HIV neurons and cytotoxic T lymphocytes. Concepts about the AIDS dementia complex and viral persistence.
Explore the source record for details and available documents.
AIDS Dementia Complex↗
SEARCH · PubMed Health
Results for “viral complexity”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Renal immune complexes in viral hepatitis.
Twenty-two patients dying of acute viral hepatitis were studied for the presence of renal immune complexes using direct immunofluorescence. A detailed light microscopic study of liver, kidney and other organs was also done and sera scanned for the presence of HBsAg. Results of light microscopy indicate that thirteen of twenty-two patients showed mild to moderate glomerular abnormalities. Immunofluorescence was positive in fifteen of twenty-two patients. IgA being positive in 28%. The incidence of HBsAg was low. It is suggested that both B and non-B type of hepatitis viruses are associated with a high incidence of renal immune complexes along with morphological alterations in the glomerulus.
Acute Disease↗
Association of polioviral proteins of the P2 genomic region with the viral replication complex and virus-induced membrane synthesis as visualized by electron microscopic immunocytochemistry and autoradiography.
Using high resolution electron microscopic autoradiography and immunocytochemistry with monoclonal antibodies against poliovirus proteins of the P2 genomic region, the location of these proteins in respect to the virus-induced vesicle formation and the viral RNA synthesis was followed during the viral replication cycle. It was found that P2 proteins become rER associated soon after their synthesis. At the site of protein and rER interaction, electron-dense patches appear. Simultaneously, membrane protrusions grow and form vesicles which finally budd off, carrying the patches on their outer surface. As shown by autoradiography, these patches are the site of viral RNA replication and, therefore, they represent the poliovirus replication complex. The vesicles with the replication complex, including replicating and replicated viral RNA, move away from the rER to form a continuously growing vesiculated area in the center of the infected cell, where virus maturation takes place. A likely function of the 2C protein is to attach the replication complex, or some of its components, to the vesicular membranes.
Antibodies, Monoclonal↗
Alphavirus positive and negative strand RNA synthesis and the role of polyproteins in formation of viral replication complexes.
The genome of alphaviruses is translated into polyproteins that are processed into a viral replicase that produces both negative and positive strands. In infected cells, negative strand synthesis is short-lived and occurs only early, whereas positive strand synthesis is stable and occurs both early and late. Analysis of temperature sensitive mutants indicated: nsP1 functioned in the initiation of transcription; nsP3 acted to form initial transcription complexes; and nsP2 and nsP4 first recognized positive strands as templates and then made negative strands the preferred templates. While nsP4 and nsP1 individually rescued early defects in transcription, nsP2 and nsP3 acted initially in cis. We interpret our results to suggest nsP1234 was cleaved to nsP4, nsP1 and nsP23, bound a positive strand and synthesized a negative strand. Cleavage of P23 or other modifications to nsP2 and nsP4 convert the initial transcription complex to a stable complex that synthesizes positive strands. Negative strand synthesis is unstable because of the failure to form initial transcription complexes after host factors that are part of the replicase are depleted or the half-life of polyprotein precursors like P23 is shortened.
Alphavirus↗
Recent progress in gene delivery using non-viral transfer complexes.
The delivery of genetic material into cells is a field that is expanding very rapidly. Non-viral delivery methods, especially ones that focus on the use of chemical agents complexed with genetic material, are the focus of this mini-review. More-recent uses of known transfection agents such as poly(ethylenimine), poly(L-lysine), and various liposomes are discussed, and some novel approaches (both chemical and methodical) are reviewed as well. A very brief look at how non-viral gene delivery research is being aimed at the clinic is also included.
Animals↗
Human immunodeficiency virus type 1 Vif protein is an integral component of an mRNP complex of viral RNA and could be involved in the viral RNA folding and packaging process.
Virion infectivity factor (Vif) is a protein encoded by human immunodeficiency virus types 1 and 2 (HIV-1 and -2) and simian immunodeficiency virus, plus other lentiviruses, and is essential for viral replication either in vivo or in culture for nonpermissive cells such as peripheral blood lymphoid cells, macrophages, and H9 T cells. Defects in the vif gene affect virion morphology and reverse transcription but not the expression of viral components. It has been shown that Vif colocalizes with Gag in cells and Vif binds to the NCp7 domain of Gag in vitro. However, it seems that Vif is not specifically packaged into virions. The molecular mechanism(s) for Vif remains unknown. In this report, we demonstrate that HIV-1 Vif is an RNA-binding protein and specifically binds to HIV-1 genomic RNA in vitro. Further, Vif binds to HIV-1 RNA in the cytoplasm of virus-producing cells to form a 40S mRNP complex. Coimmunoprecipitation and in vivo UV cross-linking assays indicated that Vif directly interact with HIV-1 RNA in the virus-producing cells. Vif-RNA binding could be displaced by Gag-RNA binding, suggesting that Vif protein in the mRNP complex may mediate viral RNA interaction with HIV-1 Gag precursors. Furthermore, we have demonstrated that these Vif mutants that lose the RNA binding activity in vitro do not support vif-deficient HIV-1 replication in H9 T cells, suggesting that the RNA binding capacity of Vif is important for its function. Further studies regarding Vif-RNA interaction in virus-producing cells will be important for studying the function of Vif in the HIV-1 life cycle.
Amino Acid Sequence↗
Influenza B virus NS2, a nuclear export protein, directly associates with the viral ribonucleoprotein complex.
In Influenza A virus and Influenza B virus, the NS2 protein (nuclear export protein) has been proposed to mediate the nucleocytoplasmic trafficking of viral ribonucleoprotein (vRNP) by forming NS2-vRNP complexes. While the binding interactions of NS2 in these complexes have been well characterized for Influenza A virus, much less is known about Influenza B virus NS2 (B/NS2). In this report, we developed a specific antiserum against B/NS2 protein and demonstrated that B/NS2 was synthesized late in infection and packaged into virions after nucleocytoplasmic transport. Fractionation of detergent-disrupted virions in several conditions showed that B/NS2 remained associated with vRNP after separation of matrix protein M1 from vRNP, whereas Influenza A virus NS2 (A/NS2) was easily separated from vRNP and remained associated with M1, in accord with previous findings that A/NS2 associates with vRNP only through its binding of encapsidated M1. The results indicated that complex formation among vRNP, M1 and NS2 of Influenza B virus was different from that of Influenza A virus, and that B/NS2 associated with vRNP in the absence and presence of M1.
Active Transport, Cell Nucleus↗
[Fluorescence-serological demonstration of complement fixation to viral antibody complexes in tissue culture].
Explore the source record for details and available documents.
Antibodies, Viral↗
Viral-antibody complexes in canine adenovirus type 1 (CAV-1)ocular lesions: leukocyte chemotaxis and enzyme release.
Canine adenovirus-type 1 (CAV-1)-antibody complexes caused severe anterior uveitis with corneal edema ("blue eye") when injected into the anterior chamber of normal dogs. The response of the anterior uvea to such immune complexes (IC) was similar to the spontaneously occurring disease. In the presence of complement (C'), IC caused release of neutrophile chemotactic factors. Following phagocytosis of IC-C' leukocytes released lysosomal enzymes, as indicated by the presence of acid phosphatase in the surrounding medium. Membrane bound viral aggregates, presumably IC, were common in neutrophiles and in macrophages that had infiltrated the anterior chamber of opaque eyes that occurred after intravenous (IV) inoculation with attenuated CAV-1. These data were incorporated into a postulated scheme for the pathogenesis of CAV-1 uveitis with corneal edema.
Acid Phosphatase↗
A novel covalent enzyme-linked immunoassay (CELIA) for simultaneously measuring free and immune complex bound antibodies with a defined specificity. II. Application to immune complexes containing viral antigens in human sera.
The coupling of viral antigens from parainfluenza virus (PIV-1), cytomegalovirus (CMV) and human immunodeficiency virus (HIV-1) to chemically functionalized polystyrene plates has permitted us to develop a covalent enzyme-linked immunoassay (CELIA) for measuring the titers of free antibody (Ab) and immune complex (IC) bound Ab directed against each of these viruses. The method was first validated for experimentally produced IC (PIV-anti-PIV) and then applied to the analysis of IC in human sera. In the case of a renal transplant patient with CMV viremia whose free Ab titers were less than 100, the method unambiguously permitted the IC bound anti-CMV titers to be determined. In the case of a survey for HIV-1 Ab, it also allowed us to identify a sub-group of seropositives with IC anti-HIV. In view of the ease and rapidity with which CELIA can be performed, this technology should enable determinations of IC bound Ab of defined specificity to be undertaken routinely in seroepidemiological surveys.
Animals↗
Herpes viral cyclin/Cdk6 complexes evade inhibition by CDK inhibitor proteins.
The passage of mammalian cells through the restriction point into the S phase of the cell cycle is regulated by the activities of Cdk4 and Cdk6 complexed with the D-type cyclins and by cyclin E/Cdk2. The activities of these holoenzymes are constrained by CDK inhibitory proteins. The importance of the restriction point is illustrated by its deregulation in many tumour cells and upon infection with DNA tumour viruses. Here we describe the properties of cyclins encoded by two herpesviruses, herpesvirus saimiri (HVS) which can transform blood lymphocytes and induce malignancies of lymphoid origin in New World primates, and human herpesvirus 8 (HHV8) implicated as a causative agent of Kaposi's sarcoma and body cavity lymphomas. Both viral cyclins form active kinase complexes with Cdk6 that are resistant to inhibition by the CDK inhibitors p16(Ink4a), p21Cip1 and p27Kip1. Furthermore, ectopic expression of a viral cyclin prevents G1 arrest imposed by each inhibitor and stimulates cell-cycle progression in quiescent fibroblasts. These results suggest a new mechanism for deregulation of the cell cycle and indicate that the viral cyclins may contribute to the oncogenic nature of these viruses.
3T3 Cells↗
Translocation portals for the substrates and products of a viral transcription complex: the bluetongue virus core.
The bluetongue virus core is a molecular machine that simultaneously and repeatedly transcribes mRNA from 10 segments of viral double-stranded RNA, packaged in a liquid crystalline array. To determine how the logistical problems of transcription within a sealed shell are solved, core crystals were soaked with various ligands and analysed by X-ray crystallography. Mg(2+) ions produce a slight expansion of the capsid around the 5-fold axes. Oligonucleotide soaks demonstrate that the 5-fold pore, opened up by this expansion, is the exit site for mRNA, whilst nucleotide soaks pinpoint a separate binding site that appears to be a selective channel for the entry and exit of substrates and by-products. Finally, nucleotides also bind to the outer core layer, providing a substrate sink.
Base Sequence↗
Open reading frame 1a-encoded subunits of the arterivirus replicase induce endoplasmic reticulum-derived double-membrane vesicles which carry the viral replication complex.
The replicase of equine arteritis virus (EAV; family Arteriviridae, order Nidovirales) is expressed in the form of two polyproteins (the open reading frame 1a [ORF1a] and ORF1ab proteins). Three viral proteases cleave these precursors into 12 nonstructural proteins, which direct both genome replication and subgenomic mRNA transcription. Immunofluorescence assays showed that most EAV replicase subunits localize to membranes in the perinuclear region of the infected cell. Using replicase-specific antibodies and cryoimmunoelectron microscopy, unusual double-membrane vesicles (DMVs) were identified as the probable site of EAV RNA synthesis. These DMVs were previously observed in cells infected with different arteriviruses but were never implicated in viral RNA synthesis. Extensive electron microscopic analysis showed that they appear to be derived from paired endoplasmic reticulum membranes and that they are most likely formed by protrusion and detachment of vesicular structures with a double membrane. Interestingly, very similar membrane rearrangements were observed upon expression of ORF1a-encoded replicase subunits nsp2 to nsp7 from an alphavirus-based expression vector. Apparently, the formation of a membrane-bound scaffold for the replication complex is a distinct step in the arterivirus life cycle, which is directed by the ORF1a protein and does not depend on other viral proteins and/or EAV-specific RNA synthesis.
Animals↗
Characterization of influenza viral transcriptional complexes.
Explore the source record for details and available documents.
Animals↗
The occurrence of circulating immune complexes and viral antigens in idiopathic thrombocytopenic purpura.
The sera of seventy-two patients with ITP were tested for their inhibitory activity on the agglutination of IgG-coated particles by RF or C1q. The majority (83%) displayed an inhibitory effect toward both agglutinators, whereas 17% were found to contain endogenous RF. A negative correlation was observed between the number of platelets and the titres of inhibitory factors. Some sera were fractionated by gel filtration. The inhibitory factors and sometimes trace amounts of IgG were distributed over several peaks eluted before monomeric 7S IgG. The IgG detected in the heavy fractions of two ITP sera corresponded to antigen-antibody complexes as shown by dissociation experiments at acid pH. In all ITP sera analysed by chromatography, DNA has been detected in the heavy fractions and appears to be the antigen of certain complexes. The sera from forty-two patients with ITP were analysed by counter-electrophoresis for the presence of viral antigens. HBs antigen was detected in twenty sera, EBV antigen in five, and adenovirus antigen in six.
Antigen-Antibody Complex↗
Immune complexes in viral hepatitis.
Explore the source record for details and available documents.
Antigen-Antibody Complex↗
Herpes simplex virus entry mediator associates in infected cells in a complex with viral proteins gD and at least gH.
We examined herpes simplex virus (HSV)-infected human HEp-2 cells or porcine cells that express herpes virus entry mediator (HVEM) for virus and receptor protein interactions. Antibody to HVEM, or its viral ligand gD, coimmunoprecipitated several similar proteins. A prominent 110-kDa protein that coprecipitated was identified as gH. The HVEM/gD/gH complex was detected with mild or stringent cell lysis conditions. It did not form in cells infected with HSV-1(KOS)Rid1 virus or with null virus lacking gD, gH, or gL. Thus, in cells a complex forms through physical associations of HVEM, gD, and at least gH.
Animals↗
Viral ribonucleoprotein complex formation and nucleolar-cytoplasmic relocalization of nucleolin in poliovirus-infected cells.
The poliovirus 3' noncoding region (3'NCR) is involved in the efficient synthesis of viral negative-stranded RNA molecules. A strong interaction between a 105-kDa host protein and the wild-type 3'NCR, but not with a replication-defective mutant 3'NCR, was detected. This 105-kDa protein was identified as nucleolin which predominantly resides in the nucleolus and has been proposed to function in the folding of rRNA precursor molecules. A functional role for nucleolin in viral genome amplification was examined in a cell-free extract which has been shown to support the assembly of infectious virus from virion RNA. At early times of viral gene expression, extracts depleted of nucleolin produced less infectious virus than extracts depleted of fibrillarin, another resident of the nucleolus, indicating a functional role of nucleolin in the early stages of the viral life cycle in this in vitro system. Immunofluorescence analysis of uninfected and infected cells showed a nucleocytoplasmic relocalization of nucleolin, but not of fibrillarin, in poliovirus-infected cells. Relocalization of nucleolin was not simply a consequence of virally induced inhibition of translation or transcription, because inhibitors of translation or transcription did not induce nucleolar-cytoplasmic relocalization of nucleolin. These findings suggest a novel virus-induced mechanism by which certain nucleolar proteins are selectively redistributed in infected cells.
Amino Acid Sequence↗