Group-Specific Antigen Expression During Embryogenesis of the Genome of the C-Type RNA Tumor Virus: Implications for Ontogenesis and Oncogenesis

Abstract

Tests for the group-specific antigen of the C-type RNA tumor virus showed that mouse embryos of all strains tested, at some stage of development in utero , revealed detectable titers of group-specific antigen in one or more of their tissues; younger, rather than older, embryos were likely to be positive, particularly in those strains which normally reveal little or no expression of the RNA genome postnatally. The antigens were found in embryos of low-leukemia strains, free of infectious virus. These new findings support a previously stated hypothesis that the genome of RNA tumor viruses, mostly switched off for infectious virus expression, is vertically transmitted as part of the natural genetic apparatus of normal mouse cells. Since group-specific antigens have also been described in chick embryos and immunological tolerance to homologous group-specific antigens has been demonstrated in hamsters and cats as well as in mice and chickens, the hypothesis has been extended to include vertebrate cells in general. Finally, the high incidence and titers of the group-specific antigen suggest that the genes for RNA tumor virus, which later in life act as determinants of cancer, may be important also as gene determinants in the developing embryo.

Production of Virions with Retrovirus Morphology by Human Embryonal Carcinoma Cells in vitro

“…Some of these viruses are oncogenic. It also has been postulated that they have a role in normal life processes such as embryogenesis, cell differentiation, immunoregulation and evolution (Huebner et al, 1970;Aaronson & Stephenson, 1976;Levy, 1977;Todaro, 1978;Temin, 1982), although there is considerable controversy about some of these putative roles (Strand et al, 1977;Weinberg, 1980;Weiss, 1982;Jaenisch, 1983).…”

A Type-C Virus in Human Rhabdomyosarcoma Cells After Inoculation into NIH Swiss Mice Treated with Antithymocyte Serum

“…Recently, methods have become available that use immunosuppressed animals treated with antithymocyte serum (AT) and that make it possible for human tumor cells to grow in a heterologous species (6)(7)(8). The NIH Swiss mouse was chosen because, although it has gs antigen and viral information expressed (9,10), it is a strain with relatively low incidence of leukemia and has never been reported to produce complete, infectious type-C virus.…”

Elimination of Endogenous Xenotropic Retroviruses from Peritoneal Macrophages in Virus-induced T Cell Lymphoma

“…This case, then, represents an additional example of the phenomenon described in our present study, namely that the elimination of endogenous xenotropic retroviruses coincides with the development of leukaemia. Another series of experiments suggested that retroviruses might play a role in normal cell differentiation (Lieberman et al, 1980;Huebner et al, 1970;Temin, 1974;Risser et al, 1978;Moroni et al, 1979). Moreover, the application of immunological procedures indicated that inhibition of macrophage function typically occurred concomitant with the onset of spontaneous T-cell leukaemia in AKR mice, and during the terminal phase of illness (Normann et at., 1981).…”