Antibody response to the rubella virus structural proteins in infants with the congenital rubella syndrome

Forty-five serum samples from 31 newborns and infants with the congenital rubella syndrome (CRS) were tested by immunoprecipitation to determine their antibody spectra to each of the structural proteins of rubella virus. Most sera (37/45) contained little or no E2 protein-specific antibody, but some (6/45) precipitated a greater amount of the E2 glycoprotein than the E1 glycoprotein. The relative E1/E2 ratio was found to decrease with time when serial serum samples from the same patient were tested. No correlation between the IgG class hemagglutination inhibition antibody titers and the E1/E2 ratio could be demonstrated. However, in some serum specimens relatively high neutralizing antibody titers were correlated with immunoprecipitation of the E2 glycopolypeptide. None of the CRS sera reacted well with the C protein. The immunoprecipitation patterns found in CRS sera were qualitatively different from those observed in a series of 25 sera from young adults with conventional serologic evidence of rubella immunity following natural infection. All of the natural immune sera recognized each of the three structural polypeptides of rubella virus.