Respiratory syncytial virus (RSV) is the single most important cause of serious lower respiratory tract disease in the infant and young child. It is estimated that up to 125,000 hospitalizations each year in the United States are associated with pneumonia or bronchiolitis from RSV infection in children less than 1 year old. The importance of RSV as a cause of serious lower respiratory tract disease in children has made it a high priority for prevention and treatment.

Efforts to develop an RSV vaccine have so far failed, and no highly effective antiviral therapy has been found. The first candidate vaccine, formalin inactivated RSV, was associated with an increase in disease severity and several deaths when vaccinated children were later infected with RSV in the community. Multiple live virus vaccine candidates have been tried, but none has been found safe and effective. Because no vaccine is available, Centers for Disease Control and Prevention (CDC) scientists began to investigate the use of therapeutic antibodies for the prevention and treatment of RSV infection.

CDC scientists identified a partner for a Cooperative Research and Development Agreement, Trellis Bioscience, to collaborate on additional studies to prove the viability of the antibodies directed against the G protein as potential therapeutic antibodies against RSV. Together, scientists at CDC and Trellis identified high-affinity fully human antibodies that mimicked the mouse monoclonal antibodies in in vitro assays and mouse models. Based on the positive results obtained during the collaboration, Trellis obtained an exclusive patent license to take these RSV anti-G antibodies into human trials, and bring to market a commercial product that shows improved safety and efficacy over currently available antibodies. These RSV anti-G antibodies have the potential to dramatically decrease the number of hospitalizations and deaths of infants, children, and the elderly due to respiratory tract disease caused by RSV infection.