[Etiology of hand-foot-and-mouth disease seen in Nanjing in 2010 and molecular characteristics analysis of EV71].

OBJECTIVE: To study the etiological agent of hand-foot-and-mouth disease (HFMD), and to genetically characterize enterovirus 71 (EV71) isolated from clinical specimens of HFMD patients in Nanjing in 2010.

METHOD: Throat swab specimens were collected from 248 inpatients with HFMD in Nanjing Children's Hospital and then viral isolation was performed. Real-time PCR was used for detection of EV71, coxsackievirus A16 (Cox A16) and other enteroviruses from the positive isolates. Twenty EV71 strains from different clinical types of cases were selected for entire VP1 coding gene amplification and sequencing, finally a phylogenetic tree was constructed among the 20 EV71 strains and EV71 representative strains of known genotypes and subgenotypes.

RESULT: From the 248 throat swabs specimens, 110 EV71 strains, 28 Cox A16 strains, and 8 other enterovirus strains were isolated and the positive rate was 44.35%, 11.29%, 3.23%, respectively. Then nucleotide sequencing was performed on the 20 EV71 strains. There was little difference in the nucleotide and the amino acid sequences among the 20 EV71 strains, the homology was 95.51%-100% and 98.32%-100%, respectively. The phylogenetic tree showed that all the 20 EV71 strains belonged to C4 subgenotype.

CONCLUSION: EV71 was the main pathogen of HFMD in Nanjing in 2010 and all the analyzed isolates belonged to C4 serotype. No significant difference was found in sequence of VP1 region of EV71 isolated from different clinical types of cases.