RNA virus expression during and after methylnitrosourea-induced T-cell leukemogenesis in mice.

The expression of RNA tumor virus was studied in BDF 1 mice after leukemogenic treatment with a single dose of methylnitrosourea (MNU) and in leukemic thymuses by a cell ELISA using antibodies against the viral glycoprotein gp 70 and by co-culture for the detection of eco- and xenotropic virus. The majority of the thymomas were positive for gp 70; ecotropic, but not xenotropic infectious virus could be detected in some of them. Early after MNU application the thymus and the bone marrow were positive for gp 70 in some animals. Later, after a phase with positive results with spleen cells, the bone marrow and the spleen were negative again. Only the thymus of some mice were positive during the last weeks before the first leukemias appeared.