Comparison of simian virus 40 large T antigen recombinant protein and DNA immunization in the induction of protective immunity from experimental pulmonary metastasis

In this report we examine the ability of a recombinant tumor antigen prepar ation to prevent the establishment of experimental pulmonary metastasis. Ba culovirus-derived recombinant simian virus 40 (SV40) large tumor antigen (T -Ag) was injected into BALB/c mice followed by challenge with an intravenou s injection of syngeneic SV40-transformed tumorigenic cells, The experiment al murine pulmonary metastasis model allows for the accurate measurement of metastatic lessions in the lungs at various times after the challenge, usi ng computer-assisted video image analysis. Following challenge, lung metast asis and survival data for the groups of mice were obtained. Animals immuni zed with recombinant SV40 T-Ag showed no detectable sign of lung metastasis and survived for more than 120 days after challenge. Antibodies specific f or SV40 T-Ag were detected in the serum of immunized mice by enzyme-linked immunosorbent assay. Splenocytes obtained from mice immunized with recombin ant SV40 T-Ag did not lyse syngeneic tumor cells, indicating that no cytoto xic T lymphocyte response was induced, Control mice developed extensive lun g metastasis and succumbed to lethal tumor within 4 weeks after challenge. These data indicate that immunization with the recombinant SV40 T-Ag induce s protective, T-Ag-specific immunity in an experimental pulmonary tumor met astasis model.