Elshafiee Esraa A, Isham Ishara M, Najimudeen Shahnas M, Perez-Contreras Ana, Barboza-Solis Catalina, Ravi Madhu, Abdul-Careem Mohamed Faizal
Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada.
Department of Zoonoses, Faculty of Veterinary Medicine, Cairo University, Giza 12211, Egypt.
Vaccines (Basel). 2022 May 16;10(5):782. doi: 10.3390/vaccines10050782.
Infectious laryngotracheitis (ILT) is caused by Gallid herpesvirus-1 (GaHV-1) or infectious laryngotracheitis virus (ILTV) and was first described in Canadian poultry flocks. In Canada, ILTV infection is endemic in backyard flocks, and commercial poultry encounters ILT outbreaks sporadically. A common practice to control ILT is the use of live attenuated vaccines. However, outbreaks still occur in poultry flocks globally due to ILTV vaccine strains reverting to virulence and emergence of new ILTV strains due to recombination in addition to circulating wildtype strains. Recent studies reported that most of the ILT outbreaks in Canada were induced by the chicken-embryo-origin (CEO) live attenuated vaccine revertant strains with the involvement of a small percentage of wildtype ILTV. It is not known if the host responses induced by these two ILTV strains are different. The objective of the study was to compare the host responses elicited by CEO revertant and wildtype ILTV strains in chickens. We infected 3-week-old specific pathogen-free chickens with the two types of ILTV isolates and subsequently evaluated the severity of clinical and pathological manifestations, in addition to host responses. We observed that both of the isolates show high pathogenicity by inducing several clinical and pathological manifestations. A significant recruitment of immune cells at both 3 and 7 days post-infection (dpi) was observed in the tracheal mucosa and the lung tissues of the infected chickens with wildtype and CEO vaccine revertant ILTV isolates when compared to uninfected controls. Overall, this study provides a better understanding of the mechanism of host responses against ILTV infection.
传染性喉气管炎（ILT）由鸡疱疹病毒1型（GaHV - 1）或传染性喉气管炎病毒（ILTV）引起，最早在加拿大家禽群中被描述。在加拿大，ILTV感染在家养禽群中呈地方性流行，商业家禽偶尔会爆发ILT。控制ILT的常用方法是使用减毒活疫苗。然而，由于ILTV疫苗株毒力回复以及除了循环野生型毒株外还因重组出现新的ILTV毒株，全球家禽群中仍有疫情爆发。最近的研究报告称，加拿大的大多数ILT疫情是由鸡胚源（CEO）减毒活疫苗回复株引起的，其中野生型ILTV的比例较小。尚不清楚这两种ILTV毒株诱导的宿主反应是否不同。本研究的目的是比较CEO回复株和野生型ILTV毒株在鸡体内引发的宿主反应。我们用这两种类型的ILTV分离株感染3周龄的无特定病原体鸡，随后除了评估宿主反应外，还评估了临床和病理表现的严重程度。我们观察到，两种分离株都通过诱导多种临床和病理表现显示出高致病性。与未感染的对照组相比，在感染野生型和CEO疫苗回复株ILTV的鸡的气管黏膜和肺组织中，在感染后3天和7天均观察到免疫细胞的大量募集。总体而言，本研究有助于更好地理解宿主针对ILTV感染的反应机制。
