Genetic Diversity of Cysteine-Rich Protective Antigen (PvCyRPA) in Field Isolates from Five Different Areas of the Brazilian Amazon.

The Cysteine-Rich Protective Antigen (PvCyRPA) has an important role in erythrocyte invasion and has been considered a target for malaria vaccine development. Nonetheless, its genetic diversity remains uncharted in Brazilian malaria-endemic areas. Therefore, we investigated the genetic polymorphism in 98 field isolates from the Brazilian Amazon and its impact on the antigenicity of predicted B-cell epitopes. Genetic diversity parameters, population genetic analysis, neutrality test and the median-joining network were analyzed, and the potential amino acid polymorphism participation in B-cell epitopes was investigated. One synonymous and 26 non-synonymous substitutions defined fifty haplotypes. The nucleotide diversity and Tajima's D values varied across the coding gene. The exon-1 sequence had greater diversity than those of exon-2. Concerning the prediction analysis, seven sequences were predicted as linear B cell epitopes, the majority contained in conformational epitopes. Moreover, important amino acid polymorphism was detected in regions predicted to contain residues participating in B-cell epitopes. Our data suggest that the gene presents a moderate polymorphism in the studied isolates and such polymorphisms alter amino acid sequences contained in potential B cell epitopes, an important observation considering the antigen potentiality as a vaccine candidate to cover distinct endemic areas worldwide.