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

To detect latent infection with human immunodeficiency virus (HIV), specimens of peripheral blood leukocytes from HIV-seronegative hemophiliacs and from sexual partners of HIV-seropositive hemophiliacs were examined by polymerase chain reaction (PCR). The primer pair SK 38/39 derived from the gag region and/or the primer pair SK 68/69 corresponding to a conserved region of the env gene were used. Whereas HIV proviral DNA was detected by PCR in samples from 86 (97%) of 89 HIV-seropositive hemophiliacs, no HIV-DNA was found in blood samples of 198 HIV-seronegative hemophiliacs at risk. Of 40 HIV-seronegative sexual partners of HIV-infected hemophiliacs, none was PCR positive. Thus, PCR is proving to be a sensitive method by which to confirm infection in seropositive hemophiliacs, while the negative results in HIV-seronegative hemophiliacs and HIV-seronegative sexual partners of HIV-seropositive hemophiliacs suggest that a prolonged seronegative period of latent HIV infection is the exception.
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PMID:Absence of human immunodeficiency virus (HIV) proviral sequences in seronegative hemophilic men and sexual partners of HIV-seropositive hemophiliacs. 154 15

To understand the role of the HIV-1 envelope protein in the assembly of virus, we constructed a proviral clone of HIV-1 where the methionine initiator codon of the env gene was substituted with a translational stop codon. Upon DNA transfection into permissive cells in culture, this clone produces virus-like particles similar in size to parental virus but are noninfectious in human T-cells, promonocytic cells, and primary macrophages. This mutant readily recombines with a deletion mutant provirus lacking the entire gag-pol region producing a recombinant virus that is infectious. Substitution of the same initiator methionine codon with valine results in a leaky missense mutant provirus capable of a low level of Env protein synthesis that leads to a productive infection. Thus, the prototype initiation codon AUG is dispensable for virus infectivity. Further, the expression of the envelope protein is not a prerequisite for the assembly of the virus particles in the HIV-1 system. These noninfectious envelope-less particles revert readily to wild-type phenotype upon cotransfection with Env-producing plasmid DNAs.
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PMID:Biological characterization of noninfectious HIV-1 particles lacking the envelope protein. 154 56

HIV-2 infections are rare in North America, with less than 30 cases identified since 1988. We conducted a surveillance for HIV-2 seroprevalence by re-evaluating 457 HIV-1 indeterminate serology specimens submitted to the Maryland Department of Health Laboratories from January 1, 1988 to July 15, 1991. All indeterminates were screened using a combination HIV-1/HIV-2 synthetic peptide EIA. The presence of HIV-2-specific antibodies in initially reactive sera was confirmed utilizing a selective HIV-2 synthetic peptide EIA and Western blotting. Eight sera from four adult males attending public health clinics in suburban Washington, D.C. were found to be specifically reactive for HIV-2 antibodies. One is a native West African; the others remain anonymous. All eight sera demonstrated a gag (core) and pol (polymerase) only pattern of reactivity on HIV-1 Western blots. Targeting selected groups of HIV-1 indeterminate sera from patients attending public health clinics may represent a more appropriate strategy to monitor the spread of HIV-2 in North America than testing similar samples from the blood donor population.
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PMID:Identifying HIV-2-seropositive individuals by reevaluating HIV-1 indeterminate sera. 845 Apr 10

The human retroviruses human immunodeficiency virus type 1 (HIV-1) and human T-cell leukemia virus type I (HTLV-I) are characterized by complex regulation of gene expression. Each virus encodes a posttranscriptional regulator, the 19-kDa HIV-1 Rev protein and the 27-kDa HTLV-I Rex protein, which is required for viral replication. Expression of these trans activators results in the cytoplasmic accumulation of unspliced or singly spliced viral mRNA which encode the gag, pol, and env gene products. The finding that the HTLV-I Rex protein is able to functionally substitute for the Rev protein of HIV-1 indicates that HIV-1 Rev and HTLV-I Rex may interact with the same component of a cellular pathway involved in either mRNA splicing or transport. In this study, we have generated functional Rev/Rex hybrid proteins by domain exchange. We have defined, using in vivo and in vitro analyses, the activation domains of Rev and Rex which are the putative targets of a common host cell factor(s) required for Rev and Rex function.
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PMID:Definition of the human immunodeficiency virus type 1 Rev and human T-cell leukemia virus type I Rex protein activation domain by functional exchange. 154 84

In this study the humoral antibody response in visna-maedi virus disease in sheep during long-term infection was analyzed utilizing immunoblot assays, neutralization tests and complement fixation tests. In immunoblot assays antibodies to several virus specific protein bands were detected, both against the viral envelope glycoproteins and internal proteins of the virus. The immunoblot reaction pattern resembled that found in HIV-1 infection in humans, consistent with reported similar molecular weight of the major proteins of these two viruses. The immunoblot band pattern was compared with the pattern of complement fixing and neutralizing antibodies through the preclinical and clinical course in natural and experimental cases of visna-maedi. Of six immunoblot bands identified as virus specific, the antibody response against three gag products and the major env glycoprotein appeared early in infection, at a similar time as the complement fixing antibodies. The response against two proteins, one presumably the transmembrane protein and the other possibly a gag precursor, was delayed.
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PMID:Comparison of immunoblots with neutralizing and complement fixing antibodies in experimental and natural cases of visna-maedi. 155 Apr 97

The nucleocapsid protein (NC) of all animal retroviruses, encoded by the gag gene, is the major structural protein of the core ribonucleoprotein complex, bound to genomic RNA in mature virions. NC is also thought to play one or more accessory roles in reverse transcription. Mature NC (p7NC) from human immunodeficiency virus type 1 (HIV-1) is a 71-amino acid, basic protein which contains two Cys3His Zn(II) retroviral-type zinc finger domains. Herein, we describe the subcloning and expression of HIV-1 NC, denoted NC71, from an inducible phage T7 RNA polymerase promoter in Escherichia coli. Purified NC71 can be reversibly reconstituted with 2 g.at Zn(II) determined by atomic absorption. Ultraviolet circulation dichroism spectroscopy has been used to characterize the complexes between highly purified NC71 and the RNA homopolynucleotide poly(A) and E. coli tRNA(mixed). On poly(A), Zn2 NC71 is characterized by an apparent site size n = 15 +/- 3 nucleotides and high affinity (Kapp = 3 x 10(7) M-1) and moderately cooperative (omega approximately 170 +/- 25) binding. A mixture of E. coli tRNA species (tRNA(mixed) was used to probe the conformational changes induced in tRNA upon binding of HIV-1 NC71. Two structural forms of tRNA(mixed), which differ in their degree of tertiary structure, were assayed for their susceptibility to denaturation by NC71. Five molar monomer equivalents of NC71 are required to denature the "inactive" tRNA in the absence of Mg2+. A Zn(II)-free, oxidized form of NC71 was also shown to unwind inactive tRNA with the same efficiency and stoichiometry. The detailed spectral changes which occur on NC-induced denaturation closely mimic temperature-induced denaturation of inactive tRNA(mixed). The prototype helix-destabilizing protein, T4 gene 32 protein, is unable to unwind this form of tRNA under the same conditions. The stoichiometry of unwinding of inactive tRNA by NC71 is consistent with the site size determined with poly(A). An "active" form of tRNA(mixed), prepared by thermal denaturation and refolding of the inactive form with Mg2+, proved less susceptible to both temperature and NC71-induced unwinding. The mechanistic implications of these findings on the reported biochemical activities of RNA:RNA annealing and replication primer tRNA positioning by NC are discussed.
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PMID:Recombinant human immunodeficiency virus type 1 nucleocapsid (NCp7) protein unwinds tRNA. 155 77

Concordance between two primer pairs and the clinical sensitivity of a single primer pair-probe system were evaluated for a human immunodeficiency virus type 1 (HIV-1) polymerase chain reaction (PCR) assay. Six-hundred sixty-three clinically defined HIV-1 specimens were analyzed in a blind fashion for HIV-1 DNA using an optimized, well-characterized PCR assay. All samples were amplified in duplicate with each of two primer pairs targeting distinct, highly conserved regions within the HIV-1 gag genome. Amplified product was detected by oligomer hybridization using 32P-labeled probes. Correlation between PCR, culture, and serology data was achieved in 661 of 663 (99.7%) specimens. After initial analysis, discordant PCR results due to discrepancies between primer pairs were observed in 9 of 663 (1.4%) specimens. All nine specimens were resolved as negative on reevaluation. After retesting of discordant PCR results, concordance between the two primer pairs was achieved in 100% of samples. These data indicate that the two primer pair systems performed comparably and that good clinical sensitivity (100%) would be achieved using a single primer-probe system. Factors and procedures that influence the reproducibility and accuracy of this HIV-1 PCR assay are discussed.
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PMID:Detection of HIV-1 DNA by PCR: evaluation of primer pair concordance and sensitivity of a single primer pair. 156 Mar 39

Geographic variation in the HIV-1 virus is extensive but incompletely documented. We herein report the first genetic characterization of HIV-1 isolates from Zambia. The genomic region encoding the GAG polyprotein has been compared among 22 Zambian isolates and 14 North American isolates using a combination of polymerase chain reaction (PCR) and DNA sequencing methods. The Zambian isolates were similar to one another but distinct from other HIV-1 isolates. They exhibited a characteristic PCR "fingerprint" wherein certain primer combinations were unable to amplify because of mispairing. The sequence of the complete gag gene of three isolates from Zambia has been determined, and phylogenetic tree analysis placed them in a branch distinct from other African isolates and North American isolates. The PCR procedure used here may be widely applicable for genetic characterization of HIV-1.
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PMID:Genetic analysis of HIV-1 isolates from Zambia and an expanded phylogenetic tree for HIV-1. 156 Mar 40

Tat-dependent expression of an endogenous lethal or deleterious foreign gene might be useful for abrogating the production of human immunodeficiency virus (HIV) from cells. This type of HIV-induced cellular killing, as well as other approaches to gene therapy for HIV infection, would be facilitated by simple HIV vectors that express introduced genes in a Tat-inducible manner. As part of studies to examine the feasibility of this concept, we constructed HIV-1 vectors that express the hygromycin B phosphotransferase gene (Hygr) in a Tat-dependent manner. Comparison of the efficiency of propagation of each vector indicates that sequences extending into the gag open reading frame are necessary in cis for efficient vector propagation. Southern blot analysis of genomic DNA isolated from vector-infected cells demonstrated that the vectors were capable of being propagated as expected without gross rearrangements or deletions. A fragment of the influenza A virus hemagglutinin (H5 HA) gene, capable of eliciting antibody and cytotoxic T-cell responses, was used as a marker for further characterization of the vector system. A Tat-dependent vector conferring the H5 HA+ phenotype was assayed by indirect immunofluorescence, and cells which contained but did not express the H5 HA gene were isolated. The activation of H5 HA expression following HIV infection of Tat- cells that stably contained but did not express the H5 HA construct was determined to be an efficient process.
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PMID:Human immunodeficiency virus vectors for inducible expression of foreign genes. 156 May 23

We have developed a method for attenuating vaccinia virus recombinants by expressing a fusion protein of a lymphokine and an immunogen. Chimeric genes were constructed that coded for gamma interferon (IFN-gamma) and structural proteins of the human immunodeficiency virus type 1 (HIV-1). In this study, we describe the biological and immunological properties of vaccinia virus recombinants expressing chimeric genes of murine or human IFN-gamma with glycoprotein gp120, gag, and a fragment of gp41. All fusion proteins retained the antigenic characteristics of both IFN-gamma and HIV as shown by immunoblot analysis. However, the antiviral activity of IFN-gamma could be demonstrated only for the IFN-gamma-gag fusion protein. In contrast, the attenuating activity of IFN-gamma for nude mice was retained by all of the recombinants, albeit at various rates. Unlike the antiviral activity, the attenuating activity of IFN-gamma was not species specific. Implications for the development of attenuated live recombinant vaccines for AIDS are discussed.
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PMID:Vaccinia virus recombinants expressing chimeric proteins of human immunodeficiency virus and gamma interferon are attenuated for nude mice. 156 33


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