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[Genetic polymorphism of the gene encoding the apical membrane antigen-1 of Plasmodium falciparum].

OBJECTIVE
To study the genetic diversity of apical membrane antigen-1 gene from Plasmodium falciparum (PfAMA-1).


METHODS
Filter paper blood samples were collected from 23 imported P. falciparum malaria patients who returned to Fujian Province from 2006 to 2012. Nested PCR were used to amplify the PfAMA-1 gene. The umplified fragments were sequenced, and analyzed by bioinformatic software.


RESULTS
All 23 samples were amplified a 505 bp band. Thirty-two nucleotides were found to be variable, resulting in 18 haplotypes. Eight of these 18 halotypes were being reported here for the first time. The parasites collected from Africa showed the higher level of variability [haplotypes diversity (Hd)= 0.0985, nucleotide diversity (π)=0.0258] as compared to the isolates from Asia (Hd=0.909, π=0.0221). The average difference of dN-dS for all 23 PfAMA-1 sequences was 0.031±0.006. Sequence-based neutrality tests were not significant in Africa and Asia (P>0.05). The minimum number of recombination events (Rm) was 10, and the linkage disequilibrium index (R2) evidently declined with the increase of nucleotide distance. A molecular phylogenetic tree constructed using the neighbor-joining method showed that the 23 isolates were assigned to three clades (G1, G2 and G3). Most samples from Africa formed G1, and G3 contained most of Asian isolates.


CONCLUSION
Plasmodium falciparum isolates from Africa show a higher genetic diversity than the isolates from Asia for PfAMA-1 gene.