Respiratory syncytial virus (RSV) is a major cause of respiratory illness in young children. RSV infection produces a variety of signs and symptoms involving different areas of the respiratory tract, from the nose to the lungs. RSV is a negative sense, enveloped RNA virus. The virion is variable in shape and size with average diameter of between 120 and 300 nm. The 63 kD RSV fusion protein of the RSS 2 strain (subtype A) directs fusion of viral and cellular membranes, results in viral penetration, and can direct fusion of infected cells with adjoining cells, resulting in the formation of syncytia or multi nucleated giant cells.
