Humoral and Cellular Immune Responses to the Circumsporozoite Protein of Plasmodium vivax in Madagascar

Abstract

Plasmodium vivax malaria is prevalent during the rainy season in the central highlands of Madagascar. In April 1991, we investigated the cellular and antibody immune responses of 53 inhabitants of Manarintsoa, a village in this area, to four antigens corresponding to B and T cell epitopes of the P. vivax circumsporozoite (CS) protein. Cellular responses were assessed by lymphocyte proliferation assay as well as by detection of interferon-gamma and interleukin-2 production in vitro. Cell culture was performed with two overlapping synthetic peptides (CSVTCGVGVRVRSRVNA [amino acids 311-326]) and VRVRSRVNAANKKPED [amino acids 319-334]) from the vicinity of the highly conserved region II of the CS protein. In at least one of the three assays, cells from seven subjects showed a positive response to CSVTCGVGVRVRSRVNA, while cells form 14 subjects responded to VRVRSRVNAANKKPED. Antibodies directed against the two recombinant antigens, NS1(81)V20 and rPvCS-2, both of which contain the entire central repeat region of the P. vivax CS protein, plus regions I and II in the case of rPvCS-2, were measured by the Falcon assay screening test-enzyme-linked immunosorbent assay. Eight and nine subjects had antibodies to NS1(81)V20 and rPvCS-2, respectively. The presence of antibody responses to both recombinant antigens was related (P = 0.02, by Fisher's exact test), but was not related to the presence of a cellular response to peptides from vicinity of region II (P > 0.1, by Fisher's exact test).(ABSTRACT TRUNCATED AT 250 WORDS)