NOVEL MODELS OF AVIAN LEUCOSIS VIRUS-INDUCED CARCINOGENESIS

The LSCC-SF-MC29 cell culture model system was further characterized by studies on the provirus content of the cells, the host range and the subgroup specificity of the produced virus. The transforming potential of the Mc29 virus was evaluated by the focus-forming and colony-forming assays on primary cell cultures and continuous cell lines of avian and mammalian origin. The in ovo effects of the myelocytomatosis virus Mc29 on 15I line White Leghorn chicken embryos were studied by routine histopathological methods. Six avian leucosis virus-specific proviral sequences were detected by PCR analysis in the genome of LSCC-SF-MC29 cells. The presence of a Mc29 provirus-specific sequence located in the gag-myc region was confirmed. Using primers designed to differentiate ALV subgroups, amplification product was obtained with subgroup B/D-specific PCR primers. As it was expected, the subgroup E-specific PCR primers amplified the endogenous ALV sequences. In vitro studies on the host range of Mc29 virus showed that the primary cultures of chicken and hamster cells and a continuous hamster cell line were susceptible, while the cultures of primary quail cells and of a permanent line of duck embryo cells were resistant to the transforming effect of the virus. In ovo, the inoculated Mc29 virus induced hyperplasic and preneoplastic lesions in the embryonal liver and pancreas and myxomas of the neck.