Evidences for intertypic and intratypic recombinant events in EV71 of hand, foot and mouth disease during an epidemic in Hubei Province, China, 2011.

Humane enterovirus 71 (HEV 71) is a common contagious agent of hand, foot and mouth disease (HFMD) which is normally mild but can caused deaths and severe neurological complications. In April 2011, an unpredicted HFMD outbreak in Xiangyang City of Hubei Province in China resulted in a high aggregation of HFMD cases including fatal cases and many severe cases. In this study, 71 clinical specimens were collected according to the different symptoms and RNA extraction and RT-PCR amplification were performed immediately. Laboratory testing and genetic analyses were used to identify the casual pathogen of this outbreak. HEV71 was confirmed as the etiological pathogen of the outbreak. Similarity and phylogenetic analyses of the VP1 gene of HEV71 from Xiangyang showed that they belong to C4a cluster of the C4 subgenotype. Intertypic recombinant events were found in the 3D region between the Xiangyang HEV71 strains and Coxsackievirus A16 (CV-A16). Intratypic recombination was found in the 3D region between two same subgenotypic Xiangyang HEV71 strains in this outbreak. It is suggested that these recombination events played important roles in the emergence of the various HEV 71 subgenotypes and different type of recombination of HEV71 might exist in one outbreak which might be the reason for the different virulent HEV71 strains in an outbreak.