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The staff of ImQuest BioSciences has decades of experience with the efficient and cost-effective development of anti-HIV therapeutics. Following an efficient and logical algorithm, the mission of ImQuest is to provide solutions to complex drug discovery and development problems that will result in the rapid and efficient progression of therapeutic agents to human clinical trials. ImQuest will join your research team to help support new or existing therapeutic development projects.
Our work begins with basic drug discovery screening programs and the follows a well-defined and understood developmental pathway, guided by the FDA Points to Consider in the Preclinical Development of Antiviral Drugs for the Treatment of HIV Infection. In this context, the major elements of anti-HIV therapeutic development include the following:
Our laboratory-generated data and technical project reports have been subjected to rigorous evaluation by the FDA, leading to the successful entrance of therapeutic agents into human clinical trials. |
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Efficacy and toxicity
ImQuest BioSciences offers a diverse and broad range of highly detailed antiviral evaluations for the evaluation of potential anti-HIV therapies. Our capabilities range from initial determinations of antiviral efficacy to highly innovative studies to fully characterize compounds exhibiting novel anti-HIV mechanisms of action. We specialize in developing your therapeutic anti-HIV agent to its utmost potential and defining the unique qualities of the molecule that will facilitate its timely development. To accomplish these HIV antiviral drug development goals, we utilize a wide range of capabilities in the following areas:
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Evaluations in established human cells |
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Evaluations in fresh human cells (PBMC and macrophage) |
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Evaluations in mechanism-based assays |
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Evaluations in other cell-based, primary anti-HIV screening assays |
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Confirmatory anti-HIV evaluations |
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Range of Action
After compounds with potent antiviral activity have been identified in cell-based primary screening assays, the next step is to examine the range-of-action of these compounds. Routinely, the following range-of-action parameters are assessed:
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Range of cell lines: Compounds are evaluated for their ability to inhibit HIV infection in a variety of phenotypically distinct established human cell lines, including T-cells, B-cells, monocyte-macrophages, dendritic cells, and fresh human primary cells. |
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Range of antiviral action: Compounds are evaluated for their ability to inhibit the replication of NSI, SI, multiple subtype (clade) and resistant viruses representative of the available quasi-species of HIV-1. Compounds are also assessed for activity against multiple representatives of other retrovirus types including, HIV-2, SHIV and SIV. Panels of various virus quasi-species and subtypes can be specifically designed for your study or preexisting panels can be used. Potential panels are: |
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Long term non-progressors and recent sero-converters. |
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Multiple SI (X4) and NSI (R5) subtypes, as well as dual tropic viruses (X4/R5). |
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Panels of subtype specific viruses with multiple representative of each subtype. |
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Resistant viruses:
1.) Expressing single or multiple mutations associated with resistance to clinically relevant therapies.
2.) Multi-drug resistant isolates derived from antiviral experienced patients.
3.) In vitro-derived viruses resistant to current antiviral drugs. |
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Up to 60 subtype B representative viruses. |
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Range of action against viruses other than HIV: Compounds are evaluated for their ability to inhibit the replication of a variety of virus isolates, including herpesviruses, cytomegalovirus, influenza and other respiratory viruses, and hepatitis B and C. |
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Chronic Infection: Compounds are evaluated for their ability to inhibit virus production from cells which are chronically infected with HIV. In these assays, HIV has already established a productive, constitutive infection of the target cells and inhibitors of the early steps of HIV replication are ineffective. These assays include the use of chronically infected CEM-SS, H9, MT2, U937 cells with a variety of laboratory adapted viruses. In addition to cell lines we also have the capability to analyze the effect of compounds on PBMCs chronically infected with a variety of low passage HIV-1 virus isolates. |
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Latent Infection: Similar to chronically infected assay systems, compounds are evaluated for their ability to inhibit virus production from latently infected cell lines which are induced to produce virus in response to stimulation by phorbol esters, tumor necrosis factor alpha (TNF-alpha) or IL-6. Assays include the use of U1, ACH-2 and OM 10.1 cells. |
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Virucidal Evaluations: Compounds are evaluated for their ability to directly inactivate virus. Compounds can be evaluated for direct or indirect virucidal activity in cell-free and cell-associated models. |
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Coreceptor Evaluations: Compounds and viruses can be evaluated for their specific effects on the CXCR4 (X4) and CCR5 (R5) coreceptor, as well as other coreceptors of potential interest. Coreceptor-based studies include: |
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Specific typing of primary virus isolates or a virus subspecies resulting from selection against specific coreceptor active agents. |
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Evaluation and identification of compounds with activity against coreceptors. |
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Secondary evaluations of inhibitors by ligand displacement and effects on chemokine ligand-induced Ca ++ flux . |
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Mechanism of Action
Once a lead compound has been identified and the range of action confirmed in secondary assays, it becomes important to determine the viral specificity of the test compound. The development of highly detailed and specific mechanism of action assays requires a very detailed understanding of the replication of the infectious agent in human cells and the effects of virus replication on the target cell. In our laboratory, assays are performed to determine the precise mechanism of anti-HIV action of a test compound. Unlike many laboratories, we have specialized in the development and performance of both cell-based and molecular/biochemical mechanism of action assays. In general, activity defined in molecular/biochemical assays is confirmed in cell-based assays to demonstrate that test compounds can actually act at the appropriate site of action in an intact target cell system.
When defining the mechanism of action of a test compound, one of the first assays performed involves defining the time at which the compound must be present to inhibit HIV replication during a synchronized single step of virus replication assay. In this way, the action of the compound can be correlated with a specific step of the HIV replication pathway based on the events in replication that occur during that time of infection.
See the Mechanism-of-Action flowchart/algorithm to gain an understanding of the different assays that might be systematically and sequentially completed to determine the mechanism-of-action of an unknown antiviral compound. Based on discussions with our highly-experienced staff, we will guide you through this testing algorithm in the most cost-effective and timely manner possible. |
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Combination Therapy
 Active anti-HIV compounds will likely be used in combination with other anti-HIV agents or with those that inhibit opportunistic infectious organisms. Thus, it is critical to evaluate the activity of the compound in combination with agents being used in the treatment of AIDS patients. We routinely evaluate the interaction of new test compounds with other anti-HIV agents including nucleoside RT inhibitors (AZT, ddI, ddC, d4T and 3TC), nonnucleoside RT inhibitors (nevirapine, Sustiva, a-APA, TSAO, costatolide, TIBO, UC781), protease inhibitors (indinavir, saquinavir, ritonavir, nelfinavir) attachment inhibitors (T20, sulfated polysaccharides, sulfonated dyes) and neutralizing antibodies. Data are evaluated using multiple statistical software packages including the Prichard and Shipman MacSynergy II, the Chou and Talalay median dose effect equation and ComboSTAT. The interactions of the compounds are evaluated in terms of efficacy (synergy, additivity, antagonism) and toxicity (synergistic toxicity, antagonistic toxicity). Compounds can be tested against a panel of virus strains in two (2) or three (3) drug combinations with investigational and clinically relevant agents. |
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Resistance Selection and Characterization
The potential for the rapid selection of drug resistance in vitro and in vivo requires that the development of a potential anti-HIV agent include analysis of the rate and extent of drug resistance in cell culture. Resistant virus isolates are routinely selected in CEM-SS cells by serial passage of the virus in the presence of increasing concentrations of the compound. Resistance evaluations may be performed in any of the available cell lines, including fresh human PBMCs, with a variety of virus isolates, including low passage clinical HIV strains. In addition, resistance selection can be performed using combinations of anti-HIV agents to evaluate the relative ability of the virus to become resistant to multiple agents that might be used in the clinic, mimicking the use of highly active antiretroviral therapy (HAART).
A flowchart is provided to elucidate the algorithm typically utilized during the selection and characterization of viruses that display drug-resistant phenotypes. Additional studies are also possible to fully characterize these drug-resistant viruses. Contact our highly-experienced scientists to discuss these options. |
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| Copyright © 2006, ImQuest BioSciences. | | | |
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