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

2000 ◽  
Vol 68 (10) ◽  
pp. 5530-5538 ◽  
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.

Evaluation of Two Sexual-stage Antigens as Bivalent Transmission-blocking Vaccines in Rodent Malaria

2021 ◽  
Author(s):  
Fan Yang ◽  
Fei Liu ◽  
Xinxin Yu ◽  
Wenqi Zheng ◽  
Yudi Wu ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Chimeric Protein ◽  
Transmission Blocking ◽  
Native Proteins ◽  
Blocking Activity ◽  
Antibody Titers ◽  
Sexual Stages ◽  
Transmission Blocking Vaccines

Abstract Background: Transmission-blocking vaccine (TBV) is a promising strategy for malaria elimination. It is hypothesized that mixing or fusing two antigens targeting different stages of sexual development may provide higher transmission-blocking activity than these antigens are used individually.Methods: We designed a chimeric protein composed of fragments of Pbg37 and PSOP25 and expressed the recombinant protein in Escherichia coli Rosetta-gami B (DE3). After immunizing mice with mixing or fusing recombinant proteins, the antibody titers of sera were analyzed by ELISA. IFA and Western blot were performed to test the reactivity of the antisera with the native proteins of the parasite. The transmission blocking activity were assessed in vitro and in vivo assay. Results: When Pbg37 and PSOP25 were co-administered in a mixture or as a fusion protein, they elicited similar antibody responses in mice as single antigens without causing immunological interference with each other. Antibodies against the mixed or fused antigens recognized the target proteins in the gametocyte, gamete, zygote and ookinete stages. The two bivalent vaccines (mixed proteins or a fusion protein) produced the superior TBA compared to that of the antibodies against individual antigens.Conclusions: There was no immunological interference between the two antigens of bivalent vaccines. And the bivalent vaccines produced significantly stronger transmission-blocking activities than single antigens. Altogether, these data provide the theoretical basis for the development of combination TBVs targeting different sexual stages.

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

2004 ◽  
Vol 72 (1) ◽  
pp. 253-259 ◽  
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.

scholarly journals Restricted or absent immune responses in human populations to Plasmodium falciparum gamete antigens that are targets of malaria transmission-blocking antibodies.

1989 ◽  
Vol 169 (1) ◽  
pp. 135-147 ◽  
Author(s):  
R Carter ◽  
P M Graves ◽  
I A Quakyi ◽  
M F Good
Keyword(s):  
Immune Response ◽  
Plasmodium Falciparum ◽  
Antibody Response ◽  
Malaria Transmission ◽  
Surface Antigens ◽  
Surface Proteins ◽  
Human Populations ◽  
Sexual Stage ◽  
Transmission Blocking ◽  
Blocking Antibodies

We have studied the antibodies to sexual stage antigens of Plasmodium falciparum in human sera from Papua New Guinea where intense transmission of P. falciparum occurs as well as the less prevalent P. malariae and P. vivax. In extracts of gametes of P. falciparum we have studied the reactivity of serum antibodies with antigens labeled with 125I on the surface of the gametes as well as intracellular gamete antigens. A prominent 27-kD sexual stage-specific intracellular protein was recognized more or less in proportion to the general antibody response to gamete proteins. The response to the gamete surface proteins, however, was quite unrepresentative of the general antibody response to the intracellular gamete proteins. No antibodies were detected against Pfs25, a 21-kD protein expressed on zygotes and ookinetes of P. falciparum and known to be a sensitive target of malaria transmission-blocking antibodies. The antibody response to two other target antigens of transmission-blocking antibodies on the surface of gametes of P. falciparum, a 230- and a 48- and 45-kD protein doublet, was very variable and independent of the response to the internal protein antigens. Several possibilities are discussed that may account for the variable response to these gamete surface antigens in individuals with otherwise good antibody responses to internal sexual stage proteins. Among these is the possibility that there is MHC restriction of the immune response to the gamete surface antigens in the human population. This interpretation accords well with evidence for MHC-restricted immune response to the same P. falciparum gamete surface antigens in studies with H-2 congenic mice (24).

scholarly journals Evaluation of two sexual-stage antigens as bivalent transmission-blocking vaccines in rodent malaria

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Fan Yang ◽  
Fei Liu ◽  
Xinxin Yu ◽  
Wenqi Zheng ◽  
Yudi Wu ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Sexual Development ◽  
Chimeric Protein ◽  
Transmission Blocking ◽  
Native Proteins ◽  
Blocking Activity ◽  
Antibody Titers ◽  
Blocking Antibodies

Abstract Background Transmission-blocking vaccine (TBV) is a promising strategy for malaria elimination. It is hypothesized that mixing or fusing two antigens targeting different stages of sexual development may provide higher transmission-blocking activity than these antigens used individually. Methods A chimeric protein composed of fragments of Pbg37 and PSOP25 was designed and expressed the recombinant protein in Escherichia coli Rosetta-gami B (DE3). After immunizing mice with individual recombinant proteins Pbg37 and PSOP25, mixed proteins (Pbg37+PSOP25), or the fusion protein (Pbg37-PSOP25), the antibody titers of individual sera were analyzed by ELISA. IFA and Western blot were performed to test the reactivity of the antisera with the native proteins in the parasite. The transmission-blocking activity of the different immunization schemes was assessed using in vitro and in vivo assays. Results When Pbg37 and PSOP25 were co-administered in a mixture or as a fusion protein, they elicited similar antibody responses in mice as single antigens without causing immunological interference with each other. Antibodies against the mixed or fused antigens recognized the target proteins in the gametocyte, gamete, zygote, and ookinete stages. The mixed proteins or the fusion protein induced antibodies with significantly stronger transmission-reducing activities in vitro and in vivo than individual antigens. Conclusions There was no immunological interference between Pbg37 and PSOP25. The bivalent vaccines, which expand the portion of the sexual development during which the transmission-blocking antibodies act, produced significantly stronger transmission-reducing activities than single antigens. Altogether, these data provide the theoretical basis for the development of combination TBVs targeting different sexual stages. Graphic Abstract

scholarly journals Saccharomyces cerevisiae-Secreted Fusion Proteins Pfs25 and Pfs28 Elicit Potent Plasmodium falciparum Transmission-Blocking Antibodies in Mice

1998 ◽  
Vol 66 (1) ◽  
pp. 59-64 ◽  
Author(s):  
Mary Margaret G. Gozar ◽  
Virginia L. Price ◽  
David C. Kaslow
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasmodium Falciparum ◽  
Fusion Proteins ◽  
Cell Epitope ◽  
Humoral Response ◽  
Chimeric Proteins ◽  
Transmission Blocking ◽  
Recombinant Fusion Proteins ◽  
Blocking Antibodies ◽  
Transmission Blocking Vaccines

ABSTRACT Transmission-blocking vaccines based on sexual-stage surface antigens of Plasmodium falciparum may assist in the control of this lethal form of human malaria. Two vaccine candidates, Pfs25 and Pfs28, were produced as single recombinant fusion proteins. The 39-kDa chimeric proteins, having a C-terminal His6 tag, were secreted by Saccharomyces cerevisiae, using the prepro-α-factor leader sequence. Pfs25-28 fusion proteins were significantly more potent than either Pfs25 or Pfs28 alone in eliciting antibodies in mice that blocked oocyst development in Anopheles freeborni mosquitoes: complete inhibition of oocyst development in the mosquito midgut was achieved with fewer vaccinations, at a lower dose, and for a longer duration than with either Pfs25 or Pfs28 alone. Increased antigen-specific immunoglobulin G titers and highly significant lymphoproliferative stimulation by Pfs28-containing antigens suggest the presence of an immunodominant helper T-cell epitope in the Pfs28 portion of the fusion proteins. This epitope may be responsible for the enhanced humoral response to both Pfs25 and Pfs28 antigens. Protein production of the fusion protein was improved 12-fold by converting Pfs28 codons to yeast-preferred codons (TBV28), using a modified ADH 2 promoter and incorporating a (Glu-Ala)2 repeat after the Kex2 cleavage site.

scholarly journals Pgs28 belongs to a family of epidermal growth factor-like antigens that are targets of malaria transmission-blocking antibodies.

1993 ◽  
Vol 177 (2) ◽  
pp. 505-510 ◽  
Author(s):  
P E Duffy ◽  
P Pimenta ◽  
D C Kaslow
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Signal Sequence ◽  
Surface Protein ◽  
Hydrophobic Region ◽  
Transmission Blocking ◽  
Epidermal Growth ◽  
Polyclonal Antisera ◽  
Blocking Antibodies

Although Pgs28, a 28-kD surface protein of Plasmodium gallinaceum oökinetes, was previously thought not to be a target of transmission-blocking antibodies, we found that polyclonal antisera to Pgs28 completely blocked parasite infectivity to Aedes aegypti mosquitoes. Antisera raised against reduced Pgs28 were less effective in blocking transmission than were antisera to nonreduced Pgs28; thus, the target epitope(s) of transmission-blocking antibodies appears to be conformation dependent. In stage-specific assays, polyclonal antisera impaired the in vitro transformation of zygotes to mature oökinetes, as well as the in vivo development of mature oökinetes to oöcysts. Using microsequence of immunoaffinity-purified Pgs28, we cloned the 666-bp open reading frame of the Pgs28 gene. The deduced amino acid sequence of Pgs28 is strikingly similar to that of a P. gallinaceum zygote surface protein, Pgs25, and its P. falciparum analogue, Pfs25. Pgs28, like Pgs25 and Pfs25, has a presumptive secretory signal sequence, followed by four epidermal growth factor-like domains, and a terminal hydrophobic region.

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

2011 ◽  
Vol 18 (8) ◽  
pp. 1343-1350 ◽  
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.

scholarly journals Transmission-Blocking Activities of Quinine, Primaquine, and Artesunate

2006 ◽  
Vol 50 (6) ◽  
pp. 1927-1930 ◽  
Author(s):  
Kesinee Chotivanich ◽  
Jetsumon Sattabongkot ◽  
Rachanee Udomsangpetch ◽  
Sornchai Looareesuwan ◽  
Nicholas P. J. Day ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Standard Deviation ◽  
Anopheles Dirus ◽  
Transmission Blocking ◽  
Transmission Potential ◽  
Membrane Feeding ◽  
Blocking Activity ◽  
The Mean ◽  
High Concentrations

ABSTRACT The infectivity of Plasmodium falciparum gametocytes after exposure in vitro to quinine, artesunate, and primaquine was assessed in Anopheles dirus, a major vector of malaria in Southeast Asia. Mature gametocytes (stage 5) of a Thai isolate of P. falciparum were exposed to the drugs for 24 h in vitro before membrane feeding to A. dirus. After 10 days, the mosquito midguts were dissected and the oocysts were counted. In this system, artesunate showed the most potent transmission-blocking activity; the mean (standard deviation [SD]) 50% and 90% effective concentrations (EC50, and EC90, respectively, in nanograms per milliliter) were 0.1 (0.02) and 0.4 (0.15), respectively. Transmission-blocking activity of quinine and primaquine was observed at relatively high concentrations (SDs): EC50 of quinine, 642 (111) ng/ml; EC50 of primaquine, 181 (23) ng/ml; EC90 of quinine, 816 (96) ng/ml; EC90 of primaquine, 543 (43) ng/ml. Artesunate both prevents the maturation of immature P. falciparum gametocytes and reduces the transmission potential of mature gametocytes. Both of these effects may contribute to reducing malaria transmission.

scholarly journals Monoclonal antibodies block transmission of genetically diverse Plasmodium falciparum strains to mosquitoes

npj Vaccines ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Roos M. de Jong ◽  
Lisette Meerstein-Kessel ◽  
Dari F. Da ◽  
Sandrine Nsango ◽  
Joseph D. Challenger ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Sexual Stage ◽  
Surface Binding ◽  
Subsequent Formation ◽  
Transmission Blocking ◽  
Block Transmission ◽  
Minor Sequence ◽  
Almost All ◽  
Blocking Antibodies ◽  
The Impact

AbstractMalaria parasite transmission to mosquitoes relies on the uptake of sexual stage parasites during a blood meal and subsequent formation of oocysts on the mosquito midgut wall. Transmission-blocking vaccines (TBVs) and monoclonal antibodies (mAbs) target sexual stage antigens to interrupt human-to-mosquito transmission and may form important tools for malaria elimination. Although most epitopes of these antigens are considered highly conserved, little is known about the impact of natural genetic diversity on the functional activity of transmission-blocking antibodies. Here we measured the efficacy of three mAbs against leading TBV candidates (Pfs48/45, Pfs25 and Pfs230) in transmission assays with parasites from naturally infected donors compared to their efficacy against the strain they were raised against (NF54). Transmission-reducing activity (TRA) was measured as reduction in mean oocyst intensity. mAb 45.1 (α-Pfs48/45) and mAb 4B7 (α-Pfs25) reduced transmission of field parasites from almost all donors with IC80 values similar to NF54. Sequencing of oocysts that survived high mAb concentrations did not suggest enrichment of escape genotypes. mAb 2A2 (α-Pfs230) only reduced transmission of parasites from a minority of the donors, suggesting that it targets a non-conserved epitope. Using six laboratory-adapted strains, we revealed that mutations in one Pfs230 domain correlate with mAb gamete surface binding and functional TRA. Our findings demonstrate that, despite the conserved nature of sexual stage antigens, minor sequence variation can significantly impact the efficacy of transmission-blocking mAbs. Since mAb 45.1 shows high potency against genetically diverse strains, our findings support its further clinical development and may inform Pfs48/45 vaccine design.

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