performed poorly [27.42 (0.66 vs 25.34 (0.73, P = 0.04]. No

Socio-behaviour challenges to phase III HIV vaccine trials in Sub ...

African Journals Online (AJOL)

Abstract. Background: A number of countries in sub-Saharan Africa are preparing for HIV vaccine efficacy trials. Social and behavioural factors related to HIV transmission require examination in each setting where these trials are considered. As part of this, several countries have also recently begun preparatory research ...

A brief review on features of falciparum malaria during pregnancy

Directory of Open Access Journals (Sweden)

Alexandre Manirakiza

2017-12-01

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

A study protocol for a randomised open-label clinical trial of artesunate-mefloquine versus chloroquine in patients with non-severe Plasmodium knowlesi malaria in Sabah, Malaysia (ACT KNOW trial).

Science.gov (United States)

Grigg, M J; William, T; Dhanaraj, P; Menon, J; Barber, B E; von Seidlein, L; Rajahram, G; Price, R N; Anstey, N M; Yeo, T W

2014-08-19

Malaria due to Plasmodium knowlesi is reported throughout South-East Asia, and is the commonest cause of it in Malaysia. P. knowlesi replicates every 24 h and can cause severe disease and death. Current 2010 WHO Malaria Treatment Guidelines have no recommendations for the optimal treatment of non-severe knowlesi malaria. Artemisinin-combination therapies (ACT) and chloroquine have each been successfully used to treat knowlesi malaria; however, the rapidity of parasite clearance has not been prospectively compared. Malaysia's national policy for malaria pre-elimination involves mandatory hospital admission for confirmed malaria cases with discharge only after two negative blood films; use of a more rapidly acting antimalarial agent would have health cost benefits. P. knowlesi is commonly microscopically misreported as P. malariae, P. falciparum or P. vivax, with a high proportion of the latter two species being chloroquine-resistant in Malaysia. A unified ACT-treatment protocol would provide effective blood stage malaria treatment for all Plasmodium species. ACT KNOW, the first randomised controlled trial ever performed in knowlesi malaria, is a two-arm open-label trial with enrolments over a 2-year period at three district sites in Sabah, powered to show a difference in proportion of patients negative for malaria by microscopy at 24 h between treatment arms (clinicaltrials.gov #NCT01708876). Enrolments started in December 2012, with completion expected by September 2014. A total sample size of 228 is required to give 90% power (α 0.05) to determine the primary end point using intention-to-treat analysis. Secondary end points include parasite clearance time, rates of recurrent infection/treatment failure to day 42, gametocyte carriage throughout follow-up and rates of anaemia at day 28, as determined by survival analysis. This study has been approved by relevant institutional ethics committees in Malaysia and Australia. Results will be disseminated to inform

Leidos Biomed Supports Clinical Trials for Vaccine Against Mosquito-borne Chikungunya | FNLCR Staging

Science.gov (United States)

An experimental vaccine for mosquito-borne chikungunya is being tested at sites in the Caribbean as part of a phase II clinical trial being managed by the Frederick National Lab. No vaccine or treatment currently exists for the viral disease, which c

N-Acetylcysteine as adjunctive treatment in severe malaria: A randomized double blinded placebo controlled clinical trial

Science.gov (United States)

Charunwatthana, Prakaykaew; Faiz, M. Abul; Ruangveerayut, Ronnatrai; Maude, Richard; Rahman, M. Ridwanur; Roberts, L. Jackson; Moore, Kevin; Yunus, Emran Bin; Hoque, M. Gofranul; Hasan, Mahatab Uddin; Lee, Sue J.; Pukrittayakamee, Sasithon; Newton, Paul N.; White, Nicholas J.; Day, Nicholas P.J.; Dondorp, Arjen M.

2009-01-01

Objective Markers of oxidative stress are reported to be increased in severe malaria. It has been suggested that the antioxidant N-acetylcysteine (NAC) may be beneficial in treatment. We studied the efficacy and safety of parenteral N-acetylcysteine as an adjunct to artesunate treatment of severe falciparum malaria. Design A randomized double-blind placebo controlled trial on the use of high dose intravenous NAC as adjunctive treatment to artesunate. Setting A provincial hospital in Western Thailand and a tertiary referral hospital in Chittagong, Bangladesh. Patients One hundred and eight adult patients with severe falciparum malaria. Interventions Patients were randomized to receive N-acetylcysteine or placebo as adjunctive treatment to intravenous artesunate. Measurements and main results A total of 56 patients were treated with NAC and 52 received placebo. NAC had no significant effect on mortality, lactate clearance times (p=0.74) or coma recovery times (p=0.46). Parasite clearance time was increased from 30h (range 6h to 144h) to 36h (range 6h to 120h) (p=0.03), but this could be explained by differences in admission parasitemia. Urinary F2-isoprostane metabolites, measured as a marker of oxidative stress, were increased in severe malaria compared to patients with uncomplicated malaria and healthy volunteers. Admission red cell rigidity correlated with mortality, but did not improve with NAC. Conclusion Systemic oxidative stress is increased in severe malaria. Treatment with N-acetylcysteine had no effect on outcome in patients with severe falciparum malaria in this setting. PMID:19114891

Antipyretic effect of ibuprofen in Gabonese children with uncomplicated falciparum malaria: a randomized, double-blind, placebo-controlled trial

Directory of Open Access Journals (Sweden)

Necek Magdalena

2008-05-01

Full Text Available Abstract Background Antipyretic drugs are widely used in children with fever, though there is a controversy about the benefit of reducing fever in children with malaria. In order to assess the effect of ibuprofen on fever compared to placebo in children with uncomplicated Plasmodium falciparum malaria in Gabon, a randomized double blind placebo controlled trial, was designed. Methods Fifty children between two and seven years of age with uncomplicated malaria were included in the study. For the treatment of fever, all patients "received" mechanical treatment when the temperature rose above 37.5°C. In addition to the mechanical treatment, continuous fanning and cooling blanket, patients were assigned randomly to receive ibuprofen (7 mg/kg body weight, every eight hours or placebo. Results The fever clearance time using a fever threshold of 37.5°C was similar in children receiving ibuprofen compared to those receiving placebo. The difference was also not statistically significant using a fever threshold of 37.8°C or 38.0°C. However, the fever time and the area under the fever curve were significantly smaller in the ibuprofen group compared to the placebo group. Conclusion Ibuprofen is effective in reducing the time with fever. The effect on fever clearance is less obvious and depends on definition of the fever threshold. Trial registration The trial registration number is: NCT00167713

Influenza Vaccination in Patients With Chronic Heart Failure: The PARADIGM-HF Trial.

Science.gov (United States)

Vardeny, Orly; Claggett, Brian; Udell, Jacob A; Packer, Milton; Zile, Michael; Rouleau, Jean; Swedberg, Karl; Desai, Akshay S; Lefkowitz, Martin; Shi, Victor; McMurray, John J V; Solomon, Scott D

2016-02-01

This study sought to examine the prevalence and predictors of influenza vaccination among participants in the PARADIGM-HF (Prospective Comparison of ARNI with ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure) study and investigate associations between receiving influenza vaccine and cardiovascular death or heart failure hospitalizations, all-cause hospitalizations, and cardiopulmonary or influenza-related hospitalizations. Influenza is associated with an increased risk for cardiovascular events in patients with heart failure. We used data from the PARADIGM-HF trial in which patients with heart failure were randomized to the angiotensin receptor neprilysin inhibitor LCZ696 (sacubitril/valsartan) or enalapril. We assessed predictors of receiving influenza vaccination, and examined the relationship between influenza vaccination and outcomes in a propensity-adjusted model. Of 8,099 study participants, 1,769 (21%) received influenza vaccination. We observed significant regional variation in vaccination rates, with highest rates in the Netherlands (77.5%), Great Britain (77.2%), and Belgium (67.5%), and lowest rates in Asia (2.6%), with intermediate rates in North America (52.8%). Top predictors of vaccination included enrolling country, white race, implanted defibrillator, older age, lower New York Heart Association functional class, lower heart rate, and a history of diabetes mellitus. Influenza vaccination was associated with a reduced risk for all-cause mortality in propensity-adjusted (hazard ratio: 0.81; 95% confidence interval: 0.67 to 0.97; p = 0.015) models. Influenza vaccination rates varied widely in patients with heart failure with reduced ejection fraction enrolled in the PARADIGM-HF trial, and vaccination was associated with reduced risk for death, although whether this association was causal cannot be determined. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Text messaging reminders for influenza vaccine in primary care: protocol for a cluster randomised controlled trial (TXT4FLUJAB).

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Herrett, Emily; van Staa, Tjeerd; Free, Caroline; Smeeth, Liam

2014-05-02

The UK government recommends that at least 75% of people aged under 64 with certain conditions receive an annual influenza vaccination. Primary care practices often fall short of this target and strategies to increase vaccine uptake are required. Text messaging reminders are already used in 30% of practices to remind patients about vaccination, but there has been no trial addressing their effectiveness in increasing influenza vaccine uptake in the UK. The aims of the study are (1) to develop the methodology for conducting cluster randomised trials of text messaging interventions utilising routine electronic health records and (2) to assess the effectiveness of using a text messaging influenza vaccine reminder in achieving an increase in influenza vaccine uptake in patients aged 18-64 with chronic conditions, compared with standard care. This cluster randomised trial will recruit general practices across three settings in English primary care (Clinical Practice Research Datalink, ResearchOne and London iPLATO text messaging software users) and randomise them to either standard care or a text messaging campaign to eligible patients. Flu vaccine uptake will be ascertained using routinely collected, anonymised electronic patient records. This protocol outlines the proposed study design and analysis methods. This study will determine the effectiveness of text messaging vaccine reminders in primary care in increasing influenza vaccine uptake, and will strengthen the methodology for using electronic health records in cluster randomised trials of text messaging interventions. This trial was approved by the Surrey Borders Ethics Committee (13/LO/0872). The trial results will be disseminated at national conferences and published in a peer-reviewed medical journal. The results will also be distributed to the Primary Care Research Network and to all participating general practices. This study is registered at controlled-trials.com ISRCTN48840025, July 2013.

Rectal dihydroartemisinin versus intravenous quinine in the treatment of severe malaria: a randomised clinical trial.

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Esamai, F; Ayuo, P; Owino-Ongor, W; Rotich, J; Ngindu, A; Obala, A; Ogaro, F; Quoqiao, L; Xingbo, G; Guangqian, L

2000-05-01

To compare the clinical efficacy and safety of rectal dihydroartemisinin (DATM--Cotecxin) and intravenous quinine in the treatment of severe malaria in children and adults. Moi Teaching and Referral Hospital, Eldoret, Kenya between July and November 1998. A total of sixty seven patients aged two to sixty years with severe malaria were studied. This was an open randomised comparative clinical trial. These were parasite clearance time, fever clearance time, efficacy and the side effect profile of the two drugs. The two groups were comparable on admission on the clinical and laboratory parameters. The parasite clearance time was shorter in the rectal DATM group than quinine group. There was no statistical difference on the fever clearance time and cure rates in the two groups. The adverse reaction profile was better with rectal DATM than with quinine, tinnitus observed more in the quinine group. Rectal DATM is faster in parasite clearance than quinine and is a safe and convenient alternative to quinine in the treatment of severe malaria.

Predicting hypothetical willingness to participate (WTP) in a future phase III HIV vaccine trial among high-risk adolescents.

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Giocos, Georgina; Kagee, Ashraf; Swartz, Leslie

2008-11-01

The present study sought to determine whether the Theory of Planned Behaviour predicted stated hypothetical willingness to participate (WTP) in future Phase III HIV vaccine trials among South African adolescents. Hierarchical logistic regression analyses showed that The Theory of Planned Behaviour (TPB) significantly predicted WTP. Of all the predictors, Subjective norms significantly predicted WTP (OR = 1.19, 95% C.I. = 1.06-1.34). A stepwise logistic regression analysis revealed that Subjective Norms (OR = 1.19, 95% C.I. = 1.07-1.34) and Attitude towards participation in an HIV vaccine trial (OR = 1.32, 95% C.I. = 1.00-1.74) were significant predictors of WTP. The addition of Knowledge of HIV vaccines and HIV vaccine trials, Perceived self-risk of HIV infection, Health-promoting behaviours and Attitudes towards HIV/AIDS yielded non-significant results. These findings provide support for the Theory of Reasoned Action (TRA) and suggest that psychosocial factors may play an important role in WTP in Phase III HIV vaccine trials among adolescents.

Phase I trial of RV3-BB rotavirus vaccine: a human neonatal rotavirus vaccine.

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Danchin, M; Kirkwood, C D; Lee, K J; Bishop, R F; Watts, E; Justice, F A; Clifford, V; Cowley, D; Buttery, J P; Bines, J E

2013-05-28

RV3 is a human neonatal rotavirus strain (G3P[6]) that has been associated with asymptomatic neonatal infection and replicates well in the infant gut. RV3-BB rotavirus vaccine has been developed as a rotavirus vaccine candidate for administration at birth. A single-centre, double-blind, randomised placebo-controlled Phase I study evaluated the safety and tolerability of a single oral dose of the second generation RV3-BB rotavirus vaccine (8.3×10(6)FFU/mL) in 20 adults, 20 children and 20 infants (10 vaccine and 10 placebo per age cohort). Vaccine take was defined as seroconversion (a 3-fold increase in serum anti-rotavirus IgA or serum neutralising antibody (SNA) from baseline at day 28 post-dose) or evidence of RV3-BB viral replication in the faeces by RT-PCR analysis 3-6 days post-vaccination. RV3-BB presence was confirmed by sequence analysis. The RV3-BB vaccine was well tolerated in all participants, with no pattern of adverse events shown to be associated with the study vaccine. In the infant cohort, vaccine take was demonstrated in 8/9 infants following a single dose of vaccine compared with 2/7 placebo recipients. In the infant vaccine group, 5/9 infants exhibited either IgA or SNA seroconversion and 7/9 infants had evidence of RV3-BB replication on days 3-6, compared with 2/7 infants who seroconverted and 0/10 infants with evidence of replication in the placebo group. Two infants in the placebo group had serological evidence of a rotavirus infection within the 28-day study period: one demonstrated an IgA and the other an SNA response, with wild-type virus replication detected in another infant. A single dose of RV3-BB rotavirus vaccine was well tolerated in adults, children and infants. Most infants (8/9) who received RV3-BB demonstrated vaccine take following a single dose. These data support progression of RV3-BB to Phase II immunogenicity and efficacy trials. Copyright © 2013 Elsevier Ltd. All rights reserved.

Malaria in Brazil: an overview.

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Oliveira-Ferreira, Joseli; Lacerda, Marcus V G; Brasil, Patrícia; Ladislau, José L B; Tauil, Pedro L; Daniel-Ribeiro, Cláudio Tadeu

2010-04-30

Malaria is still a major public health problem in Brazil, with approximately 306,000 registered cases in 2009, but it is estimated that in the early 1940s, around six million cases of malaria occurred each year. As a result of the fight against the disease, the number of malaria cases decreased over the years and the smallest numbers of cases to-date were recorded in the 1960s. From the mid-1960s onwards, Brazil underwent a rapid and disorganized settlement process in the Amazon and this migratory movement led to a progressive increase in the number of reported cases. Although the main mosquito vector (Anopheles darlingi) is present in about 80% of the country, currently the incidence of malaria in Brazil is almost exclusively (99,8% of the cases) restricted to the region of the Amazon Basin, where a number of combined factors favors disease transmission and impair the use of standard control procedures. Plasmodium vivax accounts for 83,7% of registered cases, while Plasmodium falciparum is responsible for 16,3% and Plasmodium malariae is seldom observed. Although vivax malaria is thought to cause little mortality, compared to falciparum malaria, it accounts for much of the morbidity and for huge burdens on the prosperity of endemic communities. However, in the last few years a pattern of unusual clinical complications with fatal cases associated with P. vivax have been reported in Brazil and this is a matter of concern for Brazilian malariologists. In addition, the emergence of P. vivax strains resistant to chloroquine in some reports needs to be further investigated. In contrast, asymptomatic infection by P. falciparum and P. vivax has been detected in epidemiological studies in the states of Rondonia and Amazonas, indicating probably a pattern of clinical immunity in both autochthonous and migrant populations. Seropidemiological studies investigating the type of immune responses elicited in naturally-exposed populations to several malaria vaccine candidates in

Malaria in Brazil: an overview

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Brasil Patrícia

2010-04-01

malaria vaccine candidates in Brazilian populations have also been providing important information on whether immune responses specific to these antigens are generated in natural infections and their immunogenic potential as vaccine candidates. The present difficulties in reducing economic and social risk factors that determine the incidence of malaria in the Amazon Region render impracticable its elimination in the region. As a result, a malaria-integrated control effort - as a joint action on the part of the government and the population - directed towards the elimination or reduction of the risks of death or illness, is the direction adopted by the Brazilian government in the fight against the disease.

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

Clinical Development of a Cytomegalovirus DNA Vaccine: From Product Concept to Pivotal Phase 3 Trial

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Michele Gerber

2013-09-01

Full Text Available 2013 marks a milestone year for plasmid DNA vaccine development as a first-in-class cytomegalovirus (CMV DNA vaccine enters pivotal phase 3 testing. This vaccine consists of two plasmids expressing CMV antigens glycoprotein B (gB and phosphoprotein 65 (pp65 formulated with a CRL1005 poloxamer and benzalkonium chloride (BAK delivery system designed to enhance plasmid expression. The vaccine’s planned initial indication under investigation is for prevention of CMV reactivation in CMV-seropositive (CMV+ recipients of an allogeneic hematopoietic stem cell transplant (HCT. A randomized, double-blind placebo-controlled phase 2 proof-of-concept study provided initial evidence of the safety of this product in CMV+ HCT recipients who underwent immune ablation conditioning regimens. This study revealed a significant reduction in viral load endpoints and increased frequencies of pp65-specific interferon-γ-producing T cells in vaccine recipients compared to placebo recipients. The results of this endpoint-defining trial provided the basis for defining the primary and secondary endpoints of a global phase 3 trial in HCT recipients. A case study is presented here describing the development history of this vaccine from product concept to initiation of the phase 3 trial.

Enhanced vaccine-induced CD8+ T cell responses to malaria antigen ME-TRAP by fusion to MHC class ii invariant chain.

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Alexandra J Spencer

Full Text Available The orthodox role of the invariant chain (CD74; Ii is in antigen presentation to CD4+ T cells, but enhanced CD8+ T cells responses have been reported after vaccination with vectored viral vaccines encoding a fusion of Ii to the antigen of interest. In this study we assessed whether fusion of the malarial antigen, ME-TRAP, to Ii could increase the vaccine-induced CD8+ T cell response. Following single or heterologous prime-boost vaccination of mice with a recombinant chimpanzee adenovirus vector, ChAd63, or recombinant modified vaccinia virus Ankara (MVA, higher frequencies of antigen-specific CD4+ and CD8+ T cells were observed, with the largest increases observed following a ChAd63-MVA heterologous prime-boost regimen. Studies in non-human primates confirmed the ability of Ii-fusion to augment the T cell response, where a 4-fold increase was maintained up to 11 weeks after the MVA boost. Of the numerous different approaches explored to increase vectored vaccine induced immunogenicity over the years, fusion to the invariant chain showed a consistent enhancement in CD8+ T cell responses across different animal species and may therefore find application in the development of vaccines against human malaria and other diseases where high levels of cell-mediated immunity are required.

Feasibility and acceptability of conducting HIV vaccine trials in adolescents in South Africa: Going beyond willingness to participate towards implementation

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M Wallace

2018-03-01

Full Text Available Background. HIV/AIDS remains a leading cause of death in adolescents (aged 15 - 25 years, and in sub-Saharan Africa HIV-related deaths continue to rise in this age group despite a decline in both adult and paediatric populations. This is attributable in part to high adolescent infection rates and supports the urgent need for more efficacious prevention strategies. In particular, an even partially effective HIV vaccine, given prior to sexual debut, is predicted to significantly curb adolescent infection rates. While adolescents have indicated willingness to participate in HIV vaccine trials, there are concerns around safety, uptake, adherence, and ethical and logistic issues.Objectives. To initiate a national, multisite project with the aim of identifying obstacles to conducting adolescent HIV vaccine trials in South Africa (SA.Method. A simulated HIV vaccine trial was conducted in adolescents aged 12 - 17 years across five SA research sites, using the already licensed Merck human papillomavirus vaccine Gardasil as a proxy for an HIV vaccine. Adolescents were recruited at community venues and, following a vaccine discussion group, invited to participate in the trial. Consent for trial enrolment was obtained from a parent or legal guardian, and participants aged 16 - 17 years were eligible only if sexually active. Typical vaccine trial procedures were applied during the five study visits, including the administration of vaccination injections at study visits 2, 3 and 4.Results. The median age of participants was 14 years (interquartile range 13 - 15, with 81% between the ages of 12 and 15 years at enrolment. Overall, 98% of screened participants opted to receive the vaccine, 588 participants enrolled, and 524 (89% attended the final visit.Conclusions. This trial showed that adolescents can be recruited, enrolled and retained in clinical prevention trials with parental support. While promising, these results were tempered by the coupling of sexual

Motivations to participate in a Phase I/II HIV vaccine trial: A descriptive study from Dar es Salaam, Tanzania

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E. A. M. Tarimo

2016-02-01

Full Text Available Abstract Background The search for an efficacious HIV vaccine is a global priority. To date only one HIV vaccine trial (RV144 has shown modest efficacy in a phase III trial. With existing different HIV-1 subtypes and frequent mutations, multiple trials are needed from different geographical sites particularly in sub-Saharan Africa where most HIV infections occur. Thus, motivations to participate in HIV vaccine trials among Tanzanians need to be assessed. This paper describes the motives of Police Officers who showed great interest to volunteer in HIVIS-03 in Dar es Salaam, Tanzania. Methods A descriptive cross-sectional study was conducted among Police Officers who showed interest to participate in the HIVIS-03, a phase I/II HIV vaccine trial in Dar es Salaam. Prior to detailed training sessions about HIV vaccine trials, the potential participants narrated their individual motives to participate in the trial on a piece of paper. Descriptive analysis using content approach and frequency distributions were performed. Results Of the 265 respondents, 242 (91.3 % provided their socio-demographic characteristics as well as reasons that would make them take part in the proposed trial. Majority, (39.7 %, cited altruism as the main motive. Women were more likely to volunteer due to altruism compared to men (P < 0.01. Researchers’ explanations about HIV/AIDS vaccine studies motivated 15.3 %. More men (19.6 % than women (1.7 % were motivated to volunteer due to researchers’ explanations (P < 0.001. Also, compared to other groups, those unmarried and educated up to secondary level of education were motivated to volunteer due to researchers’ explanation (P < 0.05. Other reasons were: desire to become a role model (18.6 %; to get knowledge for educating others (14.0 %; to cooperate with researchers in developing an HIV vaccine (9.5 %; to get protection against HIV infection (7.0 %, and severity of the disease within families (6.2�

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

NARCIS (Netherlands)

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

2009-01-01

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

Enrollment in YFV Vaccine Trial: An Evaluation of Recruitment Outcomes Associated with a Randomized Controlled Double-Blind Trial of a Live Attenuated Yellow Fever Vaccine.

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Frew, Paula M; Shapiro, Eve T; Lu, Lu; Edupuganti, Srilatha; Keyserling, Harry L; Mulligan, Mark J

2013-04-15

This investigation evaluated several factors associated with diverse participant enrollment of a clinical trial assessing safety, immunogenicity, and comparative viremia associated with administration of 17-D live, attenuated yellow fever vaccine given alone or in combination with human immune globulin. We obtained baseline participant information (e.g., sociodemographic, medical) and followed recruitment outcomes from 2005 to 2007. Of 355 potential Yellow Fever vaccine study participants, 231 cases were analyzed. Strong interest in study participation was observed among racial and ethnically diverse persons with 36.34% eligible following initial study screening, resulting in 18.75% enrollment. The percentage of white participants increased from 63.66% (prescreened sample) to 81.25% (enrollment group). The regression model was significant with white race as a predictor of enrollment (OR=2.744, 95% CI=1.415-5.320, p=0.003).In addition, persons were more likely to enroll via direct outreach and referral mechanisms compared to mass advertising (OR=2.433, 95% CI=1.102-5.369). The findings indicate that racially diverse populations can be recruited to vaccine clinical trials, yet actual enrollment may not reflect that diversity.

Marketing paediatric influenza vaccination: results of a major metropolitan trial

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Van Buynder, Paul G.; Carcione, Dale; Rettura, Vince; Daly, Alison; Woods, Emily

2010-01-01

Please cite this paper as: Van Buynder et al. (2010) Marketing paediatric influenza vaccination: results of a major metropolitan trial. Influenza and Other Respiratory Viruses 5(1), 33–38. Objectives  After a cluster of rapidly fulminant influenza related toddler deaths in a Western Australian metropolis, children aged six to 59 months were offered influenza vaccination in subsequent winters. Some parental resistance was expected and previous poor uptake of paediatric influenza vaccination overseas was noted. A marketing campaign addressing barriers to immunization was developed to maximise uptake. Design  Advertising occurred in major statewide newspapers, via public poster displays and static ‘eye‐lite’ displays, via press releases, via a series of rolling radio advertisements, via direct marketing to child care centres, and via a linked series of web‐sites. Parents were subsequently surveyed to assess reasons for vaccination. Main Outcome Results  The campaign produced influenza vaccination coverage above that previously described elsewhere and led to a proportionate reduction in influenza notifications in this age group compared to previous seasons. Conclusions  Influenza in children comes with significant morbidity and some mortality. Paediatric influenza vaccination is safe, well tolerated and effective if two doses are given. A targeted media campaign can increase vaccine uptake if it reinforces the seriousness of influenza and addresses community ‘myths’ about influenza and influenza vaccine. The lessons learned enabling enhancements of similar programs elsewhere. PMID:21138538

Vaccination with lipid core peptides fails to induce epitope-specific T cell responses but confers non-specific protective immunity in a malaria model.

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Simon H Apte

Full Text Available Vaccines against many pathogens for which conventional approaches have failed remain an unmet public health priority. Synthetic peptide-based vaccines offer an attractive alternative to whole protein and whole organism vaccines, particularly for complex pathogens that cause chronic infection. Previously, we have reported a promising lipid core peptide (LCP vaccine delivery system that incorporates the antigen, carrier, and adjuvant in a single molecular entity. LCP vaccines have been used to deliver several peptide subunit-based vaccine candidates and induced high titre functional antibodies and protected against Group A streptococcus in mice. Herein, we have evaluated whether LCP constructs incorporating defined CD4(+ and/or CD8(+ T cell epitopes could induce epitope-specific T cell responses and protect against pathogen challenge in a rodent malaria model. We show that LCP vaccines failed to induce an expansion of antigen-specific CD8(+ T cells following primary immunization or by boosting. We further demonstrated that the LCP vaccines induced a non-specific type 2 polarized cytokine response, rather than an epitope-specific canonical CD8(+ T cell type 1 response. Cytotoxic responses of unknown specificity were also induced. These non-specific responses were able to protect against parasite challenge. These data demonstrate that vaccination with lipid core peptides fails to induce canonical epitope-specific T cell responses, at least in our rodent model, but can nonetheless confer non-specific protective immunity against Plasmodium parasite challenge.

Intravenous artesunate plus Artemisnin based Combination Therapy (ACT) or intravenous quinine plus ACT for treatment of severe malaria in Ugandan children: a randomized controlled clinical trial.

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Byakika-Kibwika, Pauline; Achan, Jane; Lamorde, Mohammed; Karera-Gonahasa, Carine; Kiragga, Agnes N; Mayanja-Kizza, Harriet; Kiwanuka, Noah; Nsobya, Sam; Talisuna, Ambrose O; Merry, Concepta

2017-12-28

Severe malaria is a medical emergency associated with high mortality. Adequate treatment requires initial parenteral therapy for fast parasite clearance followed by longer acting oral antimalarial drugs for cure and prevention of recrudescence. In a randomized controlled clinical trial, we evaluated the 42-day parasitological outcomes of severe malaria treatment with intravenous artesunate (AS) or intravenous quinine (QNN) followed by oral artemisinin based combination therapy (ACT) in children living in a high malaria transmission setting in Eastern Uganda. We enrolled 300 participants and all were included in the intention to treat analysis. Baseline characteristics were similar across treatment arms. The median and interquartile range for number of days from baseline to parasite clearance was significantly lower among participants who received intravenous AS (2 (1-2) vs 3 (2-3), P malaria symptoms. In this high transmission setting, we observed adequate initial treatment outcomes followed by very high rates of malaria re-infection post severe malaria treatment. The impact of recurrent antimalarial treatment on the long term efficacy of antimalarial regimens needs to be investigated and surveillance mechanisms for resistance markers established since recurrent malaria infections are likely to be exposed to sub-therapeutic drug concentrations. More strategies for prevention of recurrent malaria infections in the most at risk populations are needed. The study was registered with the Pan African Clinical Trial Registry ( PACTR201110000321348 ).

Introducing rapid diagnostic tests for malaria into drug shops in Uganda: design and implementation of a cluster randomized trial.

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Mbonye, Anthony K; Magnussen, Pascal; Chandler, Clare I R; Hansen, Kristian S; Lal, Sham; Cundill, Bonnie; Lynch, Caroline A; Clarke, Siân E

2014-07-29

An intervention was designed to introduce rapid diagnostics tests for malaria (mRDTs) into registered drug shops in Uganda to encourage rational and appropriate treatment of malaria with artemisinin-based combination therapy (ACT). We conducted participatory training of drug shop vendors and implemented supporting interventions to orientate local communities (patients) and the public sector (health facility staff and district officials) to the behavioral changes in diagnosis, treatment and referral being introduced in drug shops. The intervention was designed to be evaluated through a cluster randomized trial. In this paper, we present detailed design, implementation and evaluation experiences in order to help inform future studies of a complex nature. Three preparatory studies (formative, baseline and willingness-to-pay) were conducted to explore perceptions on diagnosis and treatment of malaria at drug shops, and affordable prices for mRDTs and ACTs in order to inform the design of the intervention and implementation modalities. The intervention required careful design with the intention to be acceptable, sustainable and effective. Critical components of intervention were: community sensitization and creating awareness, training of drug shop vendors to diagnose malaria with mRDTs, treat and refer customers to formal health facilities, giving pre-referral rectal artesunate and improved record-keeping. The primary outcome was the proportion of patients receiving appropriately-targeted treatment with ACT, evaluated against microscopy on a research blood slide. Introducing mRDTs in drug shops may seem simple, but our experience of intervention design, conduct and evaluation showed this to be a complex process requiring multiple interventions and evaluation components drawing from a combination of epidemiological, social science and health economics methodologies. The trial was conducted in phases sequenced such that each benefited from the other. The main challenges

Comprehensive sieve analysis of breakthrough HIV-1 sequences in the RV144 vaccine efficacy trial.

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Edlefsen, Paul T; Rolland, Morgane; Hertz, Tomer; Tovanabutra, Sodsai; Gartland, Andrew J; deCamp, Allan C; Magaret, Craig A; Ahmed, Hasan; Gottardo, Raphael; Juraska, Michal; McCoy, Connor; Larsen, Brendan B; Sanders-Buell, Eric; Carrico, Chris; Menis, Sergey; Kijak, Gustavo H; Bose, Meera; Arroyo, Miguel A; O'Connell, Robert J; Nitayaphan, Sorachai; Pitisuttithum, Punnee; Kaewkungwal, Jaranit; Rerks-Ngarm, Supachai; Robb, Merlin L; Kirys, Tatsiana; Georgiev, Ivelin S; Kwong, Peter D; Scheffler, Konrad; Pond, Sergei L Kosakovsky; Carlson, Jonathan M; Michael, Nelson L; Schief, William R; Mullins, James I; Kim, Jerome H; Gilbert, Peter B

2015-02-01

The RV144 clinical trial showed the partial efficacy of a vaccine regimen with an estimated vaccine efficacy (VE) of 31% for protecting low-risk Thai volunteers against acquisition of HIV-1. The impact of vaccine-induced immune responses can be investigated through sieve analysis of HIV-1 breakthrough infections (infected vaccine and placebo recipients). A V1/V2-targeted comparison of the genomes of HIV-1 breakthrough viruses identified two V2 amino acid sites that differed between the vaccine and placebo groups. Here we extended the V1/V2 analysis to the entire HIV-1 genome using an array of methods based on individual sites, k-mers and genes/proteins. We identified 56 amino acid sites or "signatures" and 119 k-mers that differed between the vaccine and placebo groups. Of those, 19 sites and 38 k-mers were located in the regions comprising the RV144 vaccine (Env-gp120, Gag, and Pro). The nine signature sites in Env-gp120 were significantly enriched for known antibody-associated sites (p = 0.0021). In particular, site 317 in the third variable loop (V3) overlapped with a hotspot of antibody recognition, and sites 369 and 424 were linked to CD4 binding site neutralization. The identified signature sites significantly covaried with other sites across the genome (mean = 32.1) more than did non-signature sites (mean = 0.9) (p analysis of the breakthrough infections in the RV144 trial, this work describes a set of statistical methods and tools applicable to analysis of breakthrough infection genomes in general vaccine efficacy trials for diverse pathogens.

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

NARCIS (Netherlands)

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

2015-01-01

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

Establishing a malaria diagnostics centre of excellence in Kisumu, Kenya

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McEvoy Peter

2007-06-01

Full Text Available Abstract Background Malaria microscopy, while the gold standard for malaria diagnosis, has limitations. Efficacy estimates in drug and vaccine malaria trials are very sensitive to small errors in microscopy endpoints. This fact led to the establishment of a Malaria Diagnostics Centre of Excellence in Kisumu, Kenya. The primary objective was to ensure valid clinical trial and diagnostic test evaluations. Key secondary objectives were technology transfer to host countries, establishment of partnerships, and training of clinical microscopists. Case description A twelve-day "long" and a four-day "short" training course consisting of supervised laboratory practicals, lectures, group discussions, demonstrations, and take home assignments were developed. Well characterized slides were developed and training materials iteratively improved. Objective pre- and post-course evaluations consisted of 30 slides (19 negative, 11 positive with a density range of 50–660 parasites/μl, a written examination (65 questions, a photographic image examination (30 images of artifacts and species specific characteristics, and a parasite counting examination. Discussion and Evaluation To date, 209 microscopists have participated from 11 countries. Seventy-seven experienced microscopists participated in the "long" courses, including 47 research microscopists. Sensitivity improved by a mean of 14% (CI 9–19% from 77% baseline (CI 73–81 %, while specificity improved by a mean of 17% (CI 11–23% from 76% (CI 70–82% baseline. Twenty-three microscopists who had been selected for a four-day refresher course showed continued improvement with a mean final sensitivity of 95% (CI 91–98% and specificity of 97% (CI 95–100%. Only 9% of those taking the pre-test in the "long" course achieved a 90% sensitivity and 95% specificity, which increased to 61% of those completing the "short" course. All measures of performance improved substantially across each of the five

Can topical insect repellents reduce malaria? A cluster-randomised controlled trial of the insect repellent N,N-diethyl-m-toluamide (DEET in Lao PDR.

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Vanessa Chen-Hussey

Full Text Available BACKGROUND: Mosquito vectors of malaria in Southeast Asia readily feed outdoors making malaria control through indoor insecticides such as long-lasting insecticidal nets (LLINs and indoor residual spraying more difficult. Topical insect repellents may be able to protect users from outdoor biting, thereby providing additional protection above the current best practice of LLINs. METHODS AND FINDINGS: A double blind, household randomised, placebo-controlled trial of insect repellent to reduce malaria was carried out in southern Lao PDR to determine whether the use of repellent and long-lasting insecticidal nets (LLINs could reduce malaria more than LLINs alone. A total of 1,597 households, including 7,979 participants, were recruited in June 2009 and April 2010. Equal group allocation, stratified by village, was used to randomise 795 households to a 15% DEET lotion and the remainder were given a placebo lotion. Participants, field staff and data analysts were blinded to the group assignment until data analysis had been completed. All households received new LLINs. Participants were asked to apply their lotion to exposed skin every evening and sleep under the LLINs each night. Plasmodium falciparum and P. vivax cases were actively identified by monthly rapid diagnostic tests. Intention to treat analysis found no effect from the use of repellent on malaria incidence (hazard ratio: 1.00, 95% CI: 0.99-1.01, p = 0.868. A higher socio-economic score was found to significantly decrease malaria risk (hazard ratio: 0.72, 95% CI: 0.58-0.90, p = 0.004. Women were also found to have a reduced risk of infection (hazard ratio: 0.59, 95% CI: 0.37-0.92, p = 0.020. According to protocol analysis which excluded participants using the lotions less than 90% of the time found similar results with no effect from the use of repellent. CONCLUSIONS: This randomised controlled trial suggests that topical repellents are not a suitable intervention in addition to

Successful human infection with P. falciparum using three aseptic Anopheles stephensi mosquitoes: a new model for controlled human malaria infection.

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Matthew B Laurens

Full Text Available Controlled human malaria infection (CHMI is a powerful method for assessing the efficacy of anti-malaria vaccines and drugs targeting pre-erythrocytic and erythrocytic stages of the parasite. CHMI has heretofore required the bites of 5 Plasmodium falciparum (Pf sporozoite (SPZ-infected mosquitoes to reliably induce Pf malaria. We reported that CHMI using the bites of 3 PfSPZ-infected mosquitoes reared aseptically in compliance with current good manufacturing practices (cGMP was successful in 6 participants. Here, we report results from a subsequent CHMI study using 3 PfSPZ-infected mosquitoes reared aseptically to validate the initial clinical trial. We also compare results of safety, tolerability, and transmission dynamics in participants undergoing CHMI using 3 PfSPZ-infected mosquitoes reared aseptically to published studies of CHMI using 5 mosquitoes. Nineteen adults aged 18-40 years were bitten by 3 Anopheles stephensi mosquitoes infected with the chloroquine-sensitive NF54 strain of Pf. All 19 participants developed malaria (100%; 12 of 19 (63% on Day 11. The mean pre-patent period was 258.3 hours (range 210.5-333.8. The geometric mean parasitemia at first diagnosis by microscopy was 9.5 parasites/µL (range 2-44. Quantitative polymerase chain reaction (qPCR detected parasites an average of 79.8 hours (range 43.8-116.7 before microscopy. The mosquitoes had a geometric mean of 37,894 PfSPZ/mosquito (range 3,500-152,200. Exposure to the bites of 3 aseptically-raised, PfSPZ-infected mosquitoes is a safe, effective procedure for CHMI in malaria-naïve adults. The aseptic model should be considered as a new standard for CHMI trials in non-endemic areas. Microscopy is the gold standard used for the diagnosis of Pf malaria after CHMI, but qPCR identifies parasites earlier. If qPCR continues to be shown to be highly specific, and can be made to be practical, rapid, and standardized, it should be considered as an alternative for diagnosis.ClinicalTrials

Evaluation of Lethal Giant Larvae as a Schistosomiasis Vaccine Candidate

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Yufan Cao

2016-01-01

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

Enrolling adolescents in HIV vaccine trials: reflections on legal complexities from South Africa.

Science.gov (United States)

Slack, Catherine; Strode, Ann; Fleischer, Theodore; Gray, Glenda; Ranchod, Chitra

2007-05-13

South Africa is likely to be the first country in the world to host an adolescent HIV vaccine trial. Adolescents may be enrolled in late 2007. In the development and review of adolescent HIV vaccine trial protocols there are many complexities to consider, and much work to be done if these important trials are to become a reality. This article sets out essential requirements for the lawful conduct of adolescent research in South Africa including compliance with consent requirements, child protection laws, and processes for the ethical and regulatory approval of research. This article outlines likely complexities for researchers and research ethics committees, including determining that trial interventions meet current risk standards for child research. Explicit recommendations are made for role-players in other jurisdictions who may also be planning such trials. This article concludes with concrete steps for implementing these important trials in South Africa and other jurisdictions, including planning for consent processes; delineating privacy rights; compiling information necessary for ethics committees to assess risks to child participants; training trial site staff to recognize when disclosures trig mandatory reporting response; networking among relevant ethics committees; and lobbying the National Regulatory Authority for guidance.

Simulation of the Costs and Consequences of Potential Vaccines for Plasmodium Falciparum Malaria

OpenAIRE

Tediosi, Fabrizio

2010-01-01

Malaria is one of the major public health problems for low income countries, a major global health priority, and it has also a dramatic economic impact. Funding for malaria control is on the rise and both international donors and governments of malaria endemic countries need tools and evidence to assess which are the best and most efficient strategies to control malaria. Standard tools traditionally used to assess the public health and economic impact of malaria control inte...

Pragmatic trial of an intervention to increase human papillomavirus vaccination in safety-net clinics

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Maureen Sanderson

2017-02-01

Full Text Available Abstract Background Human papillomavirus (HPV infection has been causally linked to six cancers, and many disproportionately affect minorties. This study reports on the development and effectiveness of an intervention aimed at increasing HPV vaccine uptake among African American and Hispanic pediatric patients in safety-net clinics. Methods Formative research, community engagement, and theory guided development of the intervention. A clustered, non-randomized controlled pragmatic trial was conducted in four clinics providing healthcare for the underserved in Tennessee, U.S., with two intervention sites and two usual care sites. Patients aged 9-18 years (N = 408 and their mothers (N = 305 enrolled, with children clustered within families. The intervention consisted of two provider/staff training sessions and provision of patient education materials, consisting of a video/flyer promoting HPV vaccine. Medical records were reviewed before/after the initial visit and after 12 months. Results At the initial visit, provision of patient education materials and provider recommendation were higher at intervention sites versus usual care sites, and receipt of HPV vaccine was higher at intervention sites (45.4% versus 32.9% but not significantly after adjusting for patient’s age and mother’s education. Provider recommendation, but not education materials, increased the likelihood of vaccine receipt at the initial visit, although over one-third of intervention mothers cited the flyer/video as motivating vaccination. Completion of the 3-dose series at follow-up was lower in the intervention arm. Conclusions Future interventions should combine patient education, intensive provider/staff education, and patient reminders. Research should compare patient education focusing on HPV vaccine only versus all adolescent vaccines. Trial registration Retrospectively registered with ClinicalTrials.gov NCT02808832 , 9/12/16

Induction of CD8(+) T cell responses and protective efficacy following microneedle-mediated delivery of a live adenovirus-vectored malaria vaccine.

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Pearson, Frances E; O'Mahony, Conor; Moore, Anne C; Hill, Adrian V S

2015-06-22

There is an urgent need for improvements in vaccine delivery technologies. This is particularly pertinent for vaccination programmes within regions of limited resources, such as those required for adequate provision for disposal of used needles. Microneedles are micron-sized structures that penetrate the stratum corneum of the skin, creating temporary conduits for the needle-free delivery of drugs or vaccines. Here, we aimed to investigate immunity induced by the recombinant simian adenovirus-vectored vaccine ChAd63.ME-TRAP; currently undergoing clinical assessment as a candidate malaria vaccine, when delivered percutaneously by silicon microneedle arrays. In mice, we demonstrate that microneedle-mediated delivery of ChAd63.ME-TRAP induced similar numbers of transgene-specific CD8(+) T cells compared to intradermal (ID) administration with needle-and-syringe, following a single immunisation and after a ChAd63/MVA heterologous prime-boost schedule. When mice immunised with ChAd63/MVA were challenged with live Plasmodium berghei sporozoites, microneedle-mediated ChAd63.ME-TRAP priming demonstrated equivalent protective efficacy as did ID immunisation. Furthermore, responses following ChAd63/MVA immunisation correlated with a specific design parameter of the array used ('total array volume'). The level of transgene expression at the immunisation site and skin-draining lymph node (dLN) was also linked to total array volume. These findings have implications for defining silicon microneedle array design for use with live, vectored vaccines. Copyright © 2015 Elsevier Ltd. All rights reserved.

Stakeholder views of ethical guidance regarding prevention and care in HIV vaccine trials.

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Moorhouse, Rika; Slack, Catherine; Quayle, Michael; Essack, Zaynab; Lindegger, Graham

2014-06-30

South Africa is a major hub of HIV prevention trials, with plans for a licensure trial to start in 2015. The appropriate standards of care and of prevention in HIV vaccine trials are complex and debated issues and ethical guidelines offer some direction. However, there has been limited empirical exploration of South African stakeholders' perspectives on ethical guidance related to prevention and care in HIV vaccine trials. Site staff, Community Advisory Board members and Research Ethics Committee members involved with current HIV vaccine trials in South Africa were invited to participate in an exploration of their views. A questionnaire listed 10 care and 10 prevention recommendations drawn from two widely available sets of ethical guidelines for biomedical HIV prevention trials. Respondents (n = 98) rated each recommendation on five dimensions: "Familiarity with", "Ease of Understanding", "Ease of Implementing", "Perceived Protection", and "Agreement with" each ethical recommendation. The ratings were used to describe stakeholder perspectives on dimensions for each recommendation. Dimension ratings were averaged across the five dimensions and used as an indication of overall merit for each recommendation. Differences were explored across dimensions, between care-oriented and prevention-oriented recommendations, and between stakeholder groups. Both care and prevention recommendations were rated highly overall, with median ratings well above the scale midpoint. In general, informed consent recommendations were most positively rated. Care-related recommendations were rated significantly more positively than prevention-related recommendations, with the five lowest-rated recommendations being prevention-related. The most problematic dimension across all recommendations was "Ease of Implementing," and the least problematic was "Agreement with," suggesting the most pressing stakeholder concerns are practical rather than theoretical; that is, respondents agree with

Malaria and the Millennium Development Goals.

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Owens, Stephen

2015-02-01

Malaria, as a key disease of poverty, was singled out for special attention in the Millennium Project of 2000. Recent data suggest that malaria incidence and mortality are now declining all over the world. While these figures are cause for celebration, they must be interpreted carefully and with caution, particularly in relation to Africa. There are daunting challenges ahead for those working to achieve malaria eradication, not least of which is the poor quality of the data on which the work is based. In the absence of an affordable and fully effective vaccine, international funding for malaria control needs to be escalated still further. The money is essential to pay for universal access to a set of simple and proven interventions which would save the lives of millions of children over the next 15 years. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

The London School of Hygiene and Tropical Medicine: a new century of malaria research

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Riley Eleanor M

2000-01-01

Full Text Available The global malaria situation has scarcely improved in the last 100 years, despite major advances in our knowledge of the basic biology, epidemiology and clinical basis of the disease. Effective malaria control, leading to a significant decrease in the morbidity and mortality attributable to malaria, will require a multidisciplinary approach. New tools - drugs, vaccine and insecticides - are needed but there is also much to be gained by better use of existing tools: using drugs in combination in order to slow the development of drug resistance; targeting resources to areas of greatest need; using geographic information systems to map the populations at risk and more sophisticated marketing techniques to distribute bed nets and insecticides. Sustainable malaria control may require the deployment of a highly effective vaccine, but there is much that can be done in the meantime to reduce the burden of disease.

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...

Comprehensive sieve analysis of breakthrough HIV-1 sequences in the RV144 vaccine efficacy trial.

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Paul T Edlefsen

2015-02-01

Full Text Available The RV144 clinical trial showed the partial efficacy of a vaccine regimen with an estimated vaccine efficacy (VE of 31% for protecting low-risk Thai volunteers against acquisition of HIV-1. The impact of vaccine-induced immune responses can be investigated through sieve analysis of HIV-1 breakthrough infections (infected vaccine and placebo recipients. A V1/V2-targeted comparison of the genomes of HIV-1 breakthrough viruses identified two V2 amino acid sites that differed between the vaccine and placebo groups. Here we extended the V1/V2 analysis to the entire HIV-1 genome using an array of methods based on individual sites, k-mers and genes/proteins. We identified 56 amino acid sites or "signatures" and 119 k-mers that differed between the vaccine and placebo groups. Of those, 19 sites and 38 k-mers were located in the regions comprising the RV144 vaccine (Env-gp120, Gag, and Pro. The nine signature sites in Env-gp120 were significantly enriched for known antibody-associated sites (p = 0.0021. In particular, site 317 in the third variable loop (V3 overlapped with a hotspot of antibody recognition, and sites 369 and 424 were linked to CD4 binding site neutralization. The identified signature sites significantly covaried with other sites across the genome (mean = 32.1 more than did non-signature sites (mean = 0.9 (p < 0.0001, suggesting functional and/or structural relevance of the signature sites. Since signature sites were not preferentially restricted to the vaccine immunogens and because most of the associations were insignificant following correction for multiple testing, we predict that few of the genetic differences are strongly linked to the RV144 vaccine-induced immune pressure. In addition to presenting results of the first complete-genome analysis of the breakthrough infections in the RV144 trial, this work describes a set of statistical methods and tools applicable to analysis of breakthrough infection genomes in general vaccine

Chemistry, manufacturing and control (CMC) and clinical trial technical support for influenza vaccine manufacturers.

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Wahid, Rahnuma; Holt, Renee; Hjorth, Richard; Berlanda Scorza, Francesco

2016-10-26

With the support of the Biomedical Advanced Research and Development Authority (BARDA) of the US Department of Health and Human Services, PATH has contributed to the World Health Organization's (WHO's) Global Action Plan for Influenza Vaccines (GAP) by providing technical and clinical assistance to several developing country vaccine manufacturers (DCVMs). GAP builds regionally based independent and sustainable influenza vaccine production capacity to mitigate the overall global shortage of influenza vaccines. The program also ensures adequate influenza vaccine manufacturing capacity in the event of an influenza pandemic. Since 2009, PATH has worked closely with two DCVMs in Vietnam: the Institute of Vaccines and Medical Biologicals (IVAC) and VABIOTECH. Beginning in 2013, PATH also began working with Torlak Institute in Serbia; Instituto Butantan in Brazil; Serum Institute of India Private Ltd. in India; and Changchun BCHT Biotechnology Co. (BCHT) in China. The DCVMs supported under the GAP program all had existing influenza vaccine manufacturing capability and required technical support from PATH to improve vaccine yield, process efficiency, and product formulation. PATH has provided customized technical support for the manufacturing process to each DCVM based on their respective requirements. Additionally, PATH, working with BARDA and WHO, supported several DCVMs in the clinical development of influenza vaccine candidates progressing toward national licensure or WHO prequalification. As a result of the activities outlined in this review, several companies were able to make excellent progress in developing state-of-the-art manufacturing processes and completing early phase clinical trials. Licensure trials are currently ongoing or planned for several DCVMs. Copyright © 2016 Elsevier Ltd. All rights reserved.

School-located Influenza Vaccinations for Adolescents: A Randomized Controlled Trial.

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Szilagyi, Peter G; Schaffer, Stanley; Rand, Cynthia M; Goldstein, Nicolas P N; Vincelli, Phyllis; Hightower, A Dirk; Younge, Mary; Eagan, Ashley; Blumkin, Aaron; Albertin, Christina S; DiBitetto, Kristine; Yoo, Byung-Kwang; Humiston, Sharon G

2018-02-01

We aimed to evaluate the effect of school-located influenza vaccination (SLIV) on adolescents' influenza vaccination rates. In 2015-2016, we performed a cluster-randomized trial of adolescent SLIV in middle/high schools. We selected 10 pairs of schools (identical grades within pairs) and randomly allocated schools within pairs to SLIV or usual care control. At eight suburban SLIV schools, we sent parents e-mail notifications about upcoming SLIV clinics and promoted online immunization consent. At two urban SLIV schools, we sent parents (via student backpack fliers) paper immunization consent forms and information about SLIV. E-mails were unavailable at these schools. Local health department nurses administered nasal or injectable influenza vaccine at dedicated SLIV clinics and billed insurers. We compared influenza vaccination rates at SLIV versus control schools using school directories to identify the student sample in each school. We used the state immunization registry to determine receipt of influenza vaccination. The final sample comprised 17,650 students enrolled in the 20 schools. Adolescents at suburban SLIV schools had higher overall influenza vaccination rates than did adolescents at control schools (51% vs. 46%, p < .001; adjusted odds ratio = 1.27, 95% confidence interval 1.18-1.38, controlling for vaccination during the prior two seasons). No effect of SLIV was noted among urbanschools on multivariate analysis. SLIV did not substitute for vaccinations in primary care or other settings; in suburban settings, SLIV was associated with increased vaccinations in primary care or other settings (adjusted odds ratio = 1.10, 95% confidence interval 1.02-1.19). SLIV in this community increased influenza vaccination rates among adolescents attending suburban schools. Copyright © 2018. Published by Elsevier Inc.

A randomized clinical trial of an inactivated avian influenza A (H7N7 vaccine.

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Robert B Couch

Full Text Available BACKGROUND: Concern for a pandemic caused by a newly emerged avian influenza A virus has led to clinical trials with candidate vaccines as preparation for such an event. Most trials have involved vaccines for influenza A (H5N1, A (H7N7 or A (H9N2. OBJECTIVE: To evaluate dosage-related safety and immunogenicity of an inactivated influenza A (H7N7 vaccine in humans. DESIGN: One hundred twenty-five healthy young adults were randomized to receive two doses intramuscularly of placebo or 7.5, 15, 45 or 90 µg of HA of an inactivated subunit influenza A (H7N7 vaccine (25 per group, four weeks apart. Reactogenicity was evaluated closely for one week and for any adverse effect for six months after each dose. Serum hemagglutination-inhibiting and neutralizing antibody responses were determined four weeks after each dose and at six months. RESULTS: Reactogenicity evaluations indicated the vaccinations were well tolerated. Only one subject developed a ≥4-fold serum hemagglutination-inhibition (HAI antibody response and a final titer of ≥1:40 four weeks after dose two and only five subjects developed a neutralizing antibody rise and a final titer of ≥1:40 in tests performed at a central laboratory. Four of the five were given the 45 or 90 µg HA dosage. A more sensitive HAI assay at the study site revealed a dose-response with increasing HA dosage but only 36% in the 90 µg HA group developed a ≥4-fold rise in antibody in this test and only one of these achieved a titer of ≥1:32. CONCLUSION: This inactivated subunit influenza A (H7N7 vaccine was safe but poorly immunogenic in humans. TRIALS REGISTRATION: ClinicalTrials.gov NCT00546585.

Efficacy and effectiveness of an rVSV-vectored vaccine expressing Ebola surface glycoprotein: interim results from the Guinea ring vaccination cluster-randomised trial.

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Henao-Restrepo, Ana Maria; Longini, Ira M; Egger, Matthias; Dean, Natalie E; Edmunds, W John; Camacho, Anton; Carroll, Miles W; Doumbia, Moussa; Draguez, Bertrand; Duraffour, Sophie; Enwere, Godwin; Grais, Rebecca; Gunther, Stephan; Hossmann, Stefanie; Kondé, Mandy Kader; Kone, Souleymane; Kuisma, Eeva; Levine, Myron M; Mandal, Sema; Norheim, Gunnstein; Riveros, Ximena; Soumah, Aboubacar; Trelle, Sven; Vicari, Andrea S; Watson, Conall H; Kéïta, Sakoba; Kieny, Marie Paule; Røttingen, John-Arne

2015-08-29

A recombinant, replication-competent vesicular stomatitis virus-based vaccine expressing a surface glycoprotein of Zaire Ebolavirus (rVSV-ZEBOV) is a promising Ebola vaccine candidate. We report the results of an interim analysis of a trial of rVSV-ZEBOV in Guinea, west Africa. For this open-label, cluster-randomised ring vaccination trial, suspected cases of Ebola virus disease in Basse-Guinée (Guinea, west Africa) were independently ascertained by Ebola response teams as part of a national surveillance system. After laboratory confirmation of a new case, clusters of all contacts and contacts of contacts were defined and randomly allocated 1:1 to immediate vaccination or delayed (21 days later) vaccination with rVSV-ZEBOV (one dose of 2 × 10(7) plaque-forming units, administered intramuscularly in the deltoid muscle). Adults (age ≥18 years) who were not pregnant or breastfeeding were eligible for vaccination. Block randomisation was used, with randomly varying blocks, stratified by location (urban vs rural) and size of rings (≤20 vs >20 individuals). The study is open label and masking of participants and field teams to the time of vaccination is not possible, but Ebola response teams and laboratory workers were unaware of allocation to immediate or delayed vaccination. Taking into account the incubation period of the virus of about 10 days, the prespecified primary outcome was laboratory-confirmed Ebola virus disease with onset of symptoms at least 10 days after randomisation. The primary analysis was per protocol and compared the incidence of Ebola virus disease in eligible and vaccinated individuals in immediate vaccination clusters with the incidence in eligible individuals in delayed vaccination clusters. This trial is registered with the Pan African Clinical Trials Registry, number PACTR201503001057193. Between April 1, 2015, and July 20, 2015, 90 clusters, with a total population of 7651 people were included in the planned interim analysis. 48 of

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.

Design and rationale for the Influenza vaccination After Myocardial Infarction (IAMI) trial

DEFF Research Database (Denmark)

Fröbert, Ole; Götberg, Matthias; Angerås, Oskar

2017-01-01

BACKGROUND: Registry studies and case-control studies have demonstrated that the risk of acute myocardial infarction (AMI) is increased following influenza infection. Small randomized trials, underpowered for clinical end points, indicate that future cardiovascular events can be reduced following...... influenza vaccination in patients with established cardiovascular disease. Influenza vaccination is recommended by international guidelines for patients with cardiovascular disease, but uptake is varying and vaccination is rarely prioritized during hospitalization for AMI. METHODS/DESIGN: The Influenza...... be assigned either to in-hospital influenza vaccination or to placebo. Baseline information is collected from national heart disease registries, and follow-up will be performed using both registries and a structured telephone interview. The primary end point is a composite of time to all-cause death, a new...

The Impact of Hotspot-Targeted Interventions on Malaria Transmission in Rachuonyo South District in the Western Kenyan Highlands: A Cluster-Randomized Controlled Trial

Science.gov (United States)

Bradley, John; Knight, Philip; Stone, William; Osoti, Victor; Makori, Euniah; Owaga, Chrispin; Odongo, Wycliffe; China, Pauline; Shagari, Shehu; Doumbo, Ogobara K.; Sauerwein, Robert W.; Kariuki, Simon; Drakeley, Chris; Stevenson, Jennifer; Cox, Jonathan

2016-01-01

Background Malaria transmission is highly heterogeneous, generating malaria hotspots that can fuel malaria transmission across a wider area. Targeting hotspots may represent an efficacious strategy for reducing malaria transmission. We determined the impact of interventions targeted to serologically defined malaria hotspots on malaria transmission both inside hotspots and in surrounding communities. Methods and Findings Twenty-seven serologically defined malaria hotspots were detected in a survey conducted from 24 June to 31 July 2011 that included 17,503 individuals from 3,213 compounds in a 100-km2 area in Rachuonyo South District, Kenya. In a cluster-randomized trial from 22 March to 15 April 2012, we randomly allocated five clusters to hotspot-targeted interventions with larviciding, distribution of long-lasting insecticide-treated nets, indoor residual spraying, and focal mass drug administration (2,082 individuals in 432 compounds); five control clusters received malaria control following Kenyan national policy (2,468 individuals in 512 compounds). Our primary outcome measure was parasite prevalence in evaluation zones up to 500 m outside hotspots, determined by nested PCR (nPCR) at baseline and 8 wk (16 June–6 July 2012) and 16 wk (21 August–10 September 2012) post-intervention by technicians blinded to the intervention arm. Secondary outcome measures were parasite prevalence inside hotpots, parasite prevalence in the evaluation zone as a function of distance from the hotspot boundary, Anopheles mosquito density, mosquito breeding site productivity, malaria incidence by passive case detection, and the safety and acceptability of the interventions. Intervention coverage exceeded 87% for all interventions. Hotspot-targeted interventions did not result in a change in nPCR parasite prevalence outside hotspot boundaries (p ≥ 0.187). We observed an average reduction in nPCR parasite prevalence of 10.2% (95% CI −1.3 to 21.7%) inside hotspots 8 wk post

Over-diagnosis of malaria is not a lost cause

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Chandramohan Daniel

2006-12-01

Full Text Available Abstract Background Recent studies have highlighted the over-diagnosis of malaria in clinical settings in Africa. This study assessed the impact of a training programme implemented as part of an intervention trial on diagnostic behaviour of clinicians in a rural district hospital in a low-moderate malaria transmission setting. Methods From the beginning of 2005, a randomized controlled trial (RCT of intermittent preventive treatment for malaria in infants (IPTi has been conducted at the study hospital. As part of the RCT, the study team offered laboratory quality assurance, and supervision and training of paediatric ward staff using information on malaria epidemiology in the community. Data on clinical and blood slide confirmed cases of malaria from 2001 to 2005 were extracted from the hospital records. Results The proportion of blood slides positive for malaria parasites had decreased from 21% in 2001 to 7% in 2005 (p Conclusion It may be possible to change the diagnostic behaviour of clinicians by rigorous training using local malaria epidemiology data and supportive supervision.

Which Dengue Vaccine Approach Is the Most Promising, and Should We Be Concerned about Enhanced Disease after Vaccination? The Path to a Dengue Vaccine: Learning from Human Natural Dengue Infection Studies and Vaccine Trials.

Science.gov (United States)

de Silva, Aravinda M; Harris, Eva

2018-06-01

Dengue virus (DENV) is the most common arthropod-borne viral disease of humans. Although effective vaccines exist against other flaviviral diseases like yellow fever and Japanese encephalitis, dengue vaccine development is complicated by the presence of four virus serotypes and the possibility of partial immunity enhancing dengue disease severity. Several live attenuated dengue vaccines are being tested in human clinical trials. Initial results are mixed, with variable efficacy depending on DENV serotype and previous DENV exposure. Here, we highlight recent discoveries about the human antibody response to DENV and propose guidelines for advancing development of safe and effective dengue vaccines. Copyright © 2018 Cold Spring Harbor Laboratory Press; all rights reserved.

Health benefit for the child and promotion of the common good were the two most important reasons for participation in the FinIP vaccine trial.

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Nieminen, Heta; Syrjänen, Ritva K; Puumalainen, Taneli; Sirén, Päivi; Palmu, Arto A

2015-07-17

The Finnish Invasive Pneumococcal disease (FinIP) vaccine trial was a nationwide cluster-randomised double-blind trial designed to demonstrate the effectiveness of pneumococcal conjugate vaccine in vaccinated children and indirect effects in unvaccinated populations. Together with the parallel carriage/AOM trial, over 47,000 children were enrolled, 52% of the initial target. We conducted a questionnaire study to find out which factors affected parents' decision on their child's study participation. A questionnaire designed to evaluate parents' attitudes to vaccine trial participation in general and the FinIP trial in particular was mailed after the trial enrolment period had ended to parents of randomly selected children: 1484 who participated in the trial and 1485 who did not participate. Altogether 1438 parents (48%) responded to the questionnaire. The response rate was higher among FinIP participants (65%, 965/1484) than among FinIP non-participants (32%, 473/1485). The two most important reasons for giving consent to the FinIP trial were the potential benefit of immunisation against pneumococcal diseases (75% of consenters) and the promotion of the common good and public health (11%). The reasons reported as most important for declining consent were suspicions of vaccine safety (36%) and the double-blind trial design (12%). Up to 65% of the non-consenters declared that drug and vaccine trials should not be conducted in children at all. The expected health benefit for the child was by far the most important reason for consenting to the vaccine trial. Safety concern was the main reason for decline. Importance and necessity of clinical drug and vaccine trials among children and the rationale of the blinded studies should be thoroughly explained to the public. This may increase participation in future vaccine trials. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effectiveness of Provider and Community Interventions to Improve Treatment of Uncomplicated Malaria in Nigeria: A Cluster Randomized Controlled Trial.

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Obinna Onwujekwe

Full Text Available The World Health Organization recommends that malaria be confirmed by parasitological diagnosis before treatment using Artemisinin-based Combination Therapy (ACT. Despite this, many health workers in malaria endemic countries continue to diagnose malaria based on symptoms alone. This study evaluates interventions to help bridge this gap between guidelines and provider practice. A stratified cluster-randomized trial in 42 communities in Enugu state compared 3 scenarios: Rapid Diagnostic Tests (RDTs with basic instruction (control; RDTs with provider training (provider arm; and RDTs with provider training plus a school-based community intervention (provider-school arm. The primary outcome was the proportion of patients treated according to guidelines, a composite indicator requiring patients to be tested for malaria and given treatment consistent with the test result. The primary outcome was evaluated among 4946 (93% of the 5311 patients invited to participate. A total of 40 communities (12 in control, 14 per intervention arm were included in the analysis. There was no evidence of differences between the three arms in terms of our composite indicator (p = 0.36: stratified risk difference was 14% (95% CI -8.3%, 35.8%; p = 0.26 in the provider arm and 1% (95% CI -21.1%, 22.9%; p = 0.19 in the provider-school arm, compared with control. The level of testing was low across all arms (34% in control; 48% provider arm; 37% provider-school arm; p = 0.47. Presumptive treatment of uncomplicated malaria remains an ingrained behaviour that is difficult to change. With or without extensive supporting interventions, levels of testing in this study remained critically low. Governments and researchers must continue to explore alternative ways of encouraging providers to deliver appropriate treatment and avoid the misuse of valuable medicines.ClinicalTrials.gov NCT01350752.

Vaccines for preventing typhoid fever.