The interaction of polyoma virus with mouse-hamster somatic hybrid cells

Abstract Somatic cell hybrids have been made between derivatives of the BHK hamster line and the 3T3 mouse line. Clones were isolated in which mouse and hamster chromosomes were present in different proportions over a 10-fold range. The hybrid lines were examined for their ability to support the various stages of polyoma virus multiplication and compared with the parental mouse line, which is permissive, and the parental hamster line which is nonpermissive. The ability of the hybrid lines to support viral functions was related to the abundance of chromosomes of each of the parental species. The synthesis of the polyoma T-antigen was expressed in all hybrids calculated to contain a complete mouse genome, regardless of the amount of hamster genetic material present. Hybrids possessing a single parental hamster complement were as fully permissive for all viral functions as the mouse parent. The presence of increasing amounts of hamster genetic material produced decreasing permissiveness, in some cases depressing yield of infectious virus to as low as 10 −3 that of the mouse parent. However, only hybrids with very reduced mouse chromosome complements were totally nonpermissive, presumably because of the absence of essential mouse genes. In all hybrids producing a reduced viral yield, there was reduced viral DNA synthesis. If any viral DNA synthesis occurred, all later functions followed to some degree. Possible mechanisms for the effect of the hamster genome are suggested.