禽波氏杆菌鸡胚强毒株对雏鸡的致病性

Pathogenicity to chicks of Bordetella avium virulent isolate from chick embryo

以从孵化场将出壳鸡胚中分离到的鸡胚强毒株禽波氏杆菌LL09作为试验菌株,分别经鼻腔、眼睛和腹腔3种感染方式和1,7,14,21d不同日龄感染海蓝褐蛋雏鸡,检测其致病过程、病理变化,以及LL09在不同感染方式和不同感染日龄对雏鸡的生长抑制和NDV灭活苗免疫后HI抗体水平的影响差异。结果发现:LL09能引起雏鸡眼睛分泌物增多,咳嗽等呼吸道症状,且能入侵内脏组织,导致气管黏膜纤毛细胞脱落,肺出血,心肌细胞、肝细胞、脾细胞、肾小管上皮细胞等变性坏死等病理变化。3种感染方式中以腹腔感染危害最为严重,入侵内脏组织的比例最高,对雏鸡的生长抑制作用最强,对NDV免疫后HI抗体水平的影响最大,其次是经鼻腔感染组和经眼睛感染组。LL09分别于不同日龄感染雏鸡结果发现,感染日龄与LL09对雏鸡的危害直接相关,越早期感染,对雏鸡的体质量抑制越严重,对NDV免疫后的HI抗体水平的影响越大,内脏组织的感染几率越高。尤其是1d和7d感染组危害比较严重,而21d感染雏鸡症状不明显,且未在除气管和肺脏以外的内脏组织中检测到LL09的感染。对禽波氏杆菌LL09鸡胚强毒株的致病性检测结果表明,LL09作为鸡胚分离株,同样可以导致禽类的呼吸道感染,且能入侵内脏组织,以腹腔感染和1周内感染的危害最为严重。

Bordetella aviurn disease caused by Brdetella avium is a highly contagious disease of upper respiratory tract of poultry. It caused significant economic losses in poultry cultivation. In this study, virulent isolate LL09 screened from some B. avium isolates from chick embryos in hatchery was used as a test strain to challenge Highland brown chicks respectively by the nose, eyes and abdomen. The chicks were also challenged at different ages of 1,7,14 and 21 d, respectively. Then the pathogenicity process, pathological changes, growth inhibition and HI titers after inoculated by NDV inactivated vaccine were detected to compare the difference among different infection methods and ages. The results showed that LL09 could cause increased secretions in eyes, cough and other respiratory symptoms. It could also invade visceral tissues and lead to tracheal mucociliary cell loss, pulmonary hemorrhage, degeneration and necrosis of cardiac cells, liver cells, spleen cells and renal tubular epithelial cells. Among three kinds of infection ways, the most serious harm was observed in infection by abdomen cavity, having the highest percentage of visceral invasion,the strongest inhibition to chick growth and the most serious effect on HI antibody levels,followed by nasal infection and eye infection. It was also found that the smaller the age of infection,the stronger inhibition to the growth of chicks,the more serious effect on HI antibody levels, and also the higher proportion of visceral tissue invasion. The harm were more serious when infected on 1 d and 7 d. However,the chicks had no obvious symptoms and LL09 was not isolated from visceral tissues except lung and trachea when infected on 21 d. In conclusion, pathogenicity test results showed that B. avium LL09,as a virulent isolate from chick embryos,could not only cause infection in respiratory tracts of chicks but also invade visceral tissues. The harm is most se rious when infected by abdomen cavity and within 1 weeks.