Genomic analysis of a recombinant coxsackievirus A19 identified in Xinxiang, China, in 2019

Coxsackievirus A19 (CV-A19) is an enterovirus belonging to the species Enterovirus C, and the prototype strain 8663 was isolated from a patient with Guillain-Barré syndrome in Japan. In this study, we determined the complete genome sequence of a CV-A19 isolate identified in a stool sample from a child with hand, foot, and mouth disease in Xinxiang, Henan, China, in 2019 and named it CV-A19 strain 2019103106/XX/CHN/2019 - 2019103106 for short. The genome of this virus consists of 7409 nucleotides, including a 6624-nucleotide open reading frame encoding a potential polyprotein precursor of 2207 amino acids. Compared with strain 8663, strain 2019103106 showed 85.1% nucleotide sequence identity in the complete genome and 85.6% identity in the VP1 coding region, reflecting their genetic divergence. Phylogenetic analysis of strain 2019103106 and other representative EV-C strains with sequences available in the GenBank database showed that CV-A19 strains could be grouped into two clusters based on the complete or 214-nucleotide partial VP1 coding regions, and 2019103106 belonged to cluster 1, with the closest relationship to CV-A19 strain SWG82 from Shandong, China. Phylogenetic trees based on the P2 and P3 coding regions highlighted the divergence between strains 2019103106 and 8663, implying that strain 2019103106 had undergone recombination. Further recombination analysis suggested that strains V18A-like CV-A1 and BBD26-like CV-A19 probably recombined to yield strain 2019103106. The present study points out the genetic diversity of CV-A19. It expands our understanding of the evolution of the CV-A19 genome, but more genome sequences of epidemic strains are needed to explain the phylogeny and evolutionary history of CV-A19 comprehensively.