Molecular virology of the hepatitis C virus: implication for novel therapies

Treating hepatitis C: current standard of care and emerging direct-acting antiviral agents

Summary.  During the late 1990s and early 2000s, major advances were made in the treatment of patients with chronic hepatitis C virus (HCV) infection. Interferon, combination interferon plus ribavirin (RBV) and pegylated interferon plus RBV increased sustained virologic response (SVR) rates from ~5% to ~40-80%, depending on the genotype of HCV infection. Advances in molecular biology have allowed investigators to begin to understand the mechanisms of HCV infection and replication. Advances in understanding of viral kinetics have provided tools to identify patients who are most likely to attain SVR. With the advances in the science of HCV infection, the first part of the 21st century has seen the development and early introduction of a number of direct-acting antiviral (DAA) drugs. These novel medications interfere with critical steps in HCV replication and have the potential to significantly increase SVR rates. This article will review the key elements of HCV replication and evaluate the various classes of new and investigational DAA that have the potential to create a revolution in the management of patients with chronic hepatitis C.

Serum cystatin C correlates negatively with viral load in treatment-naïve children with chronic hepatitis C

OBJECTIVES

Hepatitis C virus (HCV) infection is a serious health problem that causes chronic infection in up to 85% of cases. HCV nonstructural (NS) cysteine protease, NS2/3, is required for viral replication in vivo. Cystatin C is a naturally occurring cysteine protease inhibitor in human cells. We aimed to investigate the relation between serum levels of cystatin C and HCV viremia in treatment-naïve children with chronic hepatitis C.

METHODS

Serum cystatin C levels were measured in 27 children with chronic hepatitis C and determined their relation with liver functions, histopathological parameters, and hepatitis C viral load. Serum cystatin C was compared with that of 25 age- and sex-matched healthy controls.

RESULTS

Cystatin C was significantly higher in patients than in controls (1.4 ± 0.47 vs 0.99 ± 0.49; P = 0.006), and in those with low viremia than in those with moderate viremia (1.55 ± 0.41 vs 0.99 ± 0.43; P = 0.013). Cystatin C was not correlated with histopathological findings in liver biopsy (P > 0.05 for all). In addition, there was no significant difference of cystatin C levels in patients with normal versus those with elevated transaminases (P > 0.05). Of importance, cystatin C correlated negatively with viral load (P < 0.0001).

CONCLUSIONS

Cystatin C levels correlated negatively with HCV viremia. This finding may reflect an inhibitory effect of cystatin C on HCV replication through inhibiting its NS2/3 and tempting for further studies for cystatin C as a possible adjuvant therapy for HCV infection.

Emerging host cell targets for hepatitis C therapy

Chronic hepatitis C virus (HCV) infection is a major burden on humanity. The current HCV therapy has limited efficacy, and there is pressing need for new and more effective therapies. Host cell factors that are required for HCV infection, replication and/or pathogenesis represent potential therapeutic targets. Of particular interest are cellular receptors that mediate HCV entry, factors that facilitate HCV replication and assembly, and intracellular pathways involving lipid biosynthesis, oxidative stress and innate immune response. A crucial challenge now is to manipulate such cellular targets pharmacologically for chronic HCV treatment, without being limited by side effects.