An Antibody Screen of a Plasmodium vivax Antigen Library Identifies Novel Merozoite Proteins Associated with Clinical Protection

Background: elimination of plasmodium vivax malaria would be greatly facilitated by the development of an effective vaccine. a comprehensive and systematic characterization of antibodies to p. vivax antigens in exposed populations is useful in guiding rational vaccine design. methodology/principal findings: in this study,we investigated antibodies to a large library of p. vivax entire ectodomain merozoite proteins in 2 asia-pacific populations,analysing the relationship of antibody levels with markers of current and cumulative malaria exposure,and socioeconomic and clinical indicators. 29 antigenic targets of natural immunity were identified. of these,12 highly-immunogenic proteins were strongly associated with age and thus cumulative lifetime exposure in solomon islanders (p<0.001–0.027). a subset of 6 proteins,selected on the basis of immunogenicity and expression levels,were used to examine antibody levels in plasma samples from a population of young papua new guinean children with well-characterized individual differences in exposure. this analysis identified a strong association between reduced risk of clinical disease and antibody levels to p12,p41,and a novel hypothetical protein that has not previously been studied,pvx_081550 (irr 0.46–0.74; p<0.001–0.041). conclusion/significance: these data emphasize the benefits of an unbiased screening approach in identifying novel vaccine candidate antigens. functional studies are now required to establish whether pvx_081550 is a key component of the naturally-acquired protective immune response,a biomarker of immune status,or both. © 2016,mdpi ag. all rights reserved.