[Analysis of the cellular tropism of human polyoma JC virus (JCV)]

Human polyomavirus JC virus (JCV) is the causative agent of the demyelinating disorder progressive multifocal leukoencephalopathy (PML). In vivo the cellular tropism of JCV has been shown to be very narrow, and replication appears to be essentially restricted to oligodendrocytes. To investigate the detail cellular tropism of JCV, we employed transfection, microinjection and CAT assays using JCV permissive cells, and several non-permissive cell lines. IMR-32 (human neuroblastoma cells) was permissive for IMR-32 adapted JC virus. A431 (human epidermoid carcinoma) and COS-7 (a SV40 transformed African green monkey kidney cell line) were used as non-permissive cells. Employing infection it could be confirmed that the virus proliferated in IMR-32, but not in A431 and COS-7 cells as measured by immunofluorescence methods. However, after microinjection of IMR-32 adapted JCV it could be shown that virus could replicate not only in IMR-32 but also in COS-7 cells. Virus could not be replicated in A431 cells. Using CAT assays the regulatory region of IMR-32 adapted JCV was shown to be active in IMR-32 and COS-7 cells, but inactive in A431 cells. The result suggests that nuclear transcription factors are also determinant of JCV cell tropism in vivo in addition to specific cellular receptors.