scholarly journals Statistical Methods for Standard Membrane-Feeding Assays to Measure Transmission Blocking or Reducing Activity in Malaria

2018 ◽  
Vol 113 (522) ◽  
pp. 534-545 ◽  
Author(s):  
Bruce J. Swihart ◽  
Michael P. Fay ◽  
Kazutoyo Miura
Keyword(s):  
Statistical Methods ◽  
Transmission Blocking ◽  
Membrane Feeding ◽  
Reducing Activity

scholarly journals Evaluation of two Plasmodium vivax sexual stage antigens as transmission-blocking vaccine candidates

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Yongzhe Zhang ◽  
Fei Liu ◽  
Yan Zhao ◽  
Fan Yang ◽  
Jie Bai ◽  
...  
Keyword(s):  
Amino Acids ◽  
Plasmodium Vivax ◽  
Recombinant Proteins ◽  
Expression System ◽  
Anopheles Dirus ◽  
Transmission Blocking ◽  
Yeast Expression System ◽  
Membrane Feeding ◽  
Reducing Activity ◽  
Membrane Feeding Assay

Abstract Background Plasmodium vivax transmission-blocking vaccines (TBVs) are receiving increasing attention. Based on excellent transmission-blocking activities of the PbPH (PBANKA_0417200) and PbSOP26 (PBANKA_1457700) antigens in Plasmodium berghei, their orthologs in P. vivax, PVX_098655 (PvPH) and PVX_101120 (PvSOP26), were selected for the evaluation of their potential as TBVs. Methods Fragments of PvPH (amino acids 22–304) and PvSOP26 (amino acids 30–272) were expressed in the yeast expression system. The recombinant proteins were used to immunize mice to obtain antisera. The transmission-reducing activities of these antisera were evaluated using the direct membrane feeding assay (DMFA) using Anopheles dirus mosquitoes and P. vivax clinical isolates. Results The recombinant proteins PvPH and PvSOP26 induced robust antibody responses in mice. The DMFA showed that the anti-PvSOP26 sera significantly reduced oocyst densities by 92.0 and 84.1% in two parasite isolates, respectively, whereas the anti-PvPH sera did not show evident transmission-reducing activity. The variation in the DMFA results was unlikely due to the genetic polymorphisms of the two genes since their respective sequences were identical in the clinical P. vivax isolates. Conclusion PvSOP26 could be a promising TBV candidate for P. vivax, which warrants further evaluation. Graphical Abstract

scholarly journals Pfs230 yields higher malaria transmission-blocking vaccine activity than Pfs25 in humans but not mice

2020 ◽  
Author(s):  
Sara A. Healy ◽  
Charles Anderson ◽  
Bruce J. Swihart ◽  
Agnes Mwakingwe ◽  
Erin E. Gabriel ◽  
...  
Keyword(s):  
Functional Activity ◽  
Rhesus Macaques ◽  
Significant Activity ◽  
Transmission Blocking ◽  
Link Type ◽  
Membrane Feeding ◽  
Antibody Titers ◽  
Human Immune Response ◽  
Reducing Activity ◽  
Transmission Blocking Vaccine

AbstractBackgroundVaccines that block human-to-mosquito Plasmodium transmission are needed for malaria eradication and clinical trials have targeted zygote antigen Pfs25 for decades. We reported that a Pfs25 protein-protein conjugate vaccine formulated in alum adjuvant induced significant serum functional activity in both US and Malian adults. However, antibody titers declined rapidly, and transmission-reducing activity required four vaccine doses. Functional immunogenicity and durability must be improved before advancing TBV further in clinical development. We hypothesized that the pre-fertilization protein Pfs230 alone or in combination with Pfs25 would improve functional activity.MethodsTransmission-blocking vaccine candidates based on gamete antigen Pfs230 or Pfs25 were conjugated with Exoprotein A, formulated in Alhydrogel®, and administered to mice, rhesus macaques, and humans. Antibody titers were measured by ELISA and transmission-reducing activity was assess by the Standard Membrane Feeding Assay.ResultsPfs25-EPA/Alhydrogel® and Pfs230D1-EPA/Alhydrogel® induced similar serum functional activity in mice, but Pfs230D1-EPA induced significantly greater activity in rhesus monkeys that was enhanced by complement. In U.S. adults, two vaccine doses induced complement-dependent activity in 4 of 5 Pfs230D1-EPA/Alhydrogel® recipients but no significant activity in five Pfs25-EPA recipients, and combination with Pfs25-EPA did not increase activity over Pfs230D1-EPA alone.ConclusionThe complement-dependent functional immunogenicity of Pfs230D1-EPA represents a significant improvement over Pfs25-EPA. The rhesus model is more predictive of the functional human immune response to Pfs230D1 than is the mouse model.Trial RegistrationClinicalTrials.govNCT02334462FundingThis work was supported by the Intramural Research Program of the National Institute of Allergy and Infectious Diseases, National Institutes of Health.

Evaluation of two Plasmodium vivax sexual-stage antigens as transmission-blocking vaccine candidates

2021 ◽  
Author(s):  
Yongzhe Zhang ◽  
Fei Liu ◽  
Yan Zhao ◽  
Fan Yang ◽  
Jie Bai ◽  
...  
Keyword(s):  
Amino Acids ◽  
Plasmodium Vivax ◽  
Recombinant Proteins ◽  
Expression System ◽  
Transmission Blocking ◽  
Yeast Expression System ◽  
Membrane Feeding ◽  
Reducing Activity ◽  
Membrane Feeding Assay ◽  
Transmission Blocking Vaccines

Abstract Background: Plasmodium vivax transmission-blocking vaccines (TBVs) have received high attention. PVX_098655 (PvPH) and PVX_101120 (PvSOP26) were predicted to be potential TBV antigens based on the studies of their orthologs in Plasmodium berghei. Methods: Fragments of PvPH (amino acids 22–304) and PvSOP26 (amino acids 30–272) were expressed in the yeast expression system. The recombinant proteins were used to immunize mice to obtain the antisera. The transmission-reducing activities of these antisera were evaluated using the standard membrane feeding assay (SMFA) using Anopheles dirus mosquitoes and P. vivax clinical isolates. Results: The recombinant proteins PvPH and PvSOP26 induced robust antibody responses in mice. With SMFA, the anti-PvSOP26 sera significantly reduced oocyst densities by 92.0% and 84.1% in two parasite isolates, while the anti-PvPH sera did not show evident transmission-reducing activity. Both PvPH and PvSOP26 showed limited gene polymorphisms in the clinical P. vivax isolates. Conclusion: PvSOP26 could be a promising TBV candidate for P. vivax.

scholarly journals Anti-Pfs25 Human Plasma Reduces Transmission of Plasmodium falciparum Isolates That Have Diverse Genetic Backgrounds

2013 ◽  
Vol 81 (6) ◽  
pp. 1984-1989 ◽  
Author(s):  
Dari F. Da ◽  
Saurabh Dixit ◽  
Jetsumon Sattabonkot ◽  
Jianbing Mu ◽  
Luc Abate ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Burkina Faso ◽  
Phase 1 ◽  
Transmission Blocking ◽  
Content Type ◽  
Phase 1 Trial ◽  
Membrane Feeding ◽  
Geographical Regions ◽  
Reducing Activity ◽  
Membrane Feeding Assay

ABSTRACTPfs25 is a leading candidate for a malaria transmission-blocking vaccine whose potential has been demonstrated in a phase 1 trial with recombinant Pfs25 formulated with Montanide ISA51. Because of limited sequence polymorphism, the anti-Pfs25 antibodies induced by this vaccine are likely to have transmission-blocking or -reducing activity against most, if not all, field isolates. To test this hypothesis, we evaluated transmission-blocking activities by membrane feeding assay of anti-Pfs25 plasma from the Pfs25/ISA51 phase 1 trial againstPlasmodium falciparumparasites from patients in two different geographical regions of the world, Thailand and Burkina Faso. In parallel, parasite isolates from these patients were sequenced for the Pfs25 gene and genotyped for seven microsatellites. The results indicate that despite different genetic backgrounds among parasite isolates, the Pfs25 sequences are highly conserved, with a single nonsynonymous nucleotide polymorphism detected in 1 of 41 patients in Thailand and Burkina Faso. The anti-Pfs25 immune plasma had significantly higher transmission-reducing activity against parasite isolates from the two geographical regions than the nonimmune controls (P< 0.0001).

scholarly journals Engineering a Virus-Like Particle as an Antigenic Platform for a Pfs47-Targeted Malaria Transmission-Blocking Vaccine

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Lampouguin Yenkoidiok-Douti ◽  
Adeline E. Williams ◽  
Gaspar E. Canepa ◽  
Alvaro Molina-Cruz ◽  
Carolina Barillas-Mury
Keyword(s):  
Plasmodium Falciparum ◽  
Amino Acid ◽  
Malaria Transmission ◽  
Transmission Blocking ◽  
High Affinity ◽  
Virus Like Particle ◽  
Antibody Titers ◽  
Reducing Activity ◽  
Sexual Stages ◽  
Transmission Blocking Vaccine

AbstractWe recently characterized Pfs47, a protein expressed on the surface of sexual stages and ookinetes of Plasmodium falciparum, as a malaria transmission-blocking vaccine (TBV) target. Mice immunization induced antibodies that conferred strong transmission-reducing activity (TRA) at a concentration of 200 μg/mL. Here, we sought to optimize the Pfs47 vaccine to elicit higher titers of high-affinity antibodies, capable of inducing strong TRA at a lower concentration. We report the development and evaluation of a Pfs47-based virus-like particle (VLP) vaccine generated by conjugating our 58 amino acid Pfs47 antigen to Acinetobacter phage AP205-VLP using the SpyCatcher:SpyTag adaptor system. AP205-Pfs47 complexes (VLP-P47) formed particles of ~22 nm diameter that reacted with polyclonal anti-Pfs47 antibodies, indicating that the antigen was accessible on the surface of the particle. Mice immunized with VLP-P47 followed by a boost with Pfs47 monomer induced significantly higher antibody titers, with higher binding affinity to Pfs47, than mice that received two immunizations with either VLP-P47 (VLP-P47/VLP-P47) or the Pfs47 monomer (P47/P47). Purified IgG from VLP-P47/P47 mice had strong TRA (83–98%) at concentrations as low as 5 μg/mL. These results indicate that conjugating the Pfs47 antigen to AP205-VLP significantly enhanced antigenicity and confirm the potential of Pfs47 as a TBV candidate.

scholarly journals Malaria vaccine candidates displayed on novel virus-like particles are immunogenic and induce transmission-blocking activity

2019 ◽  
Author(s):  
Jo-Anne Chan ◽  
David Wetzel ◽  
Linda Reiling ◽  
Kazutoyo Miura ◽  
Damien Drew ◽  
...  
Keyword(s):  
Malaria Vaccine ◽  
Vaccine Development ◽  
Transmission Blocking ◽  
Vaccine Candidates ◽  
Virus Like Particles ◽  
Malaria Vaccines ◽  
Membrane Feeding ◽  
B Virus ◽  
Vaccine Antigens ◽  
Novel Virus

ABSTRACTThe development of effective malaria vaccines remains a global health priority. Currently, the most advanced vaccine, known as RTS,S, has only shown modest efficacy in clinical trials. Thus, the development of more efficacious vaccines by improving the formulation of RTS,S for increased efficacy or to interrupt malaria transmission are urgently needed. The RTS,S vaccine is based on the presentation of a fragment of the sporozoite antigen on the surface of virus-like particles (VLPs) based on human hepatitis B virus (HBV). In this study, we have developed and evaluated a novel VLP platform based on duck HBV (known as Metavax) for malaria vaccine development. This platform can incorporate large and complex proteins into VLPs and is produced in a Hansenula cell line compatible with cGMP vaccine production. Here, we have established the expression of leading P. falciparum malaria vaccine candidates as VLPs. This includes Pfs230 and Pfs25, which are candidate transmission-blocking vaccine antigens. We demonstrated that the VLPs effectively induce antibodies to malaria vaccine candidates with minimal induction of antibodies to the duck-HBV scaffold antigen. Antibodies to Pfs230 also recognised native protein on the surface of gametocytes, and antibodies to both Pfs230 and Pfs25 demonstrated transmission-reducing activity in standard membrane feeding assays. These results establish the potential utility of this VLP platform for malaria vaccines, which may be suitable for the development of multi-component vaccines that achieve high vaccine efficacy and transmission-blocking immunity.

Plasmodium falciparum Pf77 and male development gene 1 as vaccine antigens that induce potent transmission-reducing antibodies

2021 ◽  
Vol 13 (597) ◽  
pp. eabg2112
Author(s):  
Abhai K. Tripathi ◽  
Miranda S. Oakley ◽  
Nitin Verma ◽  
Godfree Mlambo ◽  
Hong Zheng ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Phase 1 ◽  
Biological Properties ◽  
Natural Immunity ◽  
Specific Expression ◽  
Transmission Blocking ◽  
Male Development ◽  
Malaria Vaccines ◽  
Membrane Feeding ◽  
Vaccine Antigens

Malaria vaccines that disrupt the Plasmodium life cycle in mosquitoes and reduce parasite transmission in endemic areas are termed transmission-blocking vaccines (TBVs). Despite decades of research, there are only a few Plasmodium falciparum antigens that indisputably and reproducibly demonstrate transmission-blocking immunity. So far, only two TBV candidates have advanced to phase 1/2 clinical testing with limited success. By applying an unbiased transcriptomics-based approach, we have identified Pf77 and male development gene 1 (PfMDV-1) as two P. falciparum TBV antigens that, upon immunization, induced antibodies that caused reductions in oocyst counts in Anopheles mosquito midguts in a standard membrane feeding assay. In-depth studies were performed to characterize the genetic diversity of, stage-specific expression by, and natural immunity to these two molecules to evaluate their suitability as TBV candidates. Pf77 and PfMDV-1 display limited antigenic polymorphism, are pan-developmentally expressed within the parasite, and induce naturally occurring antibodies in Ghanaian adults, which raises the prospect of natural boosting of vaccine-induced immune response in endemic regions. Together, these biological properties suggest that Pf77 and PfMDV-1 may warrant further investigation as TBV candidates.

scholarly journals Monoclonal Antibody against the Plasmodium falciparum Chitinase, PfCHT1, Recognizes a Malaria Transmission-Blocking Epitope in Plasmodium gallinaceum Ookinetes Unrelated to the Chitinase PgCHT1

2002 ◽  
Vol 70 (3) ◽  
pp. 1581-1590 ◽  
Author(s):  
Rebecca C. Langer ◽  
Fengwu Li ◽  
Vsevolod Popov ◽  
Alexander Kurosky ◽  
Joseph M. Vinetz
Keyword(s):  
Monoclonal Antibody ◽  
Plasmodium Falciparum ◽  
Synthetic Peptide ◽  
Transmission Blocking ◽  
Reducing Conditions ◽  
Membrane Feeding ◽  
Epithelial Cell Surface ◽  
A Subunit ◽  
35 Kda Protein ◽  
Homologous Amino Acid

ABSTRACT To initiate invasion of the mosquito midgut, Plasmodium ookinetes secrete chitinases that are necessary to cross the chitin-containing peritrophic matrix en route to invading the epithelial cell surface. To investigate chitinases as potential immunological targets of blocking malaria parasite transmission to mosquitoes, a monoclonal antibody (MAb) was identified that neutralized the enzymatic activity of the sole chitinase of Plasmodium falciparum, PfCHT1, identified to date. This MAb, designated 1C3, previously shown to react with an apical structure of P. falciparum ookinetes, also reacts with a discrete apical structure of P. gallinaceum ookinetes. In membrane feeding assays, MAb 1C3 markedly inhibited P. gallinaceum oocyst development in mosquito midguts. MAb 1C3 affinity isolated an ∼210-kDa antigen which, under reducing conditions, became a 35-kDa antigen. This isolated 35-kDa protein cross-reacted with an antiserum raised against a synthetic peptide derived from the P. gallinaceum chitinase active site, PgCHT1, even though MAb 1C3 did not recognize native or recombinant PgCHT1 on Western blot. Therefore, this affinity-purified 35-kDa antigen appears similar to a previously identified protein, PgCHT2, a putative second chitinase of P. gallinaceum. Epitope mapping indicated MAb 1C3 recognized a region of PfCHT1 that diverges from a homologous amino acid sequence conserved within sequenced chitinases of P. berghei, P. yoelii, and P. gallinaceum (PgCHT1). A synthetic peptide derived from the mapped 1C3 epitope may be useful as a component of a subunit transmission-blocking vaccine.

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