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Berlin Brandenburg

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  • Sluis-Cremer, Nicolas  (192)
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  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 23 January 2018, Vol.115(4), pp.637-638
    Keywords: Anti-HIV Agents ; Reverse Transcriptase Inhibitors
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 2
    Language: English
    In: 2012, Vol.7(11), p.e49591
    Description: With improved access to pediatric antiretroviral therapy (ART) in resource-limited settings, more children could experience first-line ART treatment failure. ; We performed a retrospective cohort analysis using electronic medical records from HIV-infected children who initiated ART at McCord Hospital's Sinikithemba Clinic in KwaZulu-Natal, South Africa, from August 2003 to December 2010. We analyzed all records from children who began second-line ART due to first-line treatment failure. We used logistic regression to compare viral outcomes in Protease Inhibitor (PI)-based versus Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI)-based second-line ART, controlling for time on first-line ART, sex, and whether HIV genotyping guided the regimen change. ; Of the 880 children who initiated ART during this time period, 80 (9.1%) switched to second-line ART due to therapeutic failure of first-line ART after a median of 95 weeks (IQR 65–147 weeks). Eight (10%) of the failures received NNRTI-based second-line ART, all of whom failed a PI-based first-line regimen. Seventy (87.5%) received PI-based second-line ART, all of whom failed a NNRTI-based first-line regimen. Two children (2.5%) received non-standard dual therapy as second-line ART. Six months after switching ART regimens, the viral suppression rate was significantly higher in the PI group (82%) than in the NNRTI group (29%; p = 0.003). Forty-one children (51%) were tested for genotypic resistance prior to switching to second-line ART. There was no significant difference in six month viral suppression (p = 0.38) between children with and without genotype testing. ; NNRTI-based second-line ART carries a high risk of virologic failure compared to PI-based second-line ART.
    Keywords: Research Article ; Biology ; Medicine ; Virology ; Infectious Diseases ; Pediatrics And Child Health
    E-ISSN: 1932-6203
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  • 3
    Language: English
    In: The Biochemical journal, 15 October 2013, Vol.455(2), pp.179-84
    Description: EFV (efavirenz) and β-thujaplicinol [2,7-dihydroxy-4-1(methylethyl)-2,4,6-cycloheptatrien-1-one] have contrasting effects on the RNase H activity of HIV-1 RT (reverse transcriptase). EFV binds in the non-nucleoside inhibitor-binding pocket and accelerates this activity, whereas β-thujaplicinol binds in the RNase H active site and inhibits it. We have used pre-steady-state kinetic analyses to gain an insight into the mechanism by which EFV and a β-thujaplicinol analogue [19616 (2,7-dihydroxy-2,4,6-cyclo-heptatrien-1-one)] modulate RT RNase H activity. Our data show that EFV and 19616 have no effect on polymerase-dependent RNase H cleavages. However, both compounds significantly affected the rates of polymerase-independent RNase H cleavages. In regard to the latter, we found no evidence that the bound RNA/DNA template/primer substrate restricted 19616 from interacting with RT. In light of these data, we propose a model in which 19616 binds to the RNase H active site of RT after the primary polymerase-dependent RNase H cleavage has occurred and stabilizes the 3'-end of the DNA primer in the polymerase active site thus blocking the enzyme's ability to carry out the polymerase-independent cleavages. By contrast, EFV destabilizes the 3'-end of the DNA primer in the DNA polymerase active site and promotes RT-mediated polymerase-independent cleavages. Consistent with this model, we show antagonism between EFV and 19616.
    Keywords: Anti-HIV Agents -- Pharmacology ; Benzoxazines -- Pharmacology ; HIV Reverse Transcriptase -- Chemistry ; Reverse Transcriptase Inhibitors -- Pharmacology ; Ribonuclease H -- Metabolism ; Tropolone -- Analogs & Derivatives
    ISSN: 02646021
    E-ISSN: 1470-8728
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  • 4
    Language: English
    In: Antimicrobial agents and chemotherapy, July 2017, Vol.61(7)
    Description: Rilpivirine (RPV), dapivirine (DPV), and MIV-150 are in development as microbicides. It is not known whether they will block infection of circulating nonnucleoside reverse transcriptase inhibitor (NNRTI)-resistant human immunodeficiency virus type 1 (HIV-1) variants. Here, we demonstrate that the activity of DPV and MIV-150 is compromised by many resistant viruses containing single or double substitutions. High DPV genital tract concentrations from DPV ring use may block replication of resistant viruses. However, MIV-150 genital tract concentrations may be insufficient to inhibit many resistant viruses, including those harboring K103N or Y181C.
    Keywords: HIV-1 ; Miv-150 ; Nnrti ; Antiretroviral Resistance ; Dapivirine ; Prevention ; HIV Infections -- Prevention & Control ; Pyridines -- Pharmacology ; Pyrimidines -- Pharmacology ; Rilpivirine -- Pharmacology ; Urea -- Analogs & Derivatives
    ISSN: 00664804
    E-ISSN: 1098-6596
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  • 5
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 02 June 2015, Vol.112(22), pp.6979-84
    Description: Fragment-based screening methods can be used to discover novel active site or allosteric inhibitors for therapeutic intervention. Using saturation transfer difference (STD) NMR and in vitro activity assays, we have identified fragment-sized inhibitors of HIV-1 reverse transcriptase (RT) with distinct chemical scaffolds and mechanisms compared to nonnucleoside RT inhibitors (NNRTIs) and nucleoside/nucleotide RT inhibitors (NRTIs). Three compounds were found to inhibit RNA- and DNA-dependent DNA polymerase activity of HIV-1 RT in the micromolar range while retaining potency against RT variants carrying one of three major NNRTI resistance mutations: K103N, Y181C, or G190A. These compounds also inhibit Moloney murine leukemia virus RT but not the Klenow fragment of Escherichia coli DNA polymerase I. Steady-state kinetic analyses demonstrate that one of these fragments is a competitive inhibitor of HIV-1 RT with respect to deoxyribonucleoside triphosphate (dNTP) substrate, whereas a second compound is a competitive inhibitor of RT polymerase activity with respect to the DNA template/primer (T/P), and consequently also inhibits RNase H activity. The dNTP competing RT inhibitor retains activity against the NRTI-resistant mutants K65R and M184V, demonstrating a drug resistance profile distinct from the nucleotide competing RT inhibitors indolopyridone-1 (INDOPY-1) and 4-dimethylamino-6-vinylpyrimidine-1 (DAVP-1). In antiviral assays, the T/P competing compound inhibits HIV-1 replication at a step consistent with an RT inhibitor. Screening of additional structurally related compounds to the three fragments led to the discovery of molecules with improved potency against HIV-1 RT. These fragment inhibitors represent previously unidentified scaffolds for development of novel drugs for HIV-1 prevention or treatment.
    Keywords: HIV ; STD-NMR ; Allosteric Inhibitors ; Fragment-Based Drug Discovery ; Reverse Transcriptase ; Drug Discovery -- Methods ; HIV-1 -- Enzymology ; Prodrugs -- Isolation & Purification ; Reverse Transcriptase Inhibitors -- Isolation & Purification
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 6
    Language: English
    In: The Journal of biological chemistry, 24 June 2011, Vol.286(25), pp.22211-8
    Description: Deacetylation of histone proteins at the HIV type 1 (HIV-1) long terminal repeat (LTR) by histone deactylases (HDACs) can promote transcriptional repression and virus latency. As such, HDAC inhibitors (HDACI) could be used to deplete reservoirs of persistent, quiescent HIV-1 proviral infection. However, the development of HDACI to purge latent HIV-1 requires knowledge of the HDAC isoforms contributing to viral latency and the development of inhibitors specific to these isoforms. In this study, we identify the HDACs responsible for HIV-1 latency in Jurkat J89GFP cells using a chemical approach that correlates HDACI isoform specificity with their ability to reactivate latent HIV-1 expression. We demonstrate that potent inhibition or knockdown of HDAC1, an HDAC isoform reported to drive HIV-1 into latency, was not sufficient to de-repress the viral LTR. Instead, we found that inhibition of HDAC3 was necessary to activate latent HIV-1. Consistent with this finding, we identified HDAC3 at the HIV-1 LTR by chromatin immunoprecipitation. Interestingly, we show that valproic acid is a weak inhibitor of HDAC3 (IC(50) = 5.5 mm) relative to HDAC1 (IC(50) = 170 μm). Because the total therapeutic concentration of valproic acid ranges from 275 to 700 μm in adults, these data may explain why this inhibitor has no effect on the decay of latent HIV reservoirs in patients. Taken together, our study suggests an important role for HDAC3 in HIV-1 latency and, importantly, describes a chemical approach that can readily be used to identify the HDAC isoforms that contribute to HIV-1 latency in other cell types.
    Keywords: HIV-1 -- Drug Effects ; Histone Deacetylase Inhibitors -- Pharmacology ; Histone Deacetylases -- Metabolism ; Virus Activation -- Drug Effects ; Virus Latency -- Drug Effects
    E-ISSN: 1083-351X
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  • 7
    Language: English
    In: 2012, Vol.7(8), p.e42844
    Description: Isospora belli causes diarrhoea in patients with AIDS. Most respond to targeted therapy and recommendations are that secondary prophylaxis can be stopped following immune reconstitution with ART. We report eight cases of chronic isosporiasis that persisted despite standard antimicrobial therapy, secondary prophylaxis, and good immunological and virological response to ART. Median CD4 nadir was 175.5 cells/mm 3 and median highest CD4 while symptomatic was 373 cells/mm 3 . Overall 34% of stool samples and 63% of duodenal biopsy specimens were positive for oocytes. Four patients died, two remain symptomatic and two recovered. Possible explanations for persistence of symptoms include host factors such as antigen specific immune deficiency or generalised reduction in gut immunity. Parasite factors may include accumulating resistance to co-trimoxazole. Research is required to determine the optimum dose and duration of co-trimoxazole therapy and whether dual therapy may be necessary. Mortality was high and pending more data we recommend extended treatment with high-dose co-trimoxazole in similar cases.
    Keywords: Research Article ; Biology ; Medicine ; Virology ; Infectious Diseases ; Gastroenterology And Hepatology
    E-ISSN: 1932-6203
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  • 8
    Language: English
    In: Biophysical Journal, 31 January 2012, Vol.102(3), pp.484a-484a
    Keywords: Biology
    ISSN: 0006-3495
    E-ISSN: 1542-0086
    Source: ScienceDirect Journals (Elsevier)
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  • 9
    Language: English
    In: Biophysical Journal, 29 January 2013, Vol.104(2), pp.420a-421a
    Keywords: Biology
    ISSN: 0006-3495
    E-ISSN: 1542-0086
    Source: ScienceDirect Journals (Elsevier)
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  • 10
    Language: English
    In: The Biochemical journal, 15 September 2014, Vol.462(3), pp.425-32
    Description: HIV-1 resistance to zidovudine [AZT (azidothymidine)] is associated with selection of the mutations M41L, D67N, K70R, L210W, T215F/Y and K219Q/E in RT (reverse transcriptase). These mutations decrease HIV-1 susceptibility to AZT by augmenting RT's ability to excise the chain-terminating AZT-MP (AZT-monophosphate) moiety from the chain-terminated DNA primer. Although AZT-MP excision occurs at the enzyme's polymerase active site, it is mechanistically distinct from the DNA polymerase reaction. Consequently, this activity represents a novel target for drug discovery, and inhibitors that target this activity may increase the efficacy of nucleoside/nucleotide analogues, and may help to delay the onset of drug resistance. In the present study, we have developed a FRET (Förster resonance energy transfer)-based high-throughput screening assay for the AZT-MP excision activity of RT. This assay is sensitive and robust, and demonstrates a signal-to-noise ratio of 3.3 and a Z' factor of 0.69. We screened three chemical libraries (7265 compounds) using this assay, and identified APEX57219 {3,3'-[(3-carboxy-4-oxo-2,5-cyclohexadien-1-ylidene)methylene]bis[6-hydroxybenzoic acid]} as the most promising hit. APEX57219 displays a unique activity profile against wild-type and drug-resistant HIV-1 RT, and was found to inhibit virus replication at the level of reverse transcription. Mechanistic analyses revealed that APEX57219 blocked the interaction between RT and the nucleic acid substrate.
    Keywords: High-Throughput Screening Assays -- Methods ; Reverse Transcriptase Inhibitors -- Isolation & Purification ; Salicylates -- Isolation & Purification
    ISSN: 02646021
    E-ISSN: 1470-8728
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