不同禽源及基因型新城疫病毒对番鸭致病性分析

Pathogenicity characteristics of Newcastle disease virus from different avian and genotype in Muscovy ducks

鸭是新城疫病毒(NDV)重要的自然宿主,在NDV的传播和进化中起着重要作用。为研究鸭对不同NDV株易感性及在NDV传播中的作用,本研究选取5株不同禽源及基因型NDV,以不同剂量经滴鼻点眼途径接种15日龄番鸭,鉴定对鸭的致病性、排毒情况、血清抗体变化以及病毒的组织脏器分布;并设立同居鸭、鸡测定NDV水平传播能力。结果显示,疫苗病毒株La Sota和WB383(基因Ⅰ型)株能够在番鸭体内有限复制;La Sota仅诱导产生低水平抗体,而WB383诱导的抗体水平较高,未检测到这2株病毒的水平传播;F48E9对番鸭致病性强,具有较强水平传播能力;同为基因Ⅶ型病毒,鸭源MD株呈现出对番鸭高致病性,野鸭源WB363株则对番鸭致病性较低,但其水平传播能力高于MD株。实验结果显示,5株NDV对番鸭致病性差异较大,La Sota和WB383株对番鸭无致病性,排毒和水平传播能力弱;F48E9对番鸭具有高致病性;同属于基因Ⅶ型的强毒株对番鸭致病性差异较大,这种差异原因尚需进一步研究。本研究结果表明番鸭感染NDV的F48E9、WB363、MD株后水平传播能力较强,应重视其在NDV传播和进化过程中的作用研究。

Ducks are considered to be the important natural host of Newcastle disease virus （NDV）, which plays a vital role in transmission and evolution of NDV. To illuminate the susceptibility and transmission of ducks to NDV, 15-day-old Muscovy ducks were inoculated with 5 NDV strains from different avian and genotype via intraocular-nasal with three dose, and the morbidity and mortality, virus shedding, antibody titer and virus distribution were detected for the artificially infected ducks. The results showed that vaccine strain LaSota and WB383 （genotype I ） had no pathogenic for Muscovy ducks, and the virus induced low level antibody by limiting replication in ducks, and no horizontal transmission was detected. F48E9 strain was highly pathogenic to Muscovy ducks with high level horizontal transmission ability. Although the MD and WB363 stains were classified into the same genotype VII, MD was highly pathogenic to ducks, while WB363 had no pathogenic. This study indicated that LaSota and WB383 strains had no pathogenic for Muscow ducks with poor horizontal transmission ability. F48E9 strain remained the highly pathogenic for Muscovy ducks with virus shedding and horizontal transmission. The pathogenic diversity of genotype VII NDV in Muscovy Ducks needed to be further studied. As the NDV strains of F48E9, WB363 and MD have the highly horizontal transmission ability in infected Muscovy ducks, the role of ducks in NDV transmission and evolution should be emphasized.