Fowl adenovirus (FAdV) in India: evidence for emerging role as primary respiratory pathogen in chickens.

Abstract

Adenoviruses have been isolated from both clinically healthy and diseased birds worldwide. The pathogenic role of most of the FAdVs is still questionable. They can quickly take on the role of opportunistic pathogens when additional factors, particularly concurrent infections, adversely affect the health of the avian host. Immnosuppressing agents especially chicken infectious anemia and infectious bursal disease viruses are known to enhance the pathogenicity of FAdVs upon coinfection. The aim of the present study was to screen for the involvement of FAdV in poultry flocks affected with respiratory disease complex by RT-PCR. The samples were also screened by RT-PCR/PCR for other respiratory pathogens. Thirty two commercial poultry flocks with the history of respiratory disease complex from various parts of India. FAdV nucleic acid could be detected in tissue samples of 13 out of 34 farms investigated. Out of 13 FAdV positive farms, FAdV and CIAV were alone detected in 4/13 (31%) whereas, in other farms more than two respiratory pathogens were detected together. CIAV was detected in all the farms (34/34) investigated. Eosinophilic intranuclear inclusion bodies were noticed in FAdV infected laryngeal and tracheal epithelium under light microscopy. The findings of the study assert that FAdV can play the role of primary respiratory pathogen in immunocompromised birds and also in the presence of other respiratory pathogens.