Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021311 (Infection)
 38,178 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The potential of a pseudorabies virus (PRV) nucleocapsid protein (NC)-based enzyme-linked immunosorbent assay (ELISA) as a screening assay for PRV infection in subunit-vaccinated and nonvaccinated pigs was studied. The NC-ELISA compared favorably to a commercial ELISA for detecting PRV infection in nonvaccinated pigs. Virus-specific antibody was first detected by the NC-ELISA between days 14 and 21 in 5 pigs challenged intranasally with 10(4) PFU of virus. Antibody continued to be detected in these pigs through day 42, when the experiment was terminated. The NC-ELISA also detected antibody in 23 of 24 pigs from PRV-infected herds. In contrast, the commercial ELISA detected antibody 1 week earlier than the NC-ELISA in experimentally infected pigs but failed to detect antibody in 3 naturally exposed pigs that were identified by the NC-ELISA. Infection in these animals was confirmed by radioimmunoprecipitation analysis. The potential usefulness of the NC-ELISA for detecting infection in vaccinated pigs was also evaluated. The nucleocapsid-specific antibody responses of 10 PRV envelope glycoprotein subunit-vaccinated pigs were monitored prior to and following nasal exposure to a low dose (10(2.3) PFU) of PRV. Sera were collected periodically for 113 days after infection. Nucleocapsid-specific antibody responses measured by the NC-ELISA remained below the positive threshold before challenge but increased dramatically following virus exposure. Maximum ELISA responses were obtained on day 32 postchallenge (p.c.). Mean ELISA responses decreased thereafter but remained well above the positive threshold on day 113 p.c. PRV nucleocapsid protein can be used effectively as antigen in the ELISA for detecting PRV infection in both nonvaccinated and subunit-vaccinated pigs.
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PMID:Detection of pseudorabies virus infection in subunit-vaccinated and nonvaccinated pigs using a nucleocapsid-based enzyme-linked immunosorbent assay. 131 49

Marrow stromal fibroblasts (FBs) likely play an important role in the regulation of hematopoiesis within the marrow microenvironment. Infection of these cells by feline leukemia virus (FeLV) might not only contribute to the pathogenesis of FeLV-induced hematologic diseases, but could provide a reservoir for virus in the infected cat. To determine the frequency of FeLV infection among marrow FB precursor cells (fibroblast colony-forming units, CFU-F) of cats viremic with FeLV-C/Sarma and FeLV-A/61E, marrow FBs and FB cell clones were isolated and assayed for expression of FeLV gag protein. From 30% to 86% and 64% to 88% of marrow FB precursors were infected with FeLV-C/Sarma and FeLV-A/61E, respectively. CFU-F from a cat viremic with FeLV-A/61E were not affected by exposure to antibody against FeLV envelope glycoprotein gp70 and heterologous complement, whereas similarly treated hematopoietic progenitors (erythroid colony-forming units, CFU-E; erythroid burst-forming units, BFU-E; and granulocyte-macrophage colony-forming units, CFU-GM) and culture-propagated, FeLV-infected marrow FBs were effectively lysed, suggesting that infected CFU-F within the marrow microenvironment do not express a significant amount of gp70 on their cell membranes. Thus, marrow FB precursor cells appear to be a major target for FeLV in vivo. Furthermore, the low level of gp70 antigen expression on the surface of these cells in vivo may allow them to escape immune surveillance and provide a reservoir of virus during active or latent infection.
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PMID:In vivo infection of marrow stromal fibroblasts by feline leukemia virus. 132 84

Retroviral interference is manifested in chronically infected cells as a decrease in susceptibility to superinfection by virions using the same cellular receptor. The pattern of interference reflects the cellular receptor specificity of the chronically infecting retrovirus and is mediated by the viral envelope glycoprotein, which is postulated to bind competitively all cellular receptors available for viral attachment. We established retroviral interference in mice by infecting them with Friend murine leukemia virus and them measured susceptibility to superinfection by challenging the mice with the erythroproliferative spleen focus-forming virus. Infection of approximately 10% of nucleated splenocytes rendered mice 1% as susceptible to superinfection as untreated controls. The magnitude of this effect was the same in mice incapable of producing neutralizing antibodies or genetically deficient for T cells. The results indicated that retroviral interference in vivo was established rapidly with infection of a fraction of the host cell population and that the decrease in susceptibility to superinfection occurred without a detectable contribution by immunologic factors.
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PMID:Interference established in mice by infection with Friend murine leukemia virus. 150 2

Until recently, much of the effort put into development of an AIDS vaccine has focussed on the elicitation of a neutralizing antibody response. The viral target of neutralization, HIV envelope glycoprotein, has been produced in bulk through recombinant techniques, but has had little success as a vaccine. The specific epitopes to which neutralizing antibodies bind have been mapped, and although the major epitope is hypervariable, others are conserved. This allows the design of second generation vaccines. Meanwhile, vaccine studies in the SIV animal model simply using inactivated virus as immunogen have demonstrated that an effective vaccine is at least possible. A variety of HIV vaccine preparations are now under investigation and the outlook for the future is promising.
Infection 1991
PMID:Neutralizing antibodies and antigens in AIDS. 170 55

CD4 is an integral cell surface glycoprotein that is able to enhance T cell specific antigen responses when it interacts with its physiological ligand, class II major histocompatibility (MHC) molecules. In addition, CD4 is a specific cell-surface receptor for the human immunodeficiency virus-1 (HIV-1). Infection by HIV-1 is initiated by the binding of the envelope glycoprotein, gp120, to the first domain of CD4. The binding of CD4 to class II MHC is inhibited by gp120, one possible mechanism for immunosuppression in AIDS patients. In addition, the CD4/gp120 interaction may directly inhibit T cell function. Recently we have synthesized small molecules (CPFs) that specifically inhibit this interaction. CPFs bind to gp120 and prevent the binding of gp120 to CD4, and also inhibit the infectivity of HIV-1.
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PMID:The interaction of CD4 with HIV-1 gp120. 188 98

Infection by the human immunodeficiency virus (HIV) leads to progressive destruction of the CD4+ subset of T lymphocytes, resulting in immunodeficiency and AIDS. The selectivity of CD4+ cell destruction is due to the specific binding of gp120, the external envelope glycoprotein of HIV, to CD4, initiating viral entry. Binding of gp120 to CD4 on the cell surface may also lead to CD4+ cell depletion by inappropriate immune targeting, and may interfere with CD4+ cell function and ontogeny by disrupting CD4-mediated cell signaling. The CD4-gp120 interaction is thus an obvious target for AIDS therapeutics.
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PMID:The CD4-gp120 interaction and AIDS pathogenesis. 191 Jun 91

Infection with the human immunodeficiency virus (HIV-1) often produces a set of neuropsychiatric dysfunctions which have been termed the AIDS dementia complex. This complex appears due to the infection of brain cells by HIV-1. If so, brain cells might be expected to contain a binding site for the same viral envelope glycoprotein that enables HIV-1 to bind to other cells (e.g. CD4+ T-cells), gp120. The present study shows that the cells of the brain-derived U-138MG, U-373MG, SK-N-MC and SK-N-SH cell lines bind gp120 in an inhibitable fashion. Binding of gp120 to these cells is inhibited by the dyes Aurintricarboxylic acid (ATA) and Evans blue (EB), which are known to inhibit specific gp120 and HIV-1 binding, and block HIV-1 infection, in CD4-expressing cells. Binding is not inhibited by Aurin, a dye related to ATA but lacking its anti-HIV effects. As expected, anti-CD4 antibodies are ineffective in blocking gp120 binding to brain-derived cells. These results suggest that human brain-derived cells possess a specific binding site for gp120 that is not the CD4 antigen.
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PMID:Brain-derived cells contain a specific binding site for Gp120 which is not the CD4 antigen. 193 87

Infection of T-lymphocytes and macrophages by human immunodeficiency virus (HIV) is mediated by the binding of the HIV envelope glycoprotein to the cell-surface receptor glycoprotein CD4. A soluble, recombinant CD4 molecule (rCD4), produced by expression of a truncated CD4 gene in Chinese hamster ovary (CHO) cells [Smith et al. (1987) Science 238, 1704-1707], is in clinical trials as a potential therapeutic agent in the treatment of acquired immunodeficiency syndrome (AIDS). In the present study, the structures of the Asn-linked oligosaccharides of soluble rCD4 have been elucidated. The rCD4 molecule has two potential sites for N-glycosylation, Asn-271 and Asn-300. Tryptic glycopeptides containing either of the sites were purified by reversed-phase HPLC, and their oligosaccharides were released enzymatically. The structures of the oligosaccharides were determined by methylation analysis, high-pH anion-exchange chromatography, fast-atom bombardment mass spectrometry, and 1H NMR spectroscopy at 500 MHz. Asn-271 was found to carry diantennary N-acetyllactosamine-type ("complex") oligosaccharides, of which 8% were asialo, 55% were monosialyl, and 37% were disialyl. Approximately 18% of these structures contained fucose alpha(1-->6) linked to the reducing GlcNAc residue. Two different hybrid structures were found to account for 34% of the oligosaccharides attached to Asn-300. The remainder of the oligosaccharides attached to Asn-300 were diantennary N-acetyllactosamine-type, of which 10% were asialo, 61% were monosialyl, and 29% were disialyl. Approximately 9% of the hybrid structures and 40% of the N-acetyllactosamine structures at Asn-300 were found to contain fucose alpha(1-->6) linked to the innermost GlcNAc residue.
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PMID:Carbohydrate structures of recombinant soluble human CD4 expressed in Chinese hamster ovary cells. 200 69

Infection by the human immunodeficiency virus type 1 (HIV-1) is initiated through interaction of its exterior envelope glycoprotein gp120 with the CD4 receptor on target cells. To address the possible role of N-glycosylation of HIV-1 gp120 in binding CD4, we mutated different conserved N-glycosylation site Asn-residues in the vicinity of the putative CD4 binding site, as single mutations or in combinations. Authentic and mutant gp120 proteins were produced using the baculovirus expression system. All mutant proteins were produced and secreted at similar levels and could be immunoprecipitated with an HIV(+)-serum. Furthermore, all glycosylation mutants retained the full capacity to bind CD4 except for a triple mutant which showed reduced binding. Different gp120 mutant genes were then introduced in an infectious proviral DNA clone. Upon transfection of MT-2 cells, the authentic HIV-1 clone induced maximal virus production after 6 days. In the case of the triple glycosylation mutant, comparable virus production was first reached after a delay of about 12 days. Moreover, in contrast to native HIV, the mutant virus induced no typical multinucleated giant cells. These results suggest that the attached carbohydrates around the CD4-binding site of gp120, may contribute to the generation of this protein domain required for high affinity receptor interaction.
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PMID:Mutation of conserved N-glycosylation sites around the CD4-binding site of human immunodeficiency virus type 1 GP120 affects viral infectivity. 208 20

Infection of mononuclear cells by human immunodeficiency virus (HIV) begins with binding of the viral envelope glycoprotein, gp120, to its receptor, CD4. CD4 contains four extracellular immunoglobulin-like domains, the first of which (V1) is sufficient for HIV binding. V1 contains three sequences homologous to the antigen-complementarity-determining regions (CDR1 to -3) of immunoglobulin variable domains. While all three immunoglobulin CDRs are involved in antigen binding, only amino acids within and flanking the CDR2-like region of CD4 have been shown previously to be involved in gp120 binding. To investigate whether other regions in V1 take part in gp120 binding, we substituted alanine for each of 64 amino acids, including all of the hydrophilic residues in this domain. Mutations at four locations outside the CDR2-like sequence (amino acids 29, 59-64, 77-81, and 85) markedly affected gp120 binding, but not the overall structure of V1 as probed with eight conformationally sensitive monoclonal antibodies. Thus, the gp120-binding site of CD4 is not limited to the CDR2-like sequence and consists of several discontinuous segments. Several amino acids were identified that are critical for the conformation of V1; the importance of these residues suggests some differences in the folding of this domain compared to immunoglobulin variable domains. Three amino acid substitutions were found that increase the affinity for gp120 significantly (1.7- to 2-fold individually and 4.2-fold when combined), suggesting that it may be possible to improve the HIV-blocking ability of CD4-based molecules by increasing their gp120 binding affinity.
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PMID:Mapping the CD4 binding site for human immunodeficiency virus by alanine-scanning mutagenesis. 240 98


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