Differential Cellular Regulation of Three Distinct Classes of Type C RNA Viruses Endogenous to Mouse Cells

RNA metabolism of murine leukemia virus. III. Identification and quantitation of endogenous virus-specific mRNA in the uninfected BALB/c cell line JLS-V9

“…(b) M-MuLV clone no. 1 were prepared from JLS-V9 and M-MuLV clone no. 1 cells and divided into two equal parts.…”

“…The amount of virus-specific RNA in different JLS-V9 cell fractions was quantitated in comparison to cell fractions obtained from M-MuLV clone no. 1 cells (a line of NIH 3T3 cells producing Moloney murine leukemia virus). Approximately 40% of the total virus-specific mRNA was recovered in the purified polyribosomes in M-MuLV no.…”

“…Most mouse cells carry the genetic information for one or several murine type C viruses in their chromosomes. The genes for these endogenous viruses can be activated to result in virus production by a variety of methods, and the endogenous viruses from several inbred mouse strains have been characterized by biological and immunological techniques (1,14,18). Cells from BALB/c strain mice contain genes which code for several endogenous viruses.…”

“…Cells from BALB/c strain mice contain genes which code for several endogenous viruses. Two of the viruses, a xenotropic virus which grows in cells other than mouse cells and an N-tropic virus(es) (11) which grows in mouse cells of the N type, can be readily induced from BALB/c-derived cells by treatment with halogenated pyrimidines (1,5). In addition, a B-tropic endogenous virus can be isolated from old BALB/c mice (17), and a myeloma-associated virus has also been identified (3).…”

Genetic control of the organ specificity of lymphoproliferative disease virus (LPDV) of Turkeys

“…Specific organotropism is very common to retroviruses, both endogenous (Rowe and Pincus, 1972;Varmus et al, 1973;Jaenisch etal., 1975;Strand etal., 1977;Gallo et al, 1978;Jaenisch, 1979) and exogenous (Feldman and Gross, 1966;Baluda and Droham, 1972;Declevt et al, 1974;Shoyab and Baluda, 1975;Neiman et al, 1975;Jaenisch, 1976;Kawamura, 1976;Youn et al, 1977;Michalides et al, 1978;Cohen etal., 1979;Koshy etal., 1979;Asjo et al, 1981). However, since endogenous retroviruses are genetically transmitted as Mendelian genes (Aaronson and Stephenson, 1974), they localize as integrated proviruses in every somatic cell, and their organ specificity is consequently regulated mainly after the level of virus integration (Varmus et al, 1973;Jaenisch et al, 1975;Jaenisch, 1979). In contrast, the organotropism of exogenous retroviruses can be controlled at either of the two major levels: (1) at the level of infection and integration, so that viral particles can infect and subsequently replicate only in specific target tissues or (2) at the level of transcription so that viral particles can infect and integrate into cells of every tissue, but whereas the integrated viral genes will be efficiently transcribed in target organs, they will remain repressed in non-target cells.…”