| Summary: | <p>Abstract</p> <p>Background</p> <p>Transmission-blocking vaccines (TBVs) have been considered an important strategy for disrupting the malaria transmission cycle, especially for <it>Plasmodium vivax </it>malaria, which undergoes gametocytogenesis earlier during infection. Pvs25 and Pvs28 are transmission-blocking vaccine candidates for <it>P. vivax </it>malaria. Assessment of genetic diversity of the vaccine candidates will provide necessary information for predicting the performance of vaccines, which will guide us during the development of malaria vaccines.</p> <p>Results</p> <p>We sequenced the coding regions of <it>pvs25 </it>and <it>pvs28 </it>from 30 <it>P. vivax </it>isolates from Yunnan Province, identifying five amino acid haplotypes of Pvs25 and seven amino acid haplotypes of Pvs28. Among a total of four mutant residues, the predominant haplotype of Pvs25 only had the I130T substitution. For Pvs28, a total of eight amino acid substitutions were identified. The predominant haplotype of Pvs28 had two substitution at positions 52 (M52L) and 140 (T140S) with 5-6 GSGGE/D tandem repeats at the end of fourth EGF-like domain. Most amino acid substitutions were common with previous reports from South Asian isolates. Although the nucleotide diversity of <it>pvs28 </it>(π = 0.0034 ± 0.0012) was significantly higher than <it>pvs25 </it>(π = 0.0013 ± 0.0009), it was still conserved when compared with the blood stage vaccine candidates.</p> <p>Conclusions</p> <p>Genetic analysis revealed limited genetic diversity of <it>pvs25 </it>and <it>pvs28</it>, suggesting antigenic diversity may not be a particular problem for Sal I based TBVs in most <it>P. vivax</it>-endemic areas of China.</p>
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