Characterization of anti-var2CSA-PfEMP1 cytoadhesion inhibitory mouse monoclonal antibodies

Avril, Marion; Gamain, B; Lépolard, Catherine; Viaud, Nicolas; Scherf, Artur; Gysin, Jürg

doi:10.1016/j.micinf.2006.09.005

Cited by 52 publications

(41 citation statements)

References 25 publications

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“…As reported earlier, four of the six DBL domains (DBL2x, DBL3x, DBL5, and DBL6) of VAR2CSA have been shown to bind to CSA (13,14). Crystal structures have given insight into DBL3x (15, 16).…”

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confidence: 70%

Subdomain 3 of Plasmodium falciparum VAR2CSA DBL3x Is Identified as a Minimal Chondroitin Sulfate A-binding Region

Singh

Gitti²,

Diouf

et al. 2010

Journal of Biological Chemistry

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Molecular interactions between the VAR2CSA protein, expressed on the surface of Plasmodium falciparum-infected erythrocytes, and placental chondroitin sulfate A (CSA) are primarily responsible for pregnancy-associated malaria (PAM). Interrupting these interactions may prevent or ameliorate the severity of PAM. Several of the Duffy binding-like (DBL) domains of VAR2CSA, including the DBL3x domain, have been shown to bind CSA in vitro, but a more detailed understanding of how DBL domains bind CSA is needed. In this study, we demonstrate that subdomain 3 (S3), one of the three subdomains of VAR2CSA DBL3x by itself, is the major contributor toward CSA binding. NMR spectroscopy and flow cytometry analyses show that S3 and the intact DBL3x domain bind CSA similarly. Mutations within the S3 portion of DBL3x markedly affect CSA binding. Both recombinant molecules, S3 and DBL3x, are recognized by antibodies in the plasma of previously pregnant women living in malaria-endemic regions of Mali, but much less so by plasma from men of the same regions. As the S3 sequence is highly conserved in all known VAR2CSA proteins expressed by different parasite isolates obtained from various malaria endemic areas of the world, the identification of S3 as an independent CSA-binding region provides a compelling molecular basis for designing interventions against PAM.Each year, pregnancy-associated malaria (PAM) 3 poses a risk to millions of women worldwide. Although women living in malaria-endemic areas eventually develop immunity to malaria after repeated exposure to Plasmodium falciparum, they become susceptible to severe disease during pregnancy. PAM is caused by the massive sequestration of P. falciparum-infected erythrocytes (IEs) that selectively bind to CSA in the placenta, leading to severe inflammation and life-threatening outcomes for both mother and child (1).VAR2CSA, a member of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family, is primarily responsible for the binding of IEs to CSA (2). The var2csa gene is found in nearly all P. falciparum isolates (3) and is unusually conserved compared with other members of the var gene family that encode PfEMP1 molecules (4). VAR2CSA is specifically up-regulated in infected erythrocytes that are either isolated from the placenta (5) or selected in vitro for binding to CSA (2). On disruption of the var2csa gene, the ability of the infected erythrocytes to adhere to CSA is lost (6) or greatly reduced (7).The risk of PAM is highest in the first pregnancy due to lack of VAR2CSA-specific antibodies, but with increasing parity, women acquire such antibodies that block the binding of IEs to CSA in the placenta. The naturally acquired antibodies from multiparous women collected from different malaria-endemic regions of the world recognize CSA-binding IEs in the placenta (8 -12). The ability of such antibodies to block adhesion of IEs to CSA by recognizing conserved epitopes among different parasite clones, suggests that VAR2CSA-based vaccination against PAM is possible.Expressing...

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Subdomain 3 of Plasmodium falciparum VAR2CSA DBL3x Is Identified as a Minimal Chondroitin Sulfate A-binding Region

Singh

Gitti²,

Diouf

et al. 2010

Journal of Biological Chemistry

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“…Previous works have described the CSA-binding properties of single DBL domains (3,10,11). Insight derived from structural studies of DBL domains revealed the importance of the DBL3X domain in VAR2CSA CSA binding but also suggested a higher-order structure organization of VAR2CSA where the positioning of different surfaces involved in chondroitin sulfate proteoglycan (CSPG) binding forms a specific binding pocket (12)(13)(14).…”

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Parity-Dependent Recognition of DBL1X-3X Suggests an Important Role of the VAR2CSA High-Affinity CSA-Binding Region in the Development of the Humoral Response against Placental Malaria

et al. 2015

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f Plasmodium falciparum multidomain protein VAR2CSA stands today as the leading vaccine candidate against pregnancy-associated malaria (PAM). Most of the studies aiming to decrypt how naturally acquired immunity develops have assessed the immune recognition of individual VAR2CSA Duffy-binding-like (DBL) domains, thus overlooking the presence of conformational epitopes resulting from the overall folding of the full-length protein. In order to characterize the development of humoral immunity toward VAR2CSA, we made use of a large cohort of 293 Senegalese pregnant women to assess the level of recognition by plasma IgG of the full-length VAR2CSA protein of the 3D7 parasite strain (3D7-VAR2CSA), the CSA-binding multidomains 3D7-DBL1X to -DBL3X (3D7-DBL1X-3X), and the CSA nonbinding multidomains 3D7-DBL4 to -DBL6 (3D7-DBL4-6), as well as individual 3D7-DBL domains. Our results revealed a parity-dependent recognition of the full-length 3D7-VAR2CSA and of the CSA-binding region, 3D7-DBL1X-3X. Indeed, multigravid women possess significantly higher levels of antibodies directed against these constructs than primigravidae. Our results suggest an important role of antibodies targeting the CSA-binding region in the development of immunity against PAM, therefore providing new insights on how natural protection might be acquired and further information for the design of VAR2CSA-based vaccines. E ach year, pregnancy-associated malaria (PAM) is responsible for the deaths of as many as 363,000 neonates and for at least 10,000 maternal deaths worldwide (1). The massive accumulation of Plasmodium falciparum-infected erythrocytes (IEs) to the syncytiotrophoblast layer composing the maternal face of the placenta limits maternal-fetal exchanges, leading to clinical complications for both mother and child (2). This phenomenon is mediated by the VAR2CSA protein, a member of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesins, that is preferentially expressed by placental parasites (3-5) and binds to the placental chondroitin-4-sulfate A (CSA) (6). After one or two pregnancies, women acquire antibodies targeting VAR2CSA that inhibit IE sequestration and decrease the negative outcomes of PAM (7,8). In vitro assays have shown that antibodies from multigravid women are able to block the interactions between CSA and IEs originating from different parts of the world (9), showing the existence of a cross-reactive antibody response and suggesting that a relative conservation of important inhibitory epitopes within VAR2CSA proteins may exit.VAR2CSA is a 350-kDa transmembrane protein composed of six Duffy-binding-like (DBL) domains. Previous works have described the CSA-binding properties of single DBL domains (3, 10, 11). Insight derived from structural studies of DBL domains revealed the importance of the DBL3X domain in VAR2CSA CSA binding but also suggested a higher-order structure organization of VAR2CSA where the positioning of different surfaces involved in chondroitin sulfate proteoglycan (CSPG) binding forms a specific bin...

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“…Interestingly, pregnant women exposed to malaria mainly recognize the DBL3X and DBL5ε domains, suggesting that specific immune memory to these VAR2CSA domains is naturally acquired with exposure. Several single domains from VAR2CSA bind to CSA in vitro, including DBL3X, DBL5ε, and ID1-ID2, which spans the DBL2 domain (14,(16)(17)(18)(19). However, a specific and high binding affinity to CSA depends on the folded architec-ture of the full VAR2CSA protein (20).…”

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Functional Antibodies against VAR2CSA in Nonpregnant Populations from Colombia Exposed to Plasmodium falciparum and Plasmodium vivax

et al. 2014

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iIn pregnancy, parity-dependent immunity is observed in response to placental infection with Plasmodium falciparum. Antibodies recognize the surface antigen, VAR2CSA, expressed on infected red blood cells and inhibit cytoadherence to the placental tissue. In most settings of malaria endemicity, antibodies against VAR2CSA are predominantly observed in multigravid women and infrequently in men, children, and nulligravid women. However, in Colombia, we detected antibodies against multiple constructs of VAR2CSA among men and children with acute P. falciparum and Plasmodium vivax infection. The majority of men and children (>60%) had high levels of IgGs against three recombinant domains of VAR2CSA: DBL5, DBL3X, and ID1-ID2. Surprisingly, these antibodies were observed only in pregnant women, men, and children exposed either to P. falciparum or to P. vivax. Moreover, the anti-VAR2CSA antibodies are of high avidity and efficiently inhibit adherence of infected red blood cells to chondroitin sulfate A in vitro, suggesting that they are specific and functional. These unexpected results suggest that there may be genotypic or phenotypic differences in the parasites of this region or in the host response to either P. falciparum or P. vivax infection outside pregnancy. These findings may hold significant clinical relevance to the pathophysiology and outcome of malaria infections in this region.

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Characterization of anti-var2CSA-PfEMP1 cytoadhesion inhibitory mouse monoclonal antibodies

Cited by 52 publications

References 25 publications

Subdomain 3 of Plasmodium falciparum VAR2CSA DBL3x Is Identified as a Minimal Chondroitin Sulfate A-binding Region

Subdomain 3 of Plasmodium falciparum VAR2CSA DBL3x Is Identified as a Minimal Chondroitin Sulfate A-binding Region

Parity-Dependent Recognition of DBL1X-3X Suggests an Important Role of the VAR2CSA High-Affinity CSA-Binding Region in the Development of the Humoral Response against Placental Malaria

Functional Antibodies against VAR2CSA in Nonpregnant Populations from Colombia Exposed to Plasmodium falciparum and Plasmodium vivax

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