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

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.

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

Scientific Reports ◽

10.1038/s41598-019-53208-z ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 4

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.

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Induction of Plasmodium falciparum Transmission-Blocking Antibodies in Nonhuman Primates by a Combination of DNA and Protein Immunizations

Infection and Immunity ◽

10.1128/iai.72.1.253-259.2004 ◽

2004 ◽

Vol 72 (1) ◽

pp. 253-259 ◽

Cited By ~ 43

Author(s):

Cevayir Coban ◽

Mario T. Philipp ◽

Jeanette E. Purcell ◽

David B. Keister ◽

Mobolaji Okulate ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Antibody Response ◽

Dna Vaccine ◽

Nonhuman Primates ◽

Rhesus Macaques ◽

Surface Protein ◽

Mosquito Vector ◽

Transmission Blocking ◽

Membrane Feeding ◽

Antibody Titers

ABSTRACT Malaria transmission-blocking vaccination can effectively reduce and/or eliminate transmission of parasites from the human host to the mosquito vector. The immunity achieved by inducing an antibody response to surface antigens of male and female gametes and parasite stages in the mosquito. Our laboratory has developed DNA vaccine constructs, based on Pfs25 (a Plasmodium falciparum surface protein of 25 kDa), that induce a transmission-blocking immune response in mice (C. A. Lobo, R. Dhar, and N. Kumar, Infect. Immun. 67:1688-1693, 1999). To evaluate the safety, immunogenicity, and efficacy of the Pfs25 DNA vaccine in nonhuman primates, we immunized rhesus macaques (Macaca mulatta) with a DNA vaccine plasmid encoding Pfs25 or a Pfg27-Pfs25 hybrid or with the plasmid (empty plasmid) alone. Immunization with four doses of these DNA vaccine constructs elicited antibody titers that were high but nonetheless unable to reduce the parasite's infectivity in membrane feeding assays. Further boosting of the antibody response with recombinant Pfs25 formulated in Montanide ISA-720 increased antibody titers (30-fold) and significantly blocked transmission of P. falciparum gametocytes to Anopheles mosquitoes (∼90% reduction in oocyst numbers in the midgut). Our data show that a DNA prime-protein boost regimen holds promise for achieving transmission-blocking immunity in areas where malaria is endemic and could be effective in eradicating malaria in isolated areas where the level of malaria endemicity is low.

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

Parasites & Vectors ◽

10.1186/s13071-021-04909-w ◽

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

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Malaria transmission-blocking conjugate vaccine in ALFQ adjuvant induces durable functional immune responses in rhesus macaques

npj Vaccines ◽

10.1038/s41541-021-00407-3 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Puthupparampil V. Scaria ◽

Charles Anderson ◽

Olga Muratova ◽

Nada Alani ◽

Hung V. Trinh ◽

...

Keyword(s):

Immune Responses ◽

Malaria Transmission ◽

Functional Activity ◽

Rhesus Macaques ◽

Transmission Blocking ◽

Tlr4 Agonist ◽

Functional Immunity ◽

Antibody Levels ◽

Transmission Blocking Vaccines ◽

Better Than

AbstractMalaria transmission-blocking vaccines candidates based on Pfs25 and Pfs230 have advanced to clinical studies. Exoprotein A (EPA) conjugate of Pfs25 in Alhydrogel® developed functional immunity in humans, with limited durability. Pfs230 conjugated to EPA (Pfs230D1-EPA) with liposomal adjuvant AS01 is currently in clinical trials in Mali. Studies with these conjugates revealed that non-human primates are better than mice to recapitulate the human immunogenicity and functional activity. Here, we evaluated the effect of ALFQ, a liposomal adjuvant consisting of TLR4 agonist and QS21, on the immunogenicity of Pfs25-EPA and Pfs230D1-EPA in Rhesus macaques. Both conjugates generated strong antibody responses and functional activity after two vaccinations though activity declined rapidly. A third vaccination of Pfs230D1-EPA induced functional activity lasting at least 9 months. Antibody avidity increased with each vaccination and correlated strongly with functional activity. IgG subclass analysis showed induction of Th1 and Th2 subclass antibody levels that correlated with activity.

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N-Terminal Prodomain of Pfs230 Synthesized Using a Cell-Free System Is Sufficient To Induce Complement-Dependent Malaria Transmission-Blocking Activity

Clinical and Vaccine Immunology ◽

10.1128/cvi.05104-11 ◽

2011 ◽

Vol 18 (8) ◽

pp. 1343-1350 ◽

Cited By ~ 49

Author(s):

Mayumi Tachibana ◽

Yimin Wu ◽

Hideyuki Iriko ◽

Olga Muratova ◽

Nicholas J. MacDonald ◽

...

Keyword(s):

Malaria Transmission ◽

Expression System ◽

Surface Protein ◽

Western Blot Assay ◽

Free System ◽

Transmission Blocking ◽

Content Type ◽

Membrane Feeding ◽

Blocking Activity ◽

Transmission Blocking Vaccine

ABSTRACTThe aim of a malaria transmission-blocking vaccine is to block the development of malaria parasites in the mosquito and thus prevent subsequent infection of the human host. Previous studies have demonstrated that the gametocyte/gamete surface protein Pfs230 can induce transmission-blocking immunity and have evaluatedEscherichia coli-produced Pfs230 as a transmission-blocking vaccine candidate. In this study, we used the wheat germ cell-free expression system to produce N-terminal fragments of Pfs230 and evaluated the transmission-blocking activity of antisera raised against the recombinant Pfs230 protein. The rabbit antisera reacted to the surface of cultured gametocytes and gametes of thePlasmodium falciparumNF54 line, recognized the 360-kDa form of parasite-produced Pfs230 by Western blot assay, and reduced the infectivity of NF54 parasites toAnopheles stefensimosquitoes in the presence of complement in a standard membrane feeding assay. Thus, our data demonstrate that the N-terminal pro domain of Pfs230 is sufficient to induce complement-dependent transmission-blocking activity againstP. falciparum.

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Elucidating functional epitopes within the N-terminal region of malaria transmission blocking vaccine antigen Pfs230

npj Vaccines ◽

10.1038/s41541-021-00423-3 ◽

2022 ◽

Vol 7 (1) ◽

Author(s):

Kazutoyo Miura ◽

Eizo Takashima ◽

Thao P. Pham ◽

Bingbing Deng ◽

Luwen Zhou ◽

...

Keyword(s):

Malaria Transmission ◽

Synthetic Peptide ◽

Vaccine Antigen ◽

Parasite Development ◽

Transmission Blocking ◽

Peptide Antigens ◽

Membrane Feeding ◽

Functional Antibodies ◽

Enrichment Techniques ◽

Transmission Blocking Vaccine

AbstractPfs230 is a leading malaria transmission blocking vaccine (TBV) candidate. Comprising 3135 amino acids (aa), the large size of Pfs230 necessitates the use of sub-fragments as vaccine immunogens. Therefore, determination of which regions induce functional antibody responses is essential. We previously reported that of 27 sub-fragments spanning the entire molecule, only five induced functional antibodies. A “functional” antibody is defined herein as one that inhibits Plasmodium falciparum parasite development in mosquitoes in a standard membrane-feeding assay (SMFA). These five sub-fragments were found within the aa 443–1274 range, and all contained aa 543–730. Here, we further pinpoint the location of epitopes within Pfs230 that are recognized by functional antibodies using antibody depletion and enrichment techniques. Functional epitopes were not found within the aa 918–1274 region. Within aa 443–917, further analysis showed the existence of functional epitopes not only within the aa 543–730 region but also outside of it. Affinity-purified antibodies using a synthetic peptide matching aa 543–588 showed activity in the SMFA. Immunization with a synthetic peptide comprising this segment, formulated either as a carrier-protein conjugate vaccine or with a liposomal vaccine adjuvant system, induced antibodies in mice that were functional in the SMFA. These findings provide key insights for Pfs230-based vaccine design and establish the feasibility for the use of synthetic peptide antigens for a malaria TBV.

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

10.21203/rs.3.rs-373830/v1 ◽

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.

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A Region of Plasmodium falciparumAntigen Pfs25 That Is the Target of Highly Potent Transmission-Blocking Antibodies

Infection and Immunity ◽

10.1128/iai.68.10.5530-5538.2000 ◽

2000 ◽

Vol 68 (10) ◽

pp. 5530-5538 ◽

Cited By ~ 34

Author(s):

Anthony W. Stowers ◽

David B. Keister ◽

Olga Muratova ◽

David C. Kaslow

Keyword(s):

Antibody Response ◽

Sexual Stage ◽

Transmission Blocking ◽

Vaccination Strategies ◽

Membrane Feeding ◽

Blocking Activity ◽

Antibody Titers ◽

Epidermal Growth ◽

Blocking Antibodies ◽

Transmission Blocking Vaccines

ABSTRACT Each of the four epidermal growth factor (EGF)-like domains of thePlasmodium falciparum sexual-stage antigen Pfs25 has been individually expressed as a yeast-secreted recombinant protein (yEGF1 through yEGF4). All four are recognized by the immune sera of animals and humans vaccinated with TBV25H (the corresponding yeast-secreted full-length recombinant form of Pfs25), with antibody titers to yEGF1 and yEGF2 weakly correlating with the ability of the sera to block the transmission of parasites to the mosquito host. All four proteins are poorly immunogenic in mice vaccinated with aluminum hydroxide-absorbed formulations. However, all four successfully primed the mice to mount an effective secondary antibody response after a single boost with TBV25H. Sera from mice vaccinated with yEGF2-TBV25H completely block the development of oocysts in mosquito midguts in membrane-feeding assays. Further, of the four proteins, only the depletion of antibodies to yEGF2 from the sera of rabbits vaccinated with TBV25H consistently abolished the ability of those sera to block oocyst development. Thus, antibodies to the second EGF-like domain of Pfs25 appear to mediate a very potent blocking activity, even at low titers. Vaccination strategies that target antibody response towards this domain may improve the efficacy of future transmission-blocking vaccines.

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