Immunoglobulin-class-specific immune response to respiratory syncytial virus structural proteins in infants, children, and adults.

The protein specificities of IgG, IgM, and IgA antibodies induced during respiratory syncytial virus (RSV) infection in 74 patients (4 weeks to 81 years of age) were investigated using the technique of immunoblotting. Although the pattern of antibody reactivity varied among patients, most of the humoral immune response in all age groups was directed against the 48, 42, 35, and 27 K proteins. An infant's own antibody response was discernible in 55 of the 57 children below 1 year of age, despite the presence of maternally derived antibodies. Antibody against the 90 K surface glycoprotein was not detectable in those less than 1 year of age. Primary RSV infection induced antibodies only against a subset of RSV proteins. Although a broadening of the antibody response occurred with increasing age and in the course of reinfection, an immune response to all the viral structural proteins was observed rarely.