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Title: The behaviour of polyoma viral DNA in mammalian cells
Author: Nicholas, Gordon A.
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1972
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1. The physical and chemical properties of polyoma virus are described. The literature concerning the interaction of the virus with cells, permissive and non-permissive to virus replication, is reviewed. 2. A method has been developed for maintaining BHK21/13 cells (BHK cells) in a stationary condition; this involves the use of medium containing 1% calf serum. Stationary BHK cells obtained by this method had low levels of DNA synthesis, DNA polymerase activity and thymidine kinase activity. 3. No significant increase in DNA synthesis, or the activities of DNA polymerase and thymidine kinase followed the infection of stationary BHK cells with polyoma virus at an input multiplicity of 50 PFU/cell. In contrast after viral infection of stationary' mouse embryo cells under the same conditions there was a 38-fold stimulation of DNA synthesis and 7 and 3.5-fold increases in the activities of DNA polymerase and thymidine kinase respectively. 4. Replication of polyoma viral DNA could not be detected in infected stationary BHK cells. It is concluded that the position of the block in replication is either at the endonuclease-mediated conversion of parental closed cyclic duplex DNA to open cyclic duplex DNA or at the subsequent polymerisation step which should yield progeny open cyclic duplex molecules. 5. DNA-RNA hybridisation studies provided evidence that viral- specific RNA sequences were synthesised in stationary BHK cells infected with polyoma virus. Extrapolation of this data by means of a double-reciprocal plot indicated that the complete viral genome was transcribed. 6. An unsuccessful attempt was made to characterise the viral proteins synthesised in stationary BHK cells infected with polyoma virus. 7. Limited replication of polyoma viral DNA was detected after infection of growing cultures of hybrid cells formed by the fusion of BHK and L cells, although it was not detected after infection of either of the parental cell strains. Similarly, a cytopathic effect following infection with polyoma virus was observed in the case of the hybrid cells but not in the case of either of the parental cell strains. 8. The implications of these results with regard to the non-permissive nature of BHK cells is discussed. It is concluded that BHK cells are deficient in some cellular function(s) necessary for the replication of polyoma virus.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available