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P I Marcus

Publications and source records attributed to P I Marcus.

At least 19 recordsLinked to original sources
PubMed1992

Interferon induction by viruses. XXI. Vesicular stomatitis virus: interferon inducibility as a phylogenetic marker.

Forty-five vesiculovirus isolates were systematically compared for their capacity to induce interferon (IFN) in chick embryo cells under conditions such that the maximum (quantum) yield of IFN per cell and the titer of IFN-inducing particles (IFP) could validly be determined. Twelve isolates of the New Jersey (NJ) serotype of vesicular stomatitis virus (VSV) were good inducers, yielding amounts of IFN that ranged in a continuum from 300 to more than 8,000 units per 10(7) cells. These must reflect genetic differences between the closely related viruses. These differences were not reflected in the nucleotide sequence of the viral 3' leader RNA, for analysis of eight of the NJ isolates showed no correlation with the IFN yields. As found in previous smaller surveys, 28 out of 32 VSV isolates of the Indiana (IN) serotype produced little or no IFN, or even suppressed its induction. However, four exceptional IN strains were isolated during 1984 and 1985 from cattle within a relatively circumscribed geographical area in Costa Rica and Panama; all belonged to Indiana virus, type 1, subtype IV, in the proposed G-protein gene evolutionary tree. This is the first example of an IFN-inducing phenotype serving as a phylogenetic marker.

Animals↗
PubMed1990

Mycoplasmas produce double-stranded ribonuclease.

Mycoplasmas (Mollicutes) constitute a constant threat as insidious contaminants of animal cell cultures. They are responsible for myriad biochemical reactions associated with the cells they infect, and undoubtedly have been the source of metabolic and physiological activities attributed to their hosts. In an attempt to demonstrate a dsRNA-inducible double-stranded ribonuclease (dsRNase) in mammalian cells, comparable to that reported in avian cells, we discovered high levels of dsRNase "induced" by a particular stock of vesicular stomatitis virus. We now report that the double-stranded ribonuclease resulted from the activity of a contaminant in that stock--a "noncultivable" Mycoplasma hyorhinis. This report demonstrates the ubiquitous distribution of dsRNase among mycoplasmas, presents some characteristics of the enzyme and its production, and implicates once again mycoplasmas as contaminants of cell culture and potential perturbers of cellular physiology.

Animals↗
PubMed1990

Development of the interferon system. I. In chicken cells development in ovo continues on time in vitro.

When confluent monolayers of cells derived from chicken embryos of different gestational age were cultured for several days without a medium change, a condition termed in vitro aging, the cells' developed an increased capacity to express the interferon (IFN) system. The capacity to both produce IFN and to respond to its antiviral action were enhanced up to 1000- and 100-fold, respectively. Remarkably, the programmed development of the IFN system in these cells seemed to continue virtually uninterrupted after monodispersion of the cells and seeding at high cell density. Cells prepared from young embryos required more time to develop the IFN system than cells from older embryos with the yield of IFN, and sensitivity to its action, related directly to the total in ovo and in vitro age of the cells in culture. For example, essentially the same yields of IFN were obtained from cell cultures made from 5-d-old embryos "aged" for 10 d in vitro, as were obtained from 10-d-old embryos whose cells were aged in vitro for 5 d. In contrast, inducibility of 2'-5' oligoadenylate synthetase by IFN and the induction of heat shock genes by elevated temperature are not enhanced with in vitro aging. The programmed development of the IFN system that starts in ovo seems to continue on schedule in vitro, making the development of the IFN system in chick embryo cells appear as a time-dependent process.

2',5'-Oligoadenylate Synthetase↗
PubMed1990

Interferon induction by viruses. XX. Acid-labile interferon accounts for the antiviral effect induced by poly(rI).poly(rC) in primary chick embryo cells.

Primary chick embryo cells which were "aged" in vitro and exposed to poly(rI).poly(rC) developed a disproportionately high degree of resistance to virus challenge in relation to the amount of conventional acid-stable interferon (IFN) produced. Cells were often highly resistant after exposure to a few nanograms of poly(rI).poly(rC) which gave rise to little or no acid-stable IFN. Study of the mechanism(s) responsible showed that this antiviral state was not due to the double-stranded ribonuclease induced in parallel, nor to residual poly(rI).poly(rC) (which this ribonuclease destroyed), but to the production of a hitherto undescribed acid-labile chicken IFN.

Acids↗
PubMed1989

Double-stranded ribonuclease coinduced with interferon.

Double-stranded (ds) RNA and many viruses are inducers of interferon (IFN), the latter presumably because they contain, or can form, dsRNA. Concomitant with the induction of IFN in chicken embryo cells was the induction of a novel double-stranded ribonuclease (dsRNase), which was released into the medium and continued to accumulate long after IFN production ceased. Only avian cells (chicken, quail, turkey, or duck) expressed high levels of this dsRNase; mammalian, turtle, or fish cells did not. Production of the nuclease was inducer dose-dependent. Optimum pH and cation requirements distinguished it from other dsRNase activities. Degradation of dsRNA was endonucleolytic. Activity resided in a molecule of an Mr of approximately 34,500. Low levels of a single-stranded (ss) RNase activity were inseparable from the dsRNase. The role for a dsRNA-inducible dsRNase released from cells is unknown.

Animals↗
PubMed1989

Interferon induction by viruses. XIX. Vesicular stomatitis virus--New Jersey: high multiplicity passages generate interferon-inducing, defective-interfering particles.

The infectious particles of plaque-derived, low multiplicity passaged wild-type VSV of New Jersey origin consistently induce about 1800 units of interferon (IFN)/10(7) aged chick embryo cells. This inducing capacity is sensitive to both uv radiation and heat (50 degrees). Virus obtained after two successive high multiplicity passages in GMK-Vero cells consistently induced over 25,000 units of IFN/10(7) cells. The IFN induction dose-response curve showed that one IFN-inducing particle (IFP) per cell sufficed to produce a quantum yield of IFN, but infection with two or more IFPs led initially to a marked suppression in the yield of IFN. IFN induction was attributed to two distinct defective particles that differed in size, both containing snap-back RNA, i.e., covalently linked, self-complementary [+/-]RNA. The IFN-inducing capacity of these defective-interfering particles was not inactivated by uv or heat. However heat did eliminate the IFN suppressing activity observed at higher multiplicities, implicating a heat-sensitive component in the virion as a regulator of IFN yield, and involving possibly the virion transcriptase and 3'-leader RNA product.

Animals↗
PubMed1989

Interferon induction by viruses. XVIII. Vesicular stomatitis virus-New Jersey: a single infectious particle can both induce and suppress interferon production.

In contrast to wild-type vesicular stomatitis virus (VSV) of Indiana (Ind.) origin which express interferon (IFN) inducing- and IFN induction-suppressing activities as mutually exclusive properties, individual particles of wild-type VSV of the New Jersey (N.J.) serotype (Hazelhurst [H] isolate) paradoxically can both induce IFN and suppress its induction in cells coinfected with a potent inducer of IFN. The properties of IFN induction, and its suppression, appear to reside in the particle that manifests infectivity. Analyses of IFN induction dose-response curves to measure IFN-inducing particles (IFP), and IFN yield-reduction curves to measure IFN induction-suppressing particles (ISP) generated by VSV-N.J.(H) in aged chick embryo cells revealed that (i) a single particle per cell sufficed to induce a quantum (full) yield of IFN, or to suppress fully IFN production by a coinfecting inducing virus, and (ii) the addition of one or more IFP per cell did not suppress the yield of IFN beyond the plateau level. The time-course of IFN production in chick cells infected with VSV-N.J. (H) revealed about a 4-h lag, even when the cells were coinfected with a potent inducer that normally induced IFN 1 or 2 h sooner. Thus, VSV-N.J.(H) appears to regulate the production of IFN in cells--even that initiated by other inducers. Expression of IFP and ISP activities both required primary transcription, with respective genomic targets similar to those reported for VSV-Ind. N.J.(H) is the first wild-type VSV observed to express IFP and ISP activities concomitantly. A model is presented to suggest how these two antagonistic properties might be expressed by a single infectious particle.

Animals↗
PubMed1989

Interferon induction by viruses. XVII. Non-temperature-sensitive mutations regulate interferon induction by vesicular stomatitis virus.

Wild-type (wt) strains of vesicular stomatitis virus (VSV) strain Indiana are poor to non-inducers of interferon (IFN) which express IFN induction-suppressing activity. At non-permissive temperatures, temperature-sensitive (ts) mutants of this virus are either like their wt parents, or they are good to excellent inducers of IFN. IFN inducibility and IFN induction-suppressing activity are mutually exclusive phenotypes in VSV-Indiana. With one exception, all Orsay ts mutants derived by A. Flamand (CNRS, Gif-sur-Yvette, France), representing the five complementation groups, were poor to non-inducers of IFN and were also capable of suppressing IFN induction by other viruses. In contrast, all Glasgow ts mutants derived by C. R. Pringle (University of Warwick, Coventry, U.K.) were excellent inducers of IFN. We demonstrate that this difference in acquisition of IFN inducibility relates primarily to the origin of the mutations; spontaneous for Orsay, and mutagen-derived for Glasgow. Tests with newly generated spontaneous and mutagen-derived mutants, and temperature-stable revertants of IFN-inducing ts mutants indicate that IFN inducibility results from non-ts, multiple mutations rarely acquired spontaneously, but generated frequently upon mutagenesis with 5-fluorouracil. The capacity of VSV-Indiana to induce IFN is considered intrinsic to the virus, but is only manifested when the dominant IFN induction-suppressing phenotype is lost through mutagenesis. Thus, non-ts mutations appear to regulate the expression of the IFN induction-suppressing phenotype, and hence the IFN inducibility of VSV-Indiana.

Animals↗
PubMed1988

Interferon induction by viruses. XVI. 2-Aminopurine blocks selectively and reversibly an early stage in interferon induction.

A purine analogue, 2-aminopurine, reported to act as an inhibitor of protein kinase, selectively, reversibly and in a dose-dependent manner blocked a very early stage in interferon induction. With chick embryo cells and mouse L cells as hosts, and different viral inducers of interferon, maximal effects of 2-aminopurine were observed during the first 4 h of induction. At 10 mM-2-aminopurine there was a 20-fold reduction in the yield of interferon from both cell types. 2-Aminopurine and actinomycin D both prevented interferon induction with the same time course, indicating a transcriptional block to induction; however, only the action of the former was reversed upon removal of the drug. Addition of 2-aminopurine to an agarose overlay resulted in high efficiency plaque formation by vesicular stomatitis virus New Jersey (Hazelhurst) under conditions where endogenous induction of interferon and its feedback action on aged chick embryo cells normally prevented plaque formation. Two other inducible systems, representing genes involved in interferon action (both its development and activation), and those of heat shock, were not affected by 2-aminopurine. A model is presented implicating the interferon-inducible dsRNA-dependent protein kinase as an interferon induction receptor which, on interaction with dsRNA, generates an amplified signal via phosphorylation that ultimately derepresses the interferon gene(s).

2-Aminopurine↗
PubMed1987

Interferon induction by viruses. XV. Biological characteristics of interferon induction-suppressing particles of vesicular stomatitis virus.

A single interferon (IFN) induction-suppressing particle (ISP) of vesicular stomatitis virus (VSV) blocked completely the yield of IFN in a cell otherwise programmed to produce IFN. With mouse L cells as hosts, one lethal hit of UV radiation (D37 = 52.5 ergs/mm2) to the VSV genome sufficed to inactivate ISP activity; however, with "aged" primary chick embryo cells as hosts, it took 198 lethal hits (D37 = 10,395 ergs/mm2). ISP expression in chick cells did not require virus replication or amplified RNA synthesis, but did involve functional virion-associated L protein. ISP in chick cells also were capable of inhibiting, in a multiplicity-dependent manner, the plaquing efficiency of two viruses that require cellular polymerase II (pol II) for replication, e.g., pseudorabies and influenza. The refractory state to IFN inducibility that resulted from infection of chick cells with ISP (VSV tsO5 [UV = 100 hits]) was still extant after 6 days. In contrast, the plaquing efficiency of pseudorabies virus returned to control levels by 5 h after ISP infection. Chick cells infected with UV ISP remained viable, served as hosts for the replication of other viruses, and could be subcultured. Models are presented to account for these contrasting effects. The involvement of viral plus-strand leader RNA as an inhibitor of cellular pol II-dependent RNA synthesis, and the multifunctional activities of the virion-associated L protein, are discussed as possible molecules involved in the action of ISP in chick cells.

Animals↗
PubMed1985

Interferon induction by viruses. XIII. Detection and assay of interferon induction-suppressing particles.

An assay is described for detecting and measuring the capacity of a single virus particle to suppress completely the yield of interferon from a cell otherwise competent to product interferon. The assay defines virus populations in terms of a newly quantifiable attribute--interferon induction-suppressing particles (ISP). The antagonistic actions of interferon-inducing particles and interferon induction-suppressing particles are thought to determine the interferon-inducing capacity intrinsic to a virus population.

Animals↗
PubMed1985

Interferon induction by viruses. XIV. Development of interferon inducibility and its inhibition in chick embryo cells "aged" in vitro.

Studies with a number of viruses revealed a time-dependent acquisition of interferon (IFN) inducibility in primary chick embryo cells as they "aged" in vitro for 2-12 days at a confluent cell density without a medium change. The time-course for the development of IFN inducibility was established by generating and analyzing a family of dose (multiplicity)-response (IFN yield) curves, using Newcastle disease virus (NDV, strain LaSota) as the inducer. Cells produced little or no IFN for the first 4-5 days. Between 5 and 6 days the cells gradually developed the capacity to respond to NDV (and other viruses). Maximal yields of IFN were inducible by day 10. This time-dependent development of IFN inducibility was abrogated almost completely when "aging" was carried out in the presence of drugs that inhibited the synthesis of cyclic derivatives of C20 oxygenated unsaturated fatty acids, i.e., inhibitors of prostaglandin/leukotriene synthesis and the arachidonic acid cascade. Of the prostaglandin synthesis inhibitors, indomethacin was particularly effective. Cells treated on day 0 with 10 micrograms/ml of indomethacin produced 100- to 1000-fold less IFN than controls when induced on day 8. To prevent maximally the development of IFN inducibility, indomethacin must be added within the first 2 days of seeding. After about 2 days, the cells begin to escape the action of the drug. Indomethacin added at the time of induction had no effect on the yield of IFN. IFN inducibility was partially restored when indomethacin was removed during the aging process. "Aging" chick cells in low concentrations of cycloheximide (0.5 micrograms/ml) produced results comparable to incubation with indomethacin. Neither reagent had any marked effect on the rate of total protein or RNA synthesis, nor did their action prevent the induction of stress (heat shock) proteins. Cells "aged" in indomethacin were threefold less efficient in responding to the action of IFN, whereas aging in cycloheximide had no effect on IFN's action. Plaque formation on drug-treated cells was normal for viruses that were poor inducers of IFN. However, both the plaquing efficiency and plaque size of Sindbis virus (an excellent IFN inducer) were enhanced markedly on cells treated with indomethacin or low concentrations of cycloheximide during the aging process. These data implicate a family of fatty acid derivatives of arachadonic acid, including prostaglandins and leukotrienes, in the development of IFN inducibility in primary chick embryo cells "aged" in vitro.

Animals↗
PubMed1985

Interferon induction by viruses. XII. Inhibition of protein synthesis renders aged chick embryo cells refractory to interferon induction.

The initial stages of interferon induction in mouse L cells do not require protein synthesis; all steps in the induction process up to and including the transcription of interferon mRNA occurred in the presence of inhibitors of protein synthesis. In contrast, interferon induction in primary chick embryo cells aged in vitro does require a reaction that depends upon protein synthesis, unique in that it is not required for virus replication or the action of interferon.

Animals↗