Abstract
A study was conducted to characterize local fowl adenovirus serotype 4 (FAV-4) associated with hydropericardium syndrome (HPS) at molecular level. For this purpose, chicken livers naturally infected with HPS virus were aseptically collected from a field outbreak in commercial broilers from Faisalabad, Pakistan. Virus purification was done using a 15-45% (w/v) sucrose gradient. Virus was confirmed by agar gel precipitation test. Viral DNA was extracted and variable region hexon gene of 0.7 kb in size was amplified by PCR and sequenced. Nucleotide sequence (730 bp) and deduced amino acid sequence (243) of isolate was compared with already published sequences of FAV4. Sequence analysis of the variable region hexon gene confirmed that the virus belonged to avian adenovirus serotype 4. The nucleotide sequence of the Pakistani isolate had a 94% to 98% homology with Indian isolates, 97% homology with Belgium and Russian isolates and 96% homology with Canadian isolate. The amino acid sequences of the Pakistani isolate had an almost 87% to 98% homology with Indian, 92% and 95% homology with Belgian, 96% homology with Russian and 95% homology with Canadian isolate.