A SEQUENTIAL HISTOPATHOLOGIC AND IMMUNOCYTOCHEMICAL STUDY OF CHICKEN ANEMIA VIRUS-INFECTION AT ONE-DAY OF AGE

Detection systems for chicken anemia virus (CAV) antigen in paraffin s ections were evaluated. Mouse monoclonal antibodies to CAV used in con junction with an avidin-biotin-peroxidase-complex detection system gav e best results. Immunoreactivity of CAV was markedly affected by fixat ion. Fixation in neutral buffered formalin for 6 hours gave best resul ts. Use of decalcifying fluid containing formic acid eliminated immuno reactivity of CAV, whereas use of an EDTA solution did not. In a seque ntial study, CAV antigen and lesions were first detected in bone marro w, thymus, and spleen at days 3-4 postinoculation (PI). Subsequently, antigen and/or cells containing nuclear inclusions were found in many tissues, but usually within lymphoid tissue therein. Thymus, spleen, b one marrow, proventriculus, and ascending duodenum contained most anti gen. No antigen was detected after 26 days PI. The results indicated t hat CAV replicates in thymic lymphoblasts, intra- and extra-sinusoidal hemocytoblasts, and reticular cells, with consequent lymphocytic depl etion of the thymic cortex and hypoplasia of the bone marrow, and that CAV antigen is widely distributed in the body.