Gene transfer by retrovirus-derived shuttle vectors in the generation of murine bispecific monoclonal antibodies.

The present study reports on the use of gene transfer by retrovirus-derived shuttle vectors in the generation of hybrid hybridomas secreting bispecific monoclonal antibodies. neo- and dhfr- genes were infected into distinct murine hybridomas, thus conferring a dominant resistance trait to geneticin (G418) and to methotrexate. The vectors employed were replication-deficient and dependent on complementation by a helper virus provided by the irradiated packaging lines. After cocultivation with the relevant packaging cell lines, stable hybridoma lines expressing the selectable markers were easily obtained and were then suitable for conventional somatic fusion. This high-efficiency method was used to generate two bispecific monoclonal antibodies simultaneously targeting molecules expressed on cytotoxic cells (i.e., T lymphocytes and natural killer cells) against a human melanoma-associated antigen.