[Study on the pathological and molecular characteristics of AHC epidemic in Zhejiang Province in 2010]

To identify and trace the pathogen of acute hemorrhagic conjunctivitis (AHC) epidemic in Zhejiang Province in 2010. Viral nucleic acid of Enterovirus (EV) and Coxsackievirus A24 variant (CA24v) were directly detected by real-time RT-PCR from the conjunctival swab collected from suspected patients. The virus was isolated from the swab samples using Hep-2 cell. The viral RNAs were extracted from the isolated viruses and followed by RT-PCR to amplify VP1 gene and 3C protease region(3C). The amplified fragments were sequenced and phylogenetic trees were also constructed. Eight out of 13 swab samples from suspected patients were both positive for EV and CA24v RNA (61.5%), 6 CA24v strains were isolated (46.2%). The complete VP1 genes of CA24v in 4 sequenced virus strains were 915 nt in length and the complete 3C genes were 549 nt in length. All VP1 and 3C genes were confirmed without any insertion or deletion. The identity of nucleotide and amino acid in 3C between the 2010 isolated strains and the prototype strain EH24/70 were 85.2%-85.8% and 96.2%-96.7%, and that between the 2010 Zhejiang strains and the Zhejiang,Yunnan and Guangdong CA24v strains isolated between 2007-2008 were 93.4%-93.8% and 96.7%-97.3%, respectively. The phylogenetic tree of 3C indicated that the isolated CA24v viruses of Zhejiang in 2010 located in the CA24v IV genotype cluster 4 (GIV-C4) and all the VP1 genes located in the human Enterovirus C (EV-C) CA24v. These findings indicated that AHC epidemic in Zhejiang Province in 2010 was caused by CA24v GIV-C4 viruses and they most likely evolved from CA24v viruses circulating locally in external environment from 2002.