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 (ACHO) as antigens. The optimal concentration of enzyme-treated whole bacterial cells to coat wells was 2 x 10(8) cells/ml and for purified ACHO antigen the optimal concentration was 1 microgram/ml. Sera from patients with acute rheumatic fever and acute glomerulonephritis were screened for the presence of C-carbohydrate antibodies. Patients with acute post-streptococcal complications showed significantly higher titres of antibody when compared with normal healthy individuals. ELISA results were also compared with purified ACHO as an antigen; this showed a highly significant correlation (r = 0.73). Results showed that measurement of the anti-ACHO antibody by ELISA with enzyme-treated whole cells can be a useful, reliable and simple method for serological diagnosis of group A infection and sequelae.
Thakur
A
A
WHO Reference Laboratory for Streptococcal Diseases, Department of Microbiology, Lady Hardinge Medical School, New Delhi, India.
Prakash
K
K
D000907:Antibodies, Bacterial / Q000276:immunology; D002241:Carbohydrates / Q000276:immunology*; D002473:Cell Wall / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D013297:Streptococcus pyogenes / Q000276:immunology*
D000907:Antibodies, Bacterial; D002241:Carbohydrates; D007074:Immunoglobulin G