SV40 MEDIATES STABLE GENE-TRANSFER IN-VIVO

Gene transfer in vivo requires an efficient, nonreplicating, transfer agent. We report here the efficacy of recombinant, replication-deficie nt SV40 in transferring firefly luciferase (luc) production to murine hematopoietic cells and selected internal organs in vivo. Replication- deficient SV40 was made by replacing the large T antigen gene (Tag) wi th a polylinker, into which luc cDNA (luc) was cloned. Luc expression was controlled by SV40 early promotor. Tag-, luc+ SV40 DNA was transfe cted into Tag-expressing cells to yield a replication-deficient SV40-d erivative virus containing luc (SVluc). The ability of SVluc to transf er luc production in vivo was tested in two ways: SVluc was inoculated into BALB/C mice intravenously; also bone marrow cells treated with S Vluc were infused into syngeneic hosts. Luc production was followed fo r 105 days by immuno-chemical analysis of peripheral blood and selecte d internal organs using anti-luciferase antibody, and by assay of luc enzyme activity in peripheral blood. Luc was found in 20-25% of periph eral blood nucleated cells from day 20 until greater than or equal to 105 days. Luc-producing cells were also identified in liver, spleen, b rain, kidney, skin and colon from day 20, also until greater than or e qual to 105 days. Analysis of whole blood showed fluctuating levels of functionally active luc enzyme beginning on day 21, and remaining sub stantially and significantly greater than control values to day 105. T hus, SV40 may transfer sustained expression of foreign genes to bone m arrow and other organs, for at least 3 months.