Genetic Diversity Analysis of Surface-Related Antigen (SRA) in Imported From Africa to China.

surface-related antigen (SRA) is located on the surfaces of gametocyte and merozoite and has the structural and functional characteristics of potential targets for multistage vaccine development. However, little information is available regarding the genetic polymorphism of . To determine the extent of genetic variation about by characterizing the sequence, 74 samples were collected from migrant workers who returned to China from 12 countries of Africa between 2015 and 2019. The full length of the gene was amplified and sequenced. The average pairwise nucleotide diversities (π) of gene was 0.00132, and the haplotype diversity () was 0.770. The average number of nucleotide differences () for was 3.049. The ratio of non-synonymous () to synonymous () substitutions across sites (/) was 1.365. Amino acid substitutions of SRA could be categorized into 35 unique amino acid variants. Neutrality tests showed that the polymorphism of PfSRA was maintained by positive diversifying selection, which indicated its role as a potential target of protective immune responses and a vaccine candidate. Overall, the ability of the N-terminal of PfSRA antibodies to evoke inhibition of merozoite invasion of erythrocytes and conserved amino acid at low genetic diversity suggest that the N-terminal of PfSRA could be evaluated as a vaccine candidate against infection.