Humoral immune responses to Plasmodium vivax subtelomeric transmembrane proteins in Thailand

Abstract

Plasmodium vivax subtelomeric transmembrane protein (PvSTP) is a homolog of P. falciparum SURFIN 42 , a protein exposed on the parasite-infected erythrocyte (iE) surface, and is thus considered to be exposed on P. vivax-iE. Because antibodies targeting antigens located on the surface of P. falciparum-iE, such as P. falciparum erythrocyte membrane protein 1, play an important role in regulating the course of disease, we evaluated the presence of antibodies in P. vivax-infected patients against two PvSTP paralogs, PvSTPl and PvSTP2. Recombinant proteins corresponding to cysteine-rich domain (CRD) of the PvSTP extracellular region and the cytoplasmic region (CYT) were generated and used for the enzyme-linked immunosorb ent assay. Plasma samples (n = 70) reacted positively with recombinant PvSTP1-CRD (40%), PvSTP1-CYT (31%), PvSTP2-CRD (27%), and PvSTP2-CYT (56%), suggesting that PvSTPl and -2 are naturally immunogenic. Specific response against either PvSTP1 or PvSTP2 indicates the existence of specific antibodies for either PvSTP1 or -2.