Hepatitis C NS5A inhibitor daclatasvir has two modes of action CHICAGO, Feb. 18 (UPI) -- U.S. and French mathematical modelers, clinicians and molecular virologists say the anti-viral daclatasvir has two modes of action against hepatitis C virus. Mathematical modeler Harel Dahari, Dr. Scott Cotler, Dr. Thomas Layden, virologist Susan L. Uprichard, graduate student Natasha Sansone of the Loyola University Health System said daclatasvir, a direct acting anti-viral agent in development targets one of the HCV proteins -- NS5A -- causes the fastest viral decline ever seen with anti-HCV drugs at 12 hours of treatment. The study documents HCV kinetic modeling during treatment both in patients and in cell culture that provides insight into the modes of action of daclatasvir. "Ultimately, our study will help design better direct acting anti-viral drug cocktails to treat HCV," Dahari said in a statement. Our modeling of viral kinetics in treated patients predicts that daclatasvir not only blocks the synthesis of the viral RNA within infected cells but also blocks the secretion of infectious virus from the cells. The study was also co-lead by Jeremie Guedj of the Institut National de la Sante et de la Recherche Medicale in France and conducted with Alan Perelson of Los Alamos National Laboratory, Libin Rong of Oakland University and Richard Nettles of Bristol-Myers Squibb. The findings were published in the Proceedings of the National Academy of Sciences.