RESUMO
Enterovirus A71 (EV-A71) infection is known to cause hand, foot, and mouth disease (HFMD). Last year, an inactivated EV-A71 whole virus vaccine was used to prevent this disease in Yunnan, China. To obtain a viral genetic background for evaluating vaccine protection and monitor the adaptive evolution of the virus after the vaccination, a 5-year molecular epidemiology survey was performed before the vaccination. Twenty-six EV-A71 strains were separated from 561 stool specimens of patients with serious HFMD. The whole-genomic sequences of these strains were sequenced. Phylogenetic trees were constructed, and the mutation spectra were analyzed based on these viral sequences. There was no obvious mutation for the circular EV-A71 strains of the same year. Pathogenic EV-A71 strains may arise from a "subgroup" randomly each year. Whole-genomic analyses showed that a hotspot nonsynonymous substitution potentially affecting the immunogenicity of vaccines was found in the 2A gene, but not in genes of the viral capsid proteins, and the genetic diversity of whole viral genomes associated with the incidence of HFMD. Therefore, it will be valuable to monitor the genome-wide changes of EV-A71 to detect the adaptive mutations affecting immunogenicity or perform investigations using genetic diversity as a parameter.
Assuntos
Enterovirus Humano A/genética , Infecções por Enterovirus/epidemiologia , Genoma Viral , Filogenia , Antígenos Virais/genética , China/epidemiologia , Fezes/virologia , Variação Genética , Doença de Mão, Pé e Boca/epidemiologia , Doença de Mão, Pé e Boca/virologia , Humanos , Mutação , RNA Viral/genética , Vacinação , Sequenciamento Completo do GenomaRESUMO
To analyze the genomic sequence characteristics of a human Echovirus 9(ECHO-9) strain isolated from a child with Hand-foot-mouth disease (HFMD) in Kunming, Yunnan Province, in 2010. The complete genome sequence of a human echovirus 9 strain, MSH-KM812-2010 was determined. As other human enterovirus, its genome was 7,424 nucleotides (nts) in length and encoded for 2,203 amino acids (aas). In comparison to other human enteroviruses, MSH-KM812-2010 strain had the highest homology with other strains of human echovirus 9 in structural genomic regions and more homologous to other serotypes of B specie than to human echovirus 9 in non-structural genomic regions. Phylogenetic analysis based on complete VP1 gene revealed that the sequences of human echovirus 9 segregated into three distinct clades A, B and C with more than 15. 0% diversity between clades. All Chinese isolates belonged to the same clade. RDP3 and Blast revealed evident recombination in non-structural genomic regions. This report is the first to, describe the complete genome of the human echovirus 9 in China and provide an overview of the diversity of genetic characteristics of a circulating human echovirus 9.