Induction of Brain Tumors in Newborn Hamsters by Simian Adenovirus SA7¹ Free

Intracerebral inoculation of the simian adenovirus SA7 induced brain tumors in 26 of 118 hamsters inoculated as new-borns. The tumors were primarily of two histologic types. Twenty-four resembled human medulloblastomas, but two tumors were histologically similar to the perivascular sarcoma because there was reticulum in part of the tumor. Other areas contained no reticulum and were almost identical with the astrocytoma IV. The tumor cells could be grown in tissue culture only after passage on feeder layers of irradiated cells. No antibodies to the SA7 tumor antigen could be detected in the sera of tumor-bearing hamsters, although some of the brain tumors were positive for the presence of this antigen by complement fixation. One of the brain tumors has been maintained by serial subcutaneous and intracerebral passage; the resultant tumors have retained their original histologic pattern and low level of virus-induced tumor antigen. Failure to detect antibody to tumor antigen in hamsters bearing brain tumors suggests that similar results with human sera from patients with brain tumors would not rule out the possibility of viral etiology for this type of neoplasia.