Replication-defective recombinant Semliki Forest virus encoding GM-CSF as a vector system for rapid and facile generation of autologous human tumor cell vaccines

This paper describes the production of recombinant Semliki Forest virus enc oding murine or human granulocyte-macrophage colony-stimulating factor (GM- CSF) and the capacity of these vectors to transduce murine and human tumor cells ex vivo. High-titer stocks (up to 3 x 10(9) particles/ml) of conditio nally infective, replication-defective, recombinant SFV particles were gene rated using the SFV Helper-2 system. It is shown that the recombinant SFV/G M-CSF virus, as well as recombinant SFV carrying the beta -galactosidase re porter gone, efficiently transduce both murine tumor cell lines as well as primary human renal carcinoma cells. Using ELISA's specific for GM-CSF, lev els of GM-CSF production by the cells were determined. Levels of murine GM- CSF (mGM-CSF) produced by SFV/mGM-CSF transduced renal cell cancer cultures were equal to or higher than corresponding levels reported in the literatu re after transduction of similar renal carcinoma cell cultures using a retr oviral vector system. The biological activity of GM-CSF was demonstrated by using cells which are dependent on GM-CSF for growth and by using primary bone marrow cells. All the transduced cell cultures (including the human re nal cell carcinoma samples) produced GM-CSF for up to at least 4 days after transduction. The results imply that the recombinant SFV system can be use d for rapid and facile preparation of autologous cancer cell vaccines.