Hexon gene based molecular detection of fowl adenovirus associated inclusion body hepatitis in commercial broiler chicken

Inclusion body hepatitis (IBH), caused by fowl adenoviruses, is an economically important poultry disease that causes substantial economic losses to the world poultry industry. The avian adenovirus was first isolated from an outbreak of respiratory disease in quail (Olson, 1950). Aviadenoviruses affect birds, particularly chickens, ducks, geese, turkeys and pheasants. There are total 12 serotypes of Fowl adenovirus viz. FAdV-1, FAdV-2 FAdV-3, FAdV-4, FAdV-5, FAdV-6, FAdV-7, FAdV-8a, FAdV-8b, FAdV-9, FAdV-10 and FAdV11 which were classified on the basis of restriction fragment length polymorphism (RFLP) profile and sequencing data (Benkoet al., 2000). FAdV-11 is one of the primary causative agents for IBH and the disease has been reported in many countries worldwide. Recently, inclusion body hepatitis outbreaks have been increasingly reported, particularly in broiler flocks, in different regions of India, i.e., Uttar Pradesh, Madhya-Pradesh, Maharashtra, Andhra Pradesh, Karnataka, Tamil Nadu, Kerala, Odisha, West Bengal, Chhattisgarh and Mizoram (Gupta et al., 2007, Asthana et al., 2013, Suohu and Rajkhowa, 2021, Chitradevi et al., 2021). On 01/12/2024, in a well-organized poultry farm in Jabalpur region of Madhya-Pradesh, mortality was reported in a 36-day old broiler flock with capacity of 5400 birds in house. Visited Farm and based on the symptoms and postmortem examination of dead birds, inclusion body hepatitis was suspected in affected flock. Samples were collected for further diagnosis. On microscopic examination, large basophilic intranuclear inclusion bodies were present in hepatocytes which was suggestive of IBH. Polymerase Chain Reaction (PCR) was done using 897 bp hexon gene for confirmative diagnosis.