Genomic phylogenetic analyses of four major hand, foot and mouth disease-related enteroviruses.

Enteroviruses had diverged into many types, some of which cause hand, foot and mouth disease (HFMD) in children. The predominant enterovirus types associated with HFMD are EVA71, CVA16, CVA6 and CVA10. Four enterovirus types were classified into subtypes based on VP1 sequences. However, the phylogenetics of these enteroviruses is rarely concerned at the genomic level. In this study, we performed the phylogenetic analyses of the EVA71, CVA16, CVA6 and CVA10 using available full-length genomic sequences. We found that the topologies of phylogenetic trees of full-length genomic sequences and VP1 sequences were almost consistent, except few subtypes of EVA71 and CVA10. The mean genetic divergence was 15.8-27% between subtypes and less than 12% within subtypes/sub-subtypes at genomic level. Comparison of phylogenetic topologies between genomic and VP1 sequences helped us to identify two new EVA71 inter-subtype recombinants RF01_CC4 and RF02_CC4. Furthermore, EVA71 subtypes C1 and C2 and CVA10 subtype D were found to originate through inter-subtype recombination. The genomic reference sequences of these enteroviruses are provided here for subtyping. The results provide important insights into the understanding of the evolution and epidemiology of the four enteroviruses. Keywords: enterovirus; hand; foot and mouth disease; classification; genetic distance; recombination.