miRNAs expressed by interferon beta, the only approved therapy for hepatitis C, are used by mammalian cells to reduce the replication of the virus, according to a team of researchers. “This is an entirely new antiviral mechanism in mammalian organisms,” points out Michael David, Ph.D., an associate professor of biological sciences at the University of California, San Diego (UCSD) who headed the team.
The investigators began by identifying miRNAs whose expression is controlled by interferon beta. They then used computer predictions to identify potentially affected viral RNAs. The hepatitis C virus reportedly emerged as a prime candidate for eight of the miRNAs.
The UC San Diego team demonstrated that synthetic miRNAs corresponding to these inteferon beta-induced miRNAs reproduce the antiviral effects of inteferon beta on HCV replication and infection. Neutralization of these antiviral miRNAs, however, reduced the antiviral effects of inteferon beta against HCV.
The research group also found that inteferon beta treatment leads to a significant reduction in the expression of the liver-specific miR-122, an miRNA that has been previously shown to be essential for HCV replication.
Reasearchers at The Scripps Research Institute and Ohio State University also contributed to this study. The paper is published in the October 18 issue of Nature.