Plasmodium vivax RH5-interactive putative protein (RIPR) is present in micronemes and might participate in erythrocyte invasion. In this study, the polymorphism of pvripr gene was examined. In 7 P. vivax isolates from southern Mexico (SM), the pvripr gene was amplified and sequenced. Other pvripr sequences were retrieved from PlasmoDB; 15 from SM and 78 from other locations. The genetic parameters, deviation from neutrality, Z selection test, haplotype networks, FST index of differentiation and the amino acid substitutions were analysed. The phylogenetic tree of 22 SM isolates suggested 2 genetic groupings, and these isolates had lower nucleotide diversity (n = 22; π = 0.0007, Hd = 0.671) than Colombian, Peruvian and Asian parasites (π = 0.0011–0.0017, Hd > 0.9). The haplotype network of Mexican pvripr had haplotypes separated by 1–13 mutational steps among them, and a complex structure was observed in parasites from Peru, Colombia and China. No significant deviation from neutrality was estimated; however, Tajima’s D values across 3′ segment were negative in parasites from all locations. The Z test was significantly positive only for Latin American parasites, and the codon-level selection analysis showed several codons with dN–dS positive values in East Asia and Southeast Asia parasites. Given the lack of long-term in vitro culture for P. vivax, in silico epitope mapping across global sequences provides a pragmatic, hypothesis-generating framework. Globally, 12 polymorphic residues involved charged amino acid changes, many within predicted B-cell epitopes, consistent with immune-mediated selection on PvRIPR.

Cruzia tentaculata is a helminth parasite of marsupials and has a wide geographic distribution from Mexico to Argentina. The aim of this study was to analyse the genetic population structure of this nematode along the Atlantic Forest biome. Cruzia tentaculata specimens were recovered from Didelphis aurita, Didelphis albiventris and Philander quica in 9 localities. Morphological and morphometric data were investigated for phenotypic diversity among localities and hosts using multivariate discriminant analysis of principal components. Phylogenetic relationships of C. tentaculata were determined using maximum likelihood and Bayesian inference. The population structure was analysed by fixation indices, molecular variance analysis, Tajima's D and Fu's Fs neutrality tests, Mantel tests and Bayesian clustering analysis. A higher significant morphometric difference for males was observed between localities. In the haplogroup networks, 2 groups were recovered, separating locations from the north and from the south/southeast. The morphometric variation in C. tentaculata between different localities was compatible with this north and southeast/south pattern, suggesting adaptation to different ecological conditions. Population genetic analyses suggested a pattern of evolutionary processes driven by Pleistocene glacial refugia in the northeast and southeast of the Atlantic Forest based on the distribution of genetic diversity.