Abstract
We have constructed a selectable Friend murine leukaemia virus (F-MuLV) with a suppressor tRNA (supF) gene integrated into the proviral long terminal repeat. The viral construct was infectious and pathogenic and retained the marker gene when growing in vitro or in vivo. Only a few integration sites of the provirus were detected by Southern blot analysis of the DNA of erythroleukaemic cells. These results indicate that F-MuLV-induced erythroleukaemia is of clonal origin and suggest that insertional mutagenesis is involved in pathogenesis.