Coxsackievirus A16 epidemiology and VP1 gene characteristics in Qingdao region,2008-2011

Objective To illuminate the molecular epidemiology and gene characteristics of Coxsackievirus A16 (CA16) strains isolated from patients with hand,foot,and mouth disease(HFMD)in Qingdao region from 2008 to 2011.Methods The throat swabs of cases with HFMD were detected for enterovirus (EV),EV71 and CA16 by fluorescence reverse transcription-polymerase chain reaction (RT-PCR).The EV positive specimens were inoculated on appropriate cultures for virus isolation.The whole VP1 gene sequences of CA16 isolates were amplified and sequenced,then the homology and phylogeny analysis were conducted with CA16 international sequences obtained from GenBank database.Results The proportion of CA16 in etiology of HFMD from 2008 to 2011 was respectively 39.0％,10.6％,47.0％ and 2.0％.The nucleotide and amino acid difference of VP1 gene were respectively 11.0％ and 2.0％.The sequences of 46 CA16 isolates were classified into two subgenotypes of B1 a and B1 b.The number of B1 a and B1b from 2008 to 2011 were respectively 9/7,7/1,3/11 and 2/6.Conclusion The large prevalence of CA16 occurred at intervals of about two years in Qingdao from 2008 to 2011.B1 a and B1b clusters were cocirculating,especially B1a was predominant in 2009 and B1b was predominant in 2010 and till 2011 the detective rate of CA16 became extremely low in etiology of HFMD. Key words: Hand foot and mouth disease; Coxsackievirus infections; Genes