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[Transmission-blocking vaccine candidate of Plasmodium vivax Pvs25 is highly conservative among Chinese isolates].

OBJECTIVE
To investigate the genetic diversity of Plasmodium vivax transmission-blocking vaccine candidate antigen (TBV) Pvs25, with P. vivax isolates from Hubei and Zhejiang Provinces, and to compare the genetic polymorphism of Pvs25 with that from Bangladesh.


METHODS
The parasite DNA used for the genetic polymorphism assay was obtained from dried filter paper blood spots. The genes were PCR amplified and the products were purified and sequenced directly.


RESULTS
45 complete new sequences were analyzed. Only 3 nucleotide changes were found that would result in amino acid substitutions in Pvs25 in comparison with the sequence from P. vivax Sal-I strain. The measurement of nucleotide diversity (pi) was remarkably similar for the two populations, indicating that DNA sequences and deduced amino acid sequences were highly homologous among the geographically dispersed isolates or isolates from the same geographical region.


CONCLUSION
The results suggest that Pvs25 has limited antigenic polymorphism, especially compared with candidate antigens expressed by hepatic and erythrocytic stage, which may support the development and application of Pvs25-based transmission-blocking vaccine in China.