title: R-type virus-like particles in avian sarcoma virus-induced rat central nervous system tumors.
abstract: Morphologically distinct virus-like particles (VLP), similar to R-type VLP, were observed by electron microscopy in experimental rat central nervous system tumors induced with the B-77-C strain of avian sarcoma virus (ASV). R-type VLP have a characteristic internal radial structure and were observed previously only in hamster cells and in an established bovine cell line. They were not observed in the B-77 ASV inoculum used to induce the rat tumors or in the B-77 induced hamster glioma cells from which the B-77 was rescued. Nevertheless, the genome of an endogenous hamster R-type particle also might have been rescued and carried in the B-77 inoculum. Alternatively, R-type VLP may exist in a number of animal species, including the rat, and may be expressed in certain conditions such as neoplastic transformation.
mesh_terms: D000818:Animals; D001254:Astrocytoma / Q000382:microbiology*; D001358:Avian Sarcoma Viruses; D001932:Brain Neoplasms / Q000209:etiology / Q000382:microbiology*; D006224:Cricetinae / Q000382:microbiology; D014780:Viruses / Q000302:isolation & purification*