The Journal of Medical Microbiology, Vol 45, Issue 6 483-489, Copyright © 1996 by Society for General Microbiology
Type-specific antibodies to purified streptococcal M proteins from potentially rheumatogenic M-types in patients with rheumatic fever and rheumatic heart disease
A. Thakur, S. Singhal and K. Prakash
Department of Microbiology, Lady Hardinge Medical School, New Delhi, India.
This study was designed to identify the predominant serotypes of group A
streptococci (GAS) responsible for rheumatic fever (RF) and rheumatic heart
disease (RHD) in India. RF and RHD sera were screened for antibodies to M
proteins retrospectively against known rheumatogenic M types 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, were identical - serum
opacity factor (SOF) negative, T-pattern 3/13 B3264 and M-non-typable.
Because of this, M protein was isolated from only one of these four
M-non-typable strain (S-399). This was done by limited pepsin digestion and
purification by ion-exchange chromatography on DEAE-Sephadex, followed by
gel filtration. Purified M protein was found to be homologous on SDS-PAGE
(mol.wt 20 kDa), immunogenic in rabbits and to retain its antigenic
structure. This purified M protein from an M-non-typable 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 compared with that of the known rheumatogenic M
types. Results suggest that 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 vaccine to control RF and RHD.
