The Experts below are selected from a list of 5820 Experts worldwide ranked by ideXlab platform
Robin J Shattock - One of the best experts on this subject based on the ideXlab platform.
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cyanovirin n produced in rice endosperm offers effective pre exposure prophylaxis against hiv 1bal infection in vitro
Plant Cell Reports, 2016Co-Authors: Evgenia Vamvaka, Lrh Krumpe, Robin J Shattock, Koreen Ramessar, A Evans, Barry R Okeefe, Panagiotis Christou, Teresa CapellAbstract:Cyanovirin-N produced in rice endosperm provides efficient pre-exposure prophylaxis against HIV-1 BaL infection in vitro. Cyanovirin-N (CV-N) is a lectin with potent antiviral activity that has been proposed as a component of Microbicides for the prevention of infection with Human immunodeficiency virus (HIV). The production of protein-based Microbicide components requires a platform that is sufficiently economical and scalable to meet the demands of the large at-risk population, particularly in resource poor developing countries. We, therefore, expressed CV-N in rice endosperm, because the dried seed is ideal for storage and transport and crude extracts could be prepared locally and used as a Microbicide component without further purification. We found that crude extracts from rice seeds expressing up to 10 µg CV-N per gram dry seed weight showed dose-dependent gp120 binding activity, confirming that the protein was soluble, correctly folded and active. The recombinant lectin (OSCV-N) reduced the infectivity of HIV-1BaL (an R5 virus strain representing the majority of transmitted infections) by ~90 % but showed only weak neutralization activity against HIV-1RF (representative of X4 virus, rarely associated with transmission), suggesting it would be highly effective for pre-exposure prophylaxis against the vast majority of transmitted strains. Crude extracts expressing OSCV-N showed no toxicity towards human cells at working dilutions indicating that Microbicide components produced in rice endosperm are safe for direct application as topical Microbicides in humans.
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novel approaches to vaginal delivery and safety of Microbicides biopharmaceuticals nanoparticles and vaccines
Antiviral Research, 2010Co-Authors: Kevin J Whaley, Robin J Shattock, Justin Hanes, Richard A Cone, David R FriendAbstract:The HIV-1 epidemic remains unchecked despite existing technology; vaccines and Microbicides in development may help reverse the epidemic. Reverse transcriptase inhibitors (RTIs) formulated in gels tenofovir (TFV) and IVRs (dapivirine) are under clinical development. While TFV or similar products may prove successful for HIV-1, alternatives to RTIs may provide additional benefits, e.g., broader STI prevention. Biopharmaceutical agents under development as Microbicides include cyanovirin, RANTES analogues, commensals, and Mabs. Cost of manufacturing biopharmaceuticals has been reduced and they can be formulated into tablets, films, and IVRs for vaginal delivery. Nanotechnology offers a novel approach to formulate Microbicides potentially leading to uniform epithelial delivery. Delivery through vaginal mucus may be possible by controlling nanoparticle size and surface characteristics. Combining prevention modalities may be the most effective means of preventing STI transmission, importantly, codelivery of Microbicides and vaccines has demonstrated. Finally, the safety of Microbicide preparations and excipients commonly used can be assessed using a mouse/HSV-2 susceptibility model. Screening of new Microbicide candidates and formulation excipients may avoid past issues of enhancing HIV-1 transmission. This article forms part of a special supplement covering several presentations on novel Microbicide formulations from the symposium on “Recent Trends in Microbicide Formulations” held on 25 and 26 January 2010, Arlington, VA.
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reverse transcriptase inhibitors as potential colorectal Microbicides
Antimicrobial Agents and Chemotherapy, 2009Co-Authors: Carolina Herrera, Ian Mcgowan, Martin Cranage, Peter A Anton, Robin J ShattockAbstract:We investigated whether reverse transcriptase (RT) inhibitors (RTI) can be combined to inhibit human immunodeficiency virus type 1 (HIV-1) infection of colorectal tissue ex vivo as part of a strategy to develop an effective rectal Microbicide. The nucleotide RTI (NRTI) PMPA (tenofovir) and two nonnucleoside RTI (NNRTI), UC-781 and TMC120 (dapivirine), were evaluated. Each compound inhibited the replication of the HIV isolates tested in TZM-bl cells, peripheral blood mononuclear cells, and colorectal explants. Dual combinations of the three compounds, either NRTI-NNRTI or NNRTI-NNRTI combinations, were more active than any of the individual compounds in both cellular and tissue models. Combinations were key to inhibiting infection by NRTI- and NNRTI-resistant isolates in all models tested. Moreover, we found that the replication capacities of HIV-1 isolates in colorectal explants were affected by single point mutations in RT that confer resistance to RTI. These data demonstrate that colorectal explants can be used to screen compounds for potential efficacy as part of a combination Microbicide and to determine the mucosal fitness of RTI-resistant isolates. These findings may have important implications for the rational design of effective rectal Microbicides.
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scaleable manufacture of hiv 1 entry inhibitor griffithsin and validation of its safety and efficacy as a topical Microbicide component
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Barry R Okeefe, Robin J Shattock, David C Montefiori, Fakhrieh S Vojdani, Viviana Buffa, James Bakke, Jon C Mirsalis, Annalisa Dandrea, Steven D Hume, Barry BratcherAbstract:To prevent sexually transmitted HIV, the most desirable active ingredients of Microbicides are antiretrovirals (ARVs) that directly target viral entry and avert infection at mucosal surfaces. However, most promising ARV entry inhibitors are biologicals, which are costly to manufacture and deliver to resource-poor areas where effective Microbicides are urgently needed. Here, we report a manufacturing breakthrough for griffithsin (GRFT), one of the most potent HIV entry inhibitors. This red algal protein was produced in multigram quantities after extraction from Nicotiana benthamiana plants transduced with a tobacco mosaic virus vector expressing GRFT. Plant-produced GRFT (GRFT-P) was shown as active against HIV at picomolar concentrations, directly virucidal via binding to HIV envelope glycoproteins, and capable of blocking cell-to-cell HIV transmission. GRFT-P has broad-spectrum activity against HIV clades A, B, and C, with utility as a Microbicide component for HIV prevention in established epidemics in sub-Saharan Africa, South Asia, China, and the industrialized West. Cognizant of the imperative that Microbicides not induce epithelial damage or inflammatory responses, we also show that GRFT-P is nonirritating and noninflammatory in human cervical explants and in vivo in the rabbit vaginal irritation model. Moreover, GRFT-P is potently active in preventing infection of cervical explants by HIV-1 and has no mitogenic activity on cultured human lymphocytes.
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inhibition of human immunodeficiency virus type 1 infection by the candidate Microbicide dapivirine a nonnucleoside reverse transcriptase inhibitor
Antimicrobial Agents and Chemotherapy, 2009Co-Authors: Patricia S Fletcher, Sarah Harman, Hilde Azijn, Naomi Armanasco, P Manlow, D Perumal, M P De Bethune, Jeremy Nuttall, Joseph Romano, Robin J ShattockAbstract:Heterosexual transmission of human immunodeficiency virus (HIV) remains the major route of infection worldwide; thus, there is an urgent need for additional prevention strategies, particularly strategies that could be controlled by women, such as topical Microbicides. Potential Microbicide candidates must be both safe and effective. Using cellular and tissue explant models, we have evaluated the activity of the nonnucleoside reverse transcriptase inhibitor (NNRTI) dapivirine as a vaginal Microbicide. In tissue compatibility studies, dapivirine was well tolerated by epithelial cells, T cells, macrophages, and cervical tissue explants. Dapivirine demonstrated potent dose-dependent inhibitory effects against a broad panel of HIV type 1 isolates from different clades. Furthermore, dapivirine demonstrated potent activity against a wide range of NNRTI-resistant isolates. In human cervical explant cultures, dapivirine was able not only to inhibit direct infection of mucosal tissue but also to prevent the dissemination of the virus by migratory cells. Activity was retained in the presence of semen or a cervical mucus simulant. Furthermore, dapivirine demonstrated prolonged inhibitory effects: it was able to prevent both localized and disseminated infection for as long as 6 days posttreatment. The prolonged protection observed following pretreatment of genital tissue and the lack of observable toxicity suggest that dapivirine has considerable promise as a potential Microbicide candidate.
Brian Wigdahl - One of the best experts on this subject based on the ideXlab platform.
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mouse model of cervicovaginal toxicity and inflammation for preclinical evaluation of topical vaginal Microbicides
Antimicrobial Agents and Chemotherapy, 2004Co-Authors: Bradley J Catalone, Mary K Howett, Fred C. Krebs, Tina Kishcatalone, Lynn R Budgeon, Elizabeth B Neely, Maelee Ferguson, Mohamed E Labib, Robert R Rando, Brian WigdahlAbstract:Clinical trials evaluating the efficacy of nonoxynol-9 (N-9) as a topical Microbicide concluded that N-9 offers no in vivo protection against human immunodeficiency virus type 1 (HIV-1) infection, despite demonstrated in vitro inactivation of HIV-1 by N-9. These trials emphasize the need for better model systems to determine candidate Microbicide effectiveness and safety in a preclinical setting. To that end, time-dependent in vitro cytotoxicity, as well as in vivo toxicity and inflammation, associated with N-9 exposure were characterized with the goal of validating a mouse model of Microbicide toxicity. In vitro studies using submerged cell cultures indicated that human cervical epithelial cells were inherently more sensitive to N-9-mediated damage than human vaginal epithelial cells. These results correlated with in vivo findings obtained by using Swiss Webster mice in which intravaginal inoculation of 1% N-9 or Conceptrol gel (containing 4% N-9) resulted in selective and acute disruption of the cervical columnar epithelial cells 2 h postapplication accompanied by intense inflammatory infiltrates within the lamina propria. Although damage to the cervical epithelium was apparent out to 8 h postapplication, these tissues resembled control tissue by 24 h postapplication. In contrast, minimal damage and infiltration were associated with both short- and long-term exposure of the vaginal mucosa to either N-9 or Conceptrol. These analyses were extended to examine the relative toxicity of polyethylene hexamethylene biguanide (PEHMB), a polybiguanide compound under evaluation as a candidate topical Microbicide. In similar studies, in vivo exposure to 1% PEHMB caused minimal damage and inflammation of the genital mucosa, a finding consistent with the demonstration that PEHMB was >350-fold less cytotoxic than N-9 in vitro. Collectively, these studies highlight the murine model of toxicity as a valuable tool for the preclinical assessment of toxicity and inflammation associated with exposure to candidate topical Microbicides.
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sodium dodecyl sulfate and c31g as microbicidal alternatives to nonoxynol 9 comparative sensitivity of primary human vaginal keratinocytes
Antimicrobial Agents and Chemotherapy, 2000Co-Authors: Fred C. Krebs, Mary K Howett, Shendra R. Miller, Daniel Malamud, Bradley J Catalone, Patricia A Welsh, Brian WigdahlAbstract:A broad-spectrum vaginal Microbicide must be effective against a variety of sexually transmitted disease pathogens and be minimally toxic to the cell types found within the vaginal epithelium, including vaginal keratinocytes. We assessed the sensitivity of primary human vaginal keratinocytes to potential topical vaginal Microbicides nonoxynol-9 (N-9), C31G, and sodium dodecyl sulfate (SDS). Direct immunofluorescence and fluorescence-activated cell sorting analyses demonstrated that primary vaginal keratinocytes expressed epithelial cell-specific keratin proteins. Experiments that compared vaginal keratinocyte sensitivity to each agent during a continuous, 48-h exposure demonstrated that primary vaginal keratinocytes were almost five times more sensitive to N-9 than to either C31G or SDS. To evaluate the effect of multiple Microbicide exposures on cell viability, primary vaginal keratinocytes were exposed to N-9, C31G, or SDS three times during a 78-h period. In these experiments, cells were considerably more sensitive to C31G than to N-9 or SDS at lower concentrations within the range tested. When agent concentrations were chosen to result in an endpoint of 25% viability after three daily exposures, each exposure decreased cell viability at the same constant rate. When time-dependent sensitivity during a continuous 48-h exposure was examined, exposure to C31G for 18 h resulted in losses in cell viability not caused by either N-9 or SDS until at least 24 to 48 h. Cumulatively, these results reveal important variations in time- and concentration-dependent sensitivity to N-9, C31G, or SDS within populations of primary human vaginal keratinocytes cultured in vitro. These investigations represent initial steps toward both in vitro modeling of the vaginal microenvironment and studies of factors that impact the in vivo efficacy of vaginal topical Microbicides.
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inactivation of human immunodeficiency virus type 1 by nonoxynol 9 c31g or an alkyl sulfate sodium dodecyl sulfate
Antiviral Research, 1999Co-Authors: Fred C. Krebs, Mary K Howett, Shendra R. Miller, Daniel Malamud, Brian WigdahlAbstract:Abstract A highly desirable approach to prevention of human immunodeficiency virus type 1 (HIV-1) transmission during sexual intercourse is the development of nontoxic, topical, broad spectrum Microbicides effective against transmission of cell-associated and cell-free virus. Toward this end, the HIV-1 inactivation potential of surface active agents C31G and an alkyl sulfate, sodium dodecyl sulfate (SDS) was assessed. Because of its extensive use as a microbicidal agent, nonoxynol-9 (N-9) was used as a reference against which C31G and SDS were compared. Viral inactivation was measured using HIV-1 LTR-β-galactosidase indicator cells (expressing CD4 or CD4/CCR5) derived from HeLa cells, a cell line of human cervical adenocarcinoma origin. In experiments which examined inactivation of cell-free HIV-1, C31G was generally more effective than N-9. Viral inactivation by SDS occurred at twice the concentration necessary to achieve similar levels of inactivation using either N-9 or C31G. Using HeLa and HeLa-derived cells in cytotoxicity studies, it was demonstrated that SDS is as much as 11 and five times less cytotoxic than N-9 or C31G, respectively, during 48 h of continuous exposure. SDS (unlike C31G and N-9) can inactivate non-enveloped viruses such as human papillomavirus (HPV) [Howett, M.K., Neely, E.B., Christensen, N.D., Wigdahl, B., Krebs, F.C., Malamud, D., Patrick, S.D., Pickel, M.D., Welsh, P.A., Reed, C.A., Ward, M.G., Budgeon, L.R., Kreider, J.W., 1999. A broad-spectrum Microbicide with virucidal activity against sexually transmitted viruses. Antimicrob. Agents Chemother. 43(2), 314–321]. Since addition of SDS to C31G or N-9 may make the resulting microbicidal mixtures broadly effective against both enveloped and non-enveloped viruses, several surface active agent combinations were evaluated for their abilities to inactivate HIV-1. Addition of SDS to either C31G or N-9 resulted in mixtures that were only slightly less effective than equivalent concentrations of C31G or N-9 alone. To investigate inactivation of cell-associated infectivity, HIV-1 IIIB-infected SupT1 cells were treated with N-9, C31G, or SDS. Inactivation of cell-associated infectivity required higher Microbicide concentrations than were needed for inactivation of cell-free virus. However, the relative activities of N-9, C31G, or SDS were similar to those seen in assays of inactivation using cell-free virus. These studies suggest that C31G and SDS may be attractive candidates for human trials as topical Microbicides effective against HIV-1 transmission since both function at concentrations that provide effective viral inactivation with low levels of cytotoxicity. SDS Microbicides (used alone or with other Microbicides) may provide the added advantage of protection from HPV infection.
Fred C. Krebs - One of the best experts on this subject based on the ideXlab platform.
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mouse model of cervicovaginal toxicity and inflammation for preclinical evaluation of topical vaginal Microbicides
Antimicrobial Agents and Chemotherapy, 2004Co-Authors: Bradley J Catalone, Mary K Howett, Fred C. Krebs, Tina Kishcatalone, Lynn R Budgeon, Elizabeth B Neely, Maelee Ferguson, Mohamed E Labib, Robert R Rando, Brian WigdahlAbstract:Clinical trials evaluating the efficacy of nonoxynol-9 (N-9) as a topical Microbicide concluded that N-9 offers no in vivo protection against human immunodeficiency virus type 1 (HIV-1) infection, despite demonstrated in vitro inactivation of HIV-1 by N-9. These trials emphasize the need for better model systems to determine candidate Microbicide effectiveness and safety in a preclinical setting. To that end, time-dependent in vitro cytotoxicity, as well as in vivo toxicity and inflammation, associated with N-9 exposure were characterized with the goal of validating a mouse model of Microbicide toxicity. In vitro studies using submerged cell cultures indicated that human cervical epithelial cells were inherently more sensitive to N-9-mediated damage than human vaginal epithelial cells. These results correlated with in vivo findings obtained by using Swiss Webster mice in which intravaginal inoculation of 1% N-9 or Conceptrol gel (containing 4% N-9) resulted in selective and acute disruption of the cervical columnar epithelial cells 2 h postapplication accompanied by intense inflammatory infiltrates within the lamina propria. Although damage to the cervical epithelium was apparent out to 8 h postapplication, these tissues resembled control tissue by 24 h postapplication. In contrast, minimal damage and infiltration were associated with both short- and long-term exposure of the vaginal mucosa to either N-9 or Conceptrol. These analyses were extended to examine the relative toxicity of polyethylene hexamethylene biguanide (PEHMB), a polybiguanide compound under evaluation as a candidate topical Microbicide. In similar studies, in vivo exposure to 1% PEHMB caused minimal damage and inflammation of the genital mucosa, a finding consistent with the demonstration that PEHMB was >350-fold less cytotoxic than N-9 in vitro. Collectively, these studies highlight the murine model of toxicity as a valuable tool for the preclinical assessment of toxicity and inflammation associated with exposure to candidate topical Microbicides.
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sodium dodecyl sulfate and c31g as microbicidal alternatives to nonoxynol 9 comparative sensitivity of primary human vaginal keratinocytes
Antimicrobial Agents and Chemotherapy, 2000Co-Authors: Fred C. Krebs, Mary K Howett, Shendra R. Miller, Daniel Malamud, Bradley J Catalone, Patricia A Welsh, Brian WigdahlAbstract:A broad-spectrum vaginal Microbicide must be effective against a variety of sexually transmitted disease pathogens and be minimally toxic to the cell types found within the vaginal epithelium, including vaginal keratinocytes. We assessed the sensitivity of primary human vaginal keratinocytes to potential topical vaginal Microbicides nonoxynol-9 (N-9), C31G, and sodium dodecyl sulfate (SDS). Direct immunofluorescence and fluorescence-activated cell sorting analyses demonstrated that primary vaginal keratinocytes expressed epithelial cell-specific keratin proteins. Experiments that compared vaginal keratinocyte sensitivity to each agent during a continuous, 48-h exposure demonstrated that primary vaginal keratinocytes were almost five times more sensitive to N-9 than to either C31G or SDS. To evaluate the effect of multiple Microbicide exposures on cell viability, primary vaginal keratinocytes were exposed to N-9, C31G, or SDS three times during a 78-h period. In these experiments, cells were considerably more sensitive to C31G than to N-9 or SDS at lower concentrations within the range tested. When agent concentrations were chosen to result in an endpoint of 25% viability after three daily exposures, each exposure decreased cell viability at the same constant rate. When time-dependent sensitivity during a continuous 48-h exposure was examined, exposure to C31G for 18 h resulted in losses in cell viability not caused by either N-9 or SDS until at least 24 to 48 h. Cumulatively, these results reveal important variations in time- and concentration-dependent sensitivity to N-9, C31G, or SDS within populations of primary human vaginal keratinocytes cultured in vitro. These investigations represent initial steps toward both in vitro modeling of the vaginal microenvironment and studies of factors that impact the in vivo efficacy of vaginal topical Microbicides.
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inactivation of human immunodeficiency virus type 1 by nonoxynol 9 c31g or an alkyl sulfate sodium dodecyl sulfate
Antiviral Research, 1999Co-Authors: Fred C. Krebs, Mary K Howett, Shendra R. Miller, Daniel Malamud, Brian WigdahlAbstract:Abstract A highly desirable approach to prevention of human immunodeficiency virus type 1 (HIV-1) transmission during sexual intercourse is the development of nontoxic, topical, broad spectrum Microbicides effective against transmission of cell-associated and cell-free virus. Toward this end, the HIV-1 inactivation potential of surface active agents C31G and an alkyl sulfate, sodium dodecyl sulfate (SDS) was assessed. Because of its extensive use as a microbicidal agent, nonoxynol-9 (N-9) was used as a reference against which C31G and SDS were compared. Viral inactivation was measured using HIV-1 LTR-β-galactosidase indicator cells (expressing CD4 or CD4/CCR5) derived from HeLa cells, a cell line of human cervical adenocarcinoma origin. In experiments which examined inactivation of cell-free HIV-1, C31G was generally more effective than N-9. Viral inactivation by SDS occurred at twice the concentration necessary to achieve similar levels of inactivation using either N-9 or C31G. Using HeLa and HeLa-derived cells in cytotoxicity studies, it was demonstrated that SDS is as much as 11 and five times less cytotoxic than N-9 or C31G, respectively, during 48 h of continuous exposure. SDS (unlike C31G and N-9) can inactivate non-enveloped viruses such as human papillomavirus (HPV) [Howett, M.K., Neely, E.B., Christensen, N.D., Wigdahl, B., Krebs, F.C., Malamud, D., Patrick, S.D., Pickel, M.D., Welsh, P.A., Reed, C.A., Ward, M.G., Budgeon, L.R., Kreider, J.W., 1999. A broad-spectrum Microbicide with virucidal activity against sexually transmitted viruses. Antimicrob. Agents Chemother. 43(2), 314–321]. Since addition of SDS to C31G or N-9 may make the resulting microbicidal mixtures broadly effective against both enveloped and non-enveloped viruses, several surface active agent combinations were evaluated for their abilities to inactivate HIV-1. Addition of SDS to either C31G or N-9 resulted in mixtures that were only slightly less effective than equivalent concentrations of C31G or N-9 alone. To investigate inactivation of cell-associated infectivity, HIV-1 IIIB-infected SupT1 cells were treated with N-9, C31G, or SDS. Inactivation of cell-associated infectivity required higher Microbicide concentrations than were needed for inactivation of cell-free virus. However, the relative activities of N-9, C31G, or SDS were similar to those seen in assays of inactivation using cell-free virus. These studies suggest that C31G and SDS may be attractive candidates for human trials as topical Microbicides effective against HIV-1 transmission since both function at concentrations that provide effective viral inactivation with low levels of cytotoxicity. SDS Microbicides (used alone or with other Microbicides) may provide the added advantage of protection from HPV infection.
Mary K Howett - One of the best experts on this subject based on the ideXlab platform.
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mouse model of cervicovaginal toxicity and inflammation for preclinical evaluation of topical vaginal Microbicides
Antimicrobial Agents and Chemotherapy, 2004Co-Authors: Bradley J Catalone, Mary K Howett, Fred C. Krebs, Tina Kishcatalone, Lynn R Budgeon, Elizabeth B Neely, Maelee Ferguson, Mohamed E Labib, Robert R Rando, Brian WigdahlAbstract:Clinical trials evaluating the efficacy of nonoxynol-9 (N-9) as a topical Microbicide concluded that N-9 offers no in vivo protection against human immunodeficiency virus type 1 (HIV-1) infection, despite demonstrated in vitro inactivation of HIV-1 by N-9. These trials emphasize the need for better model systems to determine candidate Microbicide effectiveness and safety in a preclinical setting. To that end, time-dependent in vitro cytotoxicity, as well as in vivo toxicity and inflammation, associated with N-9 exposure were characterized with the goal of validating a mouse model of Microbicide toxicity. In vitro studies using submerged cell cultures indicated that human cervical epithelial cells were inherently more sensitive to N-9-mediated damage than human vaginal epithelial cells. These results correlated with in vivo findings obtained by using Swiss Webster mice in which intravaginal inoculation of 1% N-9 or Conceptrol gel (containing 4% N-9) resulted in selective and acute disruption of the cervical columnar epithelial cells 2 h postapplication accompanied by intense inflammatory infiltrates within the lamina propria. Although damage to the cervical epithelium was apparent out to 8 h postapplication, these tissues resembled control tissue by 24 h postapplication. In contrast, minimal damage and infiltration were associated with both short- and long-term exposure of the vaginal mucosa to either N-9 or Conceptrol. These analyses were extended to examine the relative toxicity of polyethylene hexamethylene biguanide (PEHMB), a polybiguanide compound under evaluation as a candidate topical Microbicide. In similar studies, in vivo exposure to 1% PEHMB caused minimal damage and inflammation of the genital mucosa, a finding consistent with the demonstration that PEHMB was >350-fold less cytotoxic than N-9 in vitro. Collectively, these studies highlight the murine model of toxicity as a valuable tool for the preclinical assessment of toxicity and inflammation associated with exposure to candidate topical Microbicides.
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sodium dodecyl sulfate and c31g as microbicidal alternatives to nonoxynol 9 comparative sensitivity of primary human vaginal keratinocytes
Antimicrobial Agents and Chemotherapy, 2000Co-Authors: Fred C. Krebs, Mary K Howett, Shendra R. Miller, Daniel Malamud, Bradley J Catalone, Patricia A Welsh, Brian WigdahlAbstract:A broad-spectrum vaginal Microbicide must be effective against a variety of sexually transmitted disease pathogens and be minimally toxic to the cell types found within the vaginal epithelium, including vaginal keratinocytes. We assessed the sensitivity of primary human vaginal keratinocytes to potential topical vaginal Microbicides nonoxynol-9 (N-9), C31G, and sodium dodecyl sulfate (SDS). Direct immunofluorescence and fluorescence-activated cell sorting analyses demonstrated that primary vaginal keratinocytes expressed epithelial cell-specific keratin proteins. Experiments that compared vaginal keratinocyte sensitivity to each agent during a continuous, 48-h exposure demonstrated that primary vaginal keratinocytes were almost five times more sensitive to N-9 than to either C31G or SDS. To evaluate the effect of multiple Microbicide exposures on cell viability, primary vaginal keratinocytes were exposed to N-9, C31G, or SDS three times during a 78-h period. In these experiments, cells were considerably more sensitive to C31G than to N-9 or SDS at lower concentrations within the range tested. When agent concentrations were chosen to result in an endpoint of 25% viability after three daily exposures, each exposure decreased cell viability at the same constant rate. When time-dependent sensitivity during a continuous 48-h exposure was examined, exposure to C31G for 18 h resulted in losses in cell viability not caused by either N-9 or SDS until at least 24 to 48 h. Cumulatively, these results reveal important variations in time- and concentration-dependent sensitivity to N-9, C31G, or SDS within populations of primary human vaginal keratinocytes cultured in vitro. These investigations represent initial steps toward both in vitro modeling of the vaginal microenvironment and studies of factors that impact the in vivo efficacy of vaginal topical Microbicides.
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inactivation of human immunodeficiency virus type 1 by nonoxynol 9 c31g or an alkyl sulfate sodium dodecyl sulfate
Antiviral Research, 1999Co-Authors: Fred C. Krebs, Mary K Howett, Shendra R. Miller, Daniel Malamud, Brian WigdahlAbstract:Abstract A highly desirable approach to prevention of human immunodeficiency virus type 1 (HIV-1) transmission during sexual intercourse is the development of nontoxic, topical, broad spectrum Microbicides effective against transmission of cell-associated and cell-free virus. Toward this end, the HIV-1 inactivation potential of surface active agents C31G and an alkyl sulfate, sodium dodecyl sulfate (SDS) was assessed. Because of its extensive use as a microbicidal agent, nonoxynol-9 (N-9) was used as a reference against which C31G and SDS were compared. Viral inactivation was measured using HIV-1 LTR-β-galactosidase indicator cells (expressing CD4 or CD4/CCR5) derived from HeLa cells, a cell line of human cervical adenocarcinoma origin. In experiments which examined inactivation of cell-free HIV-1, C31G was generally more effective than N-9. Viral inactivation by SDS occurred at twice the concentration necessary to achieve similar levels of inactivation using either N-9 or C31G. Using HeLa and HeLa-derived cells in cytotoxicity studies, it was demonstrated that SDS is as much as 11 and five times less cytotoxic than N-9 or C31G, respectively, during 48 h of continuous exposure. SDS (unlike C31G and N-9) can inactivate non-enveloped viruses such as human papillomavirus (HPV) [Howett, M.K., Neely, E.B., Christensen, N.D., Wigdahl, B., Krebs, F.C., Malamud, D., Patrick, S.D., Pickel, M.D., Welsh, P.A., Reed, C.A., Ward, M.G., Budgeon, L.R., Kreider, J.W., 1999. A broad-spectrum Microbicide with virucidal activity against sexually transmitted viruses. Antimicrob. Agents Chemother. 43(2), 314–321]. Since addition of SDS to C31G or N-9 may make the resulting microbicidal mixtures broadly effective against both enveloped and non-enveloped viruses, several surface active agent combinations were evaluated for their abilities to inactivate HIV-1. Addition of SDS to either C31G or N-9 resulted in mixtures that were only slightly less effective than equivalent concentrations of C31G or N-9 alone. To investigate inactivation of cell-associated infectivity, HIV-1 IIIB-infected SupT1 cells were treated with N-9, C31G, or SDS. Inactivation of cell-associated infectivity required higher Microbicide concentrations than were needed for inactivation of cell-free virus. However, the relative activities of N-9, C31G, or SDS were similar to those seen in assays of inactivation using cell-free virus. These studies suggest that C31G and SDS may be attractive candidates for human trials as topical Microbicides effective against HIV-1 transmission since both function at concentrations that provide effective viral inactivation with low levels of cytotoxicity. SDS Microbicides (used alone or with other Microbicides) may provide the added advantage of protection from HPV infection.
Salim S. Abdool Karim - One of the best experts on this subject based on the ideXlab platform.
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Antiretrovirals for HIV Prevention: The CAPRISA 004 Tenofovir Gel Trial
The CAPRISA Clinical Trials: HIV Treatment and Prevention, 2017Co-Authors: Cheryl Baxter, Leila E Mansoor, Salim S. Abdool Karim, Tanuja N. Gengiah, Quarraisha Abdool KarimAbstract:Women bear a disproportionate burden of the HIV epidemic in sub-Saharan Africa. Young women, including adolescent girls, unable to negotiate mutual faithfulness and/or condom use with their male partners are particularly vulnerable and have few HIV prevention options available to them that they can directly control. The development of technologies such as Microbicides to prevent sexual acquisition of HIV infection in young women was therefore an urgent priority. Unfortunately, all of the Microbicide trials assessing first and second generation products produced disappointing results. In 2007, CAPRISA initiated a phase IIb, two-arm, double-blind, randomised, controlled trial to evaluate the effectiveness and safety of the first antiretroviral-based Microbicide, tenofovir gel, for the prevention of sexually transmitted HIV infection. This chapter focuses on CAPRISA’s experiences in developing the protocol with specific reference to how the lessons from past Microbicide trials helped shape the development of the trial. The scientific rationale behind the dosing strategy selected for the study is provided and some of the challenges encountered during the study that may have wider implications for other research trials are described. The chapter is concluded with a brief summary of the trial results and their implications for the HIV prevention field.
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Disclosure of Microbicide gel use to sexual partners: influence on adherence in the CAPRISA 004 trial.
AIDS and behavior, 2014Co-Authors: Kathryn Therese Mngadi, Janet A. Frohlich, Leila E Mansoor, Salim S. Abdool Karim, Bernadette T. Madlala, Anna Christina. Grobler, Silvia Maarschalk, Nelisiwe Ngcobo, Quarraisha Abdool KarimAbstract:Young women in sub-Saharan Africa are disproportionately affected by HIV, making the development of women initiated and controlled methods of prevention, including Microbicides, a priority. Adherence is pivotal to Microbicide efficacy and partner related factors are known to impact adherence. An analysis of disclosure of gel use to sexual partners and adherence in CAPRISA 004 women was conducted to better understand this relationship. Partner disclosure was significantly associated with a modest 4.2 % increased adherence (71.0 vs. 66.8 %, p = 0.03). Most women rated the experience of disclosure as positive, despite 6.7 % of partners expressing a negative reaction.Participants who disclosed were more likely to reside with their regular partner (14.4 vs. 8.4 %; p = 0.01) and reported consistent condom use at baseline (32.9 vs. 20.9 %; p < 0.01). Partner disclosure needs to be better understood as a potential facilitator or barrier to Microbicide adherence.
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No Evidence for Selection of HIV-1 with Enhanced Gag-Protease or Nef Function among Breakthrough Infections in the CAPRISA 004 Tenofovir Microbicide Trial
PloS one, 2013Co-Authors: Denis Chopera, Vivek Naranbhai, Jaclyn K. Mann, Philip Mwimanzi, Saleha Omarjee, Xiaomei T. Kuang, Nonkululeko. Ndabambi, Sarah Goodier, Eric Martin, Salim S. Abdool KarimAbstract:Background Use of antiretroviral-based Microbicides for HIV-1 prophylaxis could introduce a transmission barrier that inadvertently facilitates the selection of fitter viral variants among incident infections. To investigate this, we assessed the in vitro function of gag-protease and nef sequences from participants who acquired HIV-1 during the CAPRISA 004 1% tenofovir Microbicide gel trial.
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Preservation HIV-1-specific IFNγ+ CD4+ T-cell responses in breakthrough infections after exposure to tenofovir gel in the CAPRISA 004 Microbicide trial.
Journal of acquired immune deficiency syndromes (1999), 2012Co-Authors: Marianne W. Mureithi, Quarraisha Abdool Karim, Sengeziwe Sibeko, Salim S. Abdool Karim, Lise. Werner, Vivek Naranbhai, Danielle Poole, Shabashini Reddy, Nompumelelo Mkhwanazi, Thumbi NdungʼuAbstract:The Centre for the AIDS Program of Research in South Africa 004 trial demonstrated reduction of sexual HIV-1 acquisition in women using a vaginal Microbicide containing tenofovir. A better understanding of the consequences of antiretroviral-containing Microbicides for immune responses in individuals with intercurrent HIV-1 infection is needed for future trials combining the use of Microbicides with HIV-1 vaccines. Investigation of immune responses in women who acquired HIV-1 although using tenofovir gel showed significantly higher (P = 0.01) Gag-specific IFNγ+ CD4+ T-cell responses. The use of tenofovir-containing gel around the time of infection can modulate HIV-1 immunity, and these immunological changes need to be considered in future trials combining vaccines and Microbicides.