Characteristics of murine C‐type viruses. I. Independent assortment of infectivity in one in vivo and four in vitro assays

The infective properties of mouse C‐type viruses produced by two Moloney lymphoma lines, mouse L cells (A9 and A9HT sublines) and their hybrids were investigated in one in vivo and four in vitro assays. While differences were found in the ability of the two lymphoma‐derived viruses to convert antigenically JLS‐V9 cells, they were equally efficient in the XC‐plaque test. The same viruses also transformed BALB/3T3 cells, similarly to the virus produced by A9 cells. On the other hand, transformation by the A9 virus was not accompanied by plaque formation on XC cells (except distinct single giant‐cell formation). The reverse situation, positive plaque test without transformation, was also encountered. Whether plaque forming, antigen inducing, or transforming, all viruses were immunogenic. The results indicate that virus released by a given cell line may be detected by one test and not by the other. The characteristic infectivity pattern of a virus produced by a certain cell line remained stable over a period of 7 months.