鸭瘟病毒新近分离毒株部分基因变异分析

Genetic Variability of Partial Genes of Duck Plaque Viruses Currently Isolated in Ducks

旨在研究鸭群中新流行的鸭瘟病毒(duck plaque virus,DPV)感染状况及其分子特征。本研究对2016—2017年福建不同地区疑似感染DPV的发病鸭组织样品进行了检测、病毒分离和部分基因的序列分析。从临床样品中分离获得24株DPV,发现确诊感染DPV鸭的日龄存在品种差异性,其中半番鸭和番鸭感染DPV的日龄中位值分别为90和88d,而麻鸭感染DPV的日龄中位值为287d。对DPVUL56/LORF5基因、TK/gH基因及UL2区域的序列分析表明,分离毒株均未出现基因片段缺失,与我国DPV参考强毒株的序列相似性均在99%以上,但在UL56/LORF5基因及TK基因上存在有规律性的核苷酸变异。经分子系统进化分析发现,新近流行的DPV毒株与我国参考强毒株(GroupⅠ)处于不同进化分支,为GroupⅡ进化分支,且可进一步细分为两个不同的亚分支(GroupⅡa、GroupⅡb)。以上结果揭示,新近流行的DPV毒株感染不同品种鸭存在日龄差异性,与我国DPV参考强毒株相比已出现不同程度的变异,应加强对该病毒的分子流行病学监测,实时了解其流行变异情况,为新流行鸭瘟的快速准确诊断和防控提供科学依据。

The purpose of this study was to explore the infection status and molecular characteristics of duck plaque virus(DPV)currently circulating in ducks.The duck samples suspected to be infected with DPV were collected from Fujian province during 2016-2017,and were used for virus detection,isolation and gene sequences analysis.A total of 24 DPV strains were isolated from these samples,and the median age(Me)of the confirmed DPV-positive ducks were different among duck species.The Me of DPV-positive Mule duck and Muscovy duck were 90-day old and 88-day old,respectively,while the Me of DPV-positive Sheldrake duck was 287-day old.Sequence analysis showed that UL 56/LORF 5 gene,TK/gH gene and UL 2 gene of the 24 isolates shared as high as more than 99%nucleotide homology with those of Chinese DPV reference virulent strains,and there exist regular nucleotide variations among the UL 56/LORF 5 gene and the TK gene between the current isolates and the Chinese reference virulent strains.Phylogenetic analysis showed that all of the current DPV isolates were gathered into one phylogenetic branch(GroupⅡ)which different from the Chinese reference virulent strains(GroupⅠ),and could further be divided into two sub-branches(GroupⅡa and GroupⅡb).The above results indicated that DPVs still circulated in ducks with Me-disparity among duck species,carrying some regular mutations compared to the Chinese reference virulent strains.We should strengthen the regular molecular epidemiological surveillance,and be aware of the epidemic variation of the virus.This will help for the rapid and accurate diagnosis and disease control of duck plague in China.