Isolation and characterization of a novel clade of coxsackievirus B2 associated with hand, foot, and mouth disease in Southwest China.

Coxsackievirus B2 (CVB2) is an enterovirus B (EV-B) species and can cause aseptic meningitis, myocarditis and hand, foot, and mouth disease (HFMD). We characterized a novel CVB2 (YN31V3) associated with HFMD in Yunnan, Southwest China, in 2019. Although YN31V3 and other Mainland China epidemic strains mainly belonged to genotype C, YN31V3 formed an independent branch. The genome sequence of the strain YN31V3 from this study showed a 12.91% nucleotide difference to its closest strain RW41-2/YN/CHN/2012. Recombination analyses showed that the newly isolated YN31V3 was probably a recombinant, which was closely related to CVB2 strains in the genomic P1 region and other EV-B strains in the P2 and P3 regions, respectively. YN31V3 strain had a temperature-sensitive phenotype. The challenge of suckling BALB/c mice with YN31V3 could cause symptoms of disease and severe pathological lesions.