[Study on the molecular typing and epidemiology of non-polio enterovirus in Yunnan Province, China during 2006-2010].

In order to explore the genotype distribution and molecular evolution of non-polio enterovirus (NPEVs)in Yunnan Province,the People's Republic of China, we sequenced and analyzed the partial VP1 coding region of 105 NPEVs isolated from acute flaccid paralysis (AFP) surveillance in Yunnan province during a 5- year study period from 2006 to 2010. The viral genomes of 105 NPEVs were translated to corresponding amino acid sequences and compared with those of the prototype strains, and the phylogenetic tree was constructed among these VP1 nucleotide sequences and other prototype strains from GenBank. Analysis showed that 18 isolates were classified into 7 serotypes of human enterovirus A species, while 77 isolates into 22 serotypes of B and 10 isolates into 4 serotypes of C species. However, we did not isolate any viruses which belonged to human enterovirus D species. Thus, under AFP surveillance, human enterovirus B species accounted for 73. 3% of the 105 isolates and was considered as the predominant one,followed by human enterovirus A(17. 1%) and human enterovirus C(9. 5%). Phylogenetic analysis showed that various serotypes of the virus and the corresponding prototype strains or other representative strains clustered into the same grooup, however, Yunnan strains and prototype strains were located in the different branches (except CA2,EV90 and EV76). The degree of variation was different even among the same genotype strains. This report showed that different genotype strains spread widely in Yunnan Province.