Infectious Disease Research
Virology
Hepatitis Virus Research and Development
Anti-Hepatitis C Virus (HCV) Evaluation
Since no efficient model system to replicate hepatitis C virus (HCV) has yet been developed, and due to other complicating matters unique to the study of this virus, surrogate viral systems are routinely employed in the evaluation of antiviral agents acting against HCV.
The Flaviviridae family of viruses is composed of three genera: flaviviruses, pestiviruses and hepaciviruses (HCV). Our anti-HCV evaluation program utilizes representative members of each for antiviral evaluations.
- Primary Evaluation with BVDV
Compounds are evaluated for their antiviral activities against BVDV. The end-point of the experiment is inhibition of cytopathic effects (CPE) by the drug. The analysis of this data in terms of cytoprotection allows us to calculate:
- Antiviral activity
- Compound toxicity
- Therapeutic index (toxicity/antiviral activity)
- Range of Action Studies We utilize YFV in an inhibition of CPE effects assay to determine if compounds have generalized anti-Flavivirus activity. Antiviral activity against the Flavivirus West Nile virus (BSL-3) can also be assessed.
- Combination Studies In this analysis, synergistic or antagonistic effects of drugs are distinguished from additive effects. Compounds are evaluated in combination with ribavirin, IFN alpha and other drugs to examine if there are greater than additive synergistic or antagonistic effects on both antiviral activity and cytotoxicity.
- Comprehensive Drug Toxicity Evaluation We can test compounds for toxicity against a large panel of established cell lines, human PBMCs and human primary hepatocyte cultures.
- HCV Molecular Target Assays Here we test compounds for their abilities to inhibit HCV-specific molecular targets.
- IRES assay
A dual luciferase assay can assay the ability of compounds to inhibit HCV IRES-mediated translation.
- NS5B assay
An in vitro assay of the HCV RNA-dependent RNA polymerase NS5B can be used to determine if drugs specifically inhibit this activity.
- NS3 protease assay
An in vitro assay of HCV NS3 protease substrate cleavage inhibition.
- Mechanism of Action Evaluation
A variety of mechanistic studies are possible with most of the surrogate viruses including:
- Time of drug addition studies
Indicate the point in the viral replication cycle during which the drug acts.
- RNA accumulation studies
To show inhibition viral RNA synthesis by drugs.
- Variable MOI effects
We often investigate the effect of varying viral Multipicity of Infection on the antiviral activity of test compounds.
- Alteration of intracellular nucleotide pools
Drugs such as IMPDH inhibitors act to deplete intracellular GTP and dGTP pools. Addition of an excess of guanosine can reverse the inhibition of viral replication by these drugs.
- Drug effects on virion infectivity
If test compounds are mutagenic or if their incorporation into virion RNA blocks further incorporation of ribonucleotides into the growing RNA genome then the infectivity of the viruses produced under these conditions is reduced dramatically.
Anti-Hepatitis B Virus Evaluation
Anti-Hepatitis C Virus Evaluation
