Genetic relationship of a primate RNA tumour virus genome to genes in normal mice

Abstract

HUEBNER and Todaro¹ and Temin² proposed that the genomes of RNA tumour viruses originate from genes in DNA of normal cells. Subsequently, a class of RNA tumour viruses (endogenous or class 1 viruses) was discovered and shown by molecular hybridisation to contain RNA genetically related or identical to genes in normal cells^3–8. Both the biological and hybridisation data leave little doubt that normal cells carry genes capable of giving rise to class 1 RNA tumour viruses (see refs 7 and 8 for reviews). A second class of RNA tumour viruses is more distantly related to cell genes (exogenous or class 2 viruses, see refs 7 and 8). Mouse and chicken class 2 viruses, however, are genetically related to class 1 viruses from the same species^7–12 and the genome of one class 2 mouse RNA tumour virus (Rauscher leukaemia virus) consists primarily of RNA sequences that are related distantly to genes in normal mice but not to genes found in several other animals¹³. Indirect evidence has indicated that primate RNA tumour viruses and certain mouse RNA tumour viruses are unusually closely related^10,11,14,15, suggesting that the viruses have a common origin, for example, in genes of mice. We report here that a primate RNA tumour virus isolated originally from a woolly monkey sarcoma and passaged in marmosets does contain a genome that by molecular hybridisation criteria is related to genes found in mice. The data further indicate that a small portion of the primate RNA tumour virus genome is related to genes of normal primates.