DETECTION OF ANTIBODY TO C-CARBOHYDRATE OF GROUP-A STREPTOCOCCI WITH ENZYME-TREATED WHOLE BACTERIAL-CELLS AS ANTIGEN FOR ELISA

Antibody to specific cell-wall carbohydrate of group A streptococci in human sera was determined by enzyme-linked immunosorbent assay (ELISA ) with enzyme-treated whole cells and purified group A carbohydrate (A CHO) as antigens. The optimal concentration of enzyme-treated whole ba cterial cells to coat wells was 2 x 10(8) cells/ml and for purified AC HO antigen the optimal concentration was 1 mu g/ml. Sera from patients with acute rheumatic fever and acute glomerulonephritis were screened for the presence of C-carbohydrate antibodies. Patients with acute po st-streptococcal complications showed significantly higher titres of a ntibody when compared with normal healthy individuals. ELISA results w ere also compared with purified ACHO as an antigen; this showed a high ly significant correlation (r = 0.73). Results showed that measurement of the anti-ACHO antibody by ELISA with enzyme-treated whole cells ca n be a useful, reliable and simple method for serological diagnosis of group A infection and sequelae.