Factors Influencing Tumor Induction in Hamsters by Vacuolating Virus,SV 40 . ∗

Abstract

Summary

Descriptive studies of the pathogenesis of SV₄₀ virus in the hamster model were carried out. Ninety-six per cent of animals given SV₄₀ virus when newborn, 60% of 7 day old animals, 23% of 1 month old animals, and none of 3 month old animals developed tumors. Tumors developed earlier, on the average, in the younger animals. All tumors which did develop were highly malignant, irrespective of host age at time of inoculation. Development of SV₄₀ tumors in hamsters was unrelated to appearance or absence of SV₄₀ antibody although stimulation of such antibody was progressively enhanced with increase in age at time of inoculation. Tumorigenesis was also related to virus dose, 300.000 TCD₅₀, being required to effect near 100% efficiency and 1000 TCD₅₀ being necessary for minimal response. The subcutaneous route was most efficient for tumor induction. A few tumors followed intrapulmonary or intraperitoneal inoculation and these appeared in the subcutaneous tissue. Litter or cage mate contact transmission of tumorigenesis did not occur. The significance of the findings is discussed.