| Abstract: | Newborn hamsters were inoculated with human adenovirus type 12 (Ad12) within 24 hr of birth for tumor induction, and 15 days later, intercurrently immunized with Ad12-infected cells (KB; HeLa; FL; HEK; MoE; HaE). Tumor development was then observed for 75 days thereafter. Tumor formation was prevented at a statistically significant level by immunization with any of the above-mentioned infected cells. The immunization was effective even with abortively infected cells (HaE; MoE) or with cells infected in the presence of 5-fluorodeoxyuridine. The induced immunity was Ad12-specific, since neither cells infected with Ad2, Ad7 or Ad18 nor CV-1 cells infected with SV40 were able to prevent tumor formation. The most plausible explanation to these findings could be that Ad12-specific tumor-specific transplantation antigen is induced on the surface of freshly virus-infected cells and it is responsible for induction of specific cellular immunity. This gives an experimental support to our hypothesis on the mechanism of induction of cellular immunity against virus infections and to the hypothesis proposed by Habel and by Sjögren to explain the immunoresistance against tumor cells induced following viral immunization. |
