DNA cancer vaccination strategies target SV40 large tumour antigen in a murine experimental metastasis model.

Two plasmids encoding SV40 Tag under the control of different promoters have been examined for their ability to induce complete protection against murine experimental metastasis induced with an SV40-transformed tumour cell line. BALB/c mice immunized with a plasmid encoding SV40 Tag under the control of the SV40 promoter (pSV3neo) exhibited no detectable levels of anti-SV40 Tag antibody and were only partially protected from tumour foci development in the lungs after Intravenous tumour challenge. In contrast, mice receiving a plasmid encoding SV40 Tag under the control of the CMV promoter (pCMV-Tag) demonstrated high levels of anti-SV40 Tag antibody. These mice were completely protected from lung tumour foci development after challenge. Since antibody responses were induced only by the immunization which provided complete protection from metastatic tumour challenge, these data support the notion that antibody may play an important role in protection against experimental pulmonary metastasis within this model. Our results demonstrate that DNA immunization may serve as a possible immunotherapeutic strategy against cancers expressing tumour-specific or tumour-associated antigens.