Group-specific antigen expression during embryogenesis of the genome of the C-type RNA tumor virus: implications for ontogenesis and oncogenesis

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.

Seroepidemiologic studies of coronavirus infection in adults and children

McIntosh, K. A. Z. Kapikian, H. C Turner, J. W. Hartley, R. H. Parrott and R. M. Chanock. (Lab. of Infectious Diseases, NIAID, NIH, Bethesda, Md. 20014) Sero-epidemiologic studies of coronavirus infection in adults and children. Amer. J. Epid., 1970, 97: 585–592-A seroepidemiologic study of infection by coronavirus strains 229E, OC38, OC43, and mouse hepatitis virus (MHV) strain A-59, is described. In adults with upper respiratory disease, two “outbreaks” of coronavirus infection occurred, one during the winter of 1965–1966 associated with complement fixing (CF) antibody responses to OC38, OC43 and MHV, and the other during the following winter associated with CF antibody responses to 229E. In hospitalized children, infection with 229E was rare; infection with OC38, OC43, and MHV occurred less often in hospitalized children with lower respiratory tract disease (3.5%) than in a control group with non-respiratory tract disease (8.2%). The limitations of the CF test using available coronavirus antigens are discussed.

Mouse leukemia virus activation by chemical carcinogens

The induction of lymphomas in C57BL mice by methylcholanthrene, urethan, or diethylnitrosamine was accompanied by the development of murine leukemia viral antigen in most of the lymphoid tumors. The cell-free transmission of lymphomas induced by methylcholanthrene and the development of antibody to murine leukemia virus prior to the detection of overt lymphoma in these mice suggest that unmasking of a latent leukemia virus is an indigenous actuating cause of the lymphomas.

Complement-fixing antigens in hamster tumors induced by the Bryan strain of Rous sarcoma virus

Hamster tumors transplanted subcutaneously from primary intracranial tumors which developed after inoculation of the Bryan strain of Rous sarcoma virus, contained virusspecific tumor antigens indistinguishable from those induced by the Schmidt-Ruppin strain.