An interferon-like inhibitor of viral multiplication from malignant cells (the viral autoinhibition phenomenon)

Beta interferon regulation of glucose metabolism is PI3K/Akt dependent and important for antiviral activity against coxsackievirus B3

An effective type I interferon (IFN)-mediated immune response requires the rapid expression of antiviral proteins that are necessary to inhibit viral replication and virus spread. We provide evidence that IFN-β regulates metabolic events important for the induction of a rapid antiviral response: IFN-β decreases the phosphorylation of AMP-activated protein kinase (AMPK), coincident with an increase in intracellular ATP. Our studies reveal a biphasic IFN-β-inducible uptake of glucose by cells, mediated by phosphatidylinositol 3-kinase (PI3K)/Akt, and IFN-β-inducible regulation of GLUT4 translocation to the cell surface. Additionally, we provide evidence that IFN-β-regulated glycolytic metabolism is important for the acute induction of an antiviral response during infection with coxsackievirus B3 (CVB3). Last, we demonstrate that the antidiabetic drug metformin enhances the antiviral potency of IFN-β against CVB3 both in vitro and in vivo. Taken together, these findings highlight an important role for IFN-β in modulating glucose metabolism during a virus infection and suggest that the use of metformin in combination with IFN-β during acute virus infection may result in enhanced antiviral responses.

IMPORTANCE

Type I interferons (IFN) are critical effectors of an antiviral response. These studies describe for the first time a role for IFN-β in regulating metabolism--glucose uptake and ATP production--to meet the energy requirements of a robust cellular antiviral response. Our data suggest that IFN-β regulates glucose metabolism mediated by signaling effectors similarly to activation by insulin. Interference with IFN-β-inducible glucose metabolism diminishes the antiviral response, whereas treatment with metformin, a drug that increases insulin sensitivity, enhances the antiviral potency of IFN-β.

The role of interferon in vaccinia virus infection of mouse embryo tissue culture

The production of an interferon-like substance by vaccinia virus is described. The physical properties of vaccinia interferon are shown to be similar to those of previously reported interferons. Data defining the role of vaccinia interferon in cell resistance and in establishment and maintenance of a carrier culture are presented. Elimination of virus from an infected culture is demonstrated and the role of interferon in the recovery process is considered.

A carrier state of mumps virus in human conjunctiva cells. I. General characteristics

Mumps virus produced a carrier state in human conjunctiva cells that was maintained for more than 100 subcultures over a period of 3 years. Antiserum in the medium was not required. The virus had little apparent effect on the cells which grew at a rate similar to uninfected control cells. Mumps virus was regularly found in the culture medium at levels about 0.9 log higher than the cell-associated virus. When first tested after 30 subcultures, the virus was found to have lost its cytopathogenicity for cells ordinarily susceptible to mumps virus, but was identifiable as mumps virus by neutralization with specific antiserum. Use of fluorescein-labeled antiserum revealed that 80 to 95 per cent of cells in the carrier cultures contained mumps virus antigen. The antigen was concentrated in a few sharply circumscribed, discrete masses in the cell cytoplasm rather than in many granules throughout the cytoplasm as is characteristic of cell infection by cytopathogenic mumps virus. The carrier cultures were resistant to the destructive effect of a cytopathogenic line of mumps virus, but showed little resistance to the cytopathogenic effect of vesicular stomatitis, Sendai, or Newcastle disease viruses.

PRODUCTION OF AN INTERFERON BY L CELLS INFECTED WITH WESTERN EQUINE ENCEPHALOMYELITIS VIRUS

Lockart, Royce Z., Jr. (The University of Texas, Austin). Production of an interferon by L cells infected with Western equine encephalomyelitis virus. J. Bacteriol. 85:556-566. 1963.-Two strains of Western equine encephalomyelitis virus (WEE), WEE (L+) and WEE (L-), which differed with respect to their cytopathogenicity for L cells were isolated. Both strains reproduced in L cells, and both induced the production of an interferon distinct from virus particles. L-cell monolayers were protected from degeneration by prior addition of interferon. By use of the absence of cytopathic effects (CPE) as an end point, interferon content was assayed. Monolayers failing to show CPE consistently produced less than 2% as much virus as control monolayers, indicating that virus synthesis was also inhibited. The use of this assay method was facilitated by the use of horse serum that appeared to contain antibodies against WEE and that permitted interferon to act selectively in the presence of active virus. It was found that interferon was produced during the time in which active virus was produced, and not significantly later. No interferon could be found in fluids from cells treated with inactive virus, although these are known to act as interfering agents. Interferon production was inhibited by pretreatment of L cells with sufficient amounts of interferon. It is concluded that interferon production is closely connected with WEE virus synthesis in L cells. The question is raised as to whether interferon need be a necessary intermediate for interference in L cells.

PERSISTENT POLIOVIRAL INFECTION OF INTACT HUMAN AMNIOTIC MEMBRANE WITHOUT APPARENT CYTOPATHIC EFFECT

Gresser, Ion (Children's Hospital Medical Center, Boston, Mass.), Charles Chany, and John F. Enders. Persistent polioviral infection of intact human amniotic membrane without apparent cytopathic effect. J. Bacteriol. 89:470-475. 1965.-Poliovirus type I multiplied in organ cultures of the intact amniotic membrane. The behavior of the virus in this system differed markedly from that observed in monolayer cultures of trypsinized amnion cells, since replication of new virus was demonstrable throughout a period as long as 3 months, extensive cellular destruction was not apparent, and only a small proportion of cells were found to be infected at a given time. It seems likely that the chronicity of infection is conditioned essentially by the persistent insusceptibility to polioviral infection of the large majority of cells (relative to monolayer cultures) rather than to interferon, which was present in the culture fluids. It was postulated that the greater suceptibility of cultured amnion cells to infection, as compared with cells of the intact membrane, is due in part to the enhancement of phagocytic activity attendant upon trypsinization and cultivation of the amnion cells in monolayers. Amniotic and chorionic membranes thoroughly washed free from blood contain and release in vitro antibody to poliovirus I and other viruses. Appreciation of this phenomen may be important in attempts to isolate viruses from infected tissues.

Antitumor therapy based on the use of an immune modulator, arginine butyrate and interferon

The analysis of the likely physiological role of interferon during pregnancy and antitumor protection can be employed in developing a new strategy in antitumor therapy. Indeed, pretreatment of the patients with a potent immune stimulation compensates to some extent interferon's immune repressive effects. Through the modulation of the cytoskeleton, interferon enhances macrophage activity. Moreover, butyrate by its own effect on the malignant phenotype increases interferon sensitivity in a number of malignant cells. All of these substances should be used at the lowest possible concentration delivered as closely as possible to the target area.

Antitumor effect of arginine butyrate in conjunction with Corynebacterium parvum and interferon

The antitumor effect of arginine butyrate, used alone or in conjunction with interferon (IFN), was studied using randomly selected Swiss mice inoculated i.p. with 10(6) 180 TG Crocker tumor cells. The results of these different therapeutic regimens were estimated by tumor incidence at 10 days, by the time necessary to protect 50% of the animals, and by the final survival rate. Combined treatment by IFN and arginine butyrate was effective; but in order to compensate for IFN's immune repressive effects, a single injection of Corynebacterium parvum was administered in some experiments prior to IFN and/or arginine butyrate. After this immune potentiation, both IFN and arginine butyrate used separately significantly protected the animals. However, optimal results were obtained when a single C. parvum injection was followed by nine daily alternating shots of arginine butyrate and IFN.

Interferon production by human cells in vitro

The relative capacity of several types of human cells and tissue to produce interferon was studied. Types of cells and tissue included were fibroblasts from embryos, foreskins, and biopsied skins; amnion cells; peripheral leukocytes; established lymphoid cell lines; established heteroploid cell lines; and chorioamniotic membrane. When Newcastle disease virus was used as the inducer, fibroblasts and amnion cells produced more interferon per 10(6) cells than leukocytes, lymphoid cells, and heteroploid cells. Only minor variations in interferon-producing capacity were observed among fibroblasts from 36 persons. Culture passage level, cell concentration, and inducer were factors that significantly affected interferon production.

Use of monkey-mouse hybrid cells for the study of the cellular regualtion of interferon production and action

Four clones of a somatic monkey-mouse hybrid cell line were studied. One of these clones produced both mouse and monkey interferon, while the three others produced only mouse interferon. All four were, however, sensitive to both mouse and monkey (or human) interferon. The karyotype analysis of these four hybrid clones and the parental cell lines enabled us to locate the possible genetic site governing the synthesis of monkey interferon on a small subtelocentric monkey chromosome. The genetic site responsible for the synthesis of the antiviral protein is located on a different (monkey or mouse) chromosome.

Functional heterogeneity of virions in human adenovirus types 2 and 12

Purified preparations of adenovirus types 2 and 12 were used to infect KB cells at different input multiplicities. The resulting infected cultures were scored for inclusion body formation, production of infectious centers, and cloning efficiency. Both preparations were found to contain some defective particles capable of preventing a cell from cloning but unable to induce inclusion bodies or form plaques. The proportion of such defective particles in adenovirus 12 was about 10 times that in adenovirus 2. At high input multiplicities, the percentage of cells displaying an inclusion body was less than that predicted by the Poisson distribution and reached a maximum of 40 to 60% for adenovirus 2 and 12 to 15% for adenovirus 12. This reduction may be due to interference by large numbers of non-plaque-producing particles infecting each cell. The per cent of cells forming infectious centers was substantially greater for adenovirus 2 than for adenovirus 12 when compared at the same input plaque-forming units, reaching a maximum of 35 to 73% for adenovirus 2 and 5 to 10% for adenovirus 12. The low value for adenovirus 12 may be a result of the same interference phenomenon.

Exaltation of the development of poliovirus by semicarbazide

Grossberg, Sidney E. (Institut Pasteur, Paris, France), Marguerite Lwoff, and André Lwoff. Exaltation of the development of poliovirus by semicarbazide. J. Bacteriol. 92:1473-1477. 1966.-Semicarbazide (NH(2)-NH-CO-NH(2)) remarkably increases the development of poliovirus. In single-cycle experiments, semicarbazide (SCZ) acted to (i) diminish the length of the latent period, (ii) increase the rate of production of virions, and (iii) increase the final yield of virus. These effects were demonstrable in KB cells, a human malignant cell line, and other primate cells. The dose range over which the compound exerts its effect was relatively large, i.e., from 0.3 to 20 mm, whereas higher concentrations inhibited viral growth. SCZ achieved its exalting effect only when it was added during the first 3 hr of viral development; later addition had no effect. Withdrawal of SCZ at intervals during the viral cycle confirmed that its action occurred within 3 hr after infection. The possible mode of action of SCZ is discussed. SCZ appeared to act, at least in part, by increasing the rate of synthesis of the viral ribonucleic acid.

Antiviral action of mouse interferon in heterologous cells

Buckler, Charles E. (National Institute of Allergy and Infectious Diseases, Bethesda, Md.), and Samuel Baron. Antiviral action of mouse interferon in heterologous cells. J. Bacteriol. 91:231-235. 1966.-The antiviral action of mouse interferon in cell cultures of mouse, hamster, rat, chicken, and monkey origin was investigated. Using a vesicular stomatitis virus (VSV) plaque reduction test, we found that mouse serum interferon, assayed on closely related rat or hamster cells, exerted 5% of its homologous antiviral activity. This activity was characterized as interferon by its temperature of inactivation, trypsin sensitivity, nonsedimentability, stability at pH 2, lack of inactivation by antibody to virus, and inability to be washed off cells. In the more distantly related chicken and monkey cells, mouse interferon had less than 0.1% of its homologous activity. Conflicting reports of heterologous activity of chicken and mouse interferon preparations may result in part from the observed action of noninterferon inhibitors of vaccinia virus. These inhibitors, like interferon, are stable at pH 2. They are present in mouse serum, mouse lung extracts, and allantoic fluid, and they prevent the development of vaccinia plaques when allowed to remain in contact with cells during virus growth. Unlike interferon the inhibitors are removed by adequate washing of cells prior to virus challenge, and they are not active in the VSV assay system. These findings reemphasize the need for thorough characterization of interferon preparations.