The expression of virus-specific nucleotide sequences in rous sarcoma cells

Poly(A)-enriched virus-specific mRNAs (v-mRNA) are revealed in the subcellular fractions (nuclei, mitochondria, polyribosomes and cytosol) from chicken and hamster Rous sarcoma cells. The qualitative and quantitative differences in v-mRNA populations from permissive and non-permissive tumors are shown. The sedimentation analysis of v-mRNAs allowed to ascertain the presence of three molecular classes of v-mRNA in nuclei and cytoplasm of chicken Rous sarcoma cells (35S, 28S and 22S, and 35S, 26-28S and 20S, respectively). While two size classes (33S and 20S) are shown in hamster Rous sarcoma nuclei, only 24S v-mRNA is revealed in the cytoplasm of its tumor tissue. Thus, the oncovirus gene expression is restricted in the non-permissive tumor cells, unlike of the permissive chicken Rous sarcoma cells, both in the level of transcription, and in the processing and transfer v-mRNAs from nucleus to cytoplasm. The virus gene function peculiarities in the tumors of birds and mammals are discussed.