Detection of fowl adenovirus associated with hydropericardium hepatitis syndrome by a polymerase chain reaction.

Hydropericardium hepatitis syndrome (HHS), previously unknown in the broiler industry, is an emerging disease that causes severe hydropericardium. A polymerase chain reaction (PCR) was developed to detect the fowl adenovirus (FAV) associated with HHS. The virus from infected livers was purified, with confirmation by electron microscopy and experimental infection. Methods were developed to isolate the viral DNA from purified virus and infected tissues. Available sequence data on the hexon gene of fowl adenoviruses and other adenoviruses were aligned to determine the conserved and variable regions. Primers were constructed from the alignment data. The amplified fragment consisted of the variable region of the hexon gene flanked by conserved primer sites. Optimum conditions were standardized to achieve the amplification of the desired fragment. As expected, the amplified product was found to be of 0.7 kg size. The nucleotide sequence analysis confirmed the specific nature of the product. Amplification of the specific product could be obtained not only from the DNA isolated from the purified virus but also from the total DNA extracted from infected tissues. The PCR was useful for the detection of FAV associated with HHS.