Experimental Transmission of Turkey Viral Hepatitis to Day-Old Poults and Identification of Associated Viral Particles Resembling Picornaviruses

Abstract

Turkey viral hepatitis (TVH) was experimentally reproduced in two experiments in 1-day-old poults. In the first experiment, an infectious inoculum was prepared from filtered yolk materials harvested from dead embryonating chicken eggs (ECE) previously inoculated with suspensions of liver and pancreas tissues collected from TVH-affected birds in commercial turkey flocks. One-day-old poults given a yolk-sac inoculation or oral gavage with this preparation developed lesions in the liver and pancreas characteristic of TVH at 20 days postinoculation (PI) in 60% and 14% of the experimentally infected birds, respectively. With the identical inoculum, embryo mortality occurred at 8 and 10 days PI in embryonating turkey eggs (ETE) inoculated into the yolk sac. In the second experiment, an infectious inoculum was prepared from filtered yolk materials from dead ETE harvested in the first experiment. One-day-old poults given a yolk-sac inoculation with this filtered yolk material developed lesions in the liver and pancreas within 5 days PI. At 20 days PI, 67% of the experimentally infected birds had similar lesions. With the inoculum given to these poults, embryo mortality occurred at 6, 8, and 10 days PI in ETE inoculated into the yolk sac. Virus particles 26-28 nm in diameter with icosahedral morphology typical of picornaviruses were identified by EM in the yolk sacs of ETE that died in both experiments, and inoculated ETE that died following passage of filtered suspensions of pancreatic tissues collected from affected birds in the first experiment.

Novel Picornavirus in Turkey Poults with Hepatitis, California, USA

“…The disease is often subclinical, causing minor histologic lesions, and becomes overt when the animals are stressed, resulting in varying rates of illness and death ( 1 ). Mortality rates of up to 25% have been reported ( 2 ).…”

“…The disease has been experimentally reproduced in turkey poults by inoculation with material derived from affected animals ( 1 – 4 ). A viral basis for TVH has been presumed since its initial description in 1959 because the causative agent passed through 100-nm membranes, was acid stable, was not affected by antimicrobial drugs, and could be propagated in the yolk sac of embryonated chicken eggs ( 3 – 5 ).…”

“…A viral basis for TVH has been presumed since its initial description in 1959 because the causative agent passed through 100-nm membranes, was acid stable, was not affected by antimicrobial drugs, and could be propagated in the yolk sac of embryonated chicken eggs ( 3 – 5 ). Icosahedral particles of 24 to 30 nm have been found by electron microscopy (EM) in liver lesions of birds ( 6 ) as well as in embryonated turkey eggs ( 1 ) that have been inoculated with material derived from affected birds; however, no agent has been consistently implicated ( 7 , 8 ). …”

Group I avian adenovirus and avian adeno-associated virus in turkey poults with inclusion body hepatitis

“…White foci of necrosis in the liver of turkeys similar to IBH can also be seen in certain diseases such as turkey viral hepatitis (TVH), common in turkey poults in California (Klein et al, 1991;Shivaprasad et al, 1995). However, there was no evidence of TVH in these birds based on histopathology, electron microscopy and virus isolation.…”

“…However, there was no evidence of TVH in these birds based on histopathology, electron microscopy and virus isolation. TVH is a disease of 2-to 5-week-old turkeys presumed to be caused by a picorna-like virus (Klein et al, 1991). Lesions in TVH are characterized by multifocal necrosis of hepatocytes and infiltration by lymphocytes, macrophages and plasma cells, often with syncytia formation (Shivaprasad et al, 1995).…”