| Popis: |
Background: Enterovirus has 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. Subtyping of these enteroviruses is crucial to HFMD surveillance. Because of lacking proper and uniform criteria and being based on partial VP1 sequences, however, current classification resulted in some confusing and conflicting results. Method: We reclassified EVA71, CVA16, CVA6 and CVA10 using a combined criteria of phylogenic relationship and genetic distance. Results: Using the combined criteria, we classified EVA71 into seven genotypes of A–G, CVA16 and CVA6 into three subtypes of A-C, and CVA10 into nine subtypes/sub-subtypes of A-G, H1 and H2, and identified eight unclassified subtypes that lack genomic sequences. The mean genetic divergence was 15.5-33.8% between subtypes, 12-15% between sub-subtypes, and less than 12% within subtypes/sub-subtypes. In addition, we identified two new EVA71 inter-subtype recombinants RF01_CG and RF02_CG and demonstrated that EVA71 subtypes D and F and CVA10 subtype B experienced inter-subtype recombination events during early evolution. Conclusions: The new nomenclature proposal provides a reasonable framework for proper classification of enteroviruses, which will be useful for epidemiological surveillance of HFMD, disease management, and vaccine development. |
