[Comparison between two systems for assaying the level of antibody against Streptococcus agalactiae (GBS) type III]

Levels of antibody against GBS type III in pregnant women have been determined using ELISA assay method that we originally deviced. Toyo Jozo Co. have also introduced an assay system (the Toyo kit) that resembles ours. The present study was performed to compare our system with the Toyo kit. Correctivity between the two systems was good, giving a regression curve of Y = 1.18X - 0.60 and a correlation coefficient of r = 0.794. Antibody levels in pregnant women were determined by the Toyo kit, and were found to be less than 10 micrograms/ml in almost all samples. Among 19 serum samples from vaginal carriers of GBS type III, the antibody levels ranged from 1.5 to 93.8 micrograms/ml. Among seven maternal serum samples in cases of GBS type III infection, the maximum level was 6.0 micrograms/ml. Thus, the Toyo kit showed satisfactory sensitivity for determining the level of antibody against GBS type III. Hereafter, we intend to use the Toyo kit for determining antibody levels in pregnant women.