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Role of interferon in the pathogenesis of virus diseases in mice as demonstrated by the use of anti-interferon serum. II. Studies with herpes simplex, Moloney sarcoma, vesicular stomatitis, Newcastle disease, and influenza viruses.

The effect of potent sheep anti-mouse interferon globulin was investigated in several different experimental virus diseases of mice. In anti-interferon globulin-treated mice infected intraperitoneally with herpes simplex virus (HSV) type I, the latent period was shortened, and the overall LD50 was increased several hundredfold compared to virus-infected control mice. When HSV was inoculated subcutaneously all anti-interferon globulin-treated mice died, whereas only 5% of virus-infected control mice died. Subsequent treatment with anti-interferon globulin of previously HSV-infected mice did not result in reactivation of HSV. Treatment of adult mice with anti-interferon globulin resulted in an earlier appearance of MSV-induced tumors, a greater number of mice bearing tumors, an increase in tumor size, and an increase in the duration of tumors. All tumors eventually regressed despite reinjection of anti-interferon globulin. Anti-interferon globulin treatment resulted in a rapid onset of disease and death in adult mice inoculated (intranasal) with VSV and in newborn mice infected with NDV. Anti-interferon globulin exerted no effect on the course of influenza virus infection of mice. We conclude that the early production of interferon is an importane element in the response of the mouse to several viruses exhibiting different pathogeneses.

Animals↗

Are cytotoxicity and interferon inducing activity of poly(I).poly(C) invariably linked in interferon-treated L cells.

Interferon-treated L cells exhibit a specific enhanced susceptibility to the cytotoxic and interferon inducing activities of double-stranded RNAs such as poly(1). poly(C). These activities remained closely linked through widely varying assay conditions, involving, for example, different time anddosage schedules of poly(1). poly (C),suggesting that there is at least one common step in the mechanisms leading to interferon formation and toxicity in interferon-primed cells exposed to poly(1).poly(C). However, some procedures such as addition of metabolic inhibitors (actinomycin D, cycloheximide) and repeated administration of poly(1).poly(C) suppressed the interferon inducing capacity of poly(1).poly(C) without a concomitant decrease of toxicity. Other procedures such as brief treatment of the cells with interferon or DEAE-dextran permitted full expression of the interferon inducing activity of poly(1).poly(C) without any sign of toxicity. The latter results suggest that the mechanisms underlying interferon production and toxicity of poly(1).poly(C) in interferon-treated L cells diverge from a certain point onward.

Animals↗

Effect of interferon on mouse leukaemia virus (MuLV). V. Abnormal proteins in virions of Rauscher MuLV produced in the presence of interferon.

Interferon treatment of JLSV-6 cells chronically infected with Rauscher MuLV leads to the formation of non-infectious particles ('interferon' virions) containing the structural proteins coded by the env and gag genes as well as additional virus polypeptides. The major glycoprotein detected in the control virions is gp71, but 'interferon' virions contain in addition an 85K mol. wt. (gp85) glucosamine-containing, fucose-deficient glycoprotein. This is recognized by antiserum to MuLV and may be related to env pr85. Surface iodination of intact virions indicates that gp71 and gp85 are the two major components of the external envelope. However, whereas in control virions gp71 associates with p15E (gp90), this complex was not detected in 'interferon' virions. Analysis of radio-labelled (3H-amino acids or iodinated) proteins from disrupted 'interferon' virions revealed the presence of 65K, 55K, 40K, 20K and 12K mol. wt. polypeptides which could be precipitated with antiserum against MuLV. There was a distinct difference in the patterns of incorporation of pulse-labelled 3H-amino acid polypeptides into virions in the presence and absence of interferon. Those polypeptides labelled in the presence of interferon and recovered in the extracellular virions in a chase with interferon appeared to have substantially fewer copies of p30 and more of gag pr55 polypeptide than the controls. These results indicate that in the presence of interferon there are changes in the proteolytic cleavage associated with virion assembly.

Animals↗

Purification of human interferon by antibody affinity chromatography, using highly absorbed anti-interferon.

Antibodies against partially purified human leucocyte interferon (PIF) were bound to Sepharose 4B and crude interferons applied on this affinity column were purified, up to 8 x 10(5) interferon units (IFU) per mg protein in one step. Antibodies against PIF were absorbed with immobilized crude human leucocyte interferon bound to Sepharose, whereby antibodies against impurities were predominantly removed. Extensively absorbed antisera were coupled to Sepharose and used for antibody affinity chromatography of crude interferon preparations. Leucocyte and fibroblast interferons were purified in one step with around 100% recovery, up to 1 x 10(8) IFU per mg protein, and Namalva interferon up to 2 x 10(7) IFU/mg. SDS electrophoresis of affinity-purified leucocyte interferon revealed that the interferon activity appeared in two bands (19,000 and 23,000 D).

Antibodies↗

Regulation of two interferon-inducible human genes by interferon, poly(rI).poly(rC) and viruses.

The IFI-56K and IFI-54K genes are transcriptionally stimulated when cells are treated by interferon. We have previously shown that the IFI-56K gene is in addition directly induced by poly(rI).poly(rC), and inducer of interferon-beta. Since the regulation of the IFI-56K and IFI-54K genes by interferon are very much alike, we tested whether the IFI-54K gene is also directly regulated by poly(rI).poly(rC). Treatment of various cell lines with poly(rI).poly(rC) leads to a clear accumulation of the IFI-54K mRNA to a level which sometimes even exceeds that obtained with high doses of interferon. Several interferon-resistant cell lines were investigated for the inducibility of both the IFI-56K and IFI-54K genes by interferons, poly(rI).poly(rC) and viruses (which are the natural inducers of interferon-alpha and -beta). Both genes appear to be coordinately regulated by these inducers. It was thus interesting to search for common regulatory element(s) in the control region of these two genes. The IFI-54K gene promoter region was isolated, from which a 520-base-pair segment was sequenced and compared with the promoter region of the IFI-56K gene that we had previously sequenced. The only homology was found is a well conserved 19-bp segment located just upstream of the TATA box of these genes; interestingly, this sequence is also homologous to the minimal region needed for the inducibility by poly(rI).poly(rC) of the interferon-beta gene. This conserved sequence might be responsible for the coordinate induction of the IFI-56K and IFI-54K genes by interferon, poly(rI).poly(rC) and viruses.

Base Sequence↗

Studies on the mechanism of the priming effect of interferon on interferon production by cell cultures exposed to poly(rI)-poly(rC).

Interferon induction by poly(rI).poly(rC) in primary rabbit kidney and mouse L-929 cell cultures was markedly increased if the cells were previously treated with homologous interferon. This priming effect has been established with different times of exposure of the cells to poly(rI).poly(rC), and was most pronounced for short pulses of contact of the polynucleotide with the cells (10 s, 1 min). Treatment of the cells with pancreatic ribonuclease immediately after their exposure to poly(rI).poly(rC) brought about a relatively greater reduction of the interferon response in interferon-primed cells than it did in unprimed cell cultures. Priming of the cells with interferon did not increase cell-binding of poly(rI).poly(rC), whether this cell-binding was measured quantitatively (by radioactivity, upon exposure of the cells to radiolabeled polymer) or qualitatively (by antiviral activity, by assaying the cell extract for virus plaque reduction). Similarly, interferon priming did not alter the sensitivity of cell-associated poly(rI).poly(rC) to extraneous ribonuclease treatment. Finally, priming with interferon did not decrease the rate of degradation of cell-bound poly(rI).poly(rC) by cellular nucleases nor did it increase the anti-nuclease potency of the cells. The exact mechanism by which previous exposure of the cells to interferon enhances subsequent interferon production, induced by either synthetic polynucleotides or viruses, has not yet been resolved.

Animals↗

Effects of alpha interferon induction plus ribavirin with or without amantadine in the treatment of interferon non-responsive chronic hepatitis C: a randomised trial.

BACKGROUND: Fifty per cent of chronic hepatitis C patients are non-responders to interferon. At present, there are no recommended therapeutic options for non-responders. AIMS: The safety and long term effect of alpha interferon induction plus ribavirin with or without amantadine in the treatment of interferon non-responsive chronic hepatitis C was evaluated. PATIENTS AND METHODS: A total of 114 consecutive patients were randomly divided into three groups with a final 2:2:1 ratio: group A (44 patients) received interferon alfa 2b, 3 million units (MU), three times a week, and oral ribavirin (1000 mg/day); group B (46 patients) received interferon 3 MU daily for the first four weeks and subsequently 3 MU three times a week, and ribavirin as in regimen A; and group C (24 patients) received interferon and ribavirin as in regimen B, plus oral amantadine hydrochloride (200 mg/day). The duration of treatment was 12 months. RESULTS: The end of treatment response for groups A and B was 25% and 29%, respectively, and for group C, 68% (p<0.005). At the end of one year of follow up, a sustained response was observed for six (25%) patients in group C, one (2%) patient in group A, and two (4%) patients in group B (p<0.002). The triple regimen was well tolerated and did not increase the frequency or severity of side effects. CONCLUSIONS: The study demonstrates that for the treatment of interferon non-responder hepatitis C patients, the association of interferon-ribavirin has a negligible long term effect whereas a triple regimen including interferon, ribavirin, and amantadine can be an effective and safe treatment.

Adult↗

Retreatment of non-responder or relapser chronic hepatitis C patients with interferon plus ribavirin vs interferon alone.

BACKGROUND AND AIM: Interferon-alpha treatment of chronic hepatitis C is beneficial in only 20-30% of patients. This study evaluates if combination therapy with Interferon-alfa plus ribavirin is effective in inducing a response in patients who did not respond to, or relapsed after, a standard Interferon-alfa treatment. PATIENTS AND METHODS: A total of 88 patients, 49 non-responders and 39 relapsers to previous Interferon-alfa therapy, were randomized to receive either natural Interferon-alfa (6 MU t.i.w.) plus ribavirin (1000 mg/daily) or natural Interferon-alfa alone (6 MU t.i.w.) for 6 months. All were followed for 12 months after stopping therapy. Serum aminotransferase levels were assessed monthly and HCV RNA was evaluated by RT-PCR (Amplicor, Roche) at end of therapy and the end of follow-up. RESULTS: After treatment, a higher response rate defined as return to normal of aminotransferases and absence of serum HCV RNA was observed among patients treated with Interferon-alfa-ribavirin: 4/28 (14%) vs 1/21 (5%) non-responder patients and 9/19 (47%) vs 5/20 (25%) in the relapsers group. At the end of follow-up, a sustained response was found only in the combination treatment group: 4% and 32% in non-responder and relapser patients, respectively. CONCLUSIONS: Our results suggest that retreatment with natural Interferon-alfa plus ribavirin is more effective than Interferon-alfa alone in increasing the response rate in patients with chronic hepatitis C who relapse after a previous standard IFN treatment whereas it is less effective in non-responder patients.

Adult↗

Interferon re-treatment for resistance to lamivudine plus interferon treatment.

BACKGROUND/AIMS: The most important problem of the lamivudine therapy is the frequent development of drug resistance. Treatment of chronic hepatitis B patients resistant to lamivudin remains to be established. We investigated in this study the efficacy of interferon therapy for breakthrough infection to combination therapy with interferon and lamivudine. METHODS: Interferon therapy was applied to nine patients who experienced HBV DNA breakthrough with ALT elevation for at least three months during the lamivudine treatment, which was given in combination with interferon for the first six months. These patients were compared with 10 patients who developed breakthrough but were not given interferon. All the patients continued to receive lamivudine. RESULTS: Of the nine patients who were given interferon, two lost HBV DNA and had normal ALT after six months of treatment. ALT levels returned to normal in two patients who had no virological response. Of those patients not given interferon, none lost HBV DNA, but three had normal ALT at the end of the same duration of follow-up. CONCLUSIONS: The patients with breakthrough infection during lamivudine treatment, which was combined with interferon at the beginning, may benefit from another cycle of interferon treatment.

Adolescent↗

Characteristics of immune interferon produced by human lymphocyte cultures compared to other human interferons.

A factor with antiviral activity has been produced in vitro by combined macrophage-lymphocyte cultures from patients with recent herpes labialis in response to HSV antigen stimulation. It has been designated "immune interferon" and characterized in comparison to several other human interferons. It was shown to be relatively unstable at pH 2 and at 56 degrees C. Rabbit anti-human leukocyte interferon serum was shown to be less active against immune interferon than against diploid cell interferon or against vesicle fluid interferon. The possibility of immune interferon being a totally different anti-viral protein or a protein with certain shared antigen determinants or structures with classical viral interferon is discussed. A simplified method for the assay of anti-interferon sera with microtiter plates is also described.

Antigens, Viral↗

[Induction of interferon-specific enzymes in cultures of cells sensitive and resistant to interferon].

Induction of 2'-5'-oligoadenylatesynthetase (2-5A synthetase) by interferons and theophylline by means of activation of cAMP-system in interferon susceptible and resistant cell lines were studied. In interferon resistant cell lines the basal activity of 2-5A synthetase exceeded the level of the same enzyme in interferon susceptible cell lines. Activity of 2-5A synthetase is increased in interferon susceptible cell lines by interferon treatment, but the activity of the enzyme is not altered in interferon resistant cell lines. Among the studied cell lines the induction of 2-5A synthetase by theophylline was possible only in L929 cell line. The common mechanism for the absence of 2-5A synthetase induction by interferon and theophylline in interferon resistant cells is discussed.

2',5'-Oligoadenylate Synthetase↗

[Antiviral activity of mutant interferons. A new approach to the study of structural-functional organization of interferons].

The developed approach to investing the structure-functional organization of interferon has been developed consisting in: 1) fusing genes of interferon and alpha-peptide of beta-galactosidase, the resultant protein having the interferon properties and being determined by the beta-galactosidase alpha-complementation test; 2) constructing mutant genes of interferon by the localized mutagenesis; 3) determining the mutant interferon activity; 4) deducing the amino acid sequence of mutant interferon by sequencing mutant genes; 5) analyzing structure-functional organization of interferon. In accordance with this approach, ten mutant interferons with up to 15 changes of amino acid substitutions are obtained and their antiviral activity is determined. The role of some amino acid residues in antiviral activity of interferon alpha 2 is revealed.

Amino Acid Sequence↗

Defense mechanisms against primary influenza virus infection in mice. I. The roles of interferon and neutralizing antibodies and thymus dependence of interferon and antibody production.

To investigate the defensive roles and production of interferon and antibodies, C3H/He mice were subjected to various immunosuppressive treatments and infected with influenza virus. In infected normal control mice the pattern of pulmonary viral growth can be divided into three phases. The first phase is characterized by an exponential increase of virus titer, the second by a rapid decrease, and the third by a moderate decrease. At the time of transition from the first phase to the second in pulmonary virus growth, interferon could be detected in the tracheobronchial washings of infected mice, but neutralizing antibodies could not. In infected B cell-deprived mice and infected anti-mu-treated mice, the transition from the first phase to the second occurred without any detectable antibody production, and interferon could be induced in the early stage of infection. However, the pulmonary virus in these mice increased again exponentially until the death of the mice. In infected T cell-deprived mice which could not induce interferon, but produced IgM-neutralizing antibodies, the second phase was not observed after the first phase, but a transient plateau phase could be demonstrated, and then the pulmonary virus increased again exponentially until the death of the mice. In anti-gamma-treated infected mice, pulmonary virus growth and production of interferon and neutralizing antibody were almost similar to those of infected normal control mice except for the absence of IgG neutralizing antibody production. Although anti-alpha-treated infected mice produced interferon and no IgA antibody, the transition from the first exponential increase of pulmonary virus to the second rapid decrease was seen, but then the virus increased exponentially again until the death of the mice. These results suggest that interferon plays an important role in the transition from the first phase to the second, and that T cells are required for interferon induction in mice infected with influenza virus. These data also suggest that IgA antibodies play an important role in the inhibition of virus propagation in the lungs after the disappearance of interferon. Moreover, infected T cell-deprived mice could produce only IgM neutralizing antibodies, but not IgG and IgA antibodies. Therefore, T cells are required for the production of IgG and IgA antibodies and even

Animals↗

Potentiation of the direct anticellular activity of mouse interferons: mutual synergism and interferon concentration dependence.

Mouse immune (IFN-gamma)2 and virus-type (IFN-alpha/beta) interferons were used separately and in combination in cloning studies with B-16 melanoma cells. IFN-gamma was found to be a more potent mediator of the direct anticellular effect of interferon than was IFN-alpha/beta, as shown not only by a greater sensitivity of B-16 cells to IFN-gamma but also by a steeper slope of the anticellular sensitivity curve of the IFN-gamma. The differences in the slopes of the curves defining their anticellular effect appeared to be inherent in the interferons themselves and not due to an inhibitor of interferon, a stimulator of cell growth, or another factor possessing anticellular activity. The results are consistent with the interpretation that IFN-gamma and IFN-alpha/beta exert their anticellular effects by different mechanisms. The anticellular activity of interferon against B-16 melanoma replication until development was potentiated by mixed preparations of IFN-gamma and IFN-alpha/beta. The potentiation appeared to be an expression of a property of the interferons themselves. Replication units resistant to the potentiated activity of the interferons were not detected. Potentiation levels were dependent on the concentrations of both IFN-gamma and IFN-alpha/beta and continued to increase dramatically as the interferon concentrations increased. Maximum potentiation observed was 214-fold at the highest interferon concentrations used. The data suggested that potentiation is a mutual, synergistic interaction of IFN-gamma and IFN-alpha/beta.

Animals↗

[Prevention of the anti-interferon effect of exogenous leukocyte interferon in children].

The preventive effect of exogenous leukocyte interferon used twice weekly at a 3-day interval in the period of an influenza epidemic as well as the effect of this preparation on the capacity of leukocytes to produce endogenous interferon were studied in young infants brought to nurseries. The observations covered 146 infants varying in ages from 11 months to 31/2 years, of them 104 infants were given interferon intranasally from an automizer (conditional experimental group) and 42 received no interferon (conditional) control group). During the period of interferon prophylaxis (5 weeks) a significant. 7-fold, reduction in the morbidity rate was observed in the group given interferon as compared to the control group. Observations in the time course showed a reduced incidence in the experimental group for a year. During the use of interferon in infants there was an increase in the capacity to produce endogenous interferon as manifested by a significant rise in titres by the end of interferon prophylaxis.

Aerosols↗

Effects of alpha-interferon on gamma-interferon production of peripheral blood mononuclear cells in hepatitis B virus carriers.

We studied gamma-interferon production of phytohemagglutinin-stimulated peripheral blood mononuclear cells in response to alpha-interferon in hepatitis B virus carriers and healthy individuals. The magnitude of gamma-interferon production was significantly higher in patients with anti-HBe antibody than in patients with HBe antigen and healthy individuals. Furthermore, alpha-interferon augmented the production of gamma-interferon of peripheral blood mononuclear cells from patients with active liver injury [serum alanine aminotransferase (ALT), greater than 40 U/L], but not that from patients with inactive liver injury (serum ALT, less than 40 U/L) or healthy individuals. These results suggested that alpha-interferon could enhance the cellular immune response against hepatitis B virus by augmenting the endogenous production of gamma-interferon in patients with active liver injury, implying that the responsiveness to alpha-interferon might be responsible for liver cell injury.

Adult↗

Comparison of an antiviral activity of recombinant consensus interferon with recombinant interferon-alpha-2b.

To avoid possible uncertainty in comparing biological activities of interferon samples from different sources where interferon concentrations were determined independently, we prepared chromatographically pure preparations of consensus interferon and interferon-alpha-2b (one of the two commercially available recombinant alpha interferons). We revealed that consensus interferon has a stronger antiviral activity than interferon-alpha-2b, although the effects of these two recombinant interferons on the cellular macromolecule synthesis are at similar levels.

Animals↗

The orf virus OV20.0L gene product is involved in interferon resistance and inhibits an interferon-inducible, double-stranded RNA-dependent kinase.

The parapoxvirus orf virus was resistant to type 1 (IFN-alpha) and type 2 (IFN-gamma) interferons in cultures of ovine cells. The recently identified orf virus OV20.0L gene exhibits 31% predicted amino acid identity to the vaccinia virus E3L interferon-resistance gene, and is referred to as the (putative) orf virus interferon-resistance gene (OVIFNR). The objective of this study was to determine whether OVIFNR was involved in interferon resistance. Recombinant OVIFNR as a thioredoxin fusion protein (OVIFNR-Tx) inhibited the activation (by autophosphorylation) of an interferon-inducible, double-stranded (ds) RNA-dependent kinase (PKR) of sheep, which was shown to bind dsRNA (poly I:C). PKR in other species is involved in the inhibition of protein synthesis as part of the antiviral state in infected cells. Virus-infected cell lysates, but not control lysates, from cells grown in the presence of cytosine arabinoside also contained PKR inhibitory activity, which indicated that the inhibitory activity was associated with early viral gene expression. Significantly, the OVIFNR gene expressed in interferon-treated ovine fibroblasts protected the unrelated Semliki Forest virus from the antiviral effect of both type 1 and type 2 interferons. Taken together, the results indicate that the OVIFNR gene functions as an interferon-resistance gene, the product of which inhibits PKR in a similar way to the vaccinia virus E3L gene product.

Animals↗