Diversity and prevalence of the C-terminal region of Plasmodium falciparum merozoite surface protein 1 in China.

Malaria continues to be a significant health concern for regions of southeastern Asia. Scientists have focused much effort on the development and regional testing of a vaccine against the most virulent of the pathogens that cause the disease, Plasmodium falciparum. The 19kDa COOH-terminal region of the merozoite surface protein 1 (PfMSP1-19) is considered to be a potentially important component of a malaria vaccine and yet, to date, there is little data from China with regard to Pfmsp1-19 diversity. We have collected samples from 300 individuals diagnosed with P. falciparum infections from Yunnan and Hainan provinces--two potential vaccine trial sites in China. We determined the sequence of DNA encoding PfMSP1-19 for each. We identified seven polymorphic positions; varying arrangements of which accounted for 10 distinct Pfmsp1-19 haplotypes. Four haplotypes, however, represented more than 93% of the total. Differences in the prevalence of haplotypes between Yunnan and Hainan provinces were observed, even though the distribution of haplotypes in Yunnan province seemed to be very similar to those reported for Vietnam and Thailand. These results provide necessary information for the design of a major human vaccine trial as well as a basis for subsequent interpretations of the results. On broader scale, the data should complement the existing database on the prevalence and distribution of Pfmsp1-19 haplotypes and therefore have potential use in the design of PfMSP1-19-based polyvalent vaccines for use in Southeastern Asian countries.