Physiological and genetic studies of polyoma virus

Tumour induction by transplacental infection with polyoma virus of the F1 generation of Wistar rats

Intravenous polyoma virus inoculation into pregnant Wistar rats resulted in transplacental infection of the foetus, causing tumours and hydronephroses. Cyclosporin A reduced these effects significantly.

Distribution of polyoma virus in the organs of newborn Wistar rats after subcutaneous inoculation

Polyoma virus of the Stuart Eddy strain was tritium-labelled by cultivating the virus in phosphate free Hepes buffered medium in presence of tritium labelled nucleotide triphosphates. The distribution of labelled virus in the organs and in the blood of newborn Wistar rats was examined at graded time intervals from two hours until 40 days after inoculation. The highest amounts of virus per organ was refound in the liver and the highest amount per mg organ weight in the spleen. The virus concentration in most organs exceeded by far the concentration found in the blood, indicating adsorption of virus in these organs. It was found that the distribution of tritium in the target organs for tumor appearance (kidneys and brain) did not differ basically from that in the non-target organs. As a consequence, the distribution of virus in the organs does not explain the fact that the kidneys and the brain are the predilection sites for tumor induction. Tritium labelling did not measurably influence the oncogenicity, infectivity and hemagglutinating activity of the virus.

Characterization of an adenovirus early protein required for viral DNA replication: a single strand specific DNA binding proteins

1. The human adenoviruses types 2, 5 and 12 code for the production of a single strand specific DNA binding protein. The molecular weights of these proteins were 72,000 for types 2 and 5 and 60,000 for type 12. In all three cases proteolytic breakdown fragments of these binding proteins (48,000 MW) were also observed. 2. Analysis of the methionine containing tryptic peptides of these proteins indicate that the types 2 and 5 proteins are similar and clearly distinguishable from the type 12 protein. The peptide maps of these three viral proteins are clearly different from a similar protein found in mock infected cells. 3. Temperature sensitive mutants of type 5 (H5ts125) and type 12(H12tsA275) adenoviruses fail to produce these proteins at the nonpermissive temperature. H5ts125 infected cells grown at the permissive temperature produce a 72,000 MW protein that is thermolabile, for continued binding to DNA, when compared to type 5 wild type adenovirus 72,000 MW protein. An analysis of the phenotype of this adenovirus mutant indicates that it codes for a viral function at early times after infection that is required for viral DNA replication. 4. The in vitro translation of adenovirus specific m-RNA results in the synthesis of a small amount of a 72,000 MW protein that binds to single stranded DNA just like the authentic adenovirus DNA binding proteins produced in infected cells. 5. Adenovirus anti-Tumor antigen (T) anti-serum from hamsters carrying independently derived adenovirus tumors, have been tested for the presence of antibody to purified DNA binding proteins. One antiserum is positive for these antibodies while the other is negative. These results indicate that some, but not all, adenovirus tumors contain large enough levels of the DNA binding proteins to elicit an antibody response. 6. The type 5 adenovirus temperature sensitive mutant, H5ts125, that codes for a thermolabile DNA binding protein, was complemented or suppressed at the nonpermissive temperature, for the replication of adenovirus DNA, by SV40. SV40tsA temperature sensitive mutants, defective in SV40 DNA replication, do not suppress or complement H5ts125 at the nonpermissive temperature.