Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0021051 (immunodeficiency)
71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An estimated one-third to one-half of vertical transmission of human immunodeficiency virus type 1 (HIV-1) worldwide is due to breastfeeding. The exact frequency of breast milk HIV-1 transmission is unknown, but it has been estimated to be 14% in the setting of established maternal HIV-1 infection and 29% in the setting of acute maternal infection. The timing of breast milk transmission during the course of lactation also remains unknown, but two studies have found an association between duration of breastfeeding and risk of infant infection. In one such study, prolonged breastfeeding for 15 months or longer was associated with a twofold increased transmission risk. Human immunodeficiency virus type 1 DNA can be detected in over 50% of breast milk samples and is correlated with CD4 depletion and vitamin A deficiency. The presence of breast milk HIV-1 provirus is associated with increased transmission risk. Many current intervention strategies to prevent vertical transmission of HIV-1 are aimed at in utero or perinatal transmission. In developing countries in which breastfeeding by HIV-1 infected women is recommended practice, additional intervention strategies to reduce breast milk transmission warrant evaluation.
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PMID:Breastfeeding and vertical transmission of HIV-1. 924 Aug 70

Human immunodeficiency virus type 2 (HIV-2) causes AIDS, but generally after a much longer asymptomatic period than that which follows infection with HIV-1. At the molecular level, HIV-2 is much more closely related to the simian immunodeficiency viruses than to HIV-1 and our previous studies have demonstrated that HIV-2 and HIV-1 enhancer stimulation is mediated by different sets of cellular proteins following T-cell activation. Similar to HIV-1, HIV-2 encodes a transactivating protein, Tat, which appears to be necessary for viral replication and stimulates viral transcriptional initiation and/or elongation. While Tat-1 binds to the RNA of the trans-activation responsive (TAR) region of HIV-1 and HIV-2, cellular factors that bind to the RNA transcript are also necessary for Tat to function in vivo. Since almost all previous investigations of cellular cofactors for Tat had focused on HIV-1, we undertook studies aimed at understanding the interaction between the TAR RNA region of the HIV-2 promoter (TAR-2) and cellular proteins. By using extension inhibition analysis (toeprinting) and RNA electrophoretic mobility shift assays, we demonstrated binding of a nuclear factor(s) in T cells to the base of the promoter-proximal stem-loop structure. Mutational analysis of this region revealed that both the sequence of the 3' arm and the stem structure itself are important for activation of the promoter by Tat-2. In contrast, the structure is necessary for activation of TAR-2 by Tat-1 but the sequence is less important. These results suggest that a cellular factor interacts with the 3' arm of the proximal stem-loop structure of TAR-2 and mediates Tat-2-induced increases in the level of HIV-2 transcripts.
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PMID:The sequence and structure of the 3' arm of the first stem-loop of the human immunodeficiency virus type 2 trans-activation responsive region mediate Tat-2 transactivation. 931 3

Human immunodeficiency virus type 1 (HIV-1) requires both CD4 and a coreceptor to infect cells. Macrophage-tropic (M-tropic) HIV-1 strains utilize the chemokine receptor CCR5 in conjunction with CD4 to infect cells, while T-cell-tropic (T-tropic) strains generally utilize CXCR4 as a coreceptor. Some viruses can use both CCR5 and CXCR4 for virus entry (i.e., are dual-tropic), while other chemokine receptors can be used by a subset of virus strains. Due to the genetic diversity of HIV-1, HIV-2, and simian immunodeficiency virus (SIV) and the potential for chemokine receptors other than CCR5 or CXCR4 to influence viral pathogenesis, we tested a panel of 28 HIV-1, HIV-2, and SIV envelope (Env) proteins for the ability to utilize chemokine receptors, orphan receptors, and herpesvirus-encoded chemokine receptor homologs by membrane fusion and virus infection assays. While all Env proteins used either CCR5 or CXCR4 or both, several also used CCR3. Use of CCR3 was strongly dependent on its surface expression levels, with a larger number of viral Env proteins being able to utilize this coreceptor at the higher levels of surface expression. ChemR1, an orphan receptor recently shown to bind the CC chemokine I309 (and therefore renamed CCR8), was expressed in monocyte and lymphocyte cell populations and functioned as a coreceptor for diverse HIV-1, HIV-2, and SIV Env proteins. Use of ChemR1/CCR8 by SIV strains was dependent in part on V3 loop sequences. The orphan receptor V28 supported Env-mediated cell-cell fusion by four T- or dual-tropic HIV-1 and HIV-2 strains. Three additional orphan receptors failed to function for any of the 28 Env proteins tested. Likewise, five of six seven-transmembrane-domain receptors encoded by herpesviruses did not support Env-mediated membrane fusion. However, the chemokine receptor US28, encoded by cytomegalovirus, did support inefficient infection by two HIV-1 strains. These findings indicate that additional chemokine receptors can function as HIV and SIV coreceptors and that surface expression levels can strongly influence coreceptor use.
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PMID:Utilization of chemokine receptors, orphan receptors, and herpesvirus-encoded receptors by diverse human and simian immunodeficiency viruses. 937 56

Human immunodeficiency virus type 1 (HIV-1) requires the presence of specific chemokine receptors in addition to CD4 to enter target cells. The chemokine receptor CCR5 is used by the macrophage-tropic strains of HIV-1 that predominate during the asymptomatic stages of infection. Here we identify a small tyrosine-rich region of CCR5 proximal to the N-terminal cysteine that is critical for entry of macrophage-tropic and dual-tropic variants of HIV-1. HIV-1 infection of cells expressing CCR5 mutants with changes in this region was substantially reduced compared with the infection of cells bearing wild-type CCR5. Simian immunodeficiency virus (SIVmac239) entry was also ablated on a subset of these mutants but enhanced on others. These differences in virus entry were correlated with the relative ability of soluble, monomeric HIV-1 and SIVmac239 gp120 glycoproteins to bind the CCR5 mutants. These results identify a region of CCR5 that is necessary for the physical association of the gp120 envelope glycoprotein with CCR5 and for HIV-1 infection.
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PMID:A tyrosine-rich region in the N terminus of CCR5 is important for human immunodeficiency virus type 1 entry and mediates an association between gp120 and CCR5. 944 13

Human immunodeficiency virus type 1 (HIV-1) envelope vaccines can now be evaluated for efficacy in macaques by challenging with chimeric viruses in which the env, tat and rev genes of simian immunodeficiency virus (SIV) have been replaced by those of HIV-1. Most experiments have so far been conducted using gp120 molecules derived from T-cell-adapted LAI or MN strains of HIV-1, which predominantly use the CXCR-4 co-receptor. These vaccines protect against infection by apathogenic chimeric virus carrying the same envelope sequences. In the experiment described here, four macaques were vaccinated with W61D gp120 derived from a low passage Dutch isolate and capable of inhibiting the binding of MIP1beta to the co-receptor CCR-5. This vaccine was potent, inducing high titres of binding and neutralizing antibodies against the homologous HIV-1 and tenfold lower titres against a heterologous challenge virus (SHIV(SF33)) in which the env, tat and rev genes of SIV had been replaced by those of a San Francisco isolate, HIV-1(SF33). Despite strong immune responses to the vaccine there was no evidence that it protected against challenge with this chimeric virus. The antigenic divergence between vaccine and challenge virus or the increased virulence of the challenge virus may be responsible for the inability of this vaccine to protect against infection by SHIV(SF33).
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PMID:Evaluation of a candidate human immunodeficiency virus type 1 (HIV-1) vaccine in macaques: effect of vaccination with HIV-1 gp120 on subsequent challenge with heterologous simian immunodeficiency virus-HIV-1 chimeric virus. 951 19

Human immunodeficiency virus type 1 is resistant to 3'-azido-3'-deoxythymidine (AZT) when four amino acid substitutions (D67N, K70R, T215F, and K219Q) are present simultaneously in its reverse transcriptase. Wild-type and AZT-resistant reverse transcriptases show identical binding to a 3'-azido-3'-deoxythymidine 5'-monophosphate (AZTMP)-terminated primer/RNA template. On DNA templates, the equilibrium dissociation constant (KD) for primer/template and AZT-resistant reverse transcriptase (RT) (KD = 4.1 nM) is similar to that of the wild-type enzyme (KD = 6.2 nM). However, koff is 4-25-fold lower for the AZT-resistant enzyme than for the wild-type enzyme, depending on the nucleotide and the template. The kinetic decay of a wild-type RT/primer/AZTMP-terminated DNA template complex is biphasic. Seventy percent of the initial complex decays with a rate constant greater than 0.05 s-1, and 30% with a rate constant of 0.0017 s-1. Decay of an AZT-resistant RT/AZTMP-terminated primer/DNA template complex is monophasic, with a rate constant of 0.0018 s-1. The last two nucleotides at the 3' end of the AZTMP-terminated DNA primer in complex with AZT-resistant RT, but not wild-type RT, and a DNA template are protected from exonuclease digestion, suggesting that enhanced binding of the 3' end of the AZTMP-terminated DNA primer to reverse transcriptase is involved in the mechanism of AZT resistance by human immunodeficiency virus type 1.
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PMID:Enhanced binding of azidothymidine-resistant human immunodeficiency virus 1 reverse transcriptase to the 3'-azido-3'-deoxythymidine 5'-monophosphate-terminated primer. 960 76

Human immunodeficiency virus type 1 (HIV-1) enters target cells by sequential binding to CD4 and specific seven-transmembrane-segment (7TMS) coreceptors. Viruses use the chemokine receptor CCR5 as a coreceptor in the early, asymptomatic stages of HIV-1 infection but can adapt to the use of other receptors such as CXCR4 and CCR3 as the infection proceeds. Here we identify one such coreceptor, Apj, which supported the efficient entry of several primary T-cell-line tropic (T-tropic) and dualtropic HIV-1 isolates and the simian immunodeficiency virus SIVmac316. Another 7TMS protein, CCR9, supported the less efficient entry of one primary T-tropic isolate. mRNAs for both receptors were present in phytohemagglutinin- and interleukin-2-activated peripheral blood mononuclear cells. Apj and CCR9 share with other coreceptors for HIV-1 and SIV an N-terminal region rich in aromatic and acidic residues. These results highlight properties common to 7TMS proteins that can function as HIV-1 coreceptors, and they may contribute to an understanding of viral evolution in infected individuals.
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PMID:The orphan seven-transmembrane receptor apj supports the entry of primary T-cell-line-tropic and dualtropic human immunodeficiency virus type 1. 962 Oct 75

Human immunodeficiency virus type 1 Rev export depends upon the presence of the nuclear export signal (NES), a leucine-rich stretch of hydrophobic amino acids. Recently, the nuclear NES-binding receptor has been identified as CRM1 or exportin 1. Rev export has been shown to be CRM1 dependent. The function of the atypical NES-containing Rev-like proteins of equine infectious anemia virus (EIAV) and feline immunodeficiency virus (FIV) is inhibited by leptomycin B, a drug that specifically blocks NES-CRM1 interactions. These data suggest that the function of atypical NES-containing proteins is CRM1 dependent. In contrast to the inhibition of EIAV Rev and FIV Rev, the cytoplasmic accumulation of hepatitis B virus (HBV) posttranscriptional regulatory element (PRE)-containing and Mason-Pfizer monkey virus (MPMV) constitutive transport element (CTE)-containing RNAs is not inhibited by leptomycin B treatment. We conclude that the HBV PRE, like the MPMV CTE, functions independently of an NES receptor-exportin 1 interaction.
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PMID:Leptomycin B inhibits equine infectious anemia virus Rev and feline immunodeficiency virus rev function but not the function of the hepatitis B virus posttranscriptional regulatory element. 969 59

Human immunodeficiency virus type 2 (HIV-2) is known to be one of the agents that causes acquired immunodeficiency syndrome (AIDS). It has been present in West Africa since the 1960s and is currently epidemic there. Compared with human immunodeficiency virus type 1 (HIV-1), HIV-2 is genomically different. Furthermore, it is less prevalent worldwide than HIV-1. In West Africa, seropositive rates of HIV-2 are higher in urban versus rural communities, however, there are no gender differences. Sexual contact and vertical transmission are known modes of infectivity, though HIV-2 is less contagious than HIV-1.
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PMID:Infection with the human immunodeficiency virus type 2: epidemiology and transmission (Review). 985 54

Human immunodeficiency virus type 1 (HIV-1) and other retroviruses require integration of a double-stranded DNA copy of the RNA genome into the host cell chromosome for productive infection. The viral enzyme, integrase, catalyzes the integration of retroviral DNA and represents an attractive target for developing antiretroviral agents. We identified several derivatives of dicaffeoylquinic acids (DCQAs) that inhibit HIV-1 replication in tissue culture and catalytic activities of HIV-1 integrase in vitro. The specific step at which DCQAs inhibit the integration in vitro and the mechanism of inhibition were examined in the present study. Titration experiments with different concentrations of HIV-1 integrase or DNA substrate found that the effect of DCQAs was exerted on the enzyme and not the DNA. In addition to HIV-1, DCQAs also inhibited the in vitro activities of MLV integrase and truncated variants of feline immunodeficiency virus integrase, suggesting that these compounds interacted with the central core domain of integrase. The inhibition on retroviral integrases was relatively specific, and DCQAs had no effect on several other DNA-modifying enzymes and phosphoryltransferases. Kinetic analysis and dialysis experiments showed that the inhibition of integrase by DCQAs was irreversible. The inhibition did not require the presence of a divalent cation and was unaffected by preassembling integrase onto viral DNA. The results suggest that the irreversible inhibition by DCQAs on integrase is directed toward conserved amino acid residues in the central core domain during catalysis.
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PMID:Irreversible inhibition of human immunodeficiency virus type 1 integrase by dicaffeoylquinic acids. 1007 85


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