Department of Poultry Diseases, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt.
Department of Poultry Diseases, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt.
Vet Microbiol. 2018 Jun;219:8-16. doi: 10.1016/j.vetmic.2018.04.009. Epub 2018 Apr 7.
Avian influenza and infectious laryngeotracheitis viruses are common causes of respiratory diseases in chickens with economical importance worldwide. In this study, we investigated the effect of experimental co-infection of avian influenza virus-H9N2 (AIV-H9N2) with infectious laryngeotracheitis virus (ILTV) live-attenuated vaccine (LAR-VAC) on chickens. Four experimental groups were included in this study: negative control group, AIV-H9N2 group, AIV-H9N2+LAR-VAC group, and LAR-VAC group. AIV-H9N2 was inoculated intranasally to challenged groups at 35 days of age. On the same day, LAR-VAC was ocularly administered to vaccinated groups. Chickens were observed for clinical signs, changes in body weight and mortality rates. Tissue samples, sera, tracheal and cloacal swabs, and blood were also collected at 3, 6, 9 and 12 days post-infection (PI). A significant increase in clinical signs and mortality rates were observed in the AIV-H9N2 + LAR-VAC group. Moreover, chickens coinfected with AIV-H9N2 and LAR-VAC showed a significant decrease in body weight and lymphoid organs indices. The tracheal gross and histopathological lesions and the shedding titer and period of AIV-H9N2 were significantly higher in AIV-H9N2 + LAR-VAC group when compared to other groups. Furthermore, AIV-H9N2 infection leads to humoral and cellular immunosuppression as shown by a significant decrease in the CD4/CD8 ratio and antibody responses to ILTV and a significant increase in H/L ratio. In conclusion, this is the first report of co-infection of AIV-H9N2 and ILTV vaccine in chickens, which leads to increased pathogenicity, pathological lesions, and AIV-H9N2 shedding titer and period, which can lead to severe economic losses due to poor weight gain and mortality.
禽流感和传染性喉气管炎病毒是全球范围内引起鸡呼吸道疾病的常见原因，具有重要的经济意义。在本研究中，我们研究了禽流感病毒 H9N2（AIV-H9N2）与传染性喉气管炎病毒（ILTV）活疫苗（LAR-VAC）的实验性混合感染对鸡的影响。本研究包括四个实验组：阴性对照组、AIV-H9N2 组、AIV-H9N2+LAR-VAC 组和 LAR-VAC 组。在 35 日龄时，通过滴鼻接种向 challenged 组接种 AIV-H9N2。同日，通过眼部给药向 vaccinated 组接种 LAR-VAC。观察鸡的临床症状、体重变化和死亡率。还在感染后 3、6、9 和 12 天收集组织样本、血清、气管和泄殖腔拭子和血液。在 AIV-H9N2+LAR-VAC 组中观察到临床症状和死亡率显著增加。此外，感染 AIV-H9N2 和 LAR-VAC 的鸡体重和淋巴器官指数显著下降。与其他组相比，AIV-H9N2+LAR-VAC 组的气管大体和组织病理学病变以及 AIV-H9N2 的脱落滴度和时间显著更高。此外，AIV-H9N2 感染导致体液和细胞免疫抑制，表现为 CD4/CD8 比值显著降低，对 ILTV 的抗体反应降低，H/L 比值显著升高。总之，这是首次报道 AIV-H9N2 和 ILTV 疫苗在鸡中的混合感染，导致致病性、病理病变和 AIV-H9N2 脱落滴度和时间增加，由于体重增加不良和死亡率高，可能导致严重的经济损失。
