ENHANCEMENT OF CELL-GROWTH BY INTRACELLULARLY EXPRESSED HERPES-SIMPLEX VIRUS THYMIDINE KINASE

A recombinant cell line (NIH3T3: pLtkSN) was made by infecting parenta l cells (NIH3T3) with a recombinant retrovirus (pLtkSN) encoding herpe s simplex virus thymidine kinase (HSVtk) gene. The cells expressing HS Vtk (NIH3T3: pLtkSN) grew 2.3 times more than the parental cells (NIH3 T3) in Dulbecco's Modified Eagles Media containing 10% (v/v) horse ser um. The NIH3T3: pLtkSN cells also showed a significant enhancement in the maximal cell concentration and the specific growth rate even at 2. 5% serum concentration. The specific O-2 uptake rate of NIH3T3 was 2.1 times greater than that of NIH3T3:pLtkSN. Under both O-2-limited and O-2-unlimited conditions, it appears that HSVtk plays an important rol e in enhancing the growth characteristics of animal cells.