Correlation between Low Levels of Maternal IgG Antibodies to R Protein and Neonatal Septicemia with Group B Streptococci Carrying R Protein

Abstract

A method was designed for quantitation of serum antibodies to R protein in group B streptococci (GBS). Four sera from mothers of infants with neonatal septicemia caused by type II, R+ GBS showed a binding range from 400 to 740 cpm in contrast to a range of 690–1,220 cpm in 5 parturients carrying type II, R+ strains in the urogenital tract giving birth to healthy infants (p < 0.05). The range of antibodies in sera from 8 mothers to infants infected with GBS type III, R+ was 370–750 cpm, whereas the range in sera from 10 carriers of type IIIR+ giving birth to healthy infants varied between 510 and 1,280 cpm (p < 0.01). These findings indicate that R protein is an important virulence factor in neonatal GBS septicemia/meningitis.

Human IgG Antibodies to Carbohydrate and Protein Antigens in Mouse Protection Tests with Group B Streptococci

“…The differences between the protective effect of gammaglobulin preparations against type 111, R-and type 111, R+ (Tables 2 and 3) may indicate that R-protein is of importance for the virulence of GBS in mice. We have previously found that antibodies to R-protein can be protective against type 11, R+ (22) and that mothers of infants infected with R+ GBS stains have low levels of antibodies to R-protein (25). In clinical isolates from our district, 5 1 % of tvve I1 strains and 86% of tvDe 111 strains camed R-protein (i6).…”

“…In some experiments, anti-human IgG3 serum (kindly supplied by Dr. A. Grubb, Malmo General Hospital, Sweden) was added, as described previously (25), in order to investigate the gammaglobulins with regard to antibodies to type I1 GBS belonging to the human subclass IgG3.…”

“…For quantitation of antibodies against the Ibc protein, the gammaglobulin batches were absorbed with trypsinized Ib GBS as described previously ( 3 , followed by quantitation of antibodies against untrypsinized type Ib GBS. Antibodies to R-protein were determined as previously described, using protein A (25).…”

“…The disease seems to be correlated with a relative deficiency of maternal antibodies to GBS-type antigens (2,5,16,25,37). For this reason, attention has been focused on immuneprophylaxis of the disease using vaccination (1) and administration of specific IgG antibodies to pregnant women and/or their infants.…”

Demonstration of Opsonic and Protective Activity of Human Cord Sera against Type III Group B Streptococcus that Are Independent of Type-Specific Antibody

“…R protein) may possibly be responsible for opsonic activity observed against strain K79 in some cord sera. Linden et al (27) and Christensen et al (28) have suggested that R protein antibody may be important in protecting mice against GBS strains possessing R protein. Additional studies are therefore needed to determine if the opsonic and protective activity that appear to be independent of type-specific GBS antibody may stem from antibodies directed against other surface antigens (e.g.…”