title: Studies on the methylation of avian sarcoma proviruses in permissive and non-permissive cells.
abstract: The extent of methylation of several avian oncogenic proviruses was determined by using the restriction endonucleases HpaII and MspI. The results indicated that the transformation-defective proviruses (RAV-O or B77-td), which are exogenously introduced into avian host cells, were not methylated. However, endogenous proviruses (RAV-O) or ASV proviruses present in non-permissive host cells were found to be partly or completely methylated. The methyl-sensitive restriction endonuclease PvuI, which recognizes a unique site within the long terminal repeat in the ASV genome, failed to cleave proviruses present in several non-permissive host cells. From these results we suggest that modification of the sequence around the PvuI site results in reduced levels of transcription.
mesh_terms: D000818:Animals; D001358:Avian Sarcoma Viruses / Q000235:genetics*; D002460:Cell Line; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D002645:Chickens; D004247:DNA / Q000032:analysis; D004262:DNA Restriction Enzymes; D004279:DNA, Viral / Q000032:analysis*; D005814:Genes, Viral; D008745:Methylation
chemical_list: D004279:DNA, Viral; D004247:DNA; D004262:DNA Restriction Enzymes