Analysis of the pathogen spectrum of severe hand, foot and mouth disease and genetic characteristics of enterovirus A71 in Xianyang, 2018

Abstract

Objective To understand the pathogen spectrum of severe hand, foot and mouth disease (HFMD), and analyze the genetic characteristics of enterovirus A71(EV-A71) in Xianyang in 2018. Methods Totally 67 specimens of severe cases of HFMD were collected. Enteroviruses associated with HFMD were detected by real-time PCR and the genotypes of enteroviruses were identified by VP4 region of enteroviruses. The nucleotide and amino acid sequences of VP1 region of EV-A71 were analyzed. Results A total of 30 samples were positive for enterovirus among samples from 67 severe cases with HFMD, including 9 cases of EV-A71, 11 cases of coxsackievirus A6 (CV-A6), 5 cases of coxsackievirus A16 (CV-A16), 2 cases of coxsackievirus A10 (CV-A10) and 2 cases of coxsackievirus A4 (CV-A4). The nucleotide and amino acid homologies of EV-A71 among 4 strains reached 96.7%-99.9% and 99.3%-100% respectively. The 4 strains of EV-A71 belonged to C4a subtypes by phylogenetic analysis. The six amino acid composite model was KADSTV in 4 strains of EV-A71. The EF region and GH region in antigenic determinants of 4 strains of EV-A71 kept consistent with representative reference strains, however, the EV-A71 SZK222 and SZK497 strains developed mutation at site 93 (I93V) of BC loop region. Conclusions EV-A71 and CV-A6 are major agents of severe HFMD in Xianyang in 2018. The genotype of EV-A71 belonged to C4a subtype and the VP1 gene did not show more mutations. Key words: Hand, foot and mouth disease; Severe; EV-A71; Genetic characteristic analysis