浙江省2002-2010年急性出血性结膜炎暴发疫情病原体CA24v的全基因组序列分析

Study on the complete sequence of CA24 variant isolated during the acute hemorrhagic conjunctivitis outbreaks in Zhejiang province during 2002 to 2010

目的分析2002--2010年浙江省急性出血性结膜炎（AHC）暴发疫情病原柯萨奇病毒A组24型变种（CA24v）流行株的全基因组序列与遗传特性。方法选取浙江省不同年份的CA24v流行株，采用RT-PCR扩增基因序列，并与国内外流行株进行全基因组及VPl、3C区序列比较分析。结果浙江省2002年和2010年CA24v全序列为7456～7458bp，编码含2214个氨基酸残基的多聚蛋白，2010年的Zhejiang／08／10较2002年的毒株在5’端非编码区的第97、119位各存在一个T碱基插入，Zhejiang／08／10与2002年以来的分离株各区段氨基酸同源性为94．7％～100．0％，与近60年来CA24流行代表株全序列中各区段氨基酸的平均差异率以2A区与3A区最大，分别达8．4％和7．3％，3D区最小，仅为1．9％。1987年与2002年以来的CA24v毒株在全序列上共存在38个和20个氨基酸的稳定变异。2002--2010年CA24v的组间遗传距离分析表明，3C区较VP1区更为稳定，CA24v的早年流行株Jamaica／10628／87在3D区上可能存在重组，而在近年流行株中未发现该现象。结论CA24v以时间序列为主逐年进化，地域间虽存在差异，但影响较小。自2002年起，由CA24v引起的AHc一直在浙江省本地散在流行。

Objective To analyze the genetic characteristics of the complete sequence of coxsackievirus A24 variant （CA24v） isolated from acute hemorrhagic conjunctivitis （AHC） outbreaks in Zhejiang province during 2002 to 2010. Methods Complete sequences of CA24v epidemic strains isolated in different years were amplified under the RT-PCR assay, while the sequences of whole genome, VP 1, and 3C region of Zhejiang strains were compared with epidemic strains isolated in other areas of China and abroad. Results The whole genome of Zhejiang CA24v strains isolated in 2002 and 2010 was 7456-7458 bp in length, encoding a polyglutamine protein which containing 2214 amino acid residues. There was a insertion with T on site 97 and 119 within 5＇ non-coding region between epidemic strain Zhejiang/08/10 and strains isolated in 2002. The rates of amino acid homology among Zhejiang/08/10 and other strains isolated since 2002 were between 94.7% and 100.0%. Compared with the representative strains circulated within the recent 60 years, the largest average amino acid variations had been occurred on region 2A and 3A, with the ratios as 8.4% and 7.3% respectively. The smallest variation happened in region 3D, with the ratio only as 1.9%. The rates of stable amino acid variation on the whole genome between strains isolated since 1987 and 2002 were 38 and 20. P-distance within groups appeared that region 3C was more stable than VP1 of strains isolated in 2002-2010, and the 3D of early strain Jamaica/10628/87 might have had a nature of recombination but not observed on those epidemic strains in recent years. Conclusion Within the evolution of CA24v strains, the time course was more significant than the geographical differences. There had been sporadic epidemics of AHC caused by CA24v in Zhejiang province since 2002.