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Biomedical subjects

J R Stephenson

Publications and source records attributed to J R Stephenson.

At least 199 records · Page 11Linked to original sources
PubMed1976

Endogenous type C RNA virus of Odocoileus hemionus, a mammalian species of New World origin.

Type C RNA viruses have been isolated from several Old World vertebrates, and an even larger number of Old World species have been shown to contain endogenous viral genetic sequences. The present report describes the first isolation of type C virus endogenous to a species originating in the New World. This virus, isolated from cells of the Columbian black-tailed deer, Odocoileus hemionus, is shown to possess genetic sequences in common with DNA of its species of origin. While it shares biochemical and immunologic characteristics with other mammalian type C viruses, its immunologic properties readily distinguish it from known endogenous viruses.

Animals↗
PubMed1976

Search for antigens and antibodies crossreactive with type C viruses of the woolly monkeys and gibbon ape in animal models and in humans.

Several reports have indicated the presence of type-C viral antigens in human tumors and of viruses closely related to those of the woolly monkey and gibbon ape in cultured human cells. In the present studies, attempts to detect woolly monkeys viral antigens in human tissues, or antibodies directed against structural polypeptides of woolly monkey viruses in human sera, were unsuccessful, In contrast, it was possible to demonstrate viral antigens in tissues and antibodies reactive to viral components in several animal and even primate model systems. Further evidence against the presence of woolly monkey viruses in humans is our failure to identify spontaneous or chemically induced viruses of this group in more than 200 individual cultures of human origin examined. These findings argue against the likelihood that viruses closely related to the woolly monkeys virus are associated with human tumors or are common infectious agents of man.

Animals↗
PubMed1976

Natural occurrence of tumors in mouse strains with different xenotropic and ecotropic endogenous viruses.

Natural tumor incidence and type C virus expression in HIH Swiss and BALB/c mice were investigated. The BALB/c mice showed a moderate incidence of lymphoreticular tumors containing infectious ecotropic virus. A second class of lymphoreticular tumors occurred with approximately the same incidence in both strains; though infectious virus could not be isolated from it, it contained the antigens of a common xenotropic virus. These xenotropic viral antigens were found in all NIH Swiss and BALB/c tumors examined and in normal hematopoietic tissues as well. The relationship between different classes of endogenous viruses and tumor development was discussed.

Age Factors↗
PubMed1976

Comparisons of the immunological properties of two structural polypeptides of type C RNA viruses endogenous to old world monkeys.

Immunologically very closely related type C RNA viruses are endogenous to the domestic cat and to an old world primate, the baboon. In the present studies, radioimmunological techniques have been developed for detection of the 15,000 and 30,000 molecular weight (MW) polypeptides of each virus. The much more pronounced type-specific antigenic determinants of the lower MW polypeptides made it possible to readily differentiate these viruses from each other as well as from a type C virus isolate from a second baboon species. Normal rhesus monkey tissues were partially purified and shown to contain a reactivity with MW and immunological properties similar to that of the baboon virus 30,000 MW polypeptide. Despite a similar degree of purification, antigenic reactivity like that of the baboon virus 15,000 MW polypeptide was undetectable even in the brodest immunological tests available for this polypeptide. The present findings indicate that the immunological properties of two structural polypeptides of closely related viruses endogenous to primate and feline species have undergone different rates of antigenic change in the course of evolution within their respective host cell genome.

Animals↗
PubMed1976

Radiommunoassays for the 70,000-molecular-weight glycoproteins of endogenous mouse type C viruses: viral antigen expression in normal mouse tissues and sera.

Genetic information coding for type C RNA viruses is transmitted within the DNA of mouse cells. At least three endogenous viruses have so far been immunologically distinguished by radioimmunoassays for their 12,000-molecular-weight polypeptides (p12). In the present study, the 70,000-molecular-weight glycoproteins (gp70) of three prototype viruses were purified, and competition radioimmunoassays were developed for each. By use of these immunoassays, the antigenic determinants of gp70's of different classes of endogenous virus, isolated from the same and from a variety of other mouse strains, were readily discriminated. In contrast, viruses of the same class were indistinguishable. These findings further document the existence of three distinct endogenous viruses of mouse cell. The levels of type C viral gp70 were quantitated in tissues and sera of several inbred strains. The pattern of immunological reactivity of the gp70 detected in serum was indistinguishable from that of the viral gp70 partially purified from tissues of the same strain. Moreover, in each case it was indistinguishable from that of a specific class of endogenous virus. In virus-negative tissues of BALB/c and NIH Swiss mice, the viral gp70 detected was shown to be representative of a class III endogenous virus whose p12 polypeptide was also expressed by the same cells.

Animals↗
PubMed1976

Natural immunity in mice to structural polypeptides of endogenous type C RNA viruses.

The immunological responses of inbred mice to structural components of one class of endogenous virus were investigated by means of radioimmunoassays utilizing highly purified viral proteins. Naturally occurring antiviral antibodies were demonstrated only in those strains possessing information for induction of a mouse cell-tropic endogenous virus. Moreover, these antibodies invariably appeared subsequent to the detection of spontaneous replication of this virus in the same animal. The immune responses elicited were much stronger against endogenous viral gp70 than p30, consistent with previous findings of tolerance in the mouse to the major structural antigen of its endogenous virus. However, the demonstration of an immune response to p30 under conditions of both natural and experimental immunization establishes that tolerance to this viral antigen can be overcome.

AKR murine leukemia virus↗
PubMed1976

Release of xenotropic type C RNA virus in response to lipopolysaccharide: acitivity of lipid-A portion upon B lymphocytes.

The present studies demonstrate that lipopolysaccharide (LPS) causes the release of endogenous xenotropic type-C RNA virus from BALB/c spleen cells. The evidence suggests that virus release is stimulated by the lipid-A portion of LPS and primarily involves an action of LPS on B lymphocytes. LPS had little or no effect on virus release by T lymphocytes, macrophages, or fibroblasts. These results indicate that the differentiated state of the cell plays an important role in the regulation of endogenous virus release.

Animals↗
PubMed1975

Temperature-sensitive mutants of murine leukemia virus. V. Impaired leukemogenic activity in vivo.

The in vivo biologic activities of a clonal isolate of the Rauscher strain of murine leukemia virus and several conditional lethal mutants with impaired replicative functions at the non-permissive temperature were investigated. The parental virus induced a rapidly developing lymphoid leukemia in a high percentage of NIH Swiss mice inoculated as newborns. Mice inoculated in parallel with temperature-sensitive mutant viruses showed no evidence of disease. The implications of these findings with regard to the requirements for type-C virus replication to permit oncogenic transformation of lymphoid cells in vivo are discussed.

Animals↗
PubMed1975

Antigenic characterization of type C RNA virus isolates of gibbon apes.

Type C RNA viruses initially isolated from a lymphosarcoma of a gibbon ape and from a fibrosarcoma of a woolly monkey are very closely related immunologically. However, recent studies have shown that these viruses are distinguishable in a radioimmunoassay for the 12,000-molecular-weight polypeptide (p12) of the woolly monkey virus. In the present report, an immunoassay has been developed for the p12 polypeptide of the gibbon ape type C virus. This assay is shown to further distinguish the woolly monkey and gibbon ape viruses. In type-specific assays for the p12 polypeptides of these viruses, two new type C viruses isolated from gibbons in a second colony, characterized by high incidence of hemopoietic neoplasia, are immunologically distinguishable from the original gibbon ape virus. The p12 type-specific immunoassays described in the present report may be of importance in studying the natural history of these viruses and their relationship to tumors of primates.

Animals↗
PubMed1975

Analysis of antigenic determinants of structural polypeptides of avian type C tumor viruses.

Radioimmunoassays were developed for the 19,000, 15,000, and 12,000 molecular weight polypeptides of avian myeloblastosis virus and for the 19,000 and 12,000 polypeptides of RAV-0, a subgroup E avian tumor virus. Each polypeptide was shown to possess both group- and type-specific antigenic determinants, in contrast to the 27,000 mol wt polypeptide, which contained only group-specific determinants. The corresponding low-molecular-weight polypeptides of subgroup A, B, and E viruses were shown to be immunologically indistinguishable. The findings that low-molecular-weight polypeptides of subgroup C and D viruses reacted very differently in immunoassays for the respective polypeptides of avian myeloblastosis virus or RAV-0 suggest that subgroups C and D may have evolved differently form subgroups A, B, and E.

Animals↗
PubMed1975

Differential expression of helper viral structural polypeptides in cells transformed by clonal isolates of woolly monkey sarcoma virus.

Cell lines transformed by woolly monkey sarcoma virus (WSV) in the absence of infectious virus production were analyzed for the expression of woolly monkey helper viral p30, p12, and gp70 antigens. Several lines produced high levels of both p30 and p12, whereas gp70 was not detectable. One transformed clone expressed only p12, and in another cell line, none of the helper viral antigens were detected. The properties of each sarcoma virus bred true upon transmission, indicating that each variant represents a distinct genotype. The different cell lines were examined with respect to properties characteristic of the transformed state. The in vitro growth properties and oncogenicity of each WSV-transformed clone were indistinguishable, indicating that transformation by WSV occurs independently of the expression of at least three helper viral polypeptides.

Animals↗
PubMed1975

Thermolabile reverse transcriptase of a mammalian leukemia virus mutant temperature sensitive in its replication and sarcoma virus helper functions.

Three temperature-sensitive mutants of the Rauscher strain of murine leukemia virus are defective in early post-penetration functions required both for leukemia virus infection and for initiation of transformation of cells by their pseudotypes of murine sarcoma virus. In the present study, the reverse transcriptase of one of these mutants (ts 29) is shown to be thermolabile compared with the enzymes of the wild-type virus and several other temperature-sensitive mutants. These findings provide evidence that the reverse transcriptase is required both for leukemia virus infection and for initition of transformation by the replication-defective murine sarcoma virus genome.

Absorption↗