Isolation, Cloning and In silico Study of Hexon Gene of Fowl Adenovirus 4 (FAV4) Isolates Associated with Hydro Pericardium Syndrome in Domestic Fowl

Poultry keeping in India has emerged as one of the fastest growing sector of Indian agriculture. Consequent to intensification, many nonexistent diseases have emerged and some of the existing has appeared in altered form, viz., very virulent infectious bursal disease (vvIBD), hydropericardium syndrome (HPS), chicken infectious anaemia (CIA), egg-drop syndrome 76 (EDS-76), reoviral infections and infectious bronchitis. Of these, HPS is an important emerging disease occurring in specific areas of world where broilers are reared under intensive conditions. Hydropericardium syndrome (HPS) is caused by fowl adenovirus 4 (FAV-4), which belongs to genus Aviadenovirus of family Adenoviridae [14]. The unique features of the disease are sudden onset of high mortality (>70%), hydropericardium, hepatitis with basophilic intra-nuclear inclusion bodies in the hepatocytes. Initially reported from the Angara Goth, Pakistan [9,10], the disease was first noticed in India during 1994 in poultry belt of Jammu and Kashmir [16] and thereafter, outbreaks of the disease have been reported from almost all part of the country [3,11] causing heavy economic losses to the poultry industry. FAV-4 is non-enveloped and icosahedral in shape measuring 70-90 nm in size. The virion is composed of an outer protein shell and the viral core that contains a double stranded, linear DNA of 33 to 45 kb in size, as genome. The icosahedron viral core comprises of 252 capsomeres with 12 pentons and penton attached fibers located at the vertices and 240 hexons on 20 faces and 30 edges.