Abstract:

Objective To understand the genetic types of coxsackievirus A16 (CV-A16) associated with hand, foot and mouth disease (HFMD) in Anhui Province. Methods The case data on HFMD reported in Anhui Province from 2016 to 2020 were downloaded from the Infectious Disease Reporting and Management System under the China Disease Prevention and Control Information System, and the throat swab samples were collected from HFMD children during the corresponding period. The samples of positive CV-A16 nucleic acid detected by real-time PCR were selected, and amplified for VP1 gene using reverse transcription PCR. Then the positive PCR products were sequenced. Software Molecular Evolutionary Genetics Analysis (MEGA, version 6.0) was used to construct the phylogenetic tree and for analysis of the mutation at amino acid of VP1 gene. Results In total, 16 650 cases of HFMD confirmed by laboratory studies were reported in Anhui Province from 2016 to 2020, including 3 809 cases of CV-A16 types (22.88%). The annual constituent ratio of CV-A16 was 20.72% (219/1 057), 22.91% (677/2 955), 23.89% (1 004/4 202), 42.58% (1 687/3 962) and 4.96% (222/4 474), respectively in different years. 290 VP1 sequences were obtained from 436 CV-A16 positive specimens, all of which belonged to B genotype, including 225 from B1b and 65 from B1a. The nucleotide homology of 290 VP1 sequences was in between 86.80% and 100.00%, and that of G-10 VP1 sequence was in between 74.10% and 76.80%. The nucleotide homology between 65 strains VP1 of B1a and reference strains identified as genotype B1a in GenBank database was 93.00%-99.90%.The nucleotide homology between the VP1 sequence of 225 B1b strains and the reference strains identified as genotype B1b in GenBank database was 88.40%-99.60%. The B1a and B1b genotypes consisted of 4 sub-clusters and 6 sub-clusters in genetic evolution. Amino acid variation analysis of the prototype strain G-10 revealed mutations at many sites of CV-A16. Conclusion B1a and B1b gene subtypes of HFMD CV-A16 strains were co-prevalent in Anhui Province during 2016-2020. It is necessary to continually monitor the molecular evolution of enterovirus pathogens in Anhui Province.

Key words: Hand, foot and mouth disease, CV-A16, Molecular typing, Anhui Province