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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To analyze differential antibody responsiveness of potential pathogenetic significance, sera from 66 patients with human immunodeficiency virus-1 (HIV-1) infections at various Walter Reed (WR) stages of the disease were analyzed to determine the subclass distribution of HIV antibodies. Although all IgG subclasses were involved in the HIV antibody response, the frequency was highest for IgG1 and the lowest for IgG4. When IgG subclass responses to different HIV antigens were compared qualitatively, IgG1 was the major subclass reactive with env, pol, and gag antigens; IgG2 and IgG3 were almost equally represented in response to gag gene products; and IgG4 showed minimal reactivity to p24 antigen in all HIV-infected patients regardless of their clinical presentation. In contrast, significantly lower levels of IgG2 anti-gp41 were observed in patients at WR 5 and 6 (5%) when compared to those at stage WR 1 and 2 (88%). The IgG2 response to a recombinant gp 120/41 antigen, however, remained unchanged, suggesting that the lack of IgG2 response may be associated with lack of responsiveness to the carbohydrate epitope on gp41. Indeed, parallel measurements of IgG antibody responses to group A carbohydrate were also lower in patients at WR 5 and 6 stages, without affecting antibody responses to polyribosyl ribitol phosphate and phosphocholine. As antibody responses to group A carbohydrate with its N-acetyl D-glucosamine (GlcNAc) determinant were lower at the WR 5 and 6 stage of HIV disease, GlcNAc may be one of the antigenic determinants on gp41 that plays a critical role in some of the pathologic events of HIV infection.
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PMID:IgG subclass responses to human immunodeficiency virus-1 antigens: lack of IgG2 response to gp41 correlates with clinical manifestation of disease. 198 97

The possible existence of human immunodeficiency virus type 1 (HIV-1) infection in asymptomatic seronegative at-risk individuals was investigated in a prospective study of 55 seronegative high-risk individuals (42 homosexual men and 13 heterosexual individuals) and 32 seronegative hemophiliacs treated with factor VIII or IX concentrates before viral inactivation by heat treatment and systematic screening of blood donations. Tests used include the polymerase chain reaction assay with three primer pairs (one in the gag region and two in the pol region) and tests for serum p24 antigen, anti-nef serology (Western blot), and five biologic markers frequently altered by HIV infection (CD4 lymphocyte count, serum beta 2-microglobulin and neopterin concentration, and serum IgG and IgA concentration). Although 91 of 92 HIV-1-seropositive persons were positive in testing with at least one primer pair, no positive result was observed in seronegative at-risk individuals or in 117 seronegative low-risk controls. No nef antibody was found in seronegative at-risk individuals or seronegative controls, but 44 (47%) of 92 HIV-1-seropositive persons had nef antibodies. These findings do not support the existence of frequent HIV-1 infection in seronegative at-risk individuals.
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PMID:No evidence of frequent human immunodeficiency virus type 1 infection in seronegative at-risk individuals. 200 21

We report the complete nucleotide sequence of a human immunodeficiency virus type 2 (HIV-2) isolate from Guinea-Bissau (HIV-2CAM2). The genomic organization of HIV-2CAM2 is identical to that of other HIV-2 isolates but contains a stop codon in the pol gene. The deduced amino acid sequences of the viral proteins show variation of 20% in the gag, pol and vpx regions, and 25 to 45% in the tat, env and nef regions when compared to other isolates of HIV-2. This is greater than the variation observed between isolates of HIV-1.
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PMID:Nucleotide sequence of a Guinea-Bissau-derived human immunodeficiency virus type 2 proviral clone (HIV-2CAM2). 200 37

A cell line (H2-5) producing defective doughnut-shaped particles of human immunodeficiency virus type I (HIV-1) was found to contain proviral DNA with a large deletion of 2558 bases, corresponding to the 3' half of pol gene, the vif and vpr genes, and the 5' terminal of the tat gene.
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PMID:A defective proviral DNA with a 2.6-kb deletion of human immunodeficiency virus type 1 (HIV-1) in a persistently HIV-1 infected cell clone. 201 79

We constructed five chimeric clones between human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIVMAC) and four SIVMAC mutants by recombinant DNA techniques. Three chimeric clones and all mutants with an alteration in either the vif, vpx, vpr, or nef gene were infectious to human CD4-positive cell lines. The susceptibility of macaque monkey peripheral blood mononuclear cells (PBMC) to infection by these mutants and chimeras was examined in vitro. Macaque PBMC supported the replication of wild-type and vpx, vpr, and nef mutant SIVMAC strains. A chimera carrying the long terminal repeats (LTRs), gag, pol, vif, and vpx of SIVMAC and tat, rev, vpu, and env of HIV-1 was also replication competent in PBMC. In contrast, HIV-1, the vif mutant of SIVMAC, a chimera containing rev and env of SIVMAC, and a chimera containing vpx, vpr, tat, rev, and env of SIVMAC did not grow in PBMC. Western immunoblotting analysis of the replicating chimera in PBMC confirmed the hybrid nature of the virus. These data strongly suggested that the sequence important for macaque cell tropism lies within the LTR, gag, pol, and/or vif sequences of the SIVMAC genome.
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PMID:Generation of a chimeric human and simian immunodeficiency virus infectious to monkey peripheral blood mononuclear cells. 204 Oct 78

Mutations were introduced into the P2 and P1 positions of the junctions, (a) linking reverse transcriptase (RT) and integrase (IN) (-Leu*Phe-) and (b) between the p51 and RNase H domain (-Phe*Tyr-) within p66 of RT in the HIV-1 pol polyprotein. Processing by HIV proteinase (PR) in cis was monitored upon expression of these constructs in E. coli. Whereas the presence of Leu or Phe in P1 permitted rapid cleavage at either junction, substitution of a beta-branched (Ile) hydrophobic residue essentially abolished hydrolysis. By contrast, placement of a beta-branched (Val) residue in the P2 position flanking such -Hydrophobic*Hydrophobic- junctions resulted in effective cleavage of the scissile peptide bond. Gly in P2, however, abrogated cleavage. The significance of these findings in terms of PR specificity, polyprotein processing and the generation of homodimeric (p51/p51) RT for crystallisation purposes is discussed.
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PMID:Mutating P2 and P1 residues at cleavage junctions in the HIV-1 pol polyprotein. Effects on hydrolysis by HIV-1 proteinase. 204 56

Expression, ribosomal frameshifting, and proteolytic processing of HIV-1 GAG and POL proteins were investigated in heterologous mammalian cells in order to elucidate the influence of the cellular background on these events. DNA fragments encoded by the gag and pol region were expressed in two rodent cell lines, LTK- and BHK. Both stably transfected cell lines continuously produce recombinant proteins which react with HIV-specific antisera. The GAG precursor and a 39-kDa proteolytic fragment thereof were the major recombinant proteins detected. Expression of the gag-pol region leads to the production of the GAG-POL precursor. Ribosomal frameshifting at the HIV-1 shifty sequence to a typical extent could be positively demonstrated by an enzyme assay. Despite the presence of the viral protease within the GAG-POL precursors, proteolytic processing of the HIV-derived polyproteins was extremely inefficient. The efficiency could not be enhanced by overexpression of the HIV-1 protease encoding region.
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PMID:Expression and frameshifting but extremely inefficient proteolytic processing of the HIV-1 gag and pol gene products in stably transfected rodent cell lines. 205 81

We studied the production within the CNS of anti-HIV antibodies, of non-specific IgG, and the presence of HIV antigens in the serum and CSF of 28 HIV infected patients belonging to group IV in the Center for Disease Control classification. CSF and serum were diluted under optimal conditions to equalize their IgG content, to enable us to better interpret serum and CSF reactivity by means of Western blot and ELISA. Under these conditions, no patient displayed a limited immunological response profile in CSF as compared to serum. On the contrary, there was intrathecal synthesis (ITS) of anti HIV-antibodies in Western blot test in 21 patients for gp160 and ITS was demonstrable for env, gag, and pol products. ITS of anti-HIV antibodies occurred in 17 patients when measured by ELISA. ITS of non specific IgG and HIV-antigens in CSF were less frequent. A marked anti-HIV response is evident in the CSF-CNS compartment in the later phases of the HIV infection.
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PMID:Intrathecal synthesis of anti-HIV antibodies in AIDS patients. 208 30

Translational errors are necessary so as to allow gene expression in various organisms. In retroviruses, synthesis of pol gene products necessitates either readthrough of a stop codon or frameshifting. Here we present an experimental system that permits quantification of translational errors in vivo. It consists of a family of expression vectors carrying different mutated versions of the luc gene as reporter. Mutations include both an in-frame stop codon and 1-base-pair deletions that require readthrough or frameshift, respectively, to give rise to an active product. This system is sensitive enough to detect background errors in mammalian cells. In addition, one of the vectors contains two unique cloning sites that make it possible to insert any sequence of interest. This latter vector was used to analyse the effect of a DNA fragment, proposed to be the target of high level slippage at the gag-pol junction of HIV. The effect of paromomycin and kasugamycin, two antibiotics known to influence translational ambiguity, was also tested in cultured cells. The results indicate that paromomycin diversely affects readthrough and frameshifting, while kasugamycin had no effect. This family of vectors can be used to analyse the influence of structural and external factors on translational ambiguity in both mammalian cells and bacteria.
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PMID:Expression vectors for quantitating in vivo translational ambiguity: their potential use to analyse frameshifting at the HIV gag-pol junction. 208 98

The aim of this study was to detect HIV-1 proviral DNA in lysates of peripheral blood mononuclear cells (PBMCs) by the polymerase chain reaction (PCR) and hybridization with a nonradioactive probe. PBMCs were lysed in 1% Triton X-100. PCR was then carried out using primers complementary to a conserved region of the HIV-1 pol gene. Bracket and nested amplification protocols were used. Products were identified by dot-blot hybridization or agarose gel electrophoresis and Southern hybridization, using an alkaline phosphatase-linked oligonucleotide probe specific for amplified sequences. Colorimetric and chemiluminescent substrates were used. HIV-1 DNA was detected in PBMCs of 57/59 HIV-1-seropositive individuals, 8 of which were positive only following the use of nested primers. Of 12 seropositive samples that were negative by other HIV-1 diagnostic tests (PBMC coculture and serum p24 antigen detection), 11 were positive by PCR. PCR using PBMC lysates is a very sensitive method of detecting HIV-1 proviral sequences. The use of nested primers appears to increase the sensitivity of the procedure.
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PMID:Detection of HIV-1 DNA in crude cell lysates of peripheral blood mononuclear cells by the polymerase chain reaction and nonradioactive oligonucleotide probes. 212 Apr 19


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