Genetic approaches toward elucidating the mechanisms of type-C virus-induced leukemia.

Abstract

Type-C RNA viruses may be horizontally transmitted as infectious cancer-inducing viruses or vertically transmitted from one generation to the next, often in an unexpressed form, within the host genome (for review see Aaronson and Stephenson 1976). To date the translational products of three leukemia viral genes have been identified (Baltimore 1975). The gag gene product is a polyprotein precursor that undergoes cleavage to form the major nonglycosylated viral structural proteins, which for mammalian type-C viruses are p30, p15, p12, and p10. It has been possible to determine that the information within the murine viral gag gene is arranged 5′-p15-p12-p30-p10-3′ (Barbacid et al. 1976). The products of the pol and env genes are, respectively, the viral reverse transcriptase and a precursor protein containing the major envelope glycoproteins, gp70 and p15E. Evidence primarily from the avian system indicates that the type-C viral genes are ordered 5′-gag-pol-env-3′ (for review see Wang et al. 1976).