Steer-Cope Penelope, Sandy Jeanine, O'Rourke Denise, Scott Peter, Browning Glenn, Noormohammadi Amir
A Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, 250 Princes Highway, Werribee, VIC 3030, Australia.
B Poultry CRC, P.O. Box U242, University of New England, Armidale, NSW 2351, Australia.
Avian Dis. 2017 Dec;61(4):512-519. doi: 10.1637/11718-072317-Reg.1.
Inclusion body hepatitis (IBH) is a disease affecting broiler chicken flocks worldwide. Several serotypes of fowl adenovirus (FAdV) have been implicated in disease outbreaks, with and without immunosuppression as a predisposing factor. IBH usually occurs in flocks up to 30 days of age; it is seldom seen in older birds. The objective of this study was to determine whether the pathogenicity for older birds of three FAdV field strains, belonging to serotypes 1, 8b, and 11, in the absence of immunosuppressive factors, was akin to that for younger birds, and to establish an effective and economical disease model for assessing cross-protection between serotypes. To achieve this objective, the gross pathology, histopathology, and dissemination of virus were examined at multiple time points after inoculation of 6-wk-old, specific-pathogen-free chickens via intraperitoneal injection. Both FAdV-8b and FAdV-11 generated lesions typical of those associated with outbreaks of IBH, and they were shown to be primary pathogens. The presence and severity of hepatic lesions were used to define two disease stages: degeneration (1-5 days postinoculation) and convalescence (6-14 days postinoculation). During the degenerative stage, FAdV-8b was detected in the liver, kidney, and gizzard of most birds, whereas FAdV-11 was predominantly detected in the liver, and both viruses persisted in the gizzard into convalescence. The pathogenesis of two IBH-associated FAdV strains in 6-wk-old chickens confirms their high level of virulence and also provides an effective experimental model for investigation of cross-protection between FAdVs. It also demonstrates persistence of the virus in the gizzard long after infection, supporting the notion that it is a site of viral shedding.
包涵体肝炎（IBH）是一种影响全球肉鸡群的疾病。几种禽腺病毒（FAdV）血清型与疾病暴发有关，无论是否有免疫抑制作为诱发因素。IBH通常发生在30日龄以内的鸡群中；在老龄鸡中很少见。本研究的目的是确定在没有免疫抑制因素的情况下，属于血清型1、8b和11的三种FAdV田间毒株对老龄鸡的致病性是否与对幼龄鸡的致病性相似，并建立一种有效且经济的疾病模型来评估血清型之间的交叉保护作用。为实现这一目标，通过腹腔注射对6周龄的无特定病原体鸡进行接种后，在多个时间点检查大体病理学、组织病理学和病毒传播情况。FAdV-8b和FAdV-11均产生了与IBH暴发相关的典型病变，并且它们被证明是主要病原体。肝脏病变的存在和严重程度被用于定义两个疾病阶段：变性期（接种后1 - 5天）和恢复期（接种后6 - 14天）。在变性期，大多数鸡的肝脏、肾脏和肌胃中都检测到了FAdV-8b，而FAdV-11主要在肝脏中被检测到，并且两种病毒在恢复期仍在肌胃中持续存在。两种与IBH相关的FAdV毒株在6周龄鸡中的发病机制证实了它们的高毒力，也为研究FAdV之间的交叉保护提供了一个有效的实验模型。它还证明了感染后很长时间病毒在肌胃中的持续存在，支持了肌胃是病毒脱落部位的观点。
