Experimental intraamnionic exposure of bovine fetuses with subgroup 2, type 7 Adenovirus

Three third trimester fetuses were exposed to a subgroup 2, type 7 adenovirus (adeno 7) by intraamnionic infection. The virus caused preterm delivery of two clinically ill calves and one stillbirth. The two premature calves died 12 and 72 hours after birth. An elevated serum neutralizing antibody titer (1:256) to adenovirus 7 was found in one principal calf at birth. Adenovirus 7 was recovered from several tissues of the live calves and the spleen of the stillborn calf. Fetuses exposed by intraamniotnic injection with virus carrier only, were born healthy after normal gestational periods and no viruses were isolated from the tissues. Clinically ill calves were weak, severely depressed and unable to stand and nurse. Gross postmortem lesions were nonspecific and consisted of petechial and ecchymotic hemorrhages and edema of the gastrointestinal tract. Histopathological lesions included vasculitis, necrosis of the mucosa of the forestomach, mild gastroenteritis and acute, nonsuppurative focal necrosis of the liver, kidney and adrenal gland. Intranuclear inclusion bodies were seen in pericytes, macrophages, hepatocytes, epithelial cells of adrenal cortical sinusoids of the zona glomerulosa and zona fasciculata and renal tubular epithelium.