Norovirus is a very common and highly contagious virus that causes symptoms of acute gastroenteritis including nausea, vomiting, stomach pain and diarrhea. Other symptoms include fatigue, fever and dehydration. Noroviruses are a major cause of gastrointestinal illness in closed and crowded environments, having become notorious for their common occurrence in hospitals, nursing homes, childcare facilities and cruise ships. In the United States alone, noroviruses are the most common cause of acute gastroenteritis and are estimated to cause 21 million illnesses each year and contribute to 70,000 hospitalizations and 800 deaths. Noroviruses are responsible for up to 1.1 million hospitalizations and 218,000 deaths annually in children in the developing world. There is currently no effective treatment or effective vaccine for norovirus, and the ability to curtail outbreaks is limited. Few companies, if any, are developing antiviral treatments for this disease. However, three candidate vaccines are currently in early stages of clinical testing by GlaxoSmithKline, Ligocyte and Takeda Pharmaceuticals. By targeting viral replication enzymes, we believe it is possible to develop an effective treatment for all geno-groups of the norovirus. Also, because of the significant unmet medical need and the possibility of chronic norovirus infection in immunocompromised individuals, new antiviral therapeutic approaches may warrant an accelerated path to market.