Pathological and Immunohistochemical Findings in Broilers Inoculated with a Low Virulent Strain of Infectious Laryngotracheitis Virus

ABSTRACT

This study was carried out to describe clinical, gross and histopathological findings in the respiratory tract in chickens infected intranasally with A96 strain of infectious laryngotracheitis virus (ILTV). In addition, the presence of ILTV antigens in formalin-fixed and paraffin-embedded larynx and trachea tissues was investigated with the immunoperoxidase (IP) method in the infected chickens. At various days of viral infection, nares, larynx, trachea, lungs and air sacs tissue samples of the infected chickens were obtained and fixed with formalin and embedded in paraffin. The cross sections were stained with hematoxylineosin, and the larynx and trachea sections were also stained with the IP method. Mild rales and gasping were observed in only 4 of 35 chickens. The virus caused mild inflammatory changes in the respiratory tract. It was shown that clinical, gross and histopathological findings were not specific for differential diagnosis of the disease. However, ILTV antigens were detected by the IP method in formalin-fixed and paraffin-embedded larynx and trachea sections. These results revealed that the study use of the IP method might be useful for the diagnosis of ILTV infections with non-specific lesions.