TYPE-SPECIFIC ANTIBODIES TO PURIFIED STREPTOCOCCAL M-PROTEIN FROM POTENTIALLY RHEUMATOGENIC M-TYPE IN PATIENTS WITH RHEUMATIC-FEVER AND RHEUMATIC HEART-DISEASE

This study was designed to identify the predominant serotypes of group A streptococci (GAS) responsible for rheumatic fever (RF) and rheumat ic heart disease (RHD) in India. RF and RHD sera were screened for ant ibodies to M proteins retrospectively against known rheumatogenic M ty pes and M types isolated from patients with acute RF, All GAS strains isolated from four patients with acute RF in a short outbreak of RF,we re identical - serum opacity factor (SOF) negative, T-pattern 3/13 B32 64 and M-non-typable, Because of this, M protein was isolated from onl y one of these four M-nontypable strain (S-399). This was done by limi ted pepsin digestion and purification by ion-exchange chromatography o n DEAE-Sephadex, followed by gel filtration, Purified M protein was fo und to be homologous on SDS-PAGE (mol.wt 20 kDa), immunogenic in rabbi ts and to retain its antigenic structure, This purified M protein from an M-nontypable strain (pep-MNT) was used as an antigen to screen RF and RHD sera retrospectively by ELISA for the prevalence of the M-non- typable GAS strain, The prevalence of the M-non-typable strain was com pared with that of the known rheumatogenic M types, Results suggest th at the M-non-typable strain could be a provisional new rheumatogenic M type in India and could be a candidate for a multivalent M-protein va ccine to control RF and RHD.