Rare and potent monoclonal antibodies (mAbs) against the Plasmodium falciparum (Pf) circumsporozoite protein (CSP) on infective sporozoites (SPZ) preferentially bind the PfCSP junctional tetrapeptide ...NPDP or NVDP minor repeats while cross-reacting with NANP central repeats in vitro. The extent to which each of these epitopes is required for protection in vivo is unknown. Here, we assessed whether junction-, minor repeat- and central repeat-preferring human mAbs (CIS43, L9 and 317 respectively) bound and protected against in vivo challenge with transgenic P. berghei (Pb) SPZ expressing either PfCSP with the junction and minor repeats knocked out (KO), or PbCSP with the junction and minor repeats knocked in (KI). In vivo protection studies showed that the junction and minor repeats are necessary and sufficient for CIS43 and L9 to neutralize KO and KI SPZ, respectively. In contrast, 317 required major repeats for in vivo protection. These data establish that human mAbs can prevent malaria infection by targeting three different protective epitopes (NPDP, NVDP, NANP) in the PfCSP repeat region. This report will inform vaccine development and the use of mAbs to passively prevent malaria.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Generating sufficient antibody to block infection is a key challenge for vaccines against malaria. Here, we show that antibody titers to a key target, the repeat region of the Plasmodium falciparum ...circumsporozoite protein (PfCSP), plateaued after two immunizations in a clinical trial of the radiation-attenuated sporozoite vaccine. To understand the mechanisms limiting vaccine responsiveness, we developed immunoglobulin (Ig)-knockin mice with elevated numbers of PfCSP-binding B cells. We determined that recall responses were inhibited by antibody feedback, potentially via epitope masking of the immunodominant PfCSP repeat region. Importantly, the amount of antibody that prevents boosting is below the amount of antibody required for protection. Finally, while antibody feedback limited responses to the PfCSP repeat region in vaccinated volunteers, potentially protective subdominant responses to PfCSP C-terminal regions expanded with subsequent boosts. These data suggest that antibody feedback drives the diversification of immune responses and that vaccination for malaria will require targeting multiple antigens.
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•Human antibody and B cell responses to a malaria vaccine plateau after 2 immunizations•Anti-CSP Ig-knockin mice developed to probe regulatory mechanisms•Antibody feedback via likely epitope masking limits immunodominant B cell responses•Repeated boosting diversifies the immune response as subdominant responses expand
McNamara et al. show that B cell responses to the immunodominant repeat region of the Plasmodium circumsporozoite protein plateau rapidly in humans. However, additional boosts allow subdominant responses to expand. Using a knockin mouse model, they show that these vaccine responses are regulated by antibody feedback via potential epitope masking.
The diversity of circulating human B cells is unknown. We use single-cell RNA sequencing (RNA-seq) to examine the diversity of both antigen-specific and total B cells in healthy subjects and ...malaria-exposed individuals. This reveals two B cell lineages: a classical lineage of activated and resting memory B cells and an alternative lineage, which includes previously described atypical B cells. Although atypical B cells have previously been associated with disease states, the alternative lineage is common in healthy controls, as well as malaria-exposed individuals. We further track Plasmodium-specific B cells after malaria vaccination in naive volunteers. We find that alternative lineage cells are primed after the initial immunization and respond to booster doses. However, alternative lineage cells develop an atypical phenotype with repeated boosts. The data highlight that atypical cells are part of a wider alternative lineage of B cells that are a normal component of healthy immune responses.
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•Single-cell RNA-seq reveals two distinct B cell lineages•An alternative lineage contains CXCR3+ and atypical B cells•Alternative B cells are primed after primary vaccination and respond to boosters•Alternative B cells adopt a more atypical phenotype following repeated antigen exposure
Using single-cell RNA sequencing, Sutton et al. show that a population of “atypical” B cells, normally associated with disease, are part of a wider landscape of alternative B cells that participate in normal responses to vaccination.
Discovering potent human monoclonal antibodies (mAbs) targeting the Plasmodium falciparum circumsporozoite protein (PfCSP) on sporozoites (SPZ) and elucidating their mechanisms of neutralization will ...facilitate translation for passive prophylaxis and aid next-generation vaccine development. Here, we isolated a neutralizing human mAb, L9 that preferentially bound NVDP minor repeats of PfCSP with high affinity while cross-reacting with NANP major repeats. L9 was more potent than six published neutralizing human PfCSP mAbs at mediating protection against mosquito bite challenge in mice. Isothermal titration calorimetry and multiphoton microscopy showed that L9 and the other most protective mAbs bound PfCSP with two binding events and mediated protection by killing SPZ in the liver and by preventing their egress from sinusoids and traversal of hepatocytes. This study defines the subdominant PfCSP minor repeats as neutralizing epitopes, identifies an in vitro biophysical correlate of SPZ neutralization, and demonstrates that the liver is an important site for antibodies to prevent malaria.
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•The subdominant NVDP minor repeats of PfCSP are neutralizing epitopes•Potent mAbs with junctional and NANP cross-reactivity bind PfCSP in two steps•Cytotoxic PfCSP mAbs kill sporozoites in the liver•PfCSP mAbs prevent sporozoites from exiting liver sinusoids to infect hepatocytes
Wang et al. isolate a potent neutralizing human mAb, L9 that preferentially binds NVDP minor repeats of Plasmodium falciparum circumsporozoite protein (PfCSP) on sporozoites with high affinity while cross-reacting with NANP major repeats. Their findings define the subdominant PfCSP minor repeats as neutralizing epitopes and demonstrate that the liver is an important site for antibodies to prevent malaria.
A Monoclonal Antibody for Malaria Prevention Gaudinski, Martin R; Berkowitz, Nina M; Idris, Azza H ...
The New England journal of medicine,
08/2021, Letnik:
385, Številka:
9
Journal Article
Recenzirano
Odprti dostop
Malaria remains a cause of substantial global morbidity and mortality. In this report, an engineered monoclonal antibody showed protection against malaria infection in a controlled human infection ...model.
Development of a highly effective vaccine or antibodies for the prevention and ultimately elimination of malaria is urgently needed. Here we report the isolation of a number of human monoclonal ...antibodies directed against the Plasmodium falciparum (Pf) circumsporozoite protein (PfCSP) from several subjects immunized with an attenuated Pf whole-sporozoite (SPZ) vaccine (Sanaria PfSPZ Vaccine). Passive transfer of one of these antibodies, monoclonal antibody CIS43, conferred high-level, sterile protection in two different mouse models of malaria infection. The affinity and stoichiometry of CIS43 binding to PfCSP indicate that there are two sequential multivalent binding events encompassing the repeat domain. The first binding event is to a unique 'junctional' epitope positioned between the N terminus and the central repeat domain of PfCSP. Moreover, CIS43 prevented proteolytic cleavage of PfCSP on PfSPZ. Analysis of crystal structures of the CIS43 antigen-binding fragment in complex with the junctional epitope determined the molecular interactions of binding, revealed the epitope's conformational flexibility and defined Asn-Pro-Asn (NPN) as the structural repeat motif. The demonstration that CIS43 is highly effective for passive prevention of malaria has potential application for use in travelers, military personnel and elimination campaigns and identifies a new and conserved site of vulnerability on PfCSP for next-generation rational vaccine design.
This phase 1 trial examined an engineered monoclonal antibody, L9LS, targeting the sporozoite. L9LS protected against malaria infection in a human challenge model.
In this phase 2 trial in Mali, an antimalarial monoclonal antibody (CIS43LS) at a dose of 40 mg per kilogram was approximately 88% effective at preventing
P. falciparum
infection as compared with ...placebo.
Combinations of monoclonal antibodies (mAbs) against different epitopes on the same antigen synergistically neutralize many viruses. However, there are limited studies assessing whether combining ...human mAbs against distinct regions of the Plasmodium falciparum (Pf) circumsporozoite protein (CSP) enhances in vivo protection against malaria compared to each mAb alone or whether passive transfer of PfCSP mAbs would improve protection following vaccination against PfCSP. Here, we isolated a panel of human mAbs against the subdominant C-terminal domain of PfCSP (C-CSP) from a volunteer immunized with radiation-attenuated Pf sporozoites. These C-CSP-specific mAbs had limited binding to sporozoites in vitro that was increased by combination with neutralizing human "repeat" mAbs against the NPDP/NVDP/NANP tetrapeptides in the central repeat region of PfCSP. Nevertheless, passive transfer of repeat- and C-CSP-specific mAb combinations did not provide enhanced protection against in vivo sporozoite challenge compared to repeat mAbs alone. Furthermore, combining potent repeat-specific mAbs (CIS43, L9, and 317) that respectively target the three tetrapeptides (NPDP/NVDP/NANP) did not provide additional protection against in vivo sporozoite challenge. However, administration of either CIS43, L9, or 317 (but not C-CSP-specific mAbs) to mice that had been immunized with R21, a PfCSP-based virus-like particle vaccine that induces polyclonal antibodies against the repeat region and C-CSP, provided enhanced protection against sporozoite challenge when compared to vaccine or mAbs alone. Collectively, this study shows that while combining mAbs against the repeat and C-terminal regions of PfCSP provide no additional protection in vivo, repeat mAbs do provide increased protection when combined with vaccine-induced polyclonal antibodies. These data should inform the implementation of PfCSP human mAbs alone or following vaccination to prevent malaria infection.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Long-lived plasma cells (PCs) secrete antibodies that can provide sustained immunity against infection. High-affinity cells are proposed to preferentially select into this compartment, potentiating ...the immune response. We used single-cell RNA-seq to track the germinal center (GC) development of Ighg2A10 B cells, specific for the Plasmodium falciparum circumsporozoite protein (PfCSP). Following immunization with Plasmodium sporozoites, we identified 3 populations of cells in the GC light zone (LZ). One LZ population expressed a gene signature associated with the initiation of PC differentiation and readily formed PCs in vitro. The estimated affinity of these pre-PC B cells was indistinguishable from that of LZ cells that remained in the GC. This remained true when high- or low-avidity recombinant PfCSP proteins were used as immunogens. These findings suggest that the initiation of PC development occurs via an affinity-independent process.
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•Ighg2A10 B cells follow a canonical program of germinal center affinity maturation•Single-cell RNA-seq identifies three light zone populations including pre-plasma cells•Pre-plasma cells have similar affinity to cells that remain in the germinal center•Low-avidity antigens induce more stringent germinal center selection
High-affinity cells are proposed to preferentially develop into long-lived plasma cells. Sutton et al. examine the differentiation of Ighg2A10 B cells, specific for the Plasmodium falciparum circumsporozoite protein (PfCSP), and find that cells initiating plasma cell differentiation have similar affinities to those that continue cycling in the germinal center.
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