Detection by ELISA of IgG-subclass-specific antibodies in primary respiratory syncytial (RS) virus infections.

The IgG-subclass specific antibody response was investigated in primary RS-virus infections in infants and small children by using an ELISA with monoclonal antibodies against the four human IgG subclasses. When 78 serum samples obtained from 21 patients during the first 3-4 mo following the onset of illness were studied, only IgG-1 and IgG-3 antibodies could be detected. Both of these subclass specific antibodies appeared during the second week following the beginning of illness. Approximately 4 wk after the onset of illness, IgG-1 antibodies reached maximum levels, which persisted during the following months. Approximately 3 wk after the onset of illness, IgG-3 antibodies reached maximum levels, which decreased during the following months. Both IgG-1 and IgG-3 antibodies showed neutralizing capacity.