Researchers in the United States and Canada report that they've discovered the method by which the hepatitis C virus avoids immune system attacks, which prevents people infected with the virus from potentially eliminating it before any long-term damage results. Most viruses are eventually cleared from the body by the immune system, but HCV can elude immune responses and remain in the body permanently. Between 75% and 85% of those infected with hepatitis C become chronically infected and never shed the virus from their bodies, which puts them at risk for liver damage, liver cancer, and cirrhosis. Currently available treatments can only slow HCV replication.
Scientists at the University of Texas Southwest Medical Center and McGill University in Montreal found that HCV blocks two cellular compounds used to prevent viral infection and to summon an immune system attack on invading viruses. "This really gives us the first evidence of how the virus can cause lifetime infection, as opposed to influenza, which infects you for a week," said researcher Michael Gale. The team is now studying which specific cellular genes are activated by the cellular compounds. Researchers hope to develop drugs that will either prevent HCV from interfering with the compounds or will activate the genes artificially.
The researchers also are studying Schering-Plough's experimental hepatitis C treatment SCH-6, which works to protect cell defenses against invading pathogens. The drug also is being studied by other researchers as a possible treatment for HIV infection. SCH-6 is currently in a Phase I clinical trial to gauge whether it is safe for human use. Efficacy trials for using the drug in both HIV and hepatitis treatment are expected to begin later this year or in early 2004.