ABSTRACT
@#Abstract: Objective To genotype and analyze whole genomic features of Coxsackievirus B3 (CVB3) isolated in Tianjin, to improve evolution information of CVB3 virus in Tianjin, and to provide basis for surveillance and early warning of related diseases. Methods Viral RNA was extracted from five CVB3 strains isolated in Tianjin, whole genome sequence of the virus was amplified by RT-PCR and sequenced by next-generation sequencing method, and phylogenetic and recombinant analysis were carried out. Results The open reading frame 1(ORF) of the five CVB3 strains contained 6 555 nucleotides and encoded 2 185 amino acids, and ORF2 was composed of sequences encoding 68 amino acids. The nucleotide sequence similarity ranged from 78.3%-100%, and the amino acid sequence similarity ranged from 95.7%-100%. Compared with the CVB3 prototype strain, the nucleotide sequence similarity of the five viruses was between 78.2%-79.1%, and the similarity of amino acid sequences was 94.9%-95.3%. All five viruses exhibited a T151A mutation on the VP2 protein. Additionally, the encephalitis isolate showed a K158E mutation on the VP2 protein, while one of the sewage isolates had a C234T mutation in 5' noncoding region. The five strains belonged to two different genotypes, among which the encephalitis isolate in 2016 belonged to the D genotype, while the sewage isolates in 2021 belonged to the E genotype. This is also the first report of E genotype CVB3 in northern China. The CVB3 strain may have recombinant events in non-structural protein regions, in which encephalitis isolate may recombine with a Coxsackievirus B5 (CVB5) strain, while sewage isolates may have recombinant events with a strain of ECHO virus 18 (E18). Conclusions The CVB3 isolates in Tianjin belong to D and E genotypes, and recombination events may exist in non-structural protein region of the viral genome. The results of CVB3 virus genome analysis in sewage suggests presence of CVB3 infection in the population of Tianjin, and its epidemic dominant genotype may have changed.