scispace - formally typeset
Search or ask a question
Topic

Virus

About: Virus is a research topic. Over the lifetime, 136914 publications have been published within this topic receiving 5209107 citations. The topic is also known as: infectious agent & viruses.


Papers
More filters
Journal ArticleDOI
TL;DR: It is suggested that virus-encoded IL-4 not only suppresses primary antiviral cell-mediated immune responses but also can inhibit the expression of immune memory responses, similar to the disease seen when genetically sensitive mice are infected with the virulent Moscow strain.
Abstract: Genetic resistance to clinical mousepox (ectromelia virus) varies among inbred laboratory mice and is characterized by an effective natural killer (NK) response and the early onset of a strong CD8 1 cytotoxic T-lymphocyte (CTL) response in resistant mice. We have investigated the influence of virus-expressed mouse interleukin-4 (IL-4) on the cell-mediated response during infection. It was observed that expression of IL-4 by a thymidine kinase-positive ectromelia virus suppressed cytolytic responses of NK and CTL and the expression of gamma interferon by the latter. Genetically resistant mice infected with the IL-4-expressing virus developed symptoms of acute mousepox accompanied by high mortality, similar to the disease seen when genetically sensitive mice are infected with the virulent Moscow strain. Strikingly, infection of recently immunized genetically resistant mice with the virus expressing IL-4 also resulted in significant mortality due to fulminant mousepox. These data therefore suggest that virus-encoded IL-4 not only suppresses primary antiviral cellmediated immune responses but also can inhibit the expression of immune memory responses. Ectromelia virus (ECTV; family Poxviridae, genus Orthopoxvirus) is a natural pathogen of laboratory mice that causes a generalized disease termed mousepox (13). All mice are equally susceptible to infection by footpad inoculation; however, development of clinical mousepox among inbred mouse strains differs greatly (44). In mousepox-sensitive (e.g., BALB/c) mice, the disease is an acute systemic infection with high viral titers in the liver and spleen with resultant necrosis and high mortality. In contrast, infection of mousepox-resistant (e.g., C57BL/6) mice is usually subclinical, with lower levels of viral replication in the visceral organs and development of nonfatal lesions. Genetic resistance has been found to act through the combined activity of innate host defenses including natural killer (NK) cells, alpha interferon (IFN-a), IFN-b, IFN-g, ac

525 citations

Journal ArticleDOI
15 Nov 1991-Science
TL;DR: A mathematical model of the dynamic interaction between viral diversity and the human immune system suggests the existence of an antigen diversity threshold, below which the immune system is able to regulate viral population growth but above which the virus population induces the collapse of the CD4+ lymphocyte population.
Abstract: Longitudinal studies of patients infected with HIV-1 reveal a long and variable incubation period between infection and the development of AIDS. Data from a small number of infected patients show temporal changes in the number of genetically distinct strains of the virus throughout the incubation period, with a slow but steady rise in diversity during the progression to disease. A mathematical model of the dynamic interaction between viral diversity and the human immune system suggests the existence of an antigen diversity threshold, below which the immune system is able to regulate viral population growth but above which the virus population induces the collapse of the CD4+ lymphocyte population. The model suggests that antigenic diversity is the cause, not a consequence, of immunodeficiency disease. The model is compared with available data, and is used to assess how the timing of the application of chemotherapy or immunotherapy influences the rate of progress to disease.

524 citations

Journal ArticleDOI
TL;DR: The effect of several naturally occurring dietary flavonoids including quercetin, naringin, hesperetin, and catechin on the infectivity and replication of herpes simplex virus type 1 (HSV-1), polio-virus type 1, parainfluenza virus type 3 (Pf-3), and respiratory syncytial virus (RSV) was studied in vitro in cell culture monolayers employing the technique of viral plaque reduction as discussed by the authors.
Abstract: The effect of several naturally occurring dietary flavonoids including quercetin, naringin, hesperetin, and catechin on the infectivity and replication of herpes simplex virus type 1 (HSV-1), polio-virus type 1, parainfluenza virus type 3 (Pf-3), and respiratory syncytial virus (RSV) was studied in vitro in cell culture monolayers employing the technique of viral plaque reduction. Quercetin caused a concentration-dependent reduction in the infectivity of each virus. In addition, it reduced intracellular replication of each virus when monolayers were infected and subsequently cultured in medium containing quercetin. Preincubation of tissue culture cell monolayers with quercetin did not affect the ability of the viruses to infect or replicate in the tissue culture monolayers. Hesperetin had no effect on infectivity but it reduced intracellular replication of each of the viruses. Catechin inhibited the infectivity but not the replication of RSV and HSV-1 and had negligible effects on the other viruses. Naringin had no effect on either the infectivity or the replication of any of the viruses studied. Thus, naturally occurring flavonoids possess a variable spectrum of antiviral activity against certain RNA (RSV, Pf-3, polio) and DNA (HSV-1) viruses acting to inhibit infectivity and/or replication.

524 citations

Journal ArticleDOI
TL;DR: The pH of activation of the M2 ion channels and amantadine block of the L1 ion channels were investigated and the channels were found to be activated by pH in a similar manner but differed in their apparent Kis for amantADine block.
Abstract: The influenza A virus M2 integral membrane protein has ion channel activity which can be blocked by the antiviral drug amantadine. The M2 protein transmembrane domain is highly conserved in amino acid sequence for all the human, swine, equine, and avian strains of influenza A virus, and thus, known amino acid differences could lead to altered properties of the M2 ion channel. We have expressed in oocytes of Xenopus laevis the M2 protein of human influenza virus A/Udorn/72 and the avian virus A/chicken/Germany/34 (fowl plague virus, Rostock) and derivatives of the Rostock ion channel altered in the presumed pore region. The pH of activation of the M2 ion channels and amantadine block of the M2 ion channels were investigated. The channels were found to be activated by pH in a similar manner but differed in their apparent Kis for amantadine block.

524 citations

Journal ArticleDOI
TL;DR: It is believed that the Epstein-Barr virus may be associated with chronic illness in adults and the activity of 2-5 oligoadenylate synthetase, an interferon-induced enzyme, was increased in 5 patients studied.
Abstract: Clinical, serologic, virologic, and immunologic evaluations for 31 adults with chronic illness and fatigue suggested that 23 had persisting Epstein-Barr virus infection. Among these 23 patients, cellular immune mechanisms were generally normal, but 4 had mild immunoglobulin deficiencies. However, 20 patients had abnormal serologic profiles specific for Epstein-Barr virus shown by significantly elevated titers of antibodies to the viral capsid antigen or early antigen, or by a deficiency of late-appearing antibodies. In 11 of 15 patients tested, circulating immune complexes were found. Circulating interferon was not found in 18 patients tested, but the activity of 2-5 oligoadenylate synthetase, an interferon-induced enzyme, was increased in 5 patients studied. Of 19 patients, 18 had persisting suppressor T-cell activity typically found in patients recovering from acute infectious mononucleosis. We believe that the Epstein-Barr virus may be associated with chronic illness in adults.

524 citations


Network Information
Related Topics (5)
Viral replication
33.4K papers, 1.6M citations
94% related
Antibody
113.9K papers, 4.1M citations
89% related
Virulence
35.9K papers, 1.3M citations
89% related
Vaccination
65.1K papers, 1.7M citations
87% related
Antigen
170.2K papers, 6.9M citations
87% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20242
20234,275
20228,706
20213,455
20203,848
20193,309