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Hepatitis C: controversies, strategies and challenges
1Division of Digestive Diseases, UCLA School of Medicine, Los Angeles, CA 90095-1684, USA.
Insights
Hepatitis C virus (HCV) infection is linked to IV drug use and blood transfusions. Combination therapy, including ribavirin, significantly reduces relapse rates in patients with chronic HCV.
Area of Science:
- Virology
- Hepatology
- Epidemiology
Background:
- Hepatitis C virus (HCV) is a single-stranded RNA virus with multiple genotypes and subtypes.
- Risk factors for HCV include IV drug use (42%), blood transfusions (6%), and other exposures, with 40% having no identifiable risk.
- HCV quasispecies complexity correlates with disease duration, viremia, genotype 1, and poor interferon response.
Purpose of the Study:
- To outline the epidemiology, diagnosis, and treatment of Hepatitis C virus infection.
- To discuss the impact of HCV genotypes and quasispecies on disease progression and treatment outcomes.
- To evaluate the efficacy of standard and combination therapies for chronic HCV infection.
Main Methods:
- Diagnosis involves anti-HCV enzyme immunoassay (EIA) with confirmation by recombinant immunoblot assay (RIBA) or HCV RNA detection via polymerase chain reaction (PCR).
- Standard therapy utilized interferon alfa-2b (Intron A) for 6 months.
- Treatment efficacy was assessed by complete response (normal aminotransferases, undetectable HCV RNA) and relapse rates.
Main Results:
- Standard interferon therapy yields a 40-50% response rate, with 60-80% relapse within six months.
- Longer treatment durations (12-18 months) and patient selection (low HCV RNA, no cirrhosis) may improve outcomes.
- Combination therapy with ribavirin has shown dramatically reduced relapse rates.
Conclusions:
- Chronic Hepatitis C virus infection requires careful diagnosis and management.
- Optimizing treatment duration, patient selection, and combination therapies are crucial for improving sustained virologic response.
- Combination therapy, particularly with ribavirin, offers a significant improvement in reducing relapse rates for chronic HCV.
Abstract:
Risk factors for hepatitis C infection include I.V. drug use (42%); history of blood transfusion (6%); exposure to multiple heterosexual partners (6%); exposure to a household contact (3%); health care employment (2%); or hemodialysis (1%). Forty percent of patients have no identifiable risk factors. The HCV is a single-stranded, positive-sense RNA virus. Six major genotypes have been identified; each contains a series of subtypes. In the U.S., prevalences are type 1 (74%); type 2 (15%); type 3 (6%); and type 4 (1%). Within an infected individual, HCV also exists as a spectrum of closely related genotypes referred to as a quasispecies, and more complex quasispecies correlate with longer duration of disease, higher levels of viremia, genotype 1 infection, and poorer response to interferon therapy. Diagnosis is made by measuring anti-HCV by EIA, with confirmation by RIBA or HCV RNA. Patients with chronic HCV infection, with or without aminotransferase elevation, have detectable serum RNA by PCR. Standard therapy is interferon alfa 2b (Intron A) at a dosage of 3 million units 3 times a week for 6 months. This results in a 40%-50% complete response at the end of treatment (normal aminotransferases and undetectable HCV RNA), but relapse occurs in 60%-80% of cases over the next six months. Longer (12 month to 18 month) courses are now widely advocated. Better patient selection, e.g., those with low serum HCV RNA levels and absence of cirrhosis, and increased duration of therapy may lead to better response rates. Combination therapy with other antiviral agents, such as ribavirin, has dramatically reduced relapse rates.