Transformation of human choroid cells in vitro by SV40. Ultrastructural and cytogenetic analysis of cloned cell lines.
Several clones were isolated from a Simian Virus 40-transformed human choroid cell line (HC/SV40) by the soft agar plating technique. Five of them which showed different morphology, growth capacity and cell density, were plated in monolayer and subjected to ultrastructural, immunological and cytogenetic analyses. The morphological features at both TEM and SEM were distinct for every examined clone but uniform in the cells of the same clone. In particular clone 3 (HC/SV40-C13) showed a greater increase of intracytoplasmic granules, a marker of all cells of choroid origin, while clone 2 (HC/SV40-C12) was totally devoid of them. No virus production was observed at the electron microscope. Immunofluorescence experiments revealed 100% positivity for nuclear T-antigen in all the clones, thus demonstrating the persistence of SV40 genome in these cells. Cytogenetic analysis showed a hyperdiploid number of chromosomes in clones 1 and 3, while clones 2 and 4 were clearly hypodiploid. All clones showed a general tendency to cytogenetic stabilization as compared to the karyotypes found in HC/SV40 parental cell line.