Epidemic and genetic characteristics of coxsackievirus A6 strains isolated in Guangdong province from year 2008 to 2013 / 中华微生物学和免疫学杂志

ABSTRACT

Objective To study the epidemic and genetic characteristics of coxsackievirus A6 ( CVA6) strains isolated in Guangdong province.Methods Enterovirus strains positive for neither entero-virus A71 ( EV71) nor CVA16 were isolated from Guangdong province during 2008 to 2013 to screen CVA6 isolates by real-time PCR.The entire sequences of viral genes encoding VP1 of CVA6 positive samples were amplified and sequenced.The phylogenetic analysis was performed to analyze the full-length gene sequences encoding VP1 of CVA6 isolates and sequences downloaded from GenBank by using DNAStar6.0 and MEGA5.2 software packages.Results CVA6 strains accounted for 61.4%of the 1672 non-EV71 and non-CVA16 enterovirus strains isolated in Guangdong province during year 2008 to 2013.The positive rates were respectively 10.5%(4/38), 66.7%(34/51), 36.2% (81/224), 63.0% (182/289), 62.3% (325/522) and 73.0%(400/548) from 2008 to 2013 and the differences among different years were significant (χ2=133.79, P<0.01).The CVA6 isolates could be classified into four clusters in the phylogenetic tree, designated A, B, C and D (including D1, D2 and D3 subgenogroups) genogroups.The four clusters shared nucleotide diversity ranging from 15.5% to 23.1%.The CVA6 strains isolated in Guangdong province shared 88.7%-100.0% homologies in nucleotide and 95.7%-100.0% in amino acid.Subtype D2 strains circulated during 2008 to 2012 and subtype D3 strains circulated during 2009 to 2013.Conclusion CVA6 strains were the predominant enterovirus strains among non-EV71 and non-CVA16 enterovirus strains circula-ted in Guangdong province from year 2008 to 2013.The CVA6 isolates could be classified into A, B, C and D genogroups based on the sequence analysis of VP1 region.Subgroups D2 and D3 isolates were identified and the subgroup D3 isolates were the prevalent strains in Guangdong.