Structural delineation of potent transmission-blocking epitope I on malaria antigen Pfs48/45

Kundu, Prasun; Semesi, A.; Jore, Matthijs M.; Morin, Merribeth J.; Price, Virginia L.; Liang, Alexandria Deliz; Li, J.; Miura, Kazutoyo; Sauerwein, Robert W.; King, C. Richter; Julien, Jean-Philippe

doi:10.1038/s41467-018-06742-9

Cited by 55 publications

(82 citation statements)

References 58 publications

(62 reference statements)

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“…On the other hand, N299 was found not to be glycosylated with the side chain of N299 involved in H bonding with S301. These two N-glycosylation sites (N299 and N303) are not directly involved in the binding of 6C to 85RF45.1, but the results reported here, together with Kundu et al, suggest that amino acid sequence at these sites can play important roles in the proper folding of 6C 16 . While the glycosylation at these sites are not expected to occur in the parasite, our results also suggest that mutation of the primary sequence may also disturb higher order structure.…”

Section: Discussioncontrasting

confidence: 47%

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A C-terminal Pfs48/45 malaria transmission-blocking vaccine candidate produced in the baculovirus expression system

Lee

Hickey

Miura

et al. 2020

Sci Rep

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the Plasmodium falciparum gametocyte surface protein, Pfs48/45, is a potential target for malaria transmission-blocking vaccines. However, due to its size and complexity, expression of the fulllength protein has been difficult, leading to focus on the C-terminal six cysteine domain (6C) with the use of fusion proteins to facilitate expression and folding. in this study, we utilized the baculovirus system to evaluate the expression of three Pfs48/45 proteins including the full-length protein, the 6C domain fragment and the 6C domain mutant to prevent glycosylation. Expression of the recombinant Pfs48/45 proteins was conducted in super Sf9 cells combined with the use of tunicamycin to prevent Nglycosylation. the proteins were then evaluated as immunogens in mice to demonstrate the induction of functionally active polyclonal antibody responses as measured in the standard membrane feeding assay (SMFA). Only the 6C protein was found to exhibit significant transmission-reducing activity. Further characterization of the biologically active 6C protein demonstrated it was homogeneous in terms of size, charge, conformation, absence of glycosylation, and containing proper disulfide bond pairings. this study presents an alternative expression system, without the need of a fusion protein partner, for the Pfs48/45 6C protein fragment including further evaluation as a potential transmissionblocking vaccine candidate.Malaria transmission-blocking vaccines (TBVs) are being evaluated for their potential to serve as a supplemental tool to accelerate the elimination of malaria. TBVs function via the induction of antibodies that block the fertilization or the penetration of the mosquito midgut by sexual stage parasite, thereby breaking the cycle of parasite transmission between human and mosquito hosts 1-3 . Several sexual stage antigens (e.g., Pfs25, Pfs230 and Pfs48/45) have been identified as promising TBV targets for research or early stage clinical development. In clinical testing, Pfs25, when delivered as nanoparticles 4 , induced functional antibodies. However, the responses were of low magnitude and short-lived 5,6 . In recent years, development attention has shifted to the TBV candidates Pfs230 and Pfs48/45 in view of the poor outcomes associated with Pfs25-based constructs and the fact that sera from Plasmodium infected individuals are associated with transmission-blocking antibodies attributable to these gametocyte surface antigens 7 . Moreover, affinity purified anti-Pfs48/45 and anti-Pfs230 antibodies from naturally exposed individuals can prevent the transmission of cultured P. falciparum gametocytes 8 , when concentrated nine times the physiological concentration, thereby demonstrating the functionality of these natural antibody responses and the potential for these antigens in TBV development.While the preclinical 9-11 and clinical (NCT 02942277) development of Pfs230 is in progress, the development of Pfs48/45 as a TBV candidate has remained challenging. The Pfs48/45 protein, expressed on the surface of gametocyte, s...

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Section: Discussioncontrasting

confidence: 47%

“…In recent studies, Kundu et al cloned the 6C fragment in HEK 293 cells without genetic modification of the N-glycosylation sites, N299 and N303, and the resulting crystal structure revealed that N303 is indeed 16 . After EndoH treatment, the N-acetylglucosamine attached to N303 forms H-bonds with D390 and D391 of the 6C molecule.…”

Section: Discussionmentioning

confidence: 99%

A C-terminal Pfs48/45 malaria transmission-blocking vaccine candidate produced in the baculovirus expression system

Lee

Hickey

Miura

et al. 2020

Sci Rep

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“…One of the main features of the SpyTag/SpyCatcher technology is the possibility to orientate the antigen on the VLP surface to expose the functional epitopes, which leads to the generation of a better quality of response (22). Recent progresses in the malaria-TBV field unrevealed structures and mapped epitopes of important antigen candidates that had remained elusive for long time (42)(43)(44). The combination of the new insights into the structure of these antigens, including Pfs25, and the possibility to specifically orientate them on HBsAg::SpyCatcher, offers a unique advantage in the design of novel vaccine candidates.…”

Section: Discussionmentioning

confidence: 99%

A Universal Plug-and-Display Vaccine Carrier Based on HBsAg VLP to Maximize Effective Antibody Response

Marini

Zhou

et al. 2019

Front. Immunol.

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Development of effective malaria vaccines requires delivery platforms to enhance the immunogenicity and efficacy of the target antigens. This is particularly challenging for transmission-blocking malaria vaccines (TBVs), and specifically for those based on the Pfs25 antigen, that need to elicit very high antibody titers to stop the parasite development in the mosquito host and its transmission. Presenting antigens to the immune system on virus-like particles (VLPs) is an efficient way to improve the quantity and quality of the immune response generated. Here we introduce for the first time a new VLP vaccine platform, based on the well-established hepatitis B surface antigen (HBsAg) fused to the SpyCatcher protein, so that the antigen of interest, linked to the SpyTag peptide, can be easily displayed on it (Plug-and-Display technology). As little as 10% of the SpyCatcher::HBsAg VLPs decorated with Pfs25::SpyTag (molar ratio) induces a higher antibody response and transmission-reducing activity in mice compared to the soluble protein, with 50 and 90% of the VLP coupled to the antigen further enhancing the response. Importantly, using this carrier that is a vaccine antigen itself could be beneficial, as we show that anti-HBsAg IgG antibodies are induced without interfering with the Pfs25-specific immune response generated. Furthermore, pre-existing anti-HBsAg immunity does not affect the antigen-specific response to Pfs25::SpyTag-SpyCatcher::HBsAg, suggesting that these VLPs can have a broad use as a vaccine platform.

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“…Within this family of Pfs230-like proteins, structures have been resolved for two members, which form a complex with an unknown function, Pf12 17 , 18 and Pf41 19 . Recently, the carboxyl-terminal cysteine-rich domain of Pfs48/45, identified as 6C, was cocrystalized with a TB mAb, which may aid in future vaccine design of a Pfs48/45 immunogen 20 , 21 . Pfs230 is expressed in both male and female gametocytes without a known membrane anchor and appears on the surface of gametes as a complex with Pfs48/45 22 , a glycosylphosphatidylinositol (GPI) anchored protein 23 .…”

Section: Introductionmentioning

confidence: 99%

Structure and function of a malaria transmission blocking vaccine targeting Pfs230 and Pfs230-Pfs48/45 proteins

et al. 2020

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Proteins Pfs230 and Pfs48/45 are Plasmodium falciparum transmission-blocking (TB) vaccine candidates that form a membrane-bound protein complex on gametes. The biological role of Pfs230 or the Pfs230-Pfs48/45 complex remains poorly understood. Here, we present the crystal structure of recombinant Pfs230 domain 1 (Pfs230D1M), a 6-cysteine domain, in complex with the Fab fragment of a TB monoclonal antibody (mAb) 4F12. We observed the arrangement of Pfs230 on the surface of macrogametes differed from that on microgametes, and that Pfs230, with no known membrane anchor, may exist on the membrane surface in the absence of Pfs48/45. 4F12 appears to sterically interfere with Pfs230 function. Combining mAbs against different epitopes of Pfs230D1 or of Pfs230D1 and Pfs48/45, significantly increased TB activity. These studies elucidate a mechanism of action of the Pfs230D1 vaccine, model the functional activity induced by a polyclonal antibody response and support the development of TB vaccines targeting Pfs230D1 and Pfs230D1-Pfs48/45.

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Structural delineation of potent transmission-blocking epitope I on malaria antigen Pfs48/45

Cited by 55 publications

References 58 publications

A C-terminal Pfs48/45 malaria transmission-blocking vaccine candidate produced in the baculovirus expression system

A C-terminal Pfs48/45 malaria transmission-blocking vaccine candidate produced in the baculovirus expression system

A Universal Plug-and-Display Vaccine Carrier Based on HBsAg VLP to Maximize Effective Antibody Response

Structure and function of a malaria transmission blocking vaccine targeting Pfs230 and Pfs230-Pfs48/45 proteins

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