ABSTRACT
Objective@#To study the VP1 gene of coxsackievirus A6 (CVA6) and to reveal the molecular epidemiologic characteristics of CVA6 related to hand, foot and mouth disease (HFMD) in Anyang city from 2011 to 2015.@*Methods@#Serotypes of human enterovirus (HEV) were detected with the real-time RT-PCR from the clinical specimens. Primers were designed and used to amply and sequence the VP1 region of CVA6. Phylogenetic tree was constructed and phylogenetic analysis was performed. Selection pressures of the VP1 gene were evaluated for different subgenotypes of CVA6 circulating in China in recent years.@*Results@#A total of 365 specimens with CVA6 positivity were identified in Anyang city during 2011—2015. CVA6 specimens accounted for 19.59% of all HEV-positive specimens. Phylogenetic analysis showed that all CVA6 strains were divided into four genotypes and the genotype D was further divided into two subgenotypes. Among the twenty-two Anyang sequences involved in the phylogeny of CVA6, five sequences belonged to subgenotype D1 and the other seventeen sequences belonged to subgenotype D2. The values of selection pressure of the Chinese CVA6 strains within subgenotype D1 and subgenotype D2 were 0.031 and 0.075, respectively. Only one positively selected site was detected in the VP1 gene of subgenotype D1, meanwhile four were detected in the VP1 gene of subgenotype D2.@*Conclusions@#Subgenotype D1 and its successor, subgenotype D2, circulated in Anyang city during 2011—2015. The subgenotype replacement from CVA6 subgenotype D1 to CVA6 subgenotype D2 and the continuous transmission of CVA6 subgenotype D2 were the two major causes of HFMD epidemic related to CVA6 in Anyang city during 2013—2015.