Effects of hepatitis B and hepatitis C virus replication on the actions of interferon.

Many patients chronically infected with hepatitis B or C do not respond to interferon therapy. For hepatitis B infections it is now clear that a viral factor down regulates the cells ability to respond to interferon and hence prevents effective therapy in some patients. In chronic hepatitis C infections, interferon therapy leads to the selection of interferon-resistant viral strains, but the mechanism of this resistance is not yet known.