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[Hepatitis C virus. Virological diagnosis]
1Laboratoire de Bactériologie-Virologie-Hygiène, ANGERS, France.
Insights
Hepatitis C virus (HCV), a common cause of liver disease, exhibits significant genetic diversity. Diagnosis relies on antibody tests, but RNA detection aids in treatment prediction and monitoring.
Area of Science:
- Virology
- Hepatology
- Immunology
Context:
- Hepatitis C virus (HCV) is a major global health concern, identified in 1989.
- It is a leading cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma.
- HCV is a single-stranded, positive-sense RNA virus with at least 50 identified genotypes/subtypes.
Purpose:
- To characterize the genetic organization and protein properties of HCV.
- To understand the role of HCV quasispecies in immune evasion and disease chronicity.
- To explore diagnostic and prognostic applications of HCV RNA detection.
Summary:
- HCV diagnosis typically involves anti-HCV antibody detection via ELISA.
- HCV RNA detection using genomic amplification is crucial for acute cases, ambiguous ELISA results, or immunosuppressed patients.
- Low viremia levels correlate with better response to interferon treatment, and RNA quantification can monitor antiviral drug efficacy.
Impact:
- Understanding HCV genetic diversity, particularly genotype 1's resistance to interferon, informs treatment strategies.
- The concept of HCV quasispecies provides insights into viral persistence and immune escape mechanisms.
- HCV RNA detection offers a valuable tool for predicting treatment response and monitoring therapeutic outcomes.
Abstract:
Hepatitis C virus (HCV) has been discovered in 1989 and is probably the most common cause of chronic hepatitis, cirrhosis and hepatocellular carcinoma. HCV is a single-stranded, positive-sense RNA virus, 9.4 kilobases in length. The genetic organisation and the properties of viral proteins have been characterized. At least 50 HCV genotypes or subtypes have been identified. Genotypes 1, 2 and 3 are the most commonly observed in patients from Europe and USA. Genotype 1 is more resistant to interferon treatment. The hypervariability of HCV is responsible, within a single patient, of the existence of a spectrum of very closely-related genomes reffered as quasispecies that may be a mechanism of escape from the immune response and may explain chronicity. Virological diagnosis of HCV infection is based on the detection of anti-HCV antibodies by ELISA. In some cases (acute hepatitis, problems in the interpretation of ELISA tests, or in immunosuppressed patients), it is necessary to search for HCV RNA using genomic amplification or amplification of hybridization. These technics can also be useful to predict the response to interferon, as it has been demonstrated that patients with low viremia are better responders than others. HCV RNA detection or quantification could also be useful to follow the efficiency of anti-viral drugs.