The Experts below are selected from a list of 126 Experts worldwide ranked by ideXlab platform
Elsa B. Damonte - One of the best experts on this subject based on the ideXlab platform.
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changes in antiviral susceptibility to entry inhibitors and endocytic uptake of dengue 2 Virus serially passaged in vero or c6 36 cells
Virus Research, 2014Co-Authors: Eliana G. Acosta, Elsa B. Damonte, Luana Érica Piccini, Laura B. Talarico, Viviana CastillaAbstract:The aim of the present study was to analyze the influence of Virus origin, mammalian or mosquito cell-derived, on antiviral susceptibility of DENV-2 to entry inhibitors and the association of this effect with any alteration in the mode of entry into the cell. To this end, ten serial passages of DENV-2 were performed in mosquito C6/36 cells or monkey Vero cells and the antiviral susceptibility of each Virus passage to sulfated polysaccharides (SPs), like heparin and carrageenans, was evaluated by a Virus Plaque reduction assay. After serial passaging in Vero cells, DENV-2 became increasingly resistant to SP inhibition whereas the antiviral susceptibility was not altered in Virus propagated in C6/36 cells. The change in antiviral susceptibility was associated to a differential mode of entry into the host cell. The route of endocytic entry for productive Vero cell infection was altered from a non-classical clathrin independent pathway for C6/36-grown Virus to a clathrin-mediated endocytosis when the Virus was serially propagated in Vero cells. Our results show the impact of the cellular system used for successive propagation of DENV on the initial interaction between the host cell and the virion in the next round of infection and the relevant consequences it might have during the in vitro evaluation of entry inhibitors.
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inhibition of junin Virus replication by small interfering rnas
Antiviral Research, 2009Co-Authors: Maria Carolina Artuso, Elsa B. Damonte, Paula Clarisa Ellenberg, Luis Alberto Scolaro, Cybele C GarciaAbstract:Junin Virus (JUNV), the etiological agent of the Argentine hemorrhagic fever, has a single-stranded RNA genome with ambisense expression which encodes for five proteins. In previous works we have demonstrated that the Z arenaVirus matrix protein represents an attractive target for antiviral therapy. With the aim of studying a new alternative therapeutic mechanism, four Z-specific siRNAs (Z1- to Z4-siRNAs) were tested showing variable efficacy. The most effective inhibitor was Z2-siRNA targeted at the region encompassed by nt 179-197 of Z gene. The efficacy of this Z2-siRNA against JUNV was also demonstrated in Virus-infected cells, by testing infectious Virus Plaque formation (92.8% JUNV yield reduction), viral RNA level or antigen expression, as well as in cells transfected with Z-specific reporter plasmids (91% reduction in expression of Z-EGFP fusion protein). Furthermore, the lack of effect of this Z-siRNA on the expression of other JUNV proteins, such as N and GPC, confirmed the specificity of action exerted by Z2-siRNA on Z transcript. Thus, the present study represents the first report of Virus inhibition mediated by RNA interference for a New World arenaVirus.
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anti herpes simplex Virus activity of sulfated galactans from the red seaweeds gymnogongrus griffithsiae and cryptonemia crenulata
International Journal of Biological Macromolecules, 2004Co-Authors: Laura B. Talarico, Carlos A Pujol, Rosiane G.m. Zibetti, Miguel D. Noseda, Maria Eugênia R. Duarte, Paula C S Faria, Luis A Scolaro, Elsa B. DamonteAbstract:This study presents the chemical composition and antiviral activity against herpes simplex Virus type 1 (HSV-1) and 2 (HSV-2) of sulfated galactan crude extracts and main fractions obtained from two red seaweeds collected in Brazil, Gymnogongrus griffithsiae and Cryptonemia crenulata. Most of the eighteen tested products, including homogeneous kappa/iota/nu carrageenan and DL-galactan hybrid, exhibited antiherpetic activity with inhibitory concentration 50% (IC50) values in the range 0.5-5.6 microg/ml, as determined in a Virus Plaque reduction assay in Vero cells. The galactans lacked cytotoxic effects and showed a broad spectrum of antiviral activity against HSV-1 and HSV-2. No direct Virus inactivation was observed after virion treatment with the galactans. The mode of action of these compounds could be mainly ascribed to an inhibitory effect on Virus adsorption. Most importantly, a significant protection against a murine vaginal infection with HSV-2 was afforded by topical treatment with the sulfated galactans.
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novel dl galactan hybrids from the red seaweed gymnogongrus torulosus are potent inhibitors of herpes simplex Virus and dengue Virus
Antiviral Chemistry & Chemotherapy, 2002Co-Authors: Carlos A Pujol, Marina Ciancia, José M. Estevez, Alberto S. Cerezo, Maria Josefina Carlucci, Elsa B. DamonteAbstract:A novel series of DL-galactan hybrids extracted from the red seaweed Gymnogongrus torulosus, was evaluated for its in vitro antiviral properties against herpes simplex Virus type 2 (HSV-2) and dengue Virus 2 (DEN-2). These compounds were very active against both Viruses with inhibitory concentration 50% (IC50) values in the range 0.6–16 μg/ml for HSV-2 and 0.19–1.7 μg/ml for DEN-2, respectively, as determined in a Virus Plaque reduction assay in Vero cells. The DL-galactans lacked of cytotoxic effects, on stationary as well as on actively dividing cells, and anticoagulant properties. Some of the compounds showed a variable level of direct inactivating effect on both virions, with virucidal concentration 50% values exceeding the IC50s obtained by Plaque reduction assay. Full inhibitory activity was achieved when the galactans were present during Virus adsorption period, suggesting that the mode of action of these compounds is an interference in the binding of the surface envelope glycoprotein with the cell...
Isabel Rodriguezbarraquer - One of the best experts on this subject based on the ideXlab platform.
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viridot an automated Virus Plaque immunofocus counter for the measurement of serological neutralizing responses with application to dengue Virus
PLOS Neglected Tropical Diseases, 2018Co-Authors: Isabel Rodriguezbarraquer, Leah C Katzelnick, Ana Coello Escoto, Benjamin D Mcelvany, Christian Chavez, Henrik Salje, Wensheng LuoAbstract:The gold-standard method for quantifying neutralizing antibody responses to many Viruses, including dengue Virus (DENV), is the Plaque reduction neutralization test (PRNT, also called the immunofocus reduction neutralization test). The PRNT conducted on 96-well plates is high-throughput and requires a smaller volume of antiserum than on 6- or 24-well plates, but manual Plaque counting is challenging and existing automated Plaque counters are expensive or difficult to optimize. We have developed Viridot (Viridot package), a program for R with a user interface in shiny, that counts viral Plaques of a variety of phenotypes, estimates neutralizing antibody titers, and performs other calculations of use to virologists. The Viridot Plaque counter includes an automatic parameter identification mode (misses <10 Plaques/well for 87% of diverse DENV strains [n = 1521]) and a mode that allows the user to fine-tune the parameters used for counting Plaques. We compared standardized manual and Viridot Plaque counting methods applied to the same wells by two analyses and found that Viridot Plaque counts were as similar to the same analyst's manual count (Lin’s concordance correlation coefficient, ρc = 0.99 [95% confidence interval: 0.99–1.00]) as manual counts between analysts (ρc = 0.99 [95% CI: 0.98–0.99]). The average ratio of neutralizing antibody titers based on manual counted Plaques to Viridot counted Plaques was 1.05 (95% CI: 0.98–1.14), similar to the average ratio of antibody titers based on manual Plaque counts by the two analysts (1.06 [95% CI: 0.84–1.34]). Across diverse DENV and ZIKV strains (n = 14), manual and Viridot Plaque counts were mostly consistent (range of ρc = 0.74 to 1.00) and the average ratio of antibody titers based on manual and Viridot counted Plaques was close to 1 (0.94 [0.86–1.02]). Thus, Viridot can be used for Plaque counting and neutralizing antibody titer estimation of diverse DENV strains and potentially other Viruses on 96-well plates as well as for formalization of Plaque-counting rules for standardization across experiments and analysts.
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variation in dengue Virus Plaque reduction neutralization testing systematic review and pooled analysis
BMC Infectious Diseases, 2012Co-Authors: Kaitlin Rainwaterlovett, Isabel Rodriguezbarraquer, Derek A T Cummings, Justin LesslerAbstract:The Plaque reduction neutralization test (PRNT) remains the gold standard for the detection of serologic immune responses to dengue Virus (DENV). While the basic concept of the PRNT remains constant, this test has evolved in multiple laboratories, introducing variation in materials and methods. Despite the importance of laboratory-to-laboratory comparability in DENV vaccine development, the effects of differing PRNT techniques on assay results, particularly the use of different dengue strains within a serotype, have not been fully characterized. We conducted a systematic review and pooled analysis of published literature reporting individual-level PRNT titers to identify factors associated with heterogeneity in PRNT results and compared variation between strains within DENV serotypes and between articles using hierarchical models. The literature search and selection criteria identified 8 vaccine trials and 25 natural exposure studies reporting 4,411 titers from 605 individuals using 4 different neutralization percentages, 3 cell lines, 12 Virus concentrations and 51 strains. Of 1,057 titers from primary DENV exposure, titers to the exposure serotype were consistently higher than titers to non-exposure serotypes. In contrast, titers from secondary DENV exposures (n = 628) demonstrated high titers to exposure and non-exposure serotypes. Additionally, PRNT titers from different strains within a serotype varied substantially. A pooled analysis of 1,689 titers demonstrated strain choice accounted for 8.04% (90% credible interval [CrI]: 3.05%, 15.7%) of between-titer variation after adjusting for secondary exposure, time since DENV exposure, vaccination and neutralization percentage. Differences between articles (a proxy for inter-laboratory differences) accounted for 50.7% (90% CrI: 30.8%, 71.6%) of between-titer variance. As promising vaccine candidates arise, the lack of standardized assays among diagnostic and research laboratories make unbiased inferences about vaccine-induced protection difficult. Clearly defined, widely accessible reference reagents, proficiency testing or algorithms to adjust for protocol differences would be a useful first step in improving dengue PRNT comparability and quality assurance.
Jyhhsiung Huang - One of the best experts on this subject based on the ideXlab platform.
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potential application of nonstructural protein ns1 serotype specific immunoglobulin g enzyme linked immunosorbent assay in the seroepidemiologic study of dengue Virus infection correlation of results with those of the Plaque reduction neutralization
Journal of Clinical Microbiology, 2002Co-Authors: Peiyun Shu, Likuang Chen, Shufen Chang, Yiyun Yueh, Ling Chow, Lijung Chien, Chuan Chin, Huihua Yang, Tinghsiang Lin, Jyhhsiung HuangAbstract:An NS1 serotype-specific indirect enzyme-linked immunosorbent assay (ELISA) was developed to differentiate primary and secondary dengue Virus infections and serotypes of primary dengue Virus infection. For this report, we carried out retrospective seroepidemiologic studies on serum samples collected from residents of Liuchiu Hsiang, Pingtung County, an isolated island in southern Taiwan during 1997-1998. The results demonstrated that good correlation existed between dengue Virus NS1 serotype-specific immunoglobulin G (IgG) ELISA and dengue Virus Plaque reduction neutralization test (PRNT). Our data suggested that NS1 serotype-specific IgG ELISA could replace PRNT for seroepidemiologic studies to differentiate Japanese encephalitis and dengue Virus infections and for dengue Virus serotyping.
Paul Schnitzler - One of the best experts on this subject based on the ideXlab platform.
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efficacy of an aqueous pelargonium sidoides extract against herpesVirus
Phytomedicine, 2008Co-Authors: Paul Schnitzler, Sven Schneider, F C Stintzing, Reinhold Carle, Jurgen ReichlingAbstract:The compounds of an aqueous root extract of the African medicinal plant Pelargonium sidoides were analysed by LC-MS spectroscopy and the antiviral effect of this extract against herpes simplex Virus was examined in cell culture. Besides predominant coumarins, simple phenolic structures as well as flavonoid and catechin derivatives were identified as major constituents in the Pelargonium extract. The inhibitory activity of this extract against herpes simplex Virus type 1 (HSV-1) and herpes simplex Virus type 2 (HSV-2) was tested in vitro on RC-37 cells using a Plaque reduction assay and exhibited high antiviral activity against both herpesViruses in viral suspension tests. The 50% inhibitory concentration (IC(50)) of the aqueous Pelargonium sidoides extract for herpes simplex Virus Plaque formation was determined at 0.00006% and 0.000005% for HSV-1 and HSV-2, respectively. At maximum noncytotoxic concentrations of the extract, Plaque formation was significantly reduced by more than 99.9% for HSV-1 and HSV-2 and a clear concentration-dependent antiviral activity against HSV could be demonstrated for this extract. In order to determine the mode of antiviral action, the extract was added at different times to the cells or Viruses during the infection cycle. Both herpesViruses were significantly inhibited when pretreated with the plant extract or when the extract was added during the adsorption phase, whereas acyclovir demonstrated antiviral activity only intracellularly during replication of HSV. These results indicate that P. sidoides extract affected the Virus before penetration into the host cell and reveals a different mode of action when compared to the classical drug acyclovir. Hence this extract is capable of exerting an antiviral effect on herpes simplex Virus and might be suitable for topical therapeutic use as antiviral drug both in labial and genital herpes infection.
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virucidal activity of a β triketone rich essential oil of leptospermum scoparium manuka oil against hsv 1 and hsv 2 in cell culture
Planta Medica, 2005Co-Authors: Jurgen Reichling, Christine Koch, Elisabeth Stahlbiskup, Cornelia Sojka, Paul SchnitzlerAbstract:The inhibitory activity of manuka oil against Herpes simplex Virus type 1 (HSV-1) and Herpes simplex Virus type 2 (HSV-2) was tested in vitro on RC-37 cells (monkey kidney cells) using a Plaque reduction assay. In order to determine the mode of antiviral action of the essential oil, manuka oil was added at different times to the cells or Viruses during the infection cycle. Both HSV types were significantly inhibited when the Viruses were pretreated with manuka oil 1 h prior to cell infection. At non-cytotoxic concentrations of the essential oil, Plaque formation was significantly reduced by 99.5 % and 98.9 % for HSV-1 and HSV-2, respectively. The 50 % inhibitory concentration (IC (50)) of manuka oil for Virus Plaque formation was determined at 0.0001 % v/v ( = 0.96 microg/mL) and 0.00006 % v/v ( = 0.58 microg/mL) for HSV-1 and HSV-2, respectively. On the other hand, pretreatment of host cells with the essential oil before viral infection did not affect Plaque formation. After Virus penetration into the host cells only replication of HSV-1 particle was significantly inhibited to about 41 % by manuka oil. Flavesone and leptospermone, two characteristic ss-triketones of manuka oil, inhibited the virulence of HSV-1 in the same manner as the essential oil itself. When added at non-cytotoxic concentrations to the Virus 1 h prior to cell infection, Plaque formation was reduced by 99.1 % and 79.7 % for flavesone and leptospermone, respectively.
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antiviral activity of australian tea tree oil and eucalyptus oil against herpes simplex Virus in cell culture
Die Pharmazie, 2001Co-Authors: Paul Schnitzler, K Schon, Jurge ReichlingAbstract:The antiviral effect of Australian tea tree oil (TTO) and eucalyptus oil (EUO) against herpes simplex Virus was examined. Cytotoxicity of TTO and EUO was evaluated in a standard neutral red dye uptake assay. Toxicity of TTO and EUO was moderate for RC-37 cells and approached 50% (TC 50 ) at concentrations of 0.006% and 0.03%, respectively. Antiviral activity of TTO and EUO against herpes simplex Virus type 1 (HSV-1) and herpes simplex Virus type 2 (HSV-2) was tested in vitro on RC-37 cells using a Plaque reduction assay. The 50% inhibitory concentration (IC 50 ) of TTO for herpes simplex Virus Plaque formation was 0.0009% and 0.0008% and the IC 50 of EUO was determined at 0.009% and 0.008% for HSV-1 and HSV-2, respectively. Australian tea tree oil exhibited high levels of virucidal activity against HSV-1 and HSV-2 in viral suspension tests. At noncytotoxic concentrations of TTO Plaque formation was reduced by 98.2% and 93.0% for HSV-1 and HSV-2, respectively. Noncytotoxic concentrations of EUO reduced Virus titers by 57.9% for HSV-1 and 75.4% for HSV-2. Virus titers were reduced significantly with TTO, whereas EUO exhibited distinct but less antiviral activity. In order to determine the mode of antiviral action of both essential oils, either cells were pretreated before viral infection or Viruses were incubated with TTO or EUO before infection, during adsorption or after penetration into the host cells. Plaque formation was clearly reduced, when herpes simplex Virus was pretreated with the essential oils prior to adsorption. These results indicate that TTO and EUO affect the Virus before or during adsorption, but not after penetration into the host cell. Thus TTO and EUO are capable to exert a direct antiviral effect on HSV. Although the active antiherpes components of Australian tea tree and eucalyptus oil are not yet known, their possible application as antiviral agents in recurrent herpes infection is promising.
Paul Schnitzle - One of the best experts on this subject based on the ideXlab platform.
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virucidal effect of peppermint oil on the enveloped Viruses herpes simplex Virus type 1 and type 2 in vitro
Phytomedicine, 2003Co-Authors: A Schuhmache, Jurge Reichling, Paul SchnitzleAbstract:The virucidal effect of peppermint oil, the essential oil of Mentha piperita, against herpes simplex Virus was examined. The inhibitory activity against herpes simplex Virus type 1 (HSV-1) and herpes simplex Virus type 2 (HSV-2) was tested in vitro on RC-37 cells using a Plaque reduction assay. The 50% inhibitory concentration (IC50) of peppermint oil for herpes simplex Virus Plaque formation was determined at 0.002% and 0.0008% for HSV-1 and HSV-2, respectively. Peppermint oil exhibited high levels of virucidal activity against HSV-1 and HSV-2 in viral suspension tests. At noncytotoxic concentrations of the oil, Plaque formation was significantly reduced by 82% and 92% for HSV-1 and HSV-2, respectively. Higher concentrations of peppermint oil reduced viral titers of both herpesViruses by more than 90%. A clearly time-dependent activity could be demonstrated, after 3 h of incubation of herpes simplex Virus with peppermint oil an antiviral activity of about 99% could be demonstrated. In order to determine the mode of antiviral action of the essential oil, peppermint oil was added at different times to the cells or Viruses during infection. Both herpesViruses were significantly inhibited when herpes simplex Virus was pretreated with the essential oil prior to adsorption. These results indicate that peppermint oil affected the Virus before adsorption, but not after penetration into the host cell. Thus this essential oil is capable to exert a direct virucidal effect on HSV. Peppermint oil is also active against an acyclovir resistant strain of HSV-1 (HSV-1-ACV(res)), Plaque formation was significantly reduced by 99%. Considering the lipophilic nature of the oil which enables it to penetrate the skin, peppermint oil might be suitable for topical therapeutic use as virucidal agent in recurrent herpes infection.
