Mechanisms of illness during respiratory syncytial virus infection: the lungs, the virus and the immune response.

Multiple factors, including cardiopulmonary anatomy, direct viral effects and the immune response can affect the severity of lower respiratory tract disease caused by respiratory syncytial virus (RSV). RSV is the most frequent viral respiratory cause of hospitalization in infants and young children in the world. In this review, we discuss the mechanisms of illness associated with severe RSV lower respiratory tract disease. A better understanding of the factors affecting the course of illness and their interplay should allow development of effective therapies in the future.