scholarly journals Evaluation of a Plasmodium-Specific Carrier Protein To Enhance Production of Recombinant Pfs25, a Leading Transmission-Blocking Vaccine Candidate

2017 ◽  
Vol 86 (1) ◽  
Author(s):  
Elizabeth M. Parzych ◽  
Kazutoyo Miura ◽  
Aarti Ramanathan ◽  
Carole A. Long ◽  
James M. Burns

ABSTRACTChallenges with the production and suboptimal immunogenicity of malaria vaccine candidates have slowed the development of aPlasmodium falciparummultiantigen vaccine. Attempting to resolve these issues, we focused on the use of highly immunogenic merozoite surface protein 8 (MSP8) as a vaccine carrier protein. Previously, we showed that a genetic fusion of the C-terminal 19-kDa fragment of merozoite surface protein 1 (MSP119) toP. falciparumMSP8 (PfMSP8) facilitated antigen production and folding and the induction of neutralizing antibodies to conformational B cell epitopes of MSP119. Here, using thePfMSP1/8 construct, we further optimized the recombinantPfMSP8 (rPfMSP8) carrier by the introduction of two cysteine-to-serine substitutions (CΔS) to improve the yield of the monomeric product. We then sought to test the broad applicability of this approach using the transmission-blocking vaccine candidatePfs25. The production of rPfs25-based vaccines has presented challenges. Antibodies directed against the four highly constrained epidermal growth factor (EGF)-like domains ofPfs25 block sexual-stage development in mosquitoes. The sequence encoding maturePfs25 was codon harmonized for expression inEscherichia coli. We produced a rPfs25-PfMSP8 fusion protein [rPfs25/8(CΔS)] as well as unfused, mature rPfs25. rPfs25 was purified with a modest yield but required the incorporation of refolding protocols to obtain a proper conformation. In comparison, chimeric rPfs25/8(CΔS) was expressed and easily purified, with thePfs25 domain bearing the proper conformation without renaturation. Both antigens were immunogenic in rabbits, inducing IgG that bound nativePfs25 and exhibited potent transmission-reducing activity. These data further demonstrate the utility ofPfMSP8 as a parasite-specific carrier protein to enhance the production of complex malaria vaccine targets.

2015 ◽  
Vol 83 (5) ◽  
pp. 1799-1808 ◽  
Author(s):  
Kailash P. Patra ◽  
Fengwu Li ◽  
Darrick Carter ◽  
James A. Gregory ◽  
Sheyenne Baga ◽  
...  

A vaccine to prevent the transmission of malaria parasites from infected humans to mosquitoes is an important component for the elimination of malaria in the 21st century, yet it remains neglected as a priority of malaria vaccine development. The lead candidate forPlasmodium falciparumtransmission-blocking vaccine development, Pfs25, is a sexual stage surface protein that has been produced for vaccine testing in a variety of heterologous expression systems. Any realistic malaria vaccine will need to optimize proper folding balanced against cost of production, yield, and potentially reactogenic contaminants. HereChlamydomonas reinhardtiimicroalga-produced recombinant Pfs25 protein was formulated with four different human-compatible adjuvants (alum, Toll-like receptor 4 [TLR-4] agonist glucopyranosal lipid A [GLA] plus alum, squalene–oil-in-water emulsion, and GLA plus squalene–oil-in-water emulsion) and compared for their ability to induce malaria transmission-blocking antibodies. Alga-produced recombinant Pfs25 plus GLA plus squalene–oil-in-water adjuvant induced the highest titer and avidity in IgG antibodies, measured using alga-produced recombinant Pfs25 as the enzyme-linked immunosorbent assay (ELISA) antigen. These antibodies specifically reacted with the surface ofP. falciparummacrogametes and zygotes and effectively prevented parasites from developing within the mosquito vector in standard membrane feeding assays. Alga-produced Pfs25 in combination with a human-compatible adjuvant composed of a TLR-4 agonist in a squalene–oil-in-water emulsion is an attractive new vaccine candidate that merits head-to-head comparison with other modalities of vaccine production and administration.


2018 ◽  
Vol 86 (8) ◽  
Author(s):  
Arunaditya Deshmukh ◽  
Bishwanath Kumar Chourasia ◽  
Sonali Mehrotra ◽  
Ikhlaq Hussain Kana ◽  
Gourab Paul ◽  
...  

ABSTRACTPlasmodium falciparummerozoite surface protein 3 (MSP3) is an abundantly expressed secreted merozoite surface protein and a leading malaria vaccine candidate antigen. However, it is unclear how MSP3 is retained on the surface of merozoites without a glycosylphosphatidylinositol (GPI) anchor or a transmembrane domain. In the present study, we identified an MSP3-associated network on thePlasmodiummerozoite surface by immunoprecipitation ofPlasmodiummerozoite lysate using antibody to the N terminus of MSP3 (anti-MSP3N) followed by mass spectrometry analysis. The results suggested the association of MSP3 with other merozoite surface proteins: MSP1, MSP6, MSP7, RAP2, and SERA5. Protein-protein interaction studies by enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR) analysis showed that MSP3 complex consists of MSP1, MSP6, and MSP7 proteins. Immunological characterization of MSP3 revealed that MSP3N is strongly recognized by hyperimmune serum from African and Asian populations. Furthermore, we demonstrate that human antibodies, affinity purified against recombinant MSP3N (rMSP3N), promote opsonic phagocytosis of merozoites in cooperation with monocytes. At nonphysiological concentrations, anti-MSP3N antibodies inhibited the growth ofP. falciparum in vitro. Together, the data suggest that MSP3 and especially its N-terminal region containing known B/T cell epitopes are targets of naturally acquired immunity against malaria and also comprise an important candidate for a multisubunit malaria vaccine.


2000 ◽  
Vol 68 (5) ◽  
pp. 3019-3022 ◽  
Author(s):  
Peter Vukovic ◽  
P. Mark Hogarth ◽  
Nadine Barnes ◽  
David C. Kaslow ◽  
Michael F. Good

ABSTRACT Merozoite surface protein 1 (MSP-119) is a leading malaria vaccine candidate. Specific antibodies contribute to immunity; binding to macrophages is believed to represent the main action of malaria antibodies. We show that an MSP-119-specific immunoglobulin G3 (IgG3) monoclonal antibody can passively transfer protection to mice deficient in the α chain of Fc-γRI whose macrophages cannot bind IgG3.


2011 ◽  
Vol 18 (8) ◽  
pp. 1343-1350 ◽  
Author(s):  
Mayumi Tachibana ◽  
Yimin Wu ◽  
Hideyuki Iriko ◽  
Olga Muratova ◽  
Nicholas J. MacDonald ◽  
...  

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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