Human-mouse hybrid cell lines and susceptibility to species-specific viruses

Suppression of replication of SV40 and polyoma virus in mouse-human hybrids

Mouse-human heterokaryons are permissive for the replication of both SV40 virus and polyoma virus. If the hybrids which develop from these heterokaryons segregate human chromosomes (mouse greater than human hybrids), the hybrids are permissive for replication of polyoma virus but not for replication of SV40 virus. If the subsequent hybrids segregate mouse chromosomes (human greater than mouse hybrids), such hybrids support the replication of SV40 virus but not the replication of polyoma virus, even when the hybrids contain at least one copy of each mouse chromosome. This indicates that during the transition from heterokaryon to hybrid cell, suppression of expression of species-specific function(s) required for the replication of these species-specific viruses occurs in parallel with the direction of chromosome loss and suppression of nucleolus organizer activity.

Adenovirus type 12 infection of defined mouse-human hybrid cell clones

Human adenovirus type 12 does not multiply in mouse cells; only viral T-antigen is detected. Mouse-human cell hybrid clones containing human chromosomes A3, B5, C7, C11, C12, D14, E17, F19 and F20, support synthesis of adenovirus DNA and capsid antigens.

Murine leukemia virus: restriction in fused permissive and nonpermissive cells

Cultures of human cells nonpermissive for mouse leukemia virus replication could not be induced to support virus replication by homologous fusion in the presence of Moloney leukemia virus. Human cells were also fused with permissive mouse cells, and the fate of the virus in heterokaryons was determined by a simultaneous autoradiography and fluorescent antibody technique. Heterokaryons containing the full chromosome complement of both cells were likewise nonpermissive for virus synthesis, but hybrids of human and mouse cells, which lacked up to half of the human chromosome complement, were permissive for virus synthesis. The results suggest that human cell genes can direct a repressive control over mouse leukemia virus replication.

DNA and gene therapy: transfer of mouse DNA to human and mouse embryonic cells by polyoma pseudovirions

It was demonstrated previously that polyoma pseudovirions (DNA fragments encapsidated by polyoma virus coats) are adsorbed to and uncoated by mouse-embryo cells. 24 hr after infection of secondary mouse-embryo cells with [(3)H]thymidine-labeled pseudovirus, 24% of the total radioactivity found in cells occurred in the nuclear fraction. This nuclear radioactivity represents pseudovirus DNA, as shown by its hybridization with mouse-embryo DNA. Since much of the radioactive material found in the nuclear fraction is sensitive to pancreatic DNase, it is available as uncoated DNA.24 hr after infection of human embryo cells with [(3)H]thymidine-labeled pseudovirions, 7% of the total cellular radioactivity is found in the nuclear fraction of the cells. That this radioactivity represents uncoated pseudoviral DNA was shown by sedimentation of the disrupted nuclear fraction through a neutral sucrose gradient. The pseudoviral DNA in the nuclear fraction has been nicked to some extent, as shown by the heterogeneity of the peaks found after sedimentation of the disrupted nuclear fraction through alkaline sucrose. The experiments demonstrate that polyoma pseudovirions deliver DNA to human cells.