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

Polymerase chain reaction (PCR) has been used to amplify the large fragments from viral genomic DNA of SIV from wild caught, asymptomatic Erythrocebus monkeys from Western Africa (Senegal) and also from HIV-2 infected cell lines. By using consensus primer sequences from highly conserved stretches of gag, pol and env genes, two halves of the viral genome of HIV-2 and SIV (isolated from west African Erythrocebus monkeys) have amplified by PCR. One half spans 5200 bp from within the U3 region of the 5' long terminal repeat (LTR) into pol gene and an overlapping fragment spans 3700 bp from the pol gene into U5 region of 3' LTR. Also fragments ranging from 1-2.3 kb from gag pol and env genes have been successfully amplified. Our data demonstrate that primers used to amplify large segments from viral DNA yield better results if they are derived from a consensus sequence of a highly conserved stretch of the viral genome.
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PMID:PCR amplification of large genomic fragments from human and simian immunodeficiency virus infected cell lines. 137 1

The pol I gene from HIV-1 encoding the protease, reverse transcriptase (RT) and endonuclease has been expressed in Escherichia coli. By modifying the fermentation conditions and developing a new purification scheme, the yield of purified RT has been increased substantially compared with that obtained in an earlier procedure. The expressed RT was purified to homogeneity by ammonium sulphate fractionation followed by chromatography on DEAE Sepharose, Heparin Sepharose, S Sepharose and Poly(A)-Sepharose. The purified HIV-RT is a heterodimer (p66/p51) with an isoelectric point close to 8 and with a tendency to aggregate. The proteolytic product (p51), corresponding to the N-terminal end of the RT molecule, was isolated and identified, as were also some bacterial polypeptides that co-elute with HIV-RT during the early stages of the purification. The heterodimer was crystallized in several morphological forms using the vapour-diffusion hanging drop technique. To concentrate the protein and to change the buffer for crystallization, reverse-salt-gradient chromatography and micropreparative columns were used. The best crystals diffracted to 9 A resolution. The best crystals of native RT diffracted to 9 A resolution and in complex with nucleic acids to 4.5 A resolution (using a rotating anode X-ray source).
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PMID:Purification, characterization and crystallization of recombinant HIV-1 reverse transcriptase. 137 51

In a search for synthetic peptide antigens fit to detect anti-HIV antibodies, a set of algorithms were used to predict the probable antigenic determinants of gag, pol, env and nef proteins of HIV-1 and HIV-2. Over forty peptides were synthesized by the solid-phase method. The reactivity of the peptide antigens was evaluated in ELISA on panels of HIV-1/2-positive sera. Application of the synthetic peptides for the early HIV diagnostics was examined.
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PMID:[Study of the antigenic structure of human immunodeficiency virus using synthetic peptides]. 138 9

Beside the risk of infection via HIV-1-contaminated blood, ophthalmologists are especially interested in the possibility of HIV-1 infection via tears. Therefore we tried to isolate HIV-1 from tears of 50 HIV-1-infected persons in different stages of disease by reverse transcriptase (RT) and by p24-antigen (p24-AG) in the cultures. Simultaneously we tried to isolate HIV-1 in the supernatant from peripheral blood lymphocytes (PBL), which was successful in 32 of the 50 examined specimens. HIV-1 could not be isolated from the tears of these persons. In addition, polymerasechain-reaction (PCR) was performed to detect proviral sequences (gag, pol, env) of HIV-1 in tears and blood of ten HIV-1-infected patients. While in all the examined patients gag, pol and env could be detected in the blood samples, only one tear sample was found positive for gag and pol DNA fragments. These results indicate that tears of HIV-1-positive contain extremely low quantities of tissue culture infectious doses (TCID) of HIV-1 in contrast to PBL. HIV-1 infection via tears therefore appears to be unlikely.
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PMID:Infrequent detection of HIV-1 components in tears compared to blood of HIV-1-infected persons. 138 31

Previous studies of the genetic and biologic characteristics of human immunodeficiency virus type 1 (HIV-1) have by necessity used tissue culture-derived virus. We recently reported the molecular cloning of four full-length HIV-1 genomes directly from uncultured human brain tissue (Y. Li, J. C. Kappes, J. A. Conway, R. W. Price, G. M. Shaw, and B. H. Hahn, J. Virol. 65:3973-3985, 1991). In this report, we describe the biologic properties of these four clones and the complete nucleotide sequences and genome organization of two of them. Clones HIV-1YU-2 and HIV-1YU-10 were 9,174 and 9,176 nucleotides in length, differed by 0.26% in nucleotide sequence, and except for a frameshift mutation in the pol gene in HIV-1YU-10, contained open reading frames corresponding to 5'-gag-pol-vif-vpr-tat-rev-vpu-env-nef-3' flanked by long terminal repeats. HIV-1YU-2 was fully replication competent, while HIV-1YU-10 and two other clones, HIV-1YU-21 and HIV-1YU-32, were defective. All three defective clones, however, when transfected into Cos-1 cells in any pairwise combination, yielded virions that were replication competent and transmissible by cell-free passage. The cellular host range of HIV-1YU-2 was strictly limited to primary T lymphocytes and monocyte-macrophages, a property conferred by its external envelope glycoprotein. Phylogenetic analyses of HIV-1YU-2 gene sequences revealed this virus to be a member of the North American/European HIV-1 subgroup, with specific similarity to other monocyte-tropic viruses in its V3 envelope amino acid sequence. These results indicate that HIV-1 infection of brain is characterized by the persistence of mixtures of fully competent, minimally defective, and more substantially altered viral forms and that complementation among them is readily attainable. In addition, the limited degree of genotypic heterogeneity observed among HIV-1YU and other brain-derived viruses and their preferential tropism for monocyte-macrophages suggest that viral replication within the central nervous system may differ from that within the peripheral lymphoid compartment in significant and clinically important ways. The availability of genetically and biologically well characterized HIV-1 clones from uncultured human tissue should facilitate future studies of virus-cell interactions relevant to viral pathogenesis and drug and vaccine development.
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PMID:Complete nucleotide sequence, genome organization, and biological properties of human immunodeficiency virus type 1 in vivo: evidence for limited defectiveness and complementation. 140 5

Analysis of the immunological properties of recombinant proteins of HIV-1 gene gag-pol secreted by yeast cells S. cerevisiae was carried out. The proteins under study interacted with antibodies from HIV-1-seropositive human subjects and with antibodies of rabbit immune serum to the native virus as effectively and specifically as natural HIV-1 proteins. The yeast gag-pol-protein complex was markedly immunogenic and induced in animals synthesis of antibodies of a certain specificity spectrum. A comparative immunochemical analysis of the properties of the recombinant proteins carried out by EIA and immune blot showed a certain degree of similarity between the yeast proteins and those of analogous construction produced in E. coli system.
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PMID:[The antigenic and immunogenic properties of a recombinant protein of the HIV-1 gag-pol gene secreted by Saccharomyces cerevisiae yeast cells]. 141 8

We have characterized an inhibitory RNA element in the human immunodeficiency virus type 1 (HIV-1) gag coding sequence that prevents gag expression. The inhibition exerted by this element could be overcome by the presence of the Rev-responsive element in cis and of Rev protein in trans. To understand the mechanism of function, we inactivated the inhibitory element by mutagenesis while maintaining an intact gag coding region. A constitutive high level of Rev-independent gag expression was achieved only after the introduction of 28 point mutations over a large region of 270 nucleotides within the gag coding region. To our knowledge, this is the first demonstration of inactivation of a negative RNA element within a coding region without alteration of the expressed protein. Elimination of the inhibitory element in the p17gag region, named INS-1, offered the opportunity to detect a second inhibitory element in the gag-pol region. The presence of either INS element is sufficient to inhibit gag expression, demonstrating that multiple INS elements acting independently can inhibit HIV RNA expression. Expression of gag from Rous sarcoma virus, a retrovirus that does not require Rev-like regulatory proteins, revealed that the Rous sarcoma virus p19gag region does not contain inhibitory elements. These results demonstrate the presence of a strong inhibitory element acting at the level of mRNA and provide a general method for the removal of such elements from mRNA coding regions. The inhibitory element functions in the absence of any HIV-1 proteins, suggesting that cellular factors are responsible for this inhibition.
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PMID:Mutational inactivation of an inhibitory sequence in human immunodeficiency virus type 1 results in Rev-independent gag expression. 143 10

The objective of this study was to determine the frequency and significance of nondiagnostic Western blot (WB) assays in homosexual/bisexual men at risk of infection with HIV-1. The presence of a positive enzyme-linked antibody assay (EIA) confirmed by a positive WB was used as evidence of infection and seroconversion. Indeterminate WB assays were defined as reactions to only one viral gene product of HIV-1. Three analyses were conducted to (a) determine the frequency of such reactions in men who, during a 4-year period, did not develop diagnostic serologic reactions; (b) determine, retrospectively, the preseroconversion frequency of indeterminate WB assays in 286 men who seroconverted; and (c) evaluate in vitro production of specific antibody by peripheral blood mononuclear cells (PBMCs) as a method of indicating whether or not an indeterminate WB assay represents HIV-1 infection. Reactions to products of gag, pol, or env were noted in 8.0, 4.0, and 6.7% of 1,595 first-visit tests of men who remained seronegative for 4 years. Indeterminate reactions occurred in 204 men with negative EIAs who subsequently seroconverted and in 82 men with positive EIAs preconversion. Supernatants harvested from PBMCs of 2 of 36 seroconverters obtained one or two visits preseroconversion and cultured with pokeweed mitogen were antibody-positive. All were positive at the visit, with diagnostic serology. None of the supernatants from cells of 19 men with EIA-negative WB-indeterminate serologic assays were antibody-positive. Our results suggest that persistently EIA-negative homosexual/bisexual men who have indeterminate WB assays are unlikely to be infected with HIV-1.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The significance of western blot assays indeterminate for antibody to HIV in a cohort of homosexual/bisexual men. The Multicenter AIDS Cohort Study. 145 28

Antigens in a particulate conformation were shown to be highly immunogenic in mammals. For this reason, the particle forming capacity of derivatives of the HIV-1 group specific core antigen p55 gag was assayed and compared dependent on various expression systems: recombinant bacteria, vaccinia- and baculoviruses were established encoding the entire core protein p55 either in its authentic sequence or lacking the myristylation consensus signal. Moreover, p55 gag was expressed in combination with the protease (p55-PR) or with the entire polymerase (p55-pol), respectively. Budding of 100-160 nm p55 core particles, resembling immature HIV-virions, was observed in the eucaryotic expression systems only. In comparison to the vaccinia virus driven expression of p55 in mammalian cells, considerably higher yields of particulate core antigen were obtained by infection of Spodoptera frugiperda (Sf9) insect cells with the recombinant Autographa californica nuclear polyhedrosis (AcMNPV) baculovirus. Mutation of the NH2-terminal myristylation signal sequence prevented budding of the immature core particles. Expression of the HIV p55-PR gene construct by recombinant baculovirus resulted in complete processing of the p55 gag precursor molecule in this system. The introduction of an artificial frameshift near the natural frameshift site resulted in constitutive expression of the viral protease and complete processing of p55, both in Escherichia coli and in vaccinia virus infected cells. Interestingly, significant processing of p55 resembling that of HIV infected H9 cells could also be achieved in the vaccinia system by fusing the entire pol gene to the gag gene. Moreover, processing was not found to be dependent on amino-terminal myristylation of the gag procursor molecule, which is in contrast to observations with type C and type D retrovirus. However, complete processing of p55 into p24, p17, p9 and p6 abolished particle formation. Purified immature HIV-virus like particles were highly immunogenic in rabbits, leading to a strong humoral immune response after immunization. Empty immature p55 gag particles represent a noninfectious and attractive candidate for a basic vaccine component.
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PMID:Studies on processing, particle formation, and immunogenicity of the HIV-1 gag gene product: a possible component of a HIV vaccine. 145 88

In a study population representing different CDC stages of HIV infection, 58% exhibited IgA hypergammaglobulinemia resulting from proportional increases in both the IgA1 and the IgA2 subclasses. These increases were detected early in infection, did not correlate with CD4 count, and remained elevated throughout disease progression. Absolute concentrations of polymeric IgA present within each subclass were unchanged, indicating that increased production of monomeric IgA1 and IgA2 were responsible for elevations of total IgA. These elevations were not completely attributable to a specific antibody response to viral infection, since Western blot analysis of purified IgA samples indicated that HIV-reactive IgA antibodies could be demonstrated only within the IgA1 subclass. Dominating IgA1 anti-HIV responses were also observed in two secretory IgA samples isolated from colostrum of healthy HIV seropositive mothers, suggesting that a similar isotype restriction exists in the mucosal IgA compartment. The binding of IgA1 to HIV proteins contrasted markedly to that observed with identical concentrations of IgG purified from the sera of the same patients. While IgG reacted more intensely and broadly with all HIV proteins, IgA1 antibodies were directed predominantly against envelope glycoproteins. In many patients, a total lack of IgA1 reactivity to gag and pol proteins was accompanied by intact IgG responses to these same antigens. Though all IgA samples examined reacted with HIV, fewer responses to gp160, gp120, and p24 were observed in samples from AIDS and AIDS-related complex (ARC) patients, suggesting a declining titer of IgA antibodies against these antigens may be associated with disease progression.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Serum IgA subclasses and molecular forms in HIV infection: selective increases in monomer and apparent restriction of the antibody response to IgA1 antibodies mainly directed at env glycoproteins. 145 91


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