Rapid leukemia induced by cloned Friend strain of replicating murine type-C virus Association with induction of xenotropic-related RNA sequences contained in spleen focus-forming virus

Abstract

Newborn NIH Swiss and BALB/c mice have been shown to develop a rapid splenic leukemia when inoculated with high-titered preparations of cloned Friend strain of replicating ecotropic type-C virus. Increased spleen weight can be detected as early as 21 days after injection of Friend helper leukemia virus (F-MuLV). Concomitant with the replication of F-MuLV and the development of leukemia, there is a 100- to 1000-fold increase in the spleens of levels of RNA sequences which are detectable with a spleen focus-forming virus (SFFV)-specific cDNA probe (cDNA SFFV). Since cDNA SFFV detects RNA sequences which are derived from the env gene region of xenotropic virus, the results suggest that expression of RNA sequences highly related to xenotropic virus might be important in the pathogenesis of F-MuLV-induced leukemia.