[Genetic characteristics of enterovirus 71 VP1 and epidemiology of hand-foot-mouth disease in Xinxiang in 2011].
The study was performed to examine the enterovirus 71(EV71) VP1 genetic feature and the epidemiology of hand-foot-mouth disease (HFMD) in Xinxiang in 2011. Real-time RT-PCR was used for the detection of Pan-enterovirus, Coxsackievirus A 16(CA16) and EV71 from stool specimens of HFMD. The VP1 region was amplified from 10 EV71 positive samples and the products were sequenced. EV71 genotypes were characterized by homology and phylogenetic tree analyses. Additionally, epidemic data of Xinxiang HFMD in 2011 was analyzed. The results revealed that 73% of the specimens from severe cases were determined as EV71 positive, which was significantly higher than CA16-positive ones (19%) (P < 0.01). Ten EV71 strains isolated in Xinxiang belonged to C4a cluster of sub-genotype C4, with 2.8% nucleotide and 0.9% amino acid sequences divergence among them. At position 170 in VP1 gene, an alanine(A) was predominant in 9 isolates, while a valine(V) residue was observed in one isolate. Compared to the representative C4a strains which were closely related to Xinxiang isolates, the amino acid variations of the pre-dominant Xinxiang strains generally occurred at position 292, threonine --> alanine (T --> A). A total of 1118 HFMD cases were reported in Xinxiang in 2011, and 92% of them were younger than 3 years old; the incidence rate peaked in April and December, suggesting that it is very necessary to strengthen HFMD prevention and control even in cold weather.