Segregation of RD-114 and FeLV-related sequences in crosses between domestic cat and leopard cat

TYPE C viruses of the RD-114 (ref. 1) group have been isolated, either spontaneously or after chemical induction, from cell cultures of the domestic cat (Felis catus)(2–4). Nucleic acid sequences related to the RD-114 genome are in the DNA of all domestic cats(5–8). Thus these viral genomes are transmitted vertically from parent to offspring as integral components of cat cellular DNA. Although the family Felidae consists of closely related animals, only four Felis species have been found to contain RD-114-related sequences. These include the domestic cat, the European wildcat (F. sylvestris), the sand cat (F. margarita), and the jungle cat (F. chaus); other members of the Felidae lack nucleic acid sequences related to RD-114 (ref. 9). The observation that RD-114 is partially related to the endogenous baboon type C viruses(10–12) and that sequences related to RD-114 are found in the cellular DNA of all Old World monkeys led to the postulate that this group of viruses originated from an endogenous primate type C virus(13) transmitted horizontally to the germ line of ancestors of certain Felis species during the Pliocene or early Pleistocene somewhere in the region of the Mediterranean basin(9).