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At least 1,279 records · Page 71Linked to original sources
PubMed1997

Multiple hepatitis virus infections in chronic HBsAg carriers in Naples.

In order to determine the prevalence of multiple infections with hepatitis viruses in chronic HBsAg carriers in Naples, to assess the interaction between HBV, HDV and HCV infections and to evaluate the influence of multiple virus hepatitis infections on the clinical presentation, we studied 198 HBsAg chronic carriers observed consecutively from 1971 to 1988 at our Liver Unit. Of the 198 HBsAg chronic carriers, 171 had undergone percutaneous liver biopsy. The presence of HBcAg or HDAg in the liver biopsy was considered a marker of HBV or HDV replication, respectively; the presence of anti-HCV was considered a marker of HCV infection. Anti-HCV was observed in 13.6% of the 22 subjects with normal liver, in 27.7% of the 47 patients with minimal chronic hepatitis, in 40% of the 50 with mild chronic hepatitis, in 70.6% of the 17 with moderate hepatitis, in 66.7% of the 3 with severe chronic hepatitis and in 65.6% of the 32 with active cirrhosis. Anti-HCV positive cases were antiHD positive more frequently than the anti-HCV negative (59.2% vs. 43%, p = 0.05). HDV infection exerted a clear inhibition on the HBV genome. Among the 171 HBsAg chronic carriers, the finding of an active chronic hepatitis (moderate chronic hepatitis + severe chronic hepatitis + active cirrhosis) is less frequent in subjects with HBV replication alone than in those with HDV replication or HCV infection. Patients with both HBV replication and HCV infection and those with both HDV replication and HCV infection showed a very high prevelance of active chronic hepatitis.

Adolescent↗
PubMed1997

The cell receptor level is reduced during persistent infection with influenza C virus.

Persistent influenza C virus infection of MDCK cells perpetuates the viral genome in a cell-associated form. Typically, virus production remains at a low level over extended periods, in the absence of lytic effects of replication. In this study, we demonstrate that persistently infected cells are very restricted in permissiveness for superinfection. By reconstitution experiments, using bovine brain gangliosides as artificial receptors, the degree of super-infection was markedly increased. Analysis of cellular receptor expression revealed reduced concentrations of sialoglycoproteins in general and a limited presentation of the major receptor gp40. Cocultures of persistently infected and uninfected cells (the latter carrying normal receptor levels) initiated a transient rise in virus titers. This kind of induction of virus synthesis appeared to be mainly receptor-linked, since a receptor-deprived subline, MDCK II, did not give rise to a similar effect. Susceptibility of MDCK II cocultures could be partly restored by ganglioside treatment. In accordance to related virus systems, these findings on influenza C virus suggest a role of cell receptor concentrations in the regulation of long-term persistence.

Animals↗
PubMed1986

Expression of extracellular and intracellular human IFN-gamma in mouse L cells transformed with the human IFN-gamma cDNA gene.

Cotransformation with a plasmid containing a thymidine kinase gene (pTK2) and a plasmid encoding human IFN-gamma (pTG11) has been used to establish murine L cell lines expressing human IFN-gamma. The HuIFN-gamma gene was present in 30% of the tk+ cell lines and some of these secreted low levels of IFN into the culture medium. Two of the clones obtained after transformation were selected for detailed analysis. Clone 1-12 constitutively secreted very low levels of HuIFN-gamma in the culture medium. This antiviral activity was characterized by its species specificity and antigenicity as authentic human IFN-gamma In contrast, clone 3-47 produced a HuIFN-gamma activity which could only be detected intracellularly. This clone was resistant to infection both by Vesicular stomatitis (VSV) and Mengo viruses and contained increased levels of enzymes known to be induced by interferon. Our results suggest that clone 3-47 produces a non-secreted HuIFN-gamma like molecule which is able to trigger an antiviral state in the murine cell independent of the interaction with a specific IFN-gamma surface receptor.

2',5'-Oligoadenylate Synthetase↗
PubMed1988

Interferon gamma is active on human lymphoblastoid Namalva cells without inducing an antiviral state.

We demonstrate the presence of high affinity receptors specific for interferon-gamma (IFN-gamma) in human lymphoblastoid Namalva cells. The presence of these receptors, whose binding affinity and cross-linking characteristics were not distinguishable from those of the corresponding receptors in sensitive cells, was not consistent with the lack of responsiveness of Namalva cells to IFN-gamma as regards growth inhibition, induction of 2'-5' oligoadenylate synthetase activity and inhibition of virus multiplication. Nevertheless, IFN-gamma enhanced the expression of two genes, HLA class II and c-myc. Although the mechanism of these IFN-gamma-mediated modifications is not understood, these results provide evidence that the IFN-gamma receptors present in Namalva cells are functional.

2',5'-Oligoadenylate Synthetase↗
PubMed1986

An acidic lymphokine distinct from interferon-gamma inhibits the replication of herpes simplex virus in human pulmonary macrophages.

Supernatants from concanavalin A-stimulated human peripheral blood mononuclear cells were fractionated by gel filtration and isoelectric focusing. A fraction with an isoelectric point of 2.2-3.3 containing macrophage migration inhibition factor activity inhibited the replication of herpes simplex virus type 1 in human pulmonary macrophages and U937 cells. This fraction did not inhibit the replication of herpes simplex virus in human fibroblasts. Moreover, the ability of this lymphokine fraction to inhibit viral growth in macrophages was not neutralized by antibody against interferon-gamma. These findings identify a macrophage specific antiviral lymphokine which is distinct biochemically and immunologically from interferon-gamma.

Cell Line↗
PubMed1987

Reversible susceptibility to natural cell-mediated cytotoxicity observed in altered BHK cells resistant to HVJ (Sendai virus) infection.

Altered baby hamster kidney (BHK-R) cells which were subcultured in the continuous presence of HVJ (hemagglutinating virus of Japan--the Sendai strain of parainfluenza 1 virus) showed a high susceptibility to natural cell-mediated cytotoxicity, although BHK-R cells are not transiently or persistently infected with HVJ but contain the restricted amount of sialic acid. By repeated subcultivation of BHK-R cells in growth medium free of HVJ, the sensitivity to natural killer cytotoxicity decreased to the level of normal BHK cells with a counter increase of cellular sialic acid, and the subsequent treatment of the cells with neuraminidase caused a loss of proper sialic acid residues, once again resulting in a significant enhancement of lysis by natural killer cells. In the BHK-R cell system which exhibits a reversible resistance to the interferon action, the enhancing effect induced by interferon on target cell susceptibility to natural killer activity became more pronounced in accord with the recovery of sensitivity to the antiviral action of interferon.

Animals↗
PubMed1991

The control of interferon-inducible gene expression.

The alpha beta interferons (IFNs) transiently induce genes through an IFN-stimulable DNA response element (ISRE). IFN-cell surface receptor interaction triggers the cytoplasmic activation of the complex primary transcription factor E, which on translocation and interaction with the ISRE initiates transcription. Whether E is activated directly through the receptor(s) or through a more classical second message pathway(s) and the roles of additional factors in the alpha beta and gamma IFN responses remain to be established. Meanwhile analysis of mutants has revealed complexity and overlap in the alpha, beta and gamma IFN response pathways and the products of at least two viruses have been shown to inhibit IFN-inducible gene expression.

Base Sequence↗
PubMed1985

Monoclonal antibodies to human immune interferon and their use in a sensitive solid-phase ELISA.

Two stable hybridoma cell lines secreting specific antibodies against human gamma interferon (HuIFN-gamma) were established. Both monoclonal antibodies (designated as MD-1 and MD-2) belong to the IgG1/kappa subclass and neutralize the antiviral activity of natural and recombinant DNA derived HuIFN-gamma (nHuIFN-gamma and rHuIFN-gamma respectively), although MD-1 is far more effective than MD-2. MD-1 and MD-2 recognize different epitopes and do not compete with each other in binding to HuIFN-gamma as concluded from competition assays. In a 'Western' blot, both antibodies reacted with the 20 kDa and 25 kDa polypeptides present in nHuIFN-gamma preparations. A sandwich enzyme immunoassay using microtiter plates coated with unlabeled MD-2 was developed. Biotinylated MD-1 was used as the second antibody. Bound MD-1 was detected by an avidin/alkaline phosphatase enzyme reaction. This immunoassay is highly specific and as sensitive as a bioassay. A radioimmunoassay using MD-2 coated on polystyrene balls and 125I-labeled MD-1 as the second antibody showed a sensitivity comparable to that of the enzyme immunoassay.

Antibodies, Monoclonal↗