Human enterovirus 71 epidemics: what's next?

Abstract

Human enterovirus 71 (EV71) epidemics have affected various countries in the past 40 years. EV71 commonly causes hand, foot and mouth disease (HFMD) in children, but can result in neurological and cardiorespiratory complications in severe cases. Genotypic changes of EV71 have been observed in different places over time, with the emergence of novel genotypes or subgenotypes giving rise to serious outbreaks. Since the late 1990s, intra- and inter-typic recombination events in EV71 have been increasingly reported in the Asia-Pacific region. In particular, 'double-recombinant' EV71 strains belonging to a novel genotype D have been predominant in mainland China and Hong Kong over the last decade, though co-circulating with a minority of other EV71 subgenotypes and coxsackie A viruses. Continuous surveillance and genome studies are important to detect potential novel mutants or recombinants in the near future. Rapid and sensitive molecular detection of EV71 is of paramount importance in anticipating and combating EV71 outbreaks.

Keywords: evolution; genotype; hand, foot and mouth disease; human enterovirus 71; mutation; recombination.

Fig. 1

Phylogenetic tree of the VP1 region of EV71 strains detected in various countries, showing different genotypes and subgenotypes of EV71. Eight hundred and fifty-five nucleotide positions in each VP1 region were included in the analysis. The tree was constructed by the neighbor joining method and bootstrap values calculated from 1,000 trees. The scale bar indicates the estimated number of substitutions per 100 nucleotides. EV71 strains of potential novel genotype or subgenotype were highlighted in gray. GenBank accession numbers are indicated in parentheses.

Fig. 2

Schematic diagram showing intra- and inter-typic recombination events occurred in EV71 strains SZ/HK08-5 and SZ/HK08-6 of subgenotype C4 (proposed genotype D).