Institute of Infection and Global Health, University of Liverpool, Leahurst, UK; Faculty of Veterinary Medicine, Diyala University, Iraq.
Institute of Infection and Global Health, University of Liverpool, Leahurst, UK.
Res Vet Sci. 2021 May;136:587-594. doi: 10.1016/j.rvsc.2021.04.020. Epub 2021 Apr 15.
This study investigated the pathogenesis of infectious bronchitis virus (Gammacoronavirus) strain Q1 in two commercial broiler chicken lines, and the host immune response to infection. Chicks from each line were grouped into either infected or control. Following Q1 infection at day-old, fast (Line-A) and slow (Line-B) growing chicks were monitored for clinical signs and body weights. At 3, 7, 9, 14, 21 and 28 days post infection (dpi), five birds were humanely euthanised, and trachea, kidney and proventriculus tissues were collected for quantitative RT-PCR and histopathology. Blood was collected weekly to determine IBV-specific ELISA antibody titres. Q1 infection significantly reduced the body weights of Line-A chicks at 14 and 21 dpi, but there were no significant differences in Line-B. Through qRT-PCR, significantly higher viral loads were found in the trachea, proventriculus and kidney tissues of Line-A chicks at 7-9 dpi. At day-old and at 28 dpi, the mean antibody titre in Line-B was notably higher than Line-A. Significant IFN-α mRNA expression was noted in the trachea and kidneys of Line-A, whereas no change occurred in Line-B. Chicks in Line-B, compared to those in Line-A, demonstrated a tissue-dependent increase of IFN-β, TLR3, IL-1β and IL-6 and LITAF gene transcription responses to IBV Q1. It appears that the level of maternal antibodies, growth rates, and other inherent host genetic factors could have influenced the differences in viral loads and immune responses.
本研究调查了两种商业肉鸡品系中传染性支气管炎病毒（γ冠状病毒）株 Q1 的发病机制和宿主对感染的免疫反应。从每个系中选择鸡雏分为感染组或对照组。在 1 日龄感染 Q1 后，快速（Line-A）和慢速（Line-B）生长的鸡雏被监测临床症状和体重。在感染后 3、7、9、14、21 和 28 天（dpi），每组处死五只鸡，收集气管、肾脏和前胃组织进行定量 RT-PCR 和组织病理学检查。每周采集血液以确定 IBV 特异性 ELISA 抗体滴度。Q1 感染显著降低了 Line-A 鸡雏在 14 和 21 dpi 的体重，但 Line-B 没有显著差异。通过 qRT-PCR，在 Line-A 鸡雏的气管、前胃和肾脏组织中，7-9 dpi 时发现明显更高的病毒载量。在 1 日龄和 28 dpi，Line-B 的平均抗体滴度明显高于 Line-A。Line-A 的气管和肾脏中观察到明显的 IFN-α mRNA 表达，而 Line-B 中未发生变化。与 Line-A 相比，Line-B 鸡雏的 IFN-β、TLR3、IL-1β 和 IL-6 以及 LITAF 基因转录对 IBV Q1 的反应呈现组织依赖性增加。看来母源抗体水平、生长速度和其他固有宿主遗传因素可能影响了病毒载量和免疫反应的差异。
