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P Vigier

Publications and source records attributed to P Vigier.

At least 55 records · Page 3Linked to original sources
PubMed1976

Expression of viral proteins in mammalian cells transformed by avian sarcoma viruses.

The expression of viral proteins in nine lines of hamster and rat cells transformed by avian sarcoma viruses (ASV) was studied by indirect immunofluorescence with monospecific antisera to purified gp85 and p27 of AMV-B and a polyvalent antiserum to all the p proteins of this same virus. The lines of ASV-transformed cells were either low virus producers (VP) or inducible or non-inducible non producers (NP). Cytoplasmic expression of p proteins was observed in all the cell lines except the least inducible NP cell line, and cytoplasmic expression of gp85 in all the cell lines. The degree of expression varied widely with the lines and was not related to the class of permissiveness or inducibility. However, in the inducible NP class, the expression of p proteins and gp85 was higher in the most inducible cell lines. The data also suggest that the expression of the p proteins must be uncoordinate in at least some cell lines and must also be uncoordinate with the expression of gp85. In the VP cell lines and the most inducible NP lines, g85 and some p proteins other than p27 were also expressed on the cell membrane. The membrane expression of gp85 and the p proteins which were expressed appeared to be coordinate and to parallel the degree of cytoplasmic expression. In contrast, no, or a negligible expression of viral proteins was observed on the membrane of the least inducible and the non-inducible cell lines. These results suggest that there may exist translational and/or post-translational controls of the expression of viral proteins in the ASV-transformed mammalian cells and that the permissiveness and the inducibility of the cells may depend on the insertion of viral proteins in the cell membrane. The failure of p27 to insert in the cell membrane could account for the low permissiveness or the non-permissiveness of the cells.

Alpharetrovirus↗
PubMed1976

[Lysis of Rous sarcoma virus in the presence of anti-chicken fibroblast serum and complement].

Rous sarcoma virus produced by Chick embryo fibroblasts is inactivated by an antiserum prepared against uninfected fibroblasts in the presence, but not in the absence, of complement. This inactivation which demonstrates the presence of one or more antigens of the surface of the producer cell on the viral envelope, is due to virolysis. This is demonstrated by the release of the viral internal proteins and by the fact that the viral RNA becomes entirely degradable by RNase.

Animals↗
PubMed1976

Transformation-enhancing factor(s) produced by virus-transformed and established cells.

Chick embryo fibroblasts (CEF) and hamster BHK21 cells transformed by the Schmidt-Ruppin strain of Rous sarcoma virus (SR-RSV) release into the culture medium a factor or factors which enhance 2- to 7-fold the formation of transformed foci by chich embryo fibroblasts infected with the Bryan strain of RSV (B-RSV). The factor(s) also increase the number of foci failing to revert to normal phenotype at restrictive temperature (41 degrees C) in cultures infected with a temperature-sensitive mutant (FU-19) of SR-RSV which is defective for transformation. The factor(s) is produced also by BHK21 cells transformed by other tumor viruses and by BHK21 cells passaged for a long time, but not by normal CEF, CEF transformed by B-RSV, CEF infected by FU-19 at 41 degrees C, normal hamster embryo fibroblasts, established but density-inhibited mouse fibroblasts, or BHK21 cells of early passages. The relative enhancement of the number of B-RSV foci can be more than 100-fold when the medium contains fetal calf serum which suppresses focus formation in controls. The focus-enhacing factor(s) appears to act after infection and has been termed, operationally, transformation-enhancing factor(s) or TEF. The factor produced by RS2/3 cells which enhances the formation of B-RSV foci is non-dialyzable and thermolabile, and is presumably a protein. Its molecular weight is between 10(5) and 2 X 10(5) daltons.

Animals↗
PubMed1976

Control of the uptake of amino acids by serum chick embryo cells, untransformed or transformed rous sarcoma virus.

Forty to fifty minutes after removal of serum, the net total uptake of amino acids in growing secondary cultures of normal or virus-transformed chick embryo cells, stopped or proceeded only at a highly reduced rate. In both normal and transformed cells, the initial (0-40 min) rate of the above uptake was the same in the absence of serum as in its presence. The initial rate of the total uptake of amino acids in growing transformed cells was about the same as in growing normal cells. Neither in the normal nor in the transformed cells was the rate of the total uptake of amino acids reduced by cell confluence alone. In highly dense, hyperconfluent cultures of normal cells in which cell growth was arrested, the rate of uptake in the absence or in the presence of serum was four- to fivefold lower than the rate obtained in growing normal cells under similar conditions; in the absence of serum, the net uptake stopped after 40 min in the hyperconfluent cultures as well. It appears that cells growing in tissue culture require a serum factor for maintenance of the required high rates of uptake of amino acids and that the inhibition of growth at high cell densities is a result of depletion of this factor from serum, or the inability of the cells in a dense culture to respond to the factor. A serum factor is apparently also required for maintenance of the reduced rates of uptake of amino acids observed in hyperconfluent cultures.

Amino Acids↗
PubMed1975

Infectious DNA recovered from avian tumor-virus-producing cells.

A single treatment of chick embryo fibroblasts with DNA recovered from chick embryo fibroblasts productively infected and transformed with four different strains of RSV, or productively infected with two different strains of RAV, resulted in virus production and cell transformation (in the case of RSV) two or three passages after treatment (8-25 days). The virus recovered from cultures was phenotypically identical to that produced by the donor cells. No virus production nor cell transformation resulted from treatment of control cultures with DNA digested with DNAse. Infectious RSV-DNA was recovered from purified donor cell nuclei and was associated with the precipitable fraction of DNA prepared according to the method of Hirt (1967). It also sedimented with cellular DNA in density gradients, and with high molecular weight DNA (2-4 times 10-7 daltons) in sucrose gradients, which suggests that it is associated and may be integrated with chromosomal DNA. In some experiments, DNA fractions of lower molecular weight (down to 6 times 10-6 daltons) were also infectious. DNA from virus-producing RSV-transformed cells also gave rise to virus and Rous cells in cultures of fibroblasts from gs- embryos. However, the amount of DNA required for successful infection varied widely between experiments, and no reproducible dose-effect relationship was observed. The frequency of DNA-treated cells which produced virus remained low, even when the assay cultures were pretreated with 5-bromodeoxyuridine.

Alpharetrovirus↗
PubMed1975

A structural change of the plasma membrane induced by oncogenic viruses: quantitative studies with the freeze-fracture technique.

In BHK21 hamster cells a significant increase in density of intramembranous particles occurs in freeze-fractured plasma membranes after transformation by hamster sarcoma and polyoma viruses. A similar change has been observed in chick embryo cells infected and transformed by a mutant of Rous sarcoma virus thermosensitive for transformation, at both permissive and nonpermissive temperatures. There is also an increase in particle density in chick cells infected with the Rous-associated avian leukosis virus type 1. The newly appeared particles may represent the insertion of new proteins in hydrophobic regions of plasma membrane, in response to the action of oncogenic viruses.

Animals↗
PubMed1975

Evidence for a host cell surface antigen on the envelope of avian tumour viruses.

Avian sarcoma viruses of the A, B, C, D and E subgroups are inactivated about 100-fold by the serum of rabbits immunized against chick embryo (CE) cells, in the presence, but not in the absence, of complement. The inactivation is not due to the action of the antiserum and complement on the CE cell cultures used for virus assay, nor to anti-Forssman antibodies, but it is presumably due to antibodies to some antigen(s) common to the surface of CE cells and to the virus envelope. This host cell surface antigen (HSCA) is also present on the surface of the helper viruses RAV1 and RAV2 of Bryan strain Rous sacroma virus. However, it cannot be said whether it is identical for viruses of all subgroups. A parallel electron microscopical study has revealed a characteristic swelling and loss of opacity to electrons of virus particles treated with the antiserum and complement, which appears to precede virolysis. Avian sarcoma viruses are not inactivated, in the presence or absence of complement, by antiserum to BHK21 hamster cells transformed by RSV and carrying virus-induced surface antigen (VISA). Therefore, the virus particles do not carry any surface antigen common to transformed non-permissive and permissive cells.

Animals↗
PubMed1975

Presence of chicken cell surface antigen on Rous virus activated in heterokaryons of transformed non-permissive hamster cells and chicken cells.

Incubation with antiserum to chick embryo (CE) cells, in the presence of complement, inactivates Rous sarcoma virus (RSV) produced by heterokaryons formed by non-permissive RSV-transformed hamster cells and CE cells as well as RSV produced by heterokaryons is observed following incubation with antiserum to the transformed hamster cells, plus complement. Hence, the envelope of RSV activated in heterokaryons, as that of RSV produced by CE cells, must contain a surface antigen of the CE cell, and the virus must mature only, or preferentially, at chicken-specific sites of the heterokaryon surface.

Animals↗
PubMed1975

Inhibition by methioninyl adenylate of focus formation by Rous sarcoma virus.

Methioninyl adenylate is a specific and potent inhibitor of the enzyme methionyl-tRNA synthetase and, consequently, of protein biosynthesis. In cultures of chick embryo fibroblasts infected with Rous sarcoma virus, incubation for a 2-day period with 1 to 3 mM concentrations of this inhibitor, as late as 4 days after infection, irreversibly prevented subsequent formation of foci of transformed cells. Later addition could also elicit the irreversible disappearance of already existing foci, by phenotypic reversion and/or cell killing. Virus production in transformed cells and replication in newly infected cells were also inhibited but to a lesser degree. Under the same conditions, the same concentrations of methioninyl adenylate caused only a reversible growth arrest of normal cells. The selective toxicity of the inhibitor for transformed cells is not due to a greater affinity for the target enzyme, but it may be due to the fact that inhibition of protein biosynthesis is only partially reversible in these cells, whereas it is fully reversible in normal cells.

Adenosine Monophosphate↗