Isolation and molecular characterization of infectious laryngotracheitis virus in commercial and desi chickens

Abstract

Infectious Laryngotracheitis (ILT), caused by Gallid herpesvirus 1, is one of the major respiratory diseases of poultry that is gradually spreading worldwide. Present study was carried out to detect the pathogen from the suspected cases of the disease. The tracheal tissue samples were collected from both commercial and desi chickens suspected to have died of ILT from 26 commercial poultry farms located in Namakkal, Salem and Erode districts of Tamil Nadu state of India. On post-mortem examination, haemorrhagic caseous exudate and a fibrinous pseudomembrane adherent to the tracheal mucosa were observed. PCR assay targeting ICP4 was carried out on DNA extracts from the samples. Samples from 19 farms out of 26 farms were positive for ILTV. Further, six samples were selected randomly and ILT vius isolation was attempted in embryonated chicken eggs. After seven days of incubation, plaque lesions, thickening and engorged blood vessels were noticed in the embryo. This study indicates the presence and circulation of pathogenic ILTV in both commercial and desi chickens of Karur, Erode and Namakkal regions. Some farms have recorded high pathogenicity due to the ILTV infection. Further studies on avian infectious laryngotracheitis in these areas should be carried out to devise appropriate prevention strategies.