Islam M A, Ito T, Takakuwa H, Takada A, Itakura C, Kida H
Department of Hygiene and Microbiology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Jpn J Vet Res. 1994 Dec;42(3-4):147-56.
Newcastle disease virus (NDV) was isolated from a Japanese quail (Cotornix cotornix japonica). The effect of intracerebral and intranasal passages of the NDV in chickens on the pathogenicity was studied. Pathogenicity of the viruses of different passage levels was compared with that of the original isolate by the mean death time with the minimum lethal dose in chicken embryos, intracerebral pathogenicity index in day-old chicks, intravenous pathogenicity index with 6-week-old chickens and the mortality rates of chickens and quails inoculated intravenously or intranasally. The original isolate from the quail did not kill chickens but only embryos and some one-day-old chicks, exhibiting a mesogenic character. Pathogenicity of the virus of the 10th intranasal passage was not different from that of the original isolate. The viruses passaged intracerebrally, on the other hand, killed chickens of all ages by either route of inoculation, showing a velogenic property. Virus recovery from the blood and the brain was positive only in the chickens infected with brain-passaged viruses by any route of inoculation. Virus titers in the tissues of chickens infected with the brain-passaged viruses were higher than those with the original isolate and the virus of the 10th intranasal passage. These results indicate that the enhanced pathogenicity of the mesogenic NDV isolate from the quail for chickens was induced by acquiring the properties of neurotropism and pantropism through intracerebral passage in chickens.
新城疫病毒（NDV）从一只日本鹌鹑（Cotornix cotornix japonica）中分离得到。研究了该新城疫病毒在鸡体内进行脑内和鼻内传代对其致病性的影响。通过鸡胚最小致死剂量的平均死亡时间、一日龄雏鸡的脑内致病性指数、六周龄鸡的静脉致病性指数以及经静脉或鼻内接种的鸡和鹌鹑的死亡率，比较了不同传代水平病毒的致病性与原始分离株的致病性。从鹌鹑中分离出的原始毒株不会导致鸡死亡，但只会使鸡胚和一些一日龄雏鸡死亡，表现出中等毒力特征。第10代鼻内传代病毒的致病性与原始分离株无差异。另一方面，经脑内传代的病毒通过任何接种途径都会导致各年龄段的鸡死亡，表现出强毒力特性。仅在通过任何接种途径感染脑内传代病毒的鸡的血液和脑中检测到病毒。感染脑内传代病毒的鸡组织中的病毒滴度高于感染原始分离株和第10代鼻内传代病毒的鸡。这些结果表明，鹌鹑源中等毒力新城疫病毒分离株对鸡致病性的增强是通过在鸡体内进行脑内传代获得嗜神经性和泛嗜性特性而诱导产生的。
