[Genetic characteristics of enterovirus 71 isolated in Beijing, 2006-2008].

Objective: To sequence and analyze the VP1 region of isolated enterovirus from different sources in Beijing, 2006-2008.

Methods: 9 EV71 were selected from the isolates identified through the specimen of human hand foot mouth disease (HFMD), acute flaccid paralysis (AFP) and healthy children in Beijing, 2006-2008. Reverse transcription-polymerase chain reaction (RT-PCR) method was used to amplify and sequence the whole VP1 gene of enterovirus. Phylogenetic tree was constructed, with the means of nucleotide homology and distance between/within groups analyzed.

Results: The 9 selected strains were clustered with C4 subgenotype reference strains in Phylogenetic tree and showed high nucleotide acid identity (92.1%-93.9% ) in nucleotide homology analysis, and had higher homology than C1, C2, C3 subgenotype reference strains (88.8%-89.5%, 89.4%-90.0% and 88.4%-89.3%, respectively). High homologous (95.9%-100.0%) was noticed between the isolated stains from three different sources, but low homologous (93.3% -93.9%, 92.1%-92.9%, respectively) showed between the isolated stains and C4 reference strains isolated in 1998. There appeared larger variations between groups in C4 subgenotype when analyzing the distance between groups means, especially between the reference strains and isolated strains (D = 0.052-0.071).

Conclusion: The EV71 isolated in Beijing, from 2006 to 2008 also appeared to be C4 subgenotype and there was no significant difference found in the whole sequence of VP1 gene of the strains isolated from different regions, sources, or under different diseases occurred in the same period. There were more nucleotide variations and more chances for the presence of new subgenotype, suggesting that it is necessary to strengthen the surveillance program on EV71 isolates.