He has been leading research and development activities at Roche in the area of viral diseases since 1997, most recently as Vice President and Global Head of Virology Discovery. Research performed under his direction at Roche sites in Welwyn Garden City (UK), Palo Alto (USA) and Nutley (USA) has supported clinical development of antiviral drugs such as Tamiflu for the treatment and prophylaxis of influenza virus infection, and Balapiravir, Mericitabine and Danoprevir, new antiviral agents for the treatment of HCV infection. He has led Roche Research Teams and also worked extensively in R&D collaborations with external partner companies and academic laboratories, resulting in the discovery and transition into clinical development of a number of new leads and drug candidates for the treatment of acute and chronic viral diseases including influenza, Hepatitis C, Hepatitis B, Dengue and HIV. Examples for a few of these new leads and candidates have been published, including inhibitors of novel influenza virus targets, HIV RNase H and inhibitors of HIV reverse transcriptase and HCV polymerase. Klaus also held research fellow positions at GlaxoWellcome Research and Development (Stevenage, UK) and the European Molecular Biology Laboratory (EMBL) institutes (Heidelberg, Germany and Grenoble, France). Klaus is a Founder of Riboscience LLC and a scientific consultant to Novira Therapeutics Inc.