Respiratory syncytial virus (RSV) antibodies in different immunoglobulin classes in small children.

Percent of RSV antibodies in the individual immunoglobulin classes and IgG subclasses was determined by ELISA and the immune response to RSV infection was evaluated in children 0-2 years of age. In the first 6 months percent of sera containing IgG-RSV declined to reach minimal in the 7th-9th month, then it rose to 100% in children 2 years of age. Percent of positive IgM-RSV and IgA-RSV gradually increased with age. The IgE antibodies occurred in highest percent (20%) in the youngest children, and showed a tendency to decrease in the next age groups. The IgG-1 antibodies were found in the highest percent of sera, the incidence of other subclass antibodies being lower. Diagnostic increase in antibodies was found in highest number in the IgG class and IgG-1 subclass. In the IgM class the highest percent of antibody increase was detected in 21%, and in the IgE class in about 9%.