Experimental Study of Quantification of Serum Antibodies Against Streptococcal Surface Antigens by ELISA on Microtiter Plate

Abstract

An experimental study for quantification of serum antibodies against streptococcal surface antigens was carried out, following the ELISA method, using whole bacterial cells as antigens.
Results were summarized as follows:
1) When using the streptococcus group A, B, C and G strains, specific absorbance at OD 410 nm was shown against each group of specific serum, suggesting the specificity of each reaction.
2) By using the reference strains of group A streptococcus types Ml, M4, M6 and M12, the absorbances we obtained in the immune sera reflected the antibodies against M antigens as well as the C-polysaccharide and T antibodies.
3) After the absorption with C-polysaccharide of group A streptococcus and with trypsinized antigen of the corresponding type of antigen for ELISA, only the specific M antibody remained in the human serum we tested.
4) Relatively high quantities of IgG antibodies were present in the sera of patients with valvular heart disease. These antibodies were for the types of streptococci which have been prevalent in Japan during the past 20 years.
Compared with the complicated methods of titration of M antibodies pulished, our method is easy to carry out for the examination of sera. In this study the results clearly reflected the presence of M antibodies for group A streptococcus.