Submitted to: Journal of Comparative Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2011
Publication Date: 4/10/2011
Publication URL: http://handle.nal.usda.gov/10113/61393
Citation: Harrison, L., Brown, C.C., Afonso, C.L., Zhang, J., Susta, L. 2011. Early occurrence of apoptosis in lymphoid tissues from chickens infected with strains of Newcastle disease virus of varying virulence. Journal of Comparative Pathology. 145:327-335. Interpretive Summary: Newcastle disease virus is a significant problem for food production worldwide and a constant threat to the US the poultry industry. The viruses that cause the disease (Newcastle disease virus) infect cells of the lymphoid system and cause severe clinical signs and a highly lethal disease in chickens. In order to develop better control strategies it is important to understand the mechanisms of disease. Here we have discovered that one of the mechanisms that the virus utilize to inflict damage to the chickens is to cause programmed cell death of lymphoid cells.
Technical Abstract: Newcastle disease virus (NDV), the causative agent of Newcastle disease, is a prevalent problem in the poultry industry and often the cause of severe economic loss. There are many strains of the virus and these have varying virulence. The most virulent strains cause systemic lesions of lymphoid tissues, with necrosis and severe lymphoid depletion. Less virulent strains do not cause as much necrosis, but may predispose to secondary infection with other pathogens. Apoptosis, or programmed cell death, has been demonstrated to play a role in the pathogenesis of other paramyxovirus infections, notably those caused by measles and canine distemper viruses. To investigate the role of apoptosis in lymphoid organs during NDV infection, immunohistochemistry for determination of expression of caspase-3, a marker of imminent apoptosis, was performed on formalin-fixed paraffin wax-embedded tissues (spleen, thymus, caecal tonsils and bursa of Fabricius) from 4-week-old chickens infected with NDV strains of varying virulence 2 days previously. The amount of apoptosis was proportional to the severity of the clinical disease elicited by the strains.