Multiple molecular characteristics of circulating enterovirus types among paediatric hand, foot and mouth disease patients after EV71 vaccination campaign in Wuxi, China

The molecular properties of the circulating causative agents of hand, foot and mouth disease (HFMD) in Wuxi remain unclear, posing diagnostic and prevention challenges. Additionally, in several regions of mainland China, the EV71 immunisation drastically reduced related cases and altered the HFMD pathogen spectrum, while the precise situation in Wuxi remained unknown. To address these issues, paediatric HFMD cases diagnosed in the clinic were enrolled and anal swabs were acquired in the spring of 2019. The 5′-UTR and VP1 genes were interpreted using RT-nPCR with degenerate primers to confirm their genotypes. Following that, the entire genome sequences of each viral type were recovered, allowing for the interpretation of several molecular properties. A total of 249 clinically confirmed HFMD cases had their anal swabs taken for viral identification, from which the genome sequences of seven genotypes were recovered. Coxsackievirus A16 is the most prevalent type, followed by Coxsackievirus A6, A10, A2, A4, A5 and Echovirus 11, all of which were genetically determined for the first time in Wuxi. Phylogenetic and recombination analyses were used to evaluate their evolutionary relationships with other strains found in other regions. Noticeably, a CVA16 subtype, responsible for a large proportion of the observed cases, phylogenetically clustered within clade B1a along with some strains from other countries, was the first one to be reported in China. Furthermore, some recombination events were inferred from strains detected in sporadic cases, particularly the recombination between CVA2 and CVA5 strains. Our investigation elucidated the multiple molecular characteristics of the HFMD causal enterovirus strains in Wuxi, underlining the potential hazards associated with these circulating viral types in the population and aiding in future surveillance and prevention of this disease.