Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/1997
Publication Date: N/A
Interpretive Summary: Marek's disease virus causes a severe suppression of the immune system in poultry. Understanding the nature of host response which is responsible for viral-mediated immune depression will lead to a better control strategy against this virus. Scientists at the Center for Food and Animal Research Agriculture and Agri-Food Canada, and an ARS scientist collaborated in this study to examine the host immunity to Marek's virus. The results showed that Marek's virus changed the composition of T lymphocyte and reduced the expression of the major histocompatibility antigen. These findings will lead to a better understanding of Marek's virus- induced immunosuppression in chickens.
Technical Abstract: The effects of Marek's disease virus (MDV) AC-1 strain on humoral and cellular immune responses were investigated in two strains of chickens. In MDV-infected chickens, proliferative lymphocyte responses to mitogens and NDV antigen were suppressed, whereas the cytotoxic activity of NK cells was enhanced when compared to uninfected birds. The percentage of CD4+ T cells was higher while the percentage of cells expressing MHC class II antigens was lower in MDC-infected chickens than in uninfected birds. Antibody responses were not different among groups. In conclusion, a marked increase in CD4+ T lymphocyte population occurred in the early stage of MDV infection while the expression of MHC class II antigen was severely reduced and other functional properties of immunocompetent cells were either suppressed or increased.