title: Spontaneous expression of C-type virus in DBA/2 mice is associated with an increased rate of mortality, independent of neoplastic disease.
abstract: Ecotropic C-type retroviruses isolated from both normal and dimethylbenzanthracene-treated DBA/2 mice could be classified into three major groups, Ea, Eb, and Ec, that differed in structure and biology. Weanling DBA/2 mice were generally free of viruses, but a fraction of adult individuals became virus positive and were apparently selectively associated with a high expression of the Eb viruses. Some of the ecotropic viruses from DBA/2 mice acted as exogenous pathogens. They caused viremia and a moderate incidence of leukemia when injected into C3H and ST/a mice. In addition, they caused an appreciable number of early deaths without signs of malignancy. To evaluate the natural role of the viruses, we studied the survival of spontaneously viremic and nonviremic DBA/2 mice. The viremic animals as a group were characterized by a significantly reduced life-span that was not related to neoplasia. These observations indicated that endogenous C-type retroviruses can be pathogenic without preselection of the host for disease. They also emphasize that endogenous viruses, like their exogenous counterparts, can have a broader pathogenic spectrum than normally appreciated.
authors.forename: K
authors.initials: K
authors.lastname: Ulrich
authors.forename: B A
authors.initials: BA
authors.lastname: Nexø
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D007942:Leukemia, Experimental / Q000382:microbiology; D051379:Mice; D008811:Mice, Inbred DBA / Q000382:microbiology*; D008815:Mice, Inbred Strains / Q000382:microbiology; D012190:Retroviridae / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D013045:Species Specificity; D014412:Tumor Virus Infections / Q000382:microbiology*
chemical_list: D015127:9,10-Dimethyl-1,2-benzanthracene