[B1a and b1b evolutionary branch of coxsackie virus A16 co-prevailed in Inner Mongolia Autonomous Region].

To study on the molecular evolution of Coxsackie virus A16 (CVA16)isolated from clinical speci-mens of Hand, foot and mouth Disease( HFMD) patients in Inner Mongolia in 2010. A total of 921 clinical specimens including stools, throat swabs and vesicle fluids were collected from 888 HFMD patients in out-patient service in Inner Mongolia and viral isolation was then performed, the positive viral isolates were identified by using the real-time PCR method detecting CVA16. A total of 50 CVA16 isolates were selected from the patients presenting mild symptoms, severe symptoms and the death patients randomly, and the VP1 coding regions of representative CVA16 isolates were amplified and sequenced. Finally the phylogenetic tree was constructed among the VP1 coding regions of the different genotypes and subgenotypes of CVA16 strains. Eighty two viruses were isolated form 921 clinical specimens, the positive rate was 8. 90%, of which 3 viruses were isolated from severe cases and 1 viruses was from death cases. The nucleotide acid of 50 representative CVA16 strains in Inner Mongolia were closed to CVA16 strains isolated from mainland China since 1998, especially from Beijing in 2009 and from Henan in 2010, the identity were 96. 18% approximately 98. 88% and 94. 94a approximately 98. 76%, respectively. There was a little difference in the nucleotide acid between the CVA16 strains from Inner Mongolia in 2010 and in 2007, the identity were 91. 68% approximately 96. 52% The phylogenetic tree showed that all CVA16 strains clustered within Bla and B1b evolution branch of B1 genotype. There was slight difference in the nucleotide and the amino acid in VP1 region among the 50 Inner Mongolia CVA16 strains, the identity were 89. 99% approximately 100% and 98. 31% approximately 100%, respectively, indicating that these strains belonged to many different viral transmission chains. The CVA16 strains circulated in Inner Mongolia in 2010 were all belong to B1a and B1b evolution branch of B1 genotype, and the two evolutionary branchs of Coxsackie virus A16 were co-evolved and co-prevailed in Inner Mongolia Autonomous Region.