David van de Vijver Departnemt of Virology Erasmus MC, University Medical Centre Rotterdam, The Netherlands Principles of HIV Drug Resistance The use of combinations of different classes of antiretroviral drugs has dramatically reduced mortality among patients infected with HIV. But the success of antiretroviral treatment is frequently limited by the emergence of HIV drug resistance. Importantly, drug resistant viruses can be transmitted to newly infected individuals. Transmission of drug resistant HIV is a major concern, as it could lead to a situation in which no effective drugs are available for the treatment of HIV. Less than 1% of all individuals living in the European Union are infected with HIV. Large scale studies on drug resistant HIV can therefore only be performed when several hospitals collaborate. ViroLab has been established to build a virtual laboratory which facilitates such a collaboration. In this seminar, I will discuss the pharmacological, virological and epidemiological principles of HIV drug resistance. I will also discuss the important role computer science plays in research on drug resistant HIV. (ViroLab is supported by the European Commission IST-027446) Further reading: www.virolab.org http://www.hiv.lanl.gov/content/sequence/HIV/REVIEWS/2006_7/VAN/van.html