Pathological Changes and Virus Detection in Organs of Chicken Infected with Fowl Adenovirus Serotype 8b

Abstract

Fowl adenovirus (FAdV) serotype 8b is a pathogenic viral agent of inclusion body hepatitis (IBH) in chickens with huge mortality in affected farms. It was objective of the study to determine the pathological changes and to detect FAdV by molecular method in organs of specific-pathogen-free (SPF) chickens infected with FAdV serotype 8b. FAdV isolate, UPM1901, was inoculated into day-old chicks via oral route followed by sampling at 0 hour (h) for control group and subsequently at 12h, 24h, days 3 and 7 post-inoculation (pi). Body weight, liver and bursa of Fabricius weights were measured followed by organs collection for histopathological analysis and virus detection using polymerase chain reaction (PCR). It showed that chickens in the infected group were depressed and inappetence prior sudden death with 48% total mortality within day 5pi. Mean body weight was significantly low (p<0.05) than control group at days 3 and 7pi. Swollen, haemorrhages and necrosis of liver were recorded with numerous basophilic intranuclear inclusion bodies in the hepatocytes along with haemorrhages spleen and kidney at 3 dpi onward. FAdV nucleic acid detected in bone marrow at 12h pi followed by the other organs at 24h pi in spleen, liver and cecal tonsils. At days 3 and 7pi, viral DNA was detected in all the selected organs. This study proves that pathogenic FAdV serotype 8b caused chick`s mortality, pathological changes with existence of viral DNA at 12h pi in lymphoid organ prior distributed to other organs and necessitates effective control strategies against the disease.