DNA transfection of ecotropic murine leukemia viruses in mouse cell cultures

DNA's were isolated from cells chronically infected with N-, B-, or NB-tropic murine leukemia viruses and tested for infectious activity in various mouse cell cultures. Early detection of the DNA transfection is facilitated by growing the DNA-recipient cells in medium containing 10(-6) M hydrocortisone. Appropriate shearing of the DNA preparations may increase the efficiency of the transfection. With these procedures virus production of the transfected cells can be detected by XC plaque assay as early as 4 days after DNA inoculation in NIH 3T3 cells. Susceptibility of the mouse cell cultures to DNA transfection does not parallel their susceptibility to virion infection. Progeny viruses derived from the transfection show the same N- or B-tropic host range property as do the parent viruses.