Biomedical subjects
Publications and source records attributed to C Chany.
Membrane bound monkey antigens can be localized in different clones of somatic monkey-mouse hybrid cells. These antigens are detected, using peroxidase labelled anti-monkey sera, in thin sections observed in the electron microscope. The different clones contain a small number of simian chromosomes (9 to 25) and a complete set of murin chromosomes.
Interferon sensitivity of different normal and aneusomic human cells and of different mouse-human hybrids cells has been compared. G21 trisomic cells are more sensitive than diploid cells; whereas, on the contrary, triploid cells are normal in their human interferon sensitivity. Among other aneusomic cell lines tested, E16 trisomic cells are significantly less sensitive. These data are in favor of the hypotheses that the G21 chromosome carries genetic information for structural proteins involved in the receptor system for interferon, that there is a regulatory mechanism governing the antiviral state, and that the E16 chromosome is a possible candidate for carrying information for such a depressive regulatory mechanism. None of the chromosome abnormalities studies are involved with interferon synthesis.
Ouabain, which inhibits specifically membrane-bound ATPase activity, also inhibits the establishment of the antiviral state induced by interferon. Once the antiviral state is established, ouabain is ineffective. This inhibitory effect is reversed by adding Na/K ions to the cells. On the contrary, interferon production is unaffected by the same concentrations of ouabain. It is of interest that in such interferon-yielding cells, ouabain decreases the antiviral state.
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The effect of low pH's on the development of vesicular stomatitis virus (VSV) was studied. L cells infected with VSV were incubated at pH 6.6. A 99% inhibition in the yield of infectious particles was observed by comparison with the yield at pH 7.4. Such inhibition was not due to inhibition of viral RNA synthesis, since at pH 6.6 all the known species of VSV RNA molecules were synthesized. Furthermore, all the known species of VSV proteins were also synthesized. However, no viral particles nor nucleocapsids were detected. Raising the pH to 6.9 resulted in the appearance of nucleocapsids and viral particles, although the yield of infectious virus was still inhibited by 90%. The lack of infectivity of these pH 6.9 viral particles was correlated with their inability to promote primary transcription. The hypothesis that low pH's alter the correct positioning of the viral proteins into the cell membrane is presented.
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Dose-response curves of interferons in different sensitive cells are regularly sigmoidal. In somatic monkey-mouse hybrid cells, however, a significant decrease in the slope of the curve for primate interferon was observed, while the dose-response effect was unaltered for mouse interferon. High concentrations of primate interferon were 10- to 100-times less effective in hybrid clones than in parental monkey CV-1 cells; at low concentrations the antiviral effect was 10- to 20-times higher in hybrid clones than in the parental cells. The receptor(s) for primate interferon located on the cell membrane was destroyed by trypsin but not by EDTA. Similarly, acid pH inactivated these receptor sites. We, thus, postulate that the antiviral effect is, at least partially, related to the amount of interferon taken up by the cells. Uptake could be conditioned by active cooperation of two cell-specific factors: a receptor and an activator. The activator might be missing or inactivated for primate interferon in the hybrid cells. We suggest that the putative antiviral protein is not cell-species specific, and that information for its synthesis in the hybrid cells might be located on a mouse rather than a monkey chromosome.
Interferon, covalently bound to Sepharose 4B activated by cyanogen bromide, induces the antiviral state in sensitive cells. The antiviral effect is neutralized by antiserum specific to interferon and is recovered thereafter when the antibody is detached from the interferon by treatment at low pH. Binding interferon to Sepharose increases the stability of the molecule. It is likely that the interferon molecule acts on the cell receptor without being detached from the beads. However, the data do not exclude the possibility of a small loss of interferon, or fragments of it, after contact with the cell.
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