Efficient DNA transfection and rapid assay for thymidine kinase activity and viral antigenic determinants.

We describe DEAE dextran-mediated DNA transfection in suspension which routinely gives transient gene expression in 0.1--1% of the transfected cells. We have used normal diploid human skin fibroblasts, monkey BSC cells, and mouse L or 3T6 cells with almost equal efficiency. Gene expression is detected 1--3 days after addition of the DNA. SV40 and polyoma T and V antigen are detected by in situ immunofluorescence and thymidine kinase gene expression is detected by in situ autoradiography. The high efficiency of transfection and the speed of detection together provide a means to study transfecting gene functions that does not rely on selection to obtain stable transformants. It should be possible to screen for the expression of any gene product which can be assayed by in situ immunofluorescence or autoradiographic techniques.