Morphological studies of hamster brain cells transformed in vitro by a human papovavirus BK

The cytomorphology and cytogenesis of BK virus-transformed hamster brain cells (HBBK cells) were studied. HBBK cells with indistinct processes showed a tendency to epithelial arrangement as well as characteristics of malignant tumor cells in vitro, and developed long, delicate processes when cell growth was suppressed. Glial fibrillary acidic protein was demonstrated by immunofluorescence in the cytoplasm of almost all HBBK cells. The tumors arising in hamsters after subcutaneous inoculation of HBBK cells were classified as poorly differentiated gliomas. These findings suggest that selective transformation of glial cells in hamster brain cells by BK virus occurred.