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)

A novel entry mechanism has been proposed for the avian sarcoma and leukosis virus (ASLV), whereby interaction with specific cell surface receptors activates or primes the viral envelope glycoprotein (Env), rendering it sensitive to subsequent low-pH-dependent fusion triggering in acidic intracellular organelles. However, ASLV fusion seems to proceed to a lipid mixing stage at neutral pH, leading to the suggestion that low pH might instead be required for a later stage of viral entry such as uncoating (L. J. Earp, S. E. Delos, R. C. Netter, P. Bates, and J. M. White. J. Virol. 77:3058-3066, 2003). To address this possibility, hybrid virus particles were generated with the core of human immunodeficiency virus type 1 (HIV-1), a known pH-independent virus, and with subgroups A or B ASLV Env proteins. Infection of cells by these pseudotyped virions was blocked by lysosomotropic agents, as judged by inhibition of HIV-1 DNA synthesis. Furthermore, by using HIV-1 cores that contain a Vpr-beta-lactamase fusion protein (Vpr-BlaM) to monitor viral penetration into the cytosol, we demonstrated that virions bearing ASLV Env, but not HIV-1 Env, enter the cytosol in a low-pH-dependent manner. This effect was independent of the presence of the cytoplasmic tail of ASLV Env. These studies provide strong support for the model, indicating that low pH is required for ASLV Env-dependent viral penetration into the cytosol and not for viral uncoating.
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PMID:Low pH is required for avian sarcoma and leukosis virus Env-dependent viral penetration into the cytosol and not for viral uncoating. 1536 9

The Ebola filoviruses are aggressive pathogens that cause severe and often lethal hemorrhagic fever syndromes in humans and nonhuman primates. To date, no effective therapies have been identified. To analyze the entry and fusion properties of Ebola virus, we adapted a human immunodeficiency virus type 1 (HIV-1) virion-based fusion assay by substituting Ebola virus glycoprotein (GP) for the HIV-1 envelope. Fusion was detected by cleavage of the fluorogenic substrate CCF2 by beta-lactamase-Vpr incorporated into virions and released as a result of virion fusion. Entry and fusion induced by the Ebola virus GP occurred with much slower kinetics than with vesicular stomatitis virus G protein (VSV-G) and were blocked by depletion of membrane cholesterol and by inhibition of vesicular acidification with bafilomycin A1. These properties confirmed earlier studies and validated the assay for exploring other properties of Ebola virus GP-mediated entry and fusion. Entry and fusion of Ebola virus GP pseudotypes, but not VSV-G or HIV-1 Env pseudotypes, were impaired in the presence of the microtubule-disrupting agent nocodazole but were enhanced in the presence of the microtubule-stabilizing agent paclitaxel (Taxol). Agents that impaired microfilament function, including cytochalasin B, cytochalasin D, latrunculin A, and jasplakinolide, also inhibited Ebola virus GP-mediated entry and fusion. Together, these findings suggest that both microtubules and microfilaments may play a role in the effective trafficking of vesicles containing Ebola virions from the cell surface to the appropriate acidified vesicular compartment where fusion occurs. In terms of Ebola virus GP-mediated entry and fusion to various target cells, primary macrophages proved highly sensitive, while monocytes from the same donors displayed greatly reduced levels of entry and fusion. We further observed that tumor necrosis factor alpha, which is released by Ebola virus-infected monocytes/macrophages, enhanced Ebola virus GP-mediated entry and fusion to human umbilical vein endothelial cells. Thus, Ebola virus infection of one target cell may induce biological changes that facilitate infection of secondary target cells that play a key role in filovirus pathogenesis. Finally, these studies indicate that pseudotyping in the HIV-1 virion-based fusion assay may be a valuable approach to the study of entry and fusion properties mediated through the envelopes of other viral pathogens.
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PMID:Studies of ebola virus glycoprotein-mediated entry and fusion by using pseudotyped human immunodeficiency virus type 1 virions: involvement of cytoskeletal proteins and enhancement by tumor necrosis factor alpha. 1561 20

Productive entry of human immunodeficiency virus (HIV) is believed to occur by direct fusion at the plasma membrane. Endocytic uptake of HIV particles has been observed in several studies but is considered to be nonproductive, leading to virus degradation in the lysosome. We show here that endocytosis contributes significantly to productive HIV entry in HeLa cells by using trans dominant-negative mutants of dynamin and Eps15. Inducible expression of a dominant-negative mutant of dynamin in a CD4-positive HeLa cell line reduced HIV infection by 40 to 80%. This effect was independent of the infectious dose and was observed for three different isolates. Analysis of reverse transcription products by real-time PCR and of virus entry by delivery of a virion-associated Vpr-beta-lactamase fusion protein revealed a similar reduction, indicating that the block occurred at the entry stage. A strong reduction of HIV entry was also observed upon transient transfection of a different trans dominant-negative variant of dynamin, and this reduction correlated with the relative inhibition of transferrin endocytosis. Expression of a dominant-negative variant of Eps15, which is specific for clathrin-dependent endocytosis, reduced HIV entry in HeLa cells by ca 95%, confirming the role of endocytosis for productive infection. In contrast, no effect was observed for a dominant-negative variant of caveolin. We conclude that dynamin-dependent, clathrin-mediated endocytosis can lead to productive entry of HIV in HeLa cells, suggesting this pathway as an alternative route of virus entry.
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PMID:Involvement of clathrin-mediated endocytosis in human immunodeficiency virus type 1 entry. 1565 Jan 84

The dominant paradigm of protein engineering is structure-based site-directed mutagenesis. This rational approach is generally more effective for the engineering of local properties, such as substrate specificity, than global ones such as allostery. Previous workers have modified normally unregulated reporter enzymes, including beta-galactosidase, alkaline phosphatase, and beta-lactamase, so that the engineered versions are activated (up to 4-fold) by monoclonal antibodies. A reporter that could easily be "reprogrammed" for the facile detection of novel effectors (binding or modifying activities) would be useful in high throughput screens for directed evolution or drug discovery. Here we describe a straightforward and general solution to this potentially difficult design problem. The transcription factor p53 is normally regulated by a variety of post-translational modifications. The insertion of peptides into intrinsically unstructured domains of p53 generated variants that were activated up to 100-fold by novel effectors (proteases or antibodies). An engineered p53 was incorporated into an existing high throughput screen for the detection of human immunodeficiency virus protease, an arbitrarily chosen novel effector. These results suggest that the molecular recognition properties of intrinsically unstructured proteins are relatively easy to engineer and that the absence of crystal structures should not deter the rational engineering of this class of proteins.
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PMID:Rational design of p53, an intrinsically unstructured protein, for the fabrication of novel molecular sensors. 1611 6

We surveyed the rate of chlamydial and gonococcal infections among human immunodeficiency virus (HIV)-seropositive patients in Thailand as well as the current status of antimicrobial resistance of Neisseria gonorrhoeae and determined the prevalence of penicillinase-producing N. gonorrhoeae (PPNG) in Thailand. A total of 1,158 endocervical swabs from 824 HIV-seropositive patients were collected to detect both organisms by Gen-Probe. The prevalences of chlamydial and gonococcal infection were 9.7 and 1.3%, respectively. Susceptibility of 122 gonococcal isolates to 6 drugs was determined by the disk diffusion method. None of the isolates was susceptible to penicillin or tetracycline. With respect to fluoroquinolones, more than 90% of the isolates were resistant to ciprofloxacin and ofloxacin. No gonococcal isolate with resistance to cefotaxime and ceftriaxone was detected. Among the 122 isolates, 83.6% or 102 isolates were PPNG, and most (79.5%) of these 122 isolates were further identified as PPNG plus tetracycline-resistant N. gonorrhoeae, with only 4.1% being PPNG alone. All of the 102 isolates identified as PPNG contained the bla(TEM) gene. We then performed a preliminary molecular study and identified, for the first time in Thailand, a PPNG isolate producing beta-lactamase and containing the bla(TEM) gene which was identical to the beta-lactamase TEM protein of Salmonella enterica identified as TEM-135.
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PMID:Prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae in HIV-seropositive patients and gonococcal antimicrobial susceptibility: an update in Thailand. 1993 42

Telomeres, the protein-DNA complexes at the ends of linear chromosomes, are protected and regulated by the shelterin molecules, the telomerase complex, and other accessory factors, among which is Apollo, a DNA repair factor of the beta-lactamase/beta-CASP family. Impaired telomere protection in humans causes dyskeratosis congenita and Hoyeraal-Hreidarsson (HH) syndrome, characterized by premature aging, bone marrow failure, and immunodeficiency. We identified a unique Apollo splice variant (designated Apollo-Delta) in fibroblasts from a patient with HH syndrome. Apollo-Delta generates a dominant negative form of Apollo lacking the telomeric repeat-binding factor homology (TRFH)-binding motif (TBM) required for interaction with the shelterin TRF2 at telomeres. Apollo-Delta hampers the proper replication of telomeres, leading to major telomeric dysfunction and cellular senescence, but maintains its DNA interstrand cross-link repair function in the whole genome. These results identify Apollo as a crucial actor in telomere maintenance in vivo, independent of its function as a general DNA repair factor.
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PMID:Function of Apollo (SNM1B) at telomere highlighted by a splice variant identified in a patient with Hoyeraal-Hreidarsson syndrome. 2047 56

We report the emergence of a multidrug-resistant Haemophilus influenzae strain in a patient with common variable immunodeficiency suffering from recurrent bronchopneumonia caused by H. influenzae. After the patient had received several antibiotic therapies, a strain was isolated showing resistance to ampicillin, ampicillin/sulbactam, cefazolin, cefuroxime, ciprofloxacin, and clarithromycin. Polymerase chain reaction analyses and sequencing revealed the presence of the beta-lactamase gene bla(TEM-1), two mutations (A502T and R517H) in the ftsI gene encoding the transpeptidase region of the penicillin-binding protein 3, and one mutation in the ribosomal protein gene L4 (G65D) conferring resistance to beta-lactams and macrolides, respectively. Additionally, the plasmid-encoded aac(6')-Ib-cr gene mediating slightly reduced susceptibility to quinolones and two mutations in the DNA gyrase gene gyrA and one mutation in the topoisomerase IV gene parC were identified leading to a high-level fluoroquinolone-resistant phenotype. In conclusion, the treatment of H. influenzae infections accompanied by high bacterial loads such as bronchopneumonia can be complicated by the selection of multidrug-resistant strains. Moreover, the emergence of aac(6')-Ib-cr in H. influenzae causing low fluoroquinolone resistance levels might have contributed to the selection of DNA gyrase and topoisomerase IV mutants.
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PMID:Emergence of a multidrug-resistant Haemophilus influenzae strain causing chronic pneumonia in a patient with common variable immunodeficiency. 2309 85

Infections, with multidrug-resistant Pseudomonas aeruginosa, are a major concern in the pediatric intensive care unit, especially in immunocompromised patients. Some of these strains are resistant to all beta-lactams, including carbapenems, leaving very limited treatment options remaining. These options include aminoglycosides and colistin, both of which have poor pharmacokinetic profiles with significant toxicities. Newer beta-lactam/beta-lactamase inhibitor combinations offer additional novel options to treat such infections, given their good pharmacokinetic profiles and activity against multi-drug resistant strains. Ceftolozane/tazobactam is a novel cephalosporin/beta-lactamase inhibitor combination approved in 2014. The drug demonstrates good activity against multidrug-resistant P. aeruginosa strains, including those resistant to all other antibiotics. Ceftolozane/tazobactam is currently approved in adult patients 18 years and older only. There are very limited data on its pharmacokinetic profile and clinical utility in the pediatric population. We report the use of ceftolozane/tazobactam to successfully treat pneumonia caused by multidrug-resistant P. aeruginosa in a pediatric patient with combined immunodeficiency syndrome.
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PMID:Use of Ceftolozane/tazobactam for the Treatment of Multidrug-resistant Pseudomonas aeruginosa Pneumonia in a Pediatric Patient with Combined Immunodeficiency (CID): A Case Report from a Tertiary Hospital in Saudi Arabia. 3113 92


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