Induction of tumor-specific cell-mediated immunity by a noninfectious type-C virus.

Hamsters immunized with either noninfectious hamster type-C virus (D9) or irradiated D9 tumor cells were tested for cell-mediated immune reactivity by the macrophage migration inhibition assay. The migration of peritoneal exudate cells from immunized hamsters was significantly inhibited by either D9 virus or D9 tumor extract, but not by extract of an unrelated CELO virus-induced tumor. The virus and tumor extracts had little or no effect on the migration of peritoneal exudate cells from normal hamsters. Noninfectious D9 virus produces a cell-mediated immune response in the hamster and shares antigenicity with D9 lymphoma, which releases the virus.