CHICKEN ANEMIA VIRUS INFLUENCES THE PATHOGENESIS OF MAREKS-DISEASE INEXPERIMENTAL INFECTIONS, DEPENDING ON THE DOSE OF MAREKS-DISEASE VIRUS

Eight groups of 1-day-old chickens were inoculated with 0, 250, 5000, or 100,000 white blood cells of chickens infected with Marek's disease virus strain K (MDV-WBC). Four of these groups were additionally infe cted with 10(5) TCID50 chicken anaemia virus (CAV). At day 14 after in oculation, chickens infected with CAV had reduced haematocrit levels, reduced body weights, and depletion of the thymic cortex and bone marr ow. Semi-quantitative immunohistochemical examination of nerves and vi sceral organs was performed at day 28 by immunoperoxidase staining in which a monoclonal antibody specific for leucocytes was used. CAV sign ificantly enhanced the number of lymphoproliferative lesions induced b y 5000 MDV-WBC. In contrast, CAV significantly reduced the number of l ymphoproliferative lesions induced by 100,000 MDV-WBC. Comparable resu lts were found at day 61 after macroscopic examination of nerves and v isceral organs. These findings show that the pathogenesis of MD in exp erimental infections appears to be enhanced or inhibited by CAV, depen ding on the dose of MDV.