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

Human immunodeficiency virus type 1 (HIV-1) infections of humans have a natural history characterized by a variable but usually slow progression to an immunodeficient state. We have described a molecular model of HIV-1 proviral latency in certain cell lines, characterized by extremely low or undetectable levels of unspliced genomic HIV-1-specific RNA but significant levels of multiply spliced HIV-1-specific RNA. We have utilized a quantitative reverse transcriptase-initiated polymerase chain reaction to measure the levels of various HIV-1 RNA species in peripheral blood mononuclear cells. The median level of multiply spliced HIV-1 RNA was dramatically higher than the median level of unspliced viral RNA in asymptomatic individuals. In addition, HIV-1 RNA patterns characterized by at least a 10-fold excess of multiply spliced to unspliced viral RNA were significantly more common in asymptomatic individuals than in patients with the acquired immunodeficiency syndrome. We suggest that asymptomatic clinical HIV-1 infection is characterized by a preponderance of HIV-1-infected peripheral blood cells blocked at an early stage of HIV-1 infection. This viral expression pattern, which we have called blocked early-stage latency, may constitute a reservoir of latently infected cells in certain HIV-1-infected persons.
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PMID:Blocked early-stage latency in the peripheral blood cells of certain individuals infected with human immunodeficiency virus type 1. 127 88

Human immunodeficiency virus type 1 (HIV-1) prototype, HIV1 LAV, and a Zairian virus HIV1 NDK, an isolate highly cytopathic for CD4+ lymphocytes, were used to infect eleven different CD4 negative non-lymphoid human cell lines. Eight of the lines were derived from carcinomas wherein human papillomavirus was thought to have been etiologic. All these cell lines lacked CD4 receptor and CD4 specific mRNA. After cocultivation with sensitive CEM cells, HIV-1 LAV was rescued from six infected cell lines and HIV-1 NDK from nine. Shedding of free virus into the culture medium was observed in three cell lines infected by HIV-1 NDK and in only one cell line infected by HIV-1 LAV. The infectibility of CD4 negative cell lines indicates that both HIV-1 strains were able to use a CD4 independent mechanism to infect the cells; however, HIV-1 NDK showed the higher efficiency of infection. This virus was also able to overcome the intracellular block of viral reproduction. These results suggest that a broader spectrum of cell types of non-lymphoid origin lacking the CD4 receptor can serve as a viral reservoir. In some cases they are direct producers of infectious HIV-1 particles. This suggests, that in addition to immunosuppressive mechanisms, HIV-1 could play a more direct role in induction of neoplastic changes.
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PMID:HIV-1 infectivity of human carcinoma cell lines lacking CD4 receptors. 131 32

Human immunodeficiency virus type 1 (HIV-1) seropositive individuals suffer from a depletion of T4+ T cells and have elevated plasma glutamate levels. Glutamate is also elevated in cancer patients, and several authors have shown that elevated extracellular glutamate levels inhibit competitively the membrane transport of cystine and cause a decrease of intracellular cystine. We, therefore, tested the hypothesis that high glutamate and/or low cystine levels may generally be associated with low lymphocyte reactivity or low T4+ counts. In three independent studies we tested (i) serum amino acid levels (AAL) versus T4+ counts in healthy individuals, (ii) plasma AAL versus lymphocyte responses in healthy individuals, and (iii) plasma AAL versus T4+ counts in HIV-1 seropositive individuals. When the individuals in each study were divided into four subgroups as defined by median glutamate and cystine levels, the results showed that persons with a combination of low glutamate and high cystine level (LGHC subgroups) had the highest mean T4+ count or highest lymphocyte reactivity. Moreover, the LGHC subgroup in a study of lung cancer patients had a much longer mean survival time than the other three subgroups. In HIV-1 infected patients, hyperglutamataemia is associated with hypocystinaemia and hypocysteinaemia. Azidodeoxythymidine (AZT) treated HIV patients had, on average, lower glutamate levels than patients without AZT.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:T4+ cell numbers are correlated with plasma glutamate and cystine levels: association of hyperglutamataemia with immunodeficiency in diseases with different aetiologies. 134 32

Human immunodeficiency virus type 1 (HIV-1) genomic RNA variation was studied in seven presumed donor-recipient pairs directly following sexual (6/7) or parenteral (1/7) transmission. The first RNA-positive serum sample of each recipient and the serum sample of the virus transmitter, identified by epidemiological history and taken within a time bracket of three months of the recipient seroconversion, were analyzed by polymerase chain reaction amplification followed by sequencing of eight cDNA clones of 276 bp, including the V3 coding region. The sequence populations of the recipients were without exception homogeneous, while the sequence populations of the transmitters showed varying degrees of heterogeneity. Nucleotide distance between consensus sequences of unrelated individuals from the Amsterdam population (interpatient variation) averaged 11% (range 7-15%). The largest distance between two clonal sequences of one individual (intrapatient variation) was also 11%. Consensus sequences of five recipients differed by only 0-1% from the consensus sequence of the presumed transmitter, including two pairs of which the transmission was either proven or highly probable. This contrasted with a difference of 10-12% in two pairs, casting doubt on the epidemiological relatedness. Antibody reactivity to a panel of V3 peptides with varying degrees of similarity to the V3 sequences obtained did not augment the discriminatory power of sequence analysis. Results of the sequential sequencing of samples of one transmitter suggest that this was due to an anamnestic antibody response of the transmitter to early variants. From the loss of sequence heterogeneity following transmission and the consensus sequence similarities observed within five transmitter-recipient pairs, we conclude that HIV-1 transmission results in the selection of a limited number of genomes carrying on the infection in the new host, but does not generally lead to a shift in the sequence population as defined by the consensus sequence.
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PMID:HIV-1 genomic RNA diversification following sexual and parenteral virus transmission. 137 36

Human immunodeficiency virus type 1(HIV-1) induces extensive immune cell alterations which can be detected by changes both in serum levels of soluble immune activation products and in several lymphoid phenotypic markers. The current studies were conducted in 70 HIV-1 seropositive subjects to determine whether changes among four important serum immune activation markers (neopterin, beta-2 microglobulin, soluble CD8, and soluble IL-2 receptor) and seven lymphoid phenotypic markers (CD38, HLA-DR, CD57, CD11b, CD45RA, leu8, and CD71) reflect similar or disparate aspects of immune pathology. On the basis of correlation coefficient calculation, four groups of related markers (Fig. 1) were identified: Group A, sIL-2R was related to group B where serum neopterin, beta 2M, sCD8 levels, and lymphocyte CD38 antigen expression correlated closely. Loss of CD45RA or Leu 8 antigens in group C correlated with group B and D markers increase. HLA-D in group D was a more distantly related immune activation marker. Phenotypic markers CD57, CD11b, and CD71 did not correlate with the immune activation processes reflected by the serum and phenotypic marker groups A-D. Correlations between serum and certain lymphoid phenotypic markers were generally stronger later in HIV-1 infection when CD4 levels were less than 500/mm3. This study provides information for selecting markers for investigating immune changes in HIV-1 infection and immune-related diseases. Many serum and lymphoid phenotypic markers reflect related aspects of immune dysregulation. However, some markers can indicate different aspects of disease.
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PMID:Immune changes in HIV-1 infection: significant correlations and differences in serum markers and lymphoid phenotypic antigens. 137 54

Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) (EC 2.7.7.49) with a high specific activity has been purified from the overexpressing Escherichia coli strain DH5 alpha [pJS3.7]. Steady-state kinetics of DNA synthesis catalysed by RT were analysed on polyriboadenylate 20-mer of (3'-5')deoxythymidylate [poly(rA).(dT)20] and polyribouridylate 20-mer of (3'-5')-deoxyadenylate [poly(rU).(dA)20] homopolymeric template-primers. Km values of 40 and 140 nM (3'-OH ends) and kcat values of 4 and 0.14 sec-1 were determined for the two different substrates. Oligonucleotide primers (dA)20 and (dT)20 were elongated in a terminal transferase-catalysed reaction (EC 2.7.7.31) with ddATP, 3'-dATP (cordycepin), 2',3'-epoxy-ATP and arabino-ATP; and ddTTP, 3'-azido-TTP, 3'-dUTP, 3'-F-dTTP and rUTP, respectively. The resulting oligonucleotides were hybridized to their complementary templates and the inhibitory potential of these compounds towards DNA synthesis started from unchanged primers was measured. Oligonucleotides with unextendable 3'-groups were shown to act as strong inhibitors of DNA synthesis catalysed by HIV-1 RT. In particular, poly(rA).(dT)20-[ddTMP] and poly(rU).(dA)20-[3'-dAMP] were potent competitive inhibitors, displaying Ki values of about 6 and 12 nM, respectively. Also 3'-azido-, and 3'-fluoro-terminated oligonucleotides showed competitive inhibition with inhibition constants in the range of 20-35 nM. In contrast, 2',3'-epoxy-terminated (dA)21 displayed a mixed-type inhibition with a Ki value of 67 nM. Arabino-terminated (dA)21 was found to be an uncompetitive inhibitor of HIV-1 RT with an inhibition constant of 318 nM. Arabino-terminated primers did not act as strict chain terminators because they could be elongated by HIV-1 RT. This study provides information on the structure-activity relationship of modified 3'-termini of primer molecules which might be exploited as inhibitors of HIV in the future.
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PMID:Inhibition of human immunodeficiency virus type 1 reverse transcriptase by 3'-blocked oligonucleotide primers. 137 38

The relatively low fidelity of human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT) was implicated as a major factor that contributes to the genetic variability of the virus. Extension of mismatched 3' termini of the primer DNA was shown to be a major determinant of the infidelity of HIV-1 RT. Human immunodeficiency virus type 2 (HIV-2) also shows extensive genetic variations. Therefore, we have analyzed the fidelity of the DNA-dependent DNA polymerase activity of HIV-2 RT and compared it with those of RTs of HIV-1 and murine leukemia virus (MLV). Like other retroviral RTs, the HIV-2 RT was shown to lack a 3'----5' exonuclease activity. The ability of HIV-2 RT to extend preformed 3'-terminal A:A, A:C and A:G mispairs was examined by quantitating the amount and length of extended primers. The results demonstrate a relatively efficient mispair extension by HIV-2 RT with a specificity of A:C much greater than A:A greater than A:G. The mispair extension appears to be affected mainly by the increase of apparent Km values rather than by the change in Vmax values. The relative extension frequencies from all mispairs with HIV-1 and HIV-2 RTs was 6- to 9-fold greater than that of MLV RT, suggesting that the HIV enzymes are substantially more error-prone than MLV RT.
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PMID:Fidelity of the reverse transcriptase of human immunodeficiency virus type 2. 137 91

Human immunodeficiency virus type 1 (HIV-1) was isolated from five patients with late-stage disease treated with zidovudine (ZDV) for more than 1 year. Peripheral blood mononuclear cells (PBMCs) were used for all virus isolations and to assay for drug resistance. The isolates exhibited a 10- to 100-fold decrease in ZDV susceptibility compared to pretreatment isolates. Multiple clones of a 618 bp segment of the HIV reverse transcriptase gene encompassing codons 60-250 were sequenced for each isolate. The association of alterations at codons Asp67----Asn, Lys70----Arg, Thr215----Phe or Tyr, and Lys219----Gln with ZDV resistance has been previously noted (ref. 5). In this study, the most frequent alterations was Thr215----Tyr although genotypic mixtures of Thr/Tyr and Phe/Tyr were also observed. One isolate with a Tyr215 alteration and unaltered codons at 67, 70, and 219 had high-level ZDV resistance. Alterations at codons 67, 70, and 219 did not appear to increase resistance when seen in combination with Tyr215. Virus isolates obtained from each patient by cultivation with either 0 or 4 microM ZDV were compared and found to have similar alterations at codons 67, 70, 215, and 219, although one instance of apparent in vitro selection for Tyr215 over Phe215 was observed. Assays using PBMCs for virus propagation will permit susceptibility testing of HIV isolates from most patients on antiretroviral drugs to investigate the clinical significance of drug resistance.
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PMID:Characterization of HIV isolates arising after prolonged zidovudine therapy. 138 38

Human immunodeficiency virus type 1 (HIV-1) strains display a high degree of heterogeneity in their biological properties that correlate with in vivo pathogenesis of the virus. We previously demonstrated that overlapping regions encompassing the third hypervariable domain (V3), within the envelope glycoprotein gp120 determine the tropisms of HIV-1 for T-cell lines and primary macrophages. Studies with mutant viruses carrying one or more amino acid substitutions in the V3 loop have now identified this hypervariable domain as a major determinant for these cellular host range properties. Three to five amino acid changes in this domain, but rarely a single amino acid substitution, can confer macrophage tropism and alter T-cell-line tropism. These findings emphasize the effect on cell tropism of small amino acid differences in the viral envelope and suggest that the overall conformation of the V3 loop plays the major role in determining the ability of HIV-1 to infect T-cell lines and primary macrophages.
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PMID:Small amino acid changes in the V3 hypervariable region of gp120 can affect the T-cell-line and macrophage tropism of human immunodeficiency virus type 1. 140 53

Human immunodeficiency virus type 1 (HIV-1) is the causative agent of the acquired immunodeficiency syndrome (AIDS). Currently, no satisfactory treatment for this viral disease is available. Somatic gene therapy has been proposed as an alternative to conventional therapies. Several antiviral gene therapy approaches including ribozymes, antisense inhibition, and RNA-decoy strategies, as well as dominant-negative mutants of HIV-1 proteins (Gag, Tat, and Rev) have been suggested. To prove the concept of trans-dominant inhibition of HIV-1 replication, we transduced CEM cells with a retroviral vector encoding a dominant-negative rev gene. Amplification of integrase-specific proviral sequences from high molecular weight DNA indicated successful HIV-1 human T-lymphotropic virus type IIIB (HTLV-IIIB) infection of all cells. In contrast to CEM cells and CEM cells expressing the rev wild-type (wt) gene, infection of two CEM-RevM10 clones with HIV-1 did not result in the release of significant levels of p24 Gag antigen as measured by antigen capture assay, indicating a block in HIV-1 replication due to the presence of the trans-dominant Rev protein. Furthermore, the parental CEM cells as well as CEM cells expressing the Rev wt protein were effectively killed in the course of the HIV-1 infection, whereas all CEM cells expressing the RevM10 protein were unaffected in their growth rate.
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PMID:Inhibition of human immunodeficiency virus type 1 replication in human T cells by retroviral-mediated gene transfer of a dominant-negative Rev trans-activator. 140 15


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