华东地区健康水禽携带新城疫病毒情况调查

摘要

Newcastle disease has become a severe disease in waterfowls since 1997. Domestic ducks and geese without clinical signs may act as carriers of Newcastle disease virus (NDV). However, little is understood on NDV infection status in waterfowls. In the present study, 23 NDV isolates were isolated from 1200 cloacal swab samples from domestic ducks and geese at live bird markets and farms in Eastern China and characterized for their biological and genetical features. Among these isolates, more isolates were obtained in spring and winter than that in summer, suggesting NDV circulation in domestic ducks and geese in China was temperature sensitive and hot weather might not be unsuitable for NDV spread. These NDV isolates were inoculated into chicken embryoes and the mean death time (MDT) and intracerebral pathogenicity indexes (IPCI) were determined. Phylogenetic analysis of these isolates was performed based on nt 47-470 of F genes. Thirteen isolates were clustered into Class II genotype Ib subclade and other 10 isolates into Class I clade. Among 10 Class I isolates, 3 isolates were close to genotype 2 and other 7 isolates to genotype 3b.%近年来，新城疫逐渐成为了一种严重的家养水禽疾病。尽管如此，目前对于我国水禽新城疫的流行和分布情况依然知之甚少。本研究采集了2011~2012年中国华东6省1市的部分活禽市场和养殖场表观健康家鸭和家鹅泄殖腔棉拭样品，进行新城疫病毒的分离和毒力检测工作。通过测定分离株F基因高变区nt47~420，对其进行遗传进化分析。结果显示，在1200份样品中，检测到阳性样品23份，分离率为1.92%，表明眼观健康家鸭和家鹅中携带新城疫病毒。对比寒冷的春冬两季和炎热的夏季，新城疫病毒的分离率存在明显的差别。在中国家鸭和鹅中流行的新城疫毒株依然对温度敏感，高温天气不利于新城疫疫情蔓延。对分离株的鸡胚平均死亡时间和脑内接种指数进行了测定。参考76株GenBank中已发表并鉴定基因型毒株的F基因高变区nt 47~420，对23株家养水禽分离株进行了遗传进化分析，结果发现分离株与流行的强毒株和疫苗株遗传距离较远。其中，13株与Class II基因Ib亚型遗传距离最近；3株属于Class I基因2型；7株与Class I基因3b亚型遗传距离最近。