Murine gammaherpesvirus (MHV-68) transforms cultured cells in vitro

Human dermal fibroblasts and mouse NIH/3T3 cells acquired the transformed phenotype ('criss-cross' pattern of growth) after infection with ultraviolet-irradiated murine gammaherpesvirus (MuHV-4 strain 68; MHV-68). These cells with changed phenotype could be serially cultured for 5-6 passages (35-40 days), and then they entered into crisis and most of them died. In a small number of cultures, however, foci of newly transformed cells appeared from which two stable cell lines were derived. After 6-9 cell culture passages of the MHV-68 transformed cell lines, MHV-68 DNA and virus antigen could be detected by PCR and immunofluorescence assay along with the disappearance of actin bundles, indicating that both transformed cell lines might be oncogenic.