Abstract
Evidence is presented to show that 2 polyoma strains, 3049-H+ and 210-H-, which differ in a number of biological characteristics, induce similar degrees of transplant immunity in adult hamsters, and induce similar “antigens” in tumors produced in neonatal animals. A third strain, Dulbec-co's “large plaque” virus, is nearly identical with the 3049-H+ strain, but fails to stimulate transplant immunity against tumor cells induced by the 3049-H+ virus; instead, it appears to enhance tumor growth. Evidence is also presented to show that polyoma virus replicates poorly in the hamster (as measured by virus content of liver, spleen, and kidney) and may localize more specifically in an immunologically active organ, the spleen.