[Comparison of methods of detection of bovine adenovirus serotype 3 in infected culture of calf kidney cells (MDBK)]. / Sopostavlenie metodov obnaruzheniia adenovirusa krupnogo rogatogo skota 3-go serotipa v zarazhennoi kul'ture perevivaemykh kletok pochki telenka (MDBK).

The comparative study of the dynamics of the main antigen (hexon) and viral DNA of the bovine adenovirus type 3 accumulation in the established cell line MDBK under the conditions of single- or multistep cycle of infection has been undertaken. The quantitative immunoelectrophoresis and immunoenzyme assay detected the viral antigens on the late stages of infection in the period of cellular monolayer degradation. The immunofluorescence reaction and histochemical immunoenzyme method detected the antigen in the infected cells concurrently with the primary expression of the viral cytopathic effect. The reaction of the spot molecular hybridization with the [32P]-DNA probes detected the viral DNA considerably earlier than the antigen was detected by the immunological methods, before the appearance of degenerative changes in the infected cells. Preference of the immunoenzyme assay and DNA-probes in diagnosis of the virus are discussed.

[Reduced malignancy of hybrids of tumor cells fused with lymph node lymphocytes of syngeneic rats]. / Snizhenie zlokachestvennosti gibridov opukholevykh kletok s limfotsitami limfouzlov singennykh krys.

Seven cloned hybrid cell lines were obtained by fusion of OAV2a GFRT cells with lymphocytes of syngeneic rats. Three of the cell lines showed a reduced malignity when injected subcutaneously and were incapable of infiltrative growth when injected intraperitoneally. They were partially or totally devoid of colony forming activity in soft agar. Tumors which formed after injection of clone 2 cells revealed degenerative alterations and were infiltrated with lymphocytes. Separately floating rejected tumor fragments were vigorously attacked by macrophages.

[Transforming and oncogenic properties of the adenovirus genome]. / Transformiruiushchie i onkogennye svoistva genoma adenovirusov.

Analysis of data on transforming and oncogenic properties of adenovirus genome has shown that oncogenic properties of the cells transformed by adenoviruses are not determined by the length (to a definite extent) and by the number of copies of integrating parts of the viral DNA molecules. There are numerous sites of virus genome integration into the genome of the cell. The E1 region of the viral genome (0 to 11% of the map unit) consists of two transcription units E1a and E1b and plays the leading role in the tumourigenicity of transformed cells. Proteins coded by E1a are responsible for immortalization and initiation of transformation, those coded by E1b--for complete transformation and tumourigenicity. Proteins coded by the E1a region are the universal activators of transcription. Proteins coded by the E4 region activate expression of the E1b region and increase the virus carcinogenicity.

[Comparative study of sialyltransferases in cultured cells of the rat embryo, transformed by DNA bovine adenovirus type 3]. / Sravnitel'noe izuchenie sialiltransferaz v kul'turakh kletok émbrionov krys, transformirovannykh DNK bych'ego adenovirusa tipa 3.

The specific activities of membrane-bound sialyl transferases from six cultures of cells transformed by bovine adenovirus DNA type 3 (BA-3) before and after passage through host animal organism were compared. The sialyl transferase activity was increased with respect to the high molecular weight acceptor, asialylofetuin in the majority of transformed and tumour cultures. Identification of sialylation products by paper chromatography revealed that all cell cultures contain sialyltransferases synthesizing neuraminosyl-alpha (2----6)N-acetyllactosamine. The pH dependence of activities of the membrane-bound enzymes were studied. An additional pH optimum (5.5-6.0) of endogenous activity was revealed in most of transformed cultures. Using isoelectrofocusing of detergent extracts in sucrose density gradient, the presence of multiple forms of the enzyme was revealed in all cultures under study. In most virulent strains, Op2a/4 and OAB2a, the forms possessing a high exogenous activity at pH gradient 6.0-6.5 were activated. The multiple forms of line Op2a/4 were investigated at pH 5.8-6.3 and 7.6-8.0. It was shown that the forms with different pI have different pH optima. A correlation between the changes in the activities of sialyl transferases and the increase of oncogenicity of transformed cells after their passage through host organism was detected only in one group of transformed cells.

[Mutagenic action of the DNA of the highly oncogenic bovine adenovirus type 3 (BAV-3)]. / Mutagennoe deistvie DNK vysokoonkogennogo bych'ego adenovirusa tipa 3 (BAV-3).

The induction of mutations to the 6-mercaptopurine resistance has been studied in Chinese hamster cells after transfection with highly oncogenic bovine adenovirus type 3 DNA (BAV-3). A statistically significant increase in the yield of resistant mutants is induced by viral DNA after two days expression time. The value of induction varies from 56,12 X 10(-5) to 70,02 X 10(-5). The comparison of the mutagenic activity of DNA and the intact viral particles has revealed that the number of DNA molecules must be higher than after infection with the whole virus to obtain a similar effect.

[Isolation and biological properties of rat embryo cells transformed by the DNA of bovine adenovirus type 3 (BA-3)]. / Poluchenie i biologiheskie svoistva kletok émbriona krysy, transformirovannykh DNK bych'ego adenovirusa tipa 3 (BA-3).

Cloned cultures of rat embryo cells transformed by BA-3 DNA and those transformed by the virus in hamsters were obtained. It was found that these cultures contain T-antigen and do not differ in oncogenicity for hosts. The adenovirus type 5 DNA transformed cells of the same primary culture of rat embryo fibroblasts produced no tumors in syngeneic newborn rats. The role of the viral genome in oncogenicity of the cells transformed by it is discussed.

[Production and characteristics of seven rat embryo cell lines transformed by adenovirus type 5 and its DNA]. / Poluchenie i kharakteristika semi linii kletok émbriona krysy, transformirovannykh adenovirusom tipa 5 i ego DNK.

Seven cell lines transformed by adenovirus type 5 and its DNA were obtained. It was shown that different cell lines contain the fragments of viral DNA which differ in length and number of copies per DNA of diploid cells. They contain from the left end 6% of the viral DNA to complete or almost complete viral genome. All studied cell lines were sensitive to reinfection with adenovirus type 5. They produced no virus being cocultivated with cell sensitive to the virus. No cell line was able to induce tumors even in immunosuppressed newborn rats. All cell lines formed colonies in soft agar. The level of virus-specific antigens was higher in cells that contained a large part of the viral genome. The methods used did not allow to correlate the biological properties of the transformed cells with the length and the number of copies of the integrated part of the viral genome.

Studies of the transcription of viral genome in adenovirus 5 transformed cells.

Transcription of the human adenovirus 5 genome in transformed rat embryo cells (DFK3) was investigated using two different approaches. Preferential digestion of transcribed viral sequences by DNase I was analysed using kinetics of renaturation of 32P-labeled Ad5 HpaI restriction fragments in the presence of material which was stable after nuclease treatment. The second approach was the hybridization of 32P-labeled nuclear RNA from transformed cells with Ad5 restriction fragments which were attached to a nitrocellulose filter. These two methods gave similar results. It was found that not all integrated regions of the Ad5 genome are active in transformed cells. 2,5 copies of the HpaI-E fragment of Ad5 DNA were found in transformed DFK3 cell line. Nuclear RNA from these cells hybridized to HpaI-E fragment of Ad5 DNA, but only about half of sequences of the integrated HpaI-E fragment was sensitive to DNase I digestion.

Studies of the UV-sensitivity of virus-specific RNA synthesis in cells infected or transformed by adenovirus 5 and SV 40.

The effect of UV-irradiation on host and virus-specific RNA synthesis in cells infected or transformed by tumor viruses (Ad 5 and SV 40) was studied. It was found that the synthesis of host and Ad 5 RNA in infected KB cells was almost euqally inhibited upon UV-irradiation; the transcription of the EcoRI produced fragements--fragment B was inhibited to a greater extent than fragment A, suggesting that the transcription of the whole Ad 5 genome starts from the left side. The transcription of viral sequences in transformed cells, on the other hand, was more resistant to UV-irradiation than the transcription of the host ones. The results obtained suggest that the small size of the virus transcriptions, or their location at the beginning of large host transcriptions, may be responsible for the observed data.