VARIATIONS IN ANTIBODY RESPONSE TO PLASMODIUM VIVAX DUFFY BINDING PROTEIN REGION II OF INFECTED INDIVIDUALS IN THAILAND
VARIATION IN ANTIBODY RESPONSE TO PVDBPII
Keywords:Plasmodium vivax, Duffy binding protein, IgG subclass, malaria infection, polymorphism
Duffy binding protein region II of Plasmodium vivax (PvDBPII) is a key target for vaccine-mediated immunity despite its highly polymorphic nature. Genetic diversity of PvDBPII within and between P. vivax isolates vary according to geographic regions, which might affect host immune response. This study evaluated DBPII allelic variations and naturally acquired immunity in P. vivax-infected individuals from malaria endemic areas of Thailand. Twenty-three 15-mer DBP peptides (DBPps) covering a critical binding motif in PvDBPII of P. vivax Thai isolates were evaluated for their immunogenicity in P. vivax-infected individuals (n = 82) compared to healthy non-parasite exposed controls (n = 39). Eighty-seven percent P. vivax-infected individuals had significantly higher anti-PvDBPII total IgG against six DBPps compared to controls. Anti-PvDBPII IgG1 was the most prominent subclass. Low IgG3 levels against Thai P. vivax-specific DBPp4 and DBPp5 and non-polymorphic DBPp22 were also detected. High IgG1 and low IgG3 response to DBPp4 and DBPp5 were associated with DBPp4 L333F (CTT>TTT) and DBPp5 S351C (AGT>TGT) mutations, in which the point mutation was C/A>T, whereas T/C>A/C mutation was present in other DBPps. These preliminary data revealed variations in levels of anti-PvDBPII IgG subclasses in P. vivax-infected individuals, which might impact vaccine development strategies against vivax malaria.