Community Research and Development Information Service - CORDIS

Methods for studying HCV

Hepatitis C Virus (HCV) is a major health issue worldwide with millions of infected individuals. The limited efficacy of existing treatments is a reason to revisit HCV biology.
Methods for studying HCV
HCV is the major cause of liver cirrhosis and hepatocellular carcinoma. Current treatment options have limited efficacy and result in effective viral suppression only in about 50 % of treated patients. In addition, HCV exhibits high genetic variability, which allows it to escape drug pressure and immune responses. This remarkable ability is due to the lack of proofreading activity of the viral RNA polymerase and leads to the generation of recombinant genomes. Furthermore, this genetic diversity hampers the development of effective vaccines.

The primary objective of the EU-funded HCVPACK (Development of two complementary systems for the study of recombination and packaging of hepatitis C virus genomic RNA using fluorescent proteins and live imaging) project was to develop assays for studying the RNA biology of HCV. These assays enabled the estimation of HCV recombination frequencies under different conditions and the detection of viral RNA in live cells.

Researchers demonstrated that the virus could recombine efficiently under heavy selective pressure, even in the absence of replication. They observed that recombinant HCV genomes underwent additional recombination cycles to obtain higher fitness and remove redundant sequences. Collectively, the study results underscore the importance of recombination in HCV evolution and life cycle.

To visualise the HCV RNA genome within cells and examine the packaging mechanism and efficiency of HCV, scientists investigated the assembly of different viral genotypes. They did not observe any significant differences in the distribution of Core and NS5A among all major HCV genotypes, suggesting a common assembly pathway for all strains. The tracking of HCV genomic RNA was based on the capability of inserting and recognising specific stem-loop structures within the genomes by fluorescently labelled RNA-binding proteins. Detection required a highly sensitive microscopy system with a state-of-the-art electron multiplying charge-coupled device camera.

Taken together, the proposed assays have the capacity to advance understanding of the HCV life cycle, especially given the role of viral recombination in the development of drug resistance. This will undoubtedly lead to novel therapies and improve the outcome of HCV infection.

Related information

Keywords

HCV, hepatitis C virus, genetic variability, recombination, life cycle
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