1株肾型鸡传染性支气管炎病毒的鉴定

Identification of one strain of nephropathogenic avian infectious bronchitis virus

鸡传染性支气管炎病毒(IBV)具有不同致病特性,将IBV XDC-2株接种9日龄SPF鸡胚培养,可引起鸡胚死亡和出现侏儒胚,病毒EID50达5×10-5.33/mL。将IBV XDC-2株接种18日龄SPF鸡,饲养观察14 d,病鸡临床症状表现为:精神沉郁,羽毛凌乱,双翅下垂,轻微腹泻,多数拉白色水样稀粪。病死鸡出现肾肿大、呈花斑状、大量尿酸盐沉积。鸡发病率为100%,死亡率为25%。死亡鸡肺脏、肾组织制作组织切片,发现病理变化明显,主要为:肾小管扩张,上皮细胞呈玻璃样变性,部分管腔内可见坏死脱落之上皮细胞,于肾间质可见大量单核细胞浸润,肾间质有充血、出血现象;肺内动脉、毛细血管充血,淋巴细胞浸润。死亡鸡肺脏、肾组织接种鸡胚分离病毒,RT-PCR检测结果为阳性,表明该分离株为鸡传染性支气管炎病毒,具有很强的嗜肾性。

Nine-day-old SPF chicken embryos were firstly inoculated with avian infectious bronchitis virus （IBV） XDC-2 strain and the virus titre was detected. The results showed that the virus could cause embryos to die and form dwarf embryos. The EIDso of the virus was 5×10-5. 33/mL. Then twenty 18-day-old SPF chickens were inoculated with IBV XDC-2 and 5 chickens were injected with sterile PBS as control,and observed daily for any clinical signs. At 14 days post challenge, all chickens were euthanized and macroscopic examination was performed to find any lesions in organs. And kidney and lung tissues were selected for microscopic examination and virus detection was performed by viral isolation and RT-PCR. The results showed that after 3 days of infection all chicken inoculated the virus showed the clinical signs： depression, ruffled and depressed feathers, slight diarrhea, mostly the white water-like manure. And 3/12 chickens were died. Gross lesion examination of dead chicken showed kidney enlargement, nephropathy, and massive uric acid salt deposit. Histopathological examination revealed that kidney had tubular ectasia, glassy degeneration of epithelial ceils, endothelial cell necrosis and exfoliation in some vessel lumens, monocytes infiltration in renal interstitium, and hyperremia and hemorrhage in the interstitial substance. The lung showed intrapulmonary artery and capillary blood congestion and lymphocytic infiltration. The virus could be isolated from kidney and lung tissues and detected by RT-PCR. It indicated that IBV XDC-2 was a predominantly nephrotropicly avian infectious bronchitis virus.