Respiratory syncytial virus and T cells: interplay between the virus and the host adaptive immune system.

Respiratory syncytial virus (RSV) is a major cause of morbidity in young infants and is increasingly recognized as an important cause of serious illness/morbidity in the elderly. This agent has also been implicated both in the etiopathogenesis of asthma/airway hyperreactivity and in the exacerbation of wheezing episodes in individuals with asthma. This review deals with our current knowledge of the host adaptive immune response to RSV, focusing on the interaction of the virus with T lymphocytes. Current information on the impact of RSV infection on the function of responding CD4 (+) and, in particular, CD8 (+) T lymphocytes will be reviewed; and the potential implications of this virus/immune cell interaction on the development of RSV-induced disease in the respiratory tract will be discussed. In addition, the long-standing conundrum concerning the development of an effective vaccine against RSV will be discussed in the context of the vaccine-induced enhanced disease during RSV infection and the interplay between the virus and immune/memory T cells in the development of pulmonary injury in vaccinated individuals after the RSV infection.