[Effects of interferons on hepatitis C virus infection]

The consequences of hepatitis C virus infections (chronic hepatitis, liver cirrhosis and hepatocellular carcinoma) are one of the major problems in clinical medicine. The persistence of infection in spite of high specific antibody titre suggests that the virus has the abillity to "escape" the immunological response.

Interferons are important components of the early host response to infection. They have antiviral, antiproliferative, and immunomodulatory activities. Many viruses have developed the ability to "annul" or alleviate the action of interferon by preventing its synthesis or by interfering with signaling pathways in the cells. During acute infection some of the non-structural proteins of HCV block regulatory factors that are responsible for the synthesis of endogenous infection. Within a cell, interferon induces a number of genes to produce proteins that prevent virus replication. Among them, the most important are RNA-dependent protein kinase and the eukaryotic initiation factor. However, viral proteins, especially viral envelope proteins and nonstructural protein 5A, prevent their phosphorylation and activation which enhance virus replication. These are the facts that have to be considered when using IFN in chronic hepatitis C patients.