Molecular epidemiology of coxsackie A type 24 variant in Taiwan, 2000–2007

Abstract

Background Epidemics of acute hemorrhagic conjunctivitis (AHC) caused by a coxsackievirus A24 variant (CA24v) appeared in Taiwan in 2000–2002 and again in 2006–2007. Objective To analyze the molecular epidemiology of CA24v in recent outbreaks in Taiwan. Study design A 510 bp fragment of 3C pro region was analyzed in 30 CA24v isolates during 2000–2007. Phylogenetic tree was constructed along with 130 CA24v isolates available from the GenBank. Moreover, the 235 bp of 3′VP1 region was similarly analyzed in 15 randomly selected strains isolated during 1985–2007. Phylogenetic dendrogram was constructed for the 3′VP1 region in 105 CA24v strains worldwide. Genetic distances were calculated using Kimura 2-parameter model, and phylogenetic trees were constructed by neighbor-joining method. Results The 3C pro dendrogram depicted genotype IV (GIV), a new genotype that can be further divided into three clusters (C1–C3). The 2000–2002 outbreaks were caused by genotype IV-cluster 1 (GIV-C1) and GIV-C2. Strains isolated in the 2006–2007 outbreak belong to GIV-C3, also in the same cluster as Singapore strains from 2005. Analysis on 3′VP1 revealed only GI, GIII and GIV in line with the classification in 3C pro dendrogram. All genotype IV strains were also divided into three clusters, though the GIV-C 2′ were isolated from broader geographic areas and over a longer period of time. Conclusions Analysis of the 3C pro region is more insightful than the 3′VP1 region in the molecular epidemiology of CA24v. The 3C pro dendrogram accurately and chronologically identified all stains involved in the worldwide outbreaks.