Studies on Adenovirus Type 12 3. Proliferation capacity of adenovirus 12 in hamsters of different age

Since the discovery that adenovirus type 12 inoculated into newborn hamsters develop tumor in a high percentage of the animals, other types 18, 7 and 31 were also found to induce tumors to a lesser extent. In the elucitaion of the mechanism of carcinogenesis due to virus the study of changes in virus growth appears to be most important. For this reason, adeno-virus type 12 was inoculated to hamsters ranging in age from newborn to 14, 45 and 65 days old. These animals were sacrificed at diffe ent time intervals after the inoculation, and the kidney, liver, peritoneum and lung were removed, and examined for virus. For the detection of virus in these organs, the method of s'ant agar culture was employed as it was found to be simple and easy to manipulated, as reported previously. As a result it was found that: 1. In the inoculation of this virus to newborn hamsters, the virus could be isolated from various organs up to l1 days after the inoculation. In this instance, the virus was found to be most active in the organs 1-7 days after the inoculaticn, indicating some proliferation of the virus. 2. With the hamsters 14 days old, it was possible to isolate the virus for 3 days after the inoculation. 3. In the case of animals 45 and 65 days old, the virus disappeared within 24 days of the inoculation. 4. In the inoculation of the virus to newborns, the tumor growth was noted at autopsy 30 days later, while no tumor could be observed in those animals over 14 days old