Plasmodium vivax apical membrane antigen 1I-II from Nicaragua (2012-2013): genetic and antigenic polymorphism

Objective. Genetic and antigenic polymorphism of P. vivax apical membrane antigen-1 (pvama1I-II) from Nicaragua was examined. Materials and methods. Infected blood samples from patients were obtained during 2012-2013. A gene fragment comprising domains I-II was amplified and sequenced, and the genetic parameters, haplotype relationships, genetic structure, and amino acid variation in predicted B cell epitopes were analyzed. Results. 65 sequences of pvama1III had 19 nonsynonymous and five synonymous nucleotide changes. Nicaraguan parasites had low diversity, high linkage disequilibrium, and few recombination events. Neutrality tests indicate a positive and divergent selection, and three genetic clusters with loss of haplotypes were demonstrated. Amino acid variation predominated in predicted B cell epitopes and was closely related to that in Latin American parasites. Conclusions. Nicaraguan P. vivax is a moderately differentiated population under contraction and focalization processes, and the antigenic diversity resembles that of Latin American parasites. This information is relevant for vaccine development and epidemiological surveillance.