Simian virus 40 DNA replication correlates with expression of a particular subclass of T antigen in a human glial cell line

Abstract

Immunocytochemistry and in situ hybridization were used to identify simian virus 40 (SV40) large T-antigen expression and viral DNA replication in individual cells of infected semipermissive human cell lines. SV40 infection aborts before T-antigen expression in many cells of each of the human cell lines examined. In all but one of the human cell lines, most of the T-antigen-producing cells replicated viral DNA. However, in the A172 line of human glial cells only a small percentage of the T-antigen-expressing cells replicated viral DNA. Since different structural and functional classes of T antigen can be recognized with anti-T monoclonal antibodies, we examined infected A172 cells with a panel of 10 anti-T monoclonal antibodies to determine whether viral DNA replication might correlate with the expression of a particular epitope of T antigen. One anti-T monoclonal antibody, PAb 100, did specifically recognize that subset of A172 cells which replicated SV40 DNA. The percentage of PAb 100-reactive A172 cells was dramatically increased by the DNA synthesis inhibitors hydroxyurea and aphidicolin. Removal of the hydroxyurea was followed by an increase in the percentage of cells replicating viral DNA corresponding to the increased percentage reactive with PAb 100. The pattern of SV40 infection in A172 cells was not altered by infection with viable viral mutants containing lesions in the small t protein, the agnoprotein, or the enhancer region. Finally, in situ hybridization was used to show that the percentage of human cells expressing T antigen was similar to the percentage transcribing early SV40 mRNA. Thus, the block to T-antigen expression in human cells is at a stage prior to transcription of early SV40 mRNA.

Establishment and Characterization of a Human T‐Lymphocyte Cell Line Immortalized by SV40 and with Abnormal Expression of TCR/CD3

“…A number of cultured cell lines originating either from humans [24][25][26][27] or rodents [28,29] SV40 transformation, including haematopoietic [24], nervous [25], fibroblastic [30,31], smooth muscle [32] and epithelial [26,27] cells. These cell lines have been obtained either after infection with SV40 viral particles [30] or after transfection with SV40 DNA [24] or with a plasmid carrying the large T antigen [26,27,31].…”

The evolution of small DNA viruses of eukaryotes: Past and present considerations

“…Others have also proposed that DNA virus persistence is due to an inability to express early viral genes because some cell types appear to lack transcription factors that are needed; that is, virus infection selects for cells that do not express early genes (182). Yet early gene expression without replication has been seen with both polyomaviruses and papillomaviruses (100,183). Also, such a proposal does not seem to account for observations with the papillomaviruses and polyomaviruses, in which cell cycle blockers (such as butyrate) that do not affect efficient early region transcription nevertheless prevent virus replication (96)(97)(98)(99).…”