Pathological and in situ hybridisation findings in calves experimentally infected with bovine adenovirus type 4

Three colostrum deprived calves were inoculated intravenously with a strain of bovine adenovirus type 4 (BAV-4) isolated from a calf with acute fibrinous enteritis. The calves were monitored clinically and submitted to post mortem examination at 5, 6 and 10 days post inoculation (p.i.) respectively. The 3 animals showed raise in temperature and diarrhoea. Acute enteritis was observed in calves submitted to post mortem examination at 5 and 6 days p.i. In these animals viral DNA was specifically detected on histological sections by an in situ hybridization (ISH) technique; BAV-4 was isolated from most of the organs and numerous adenovirus-positive endothelial cells were present in the gastrointestinal tract, mesenteric lymph nodes and liver. In the calf examined 10 days p.i. no lesions were observed and rare ISH positive cells were detected. These results indicate that in experimental conditions our strain of BAV-4 is capable to induce clinical signs and lesions similar to those reported in field cases.