Phylodynamic analysis of Coxsackievirus CA24v

• Main Authors: Jing-Yun Zeng, 曾靜雲
• Other Authors: Pei-Yu Chu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/dpwdg6

碩士 === 高雄醫學大學 === 醫學檢驗生物技術學研究所 === 102 === Acute hemorrhagic conjunctivitis (AHC) is a highly contagious disease characterized by sudden subconjunctival hemorrhage resulting in pain, swelling, and photophobia. Coxsackievirus A24 variant (CA24v) is one pathogenic cause of AHC. Our previous reports depicted chronological trends in epidemics involving Genotypes 1-IV (GI-GIV). To understand epidemiological trends in recent CA24v outbreaks in Taiwan, a VP1-based phylogenetic analysis was performed to explore the evolution of CA24v and its epidemiological relationships. Eighteen strains of CA24v strains isolated in Taiwan during 1985-2010 were randomly selected for analysis. A VP1 gene fragment (804bp) and gene fragment (636bp) were analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) and sequencing. Multiple sequence alignments were performed in another 41 sequences isolated worldwide. One additional prototype CA24 strain and Poliovirus-1, 2, 3 were also sampled as outgroup. The phylogenetic tree was constructed by performing neighbor-joining and maximum likelihood methods with MEGA5.0 software. The phylogenetic analysis results were consistent with previous reports. All viral strains clustered by isolation year had high bootstrap values (>75). Due to the insufficient number of VP1 virus sequences isolated before 1985, the prototype strain of CA24v was divided into a separate branch and designated Genotype I. No GII sequences (isolated during 1975-1976) were observed. Strains isolated in 1985-1986 were clustered into GIII. Interestingly, all strains isolated in 1991 and one strain isolated in 2008 were clustered into GIV-C2’. The 2010 strains were clustered into a new subcluster GIV-C4.This study further supports our previous report of clear chronological trends revealed by the CA24v dendrogram, i.e., one outbreak for each emerging subgenotype. Most CA24v outbreaks resulted from a newly emerging subcluster that circulated for 2-3 years before being replaced by the next emerging subcluster. For example, the new genetic subtype GIV-C4 caused the 2000-2010 outbreaks. In contrast, the 1991 isolates in this study were clustered into subgenotype GIV-C2, which was characterized by a wide range of isolation years (1984-2006) and a broad geographic region (e.g., China, Taiwan, Korea, Japan and India (Asia); Brazil and Guadeloupe (South America); Tunisia and Gabon (Africa); Spain (Europe); and Australia (Oceania)). Because of the wide geographic distribution of GIV-C2, this subset needs further molecular characterization and further study of its temporal and spatial distribution.