TYPING OF GROUP A STREPTOCOCCI BY IMMUNOFLUORESCENCE

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Abstract
Karakawa, WalterW. (Connecticut State Department of Health, Hartford),Earle K. Borman, and Clarence R. McFarland. Typing of group A streptococci by immunofluorescence. I. Preparation and properties of type 1 fluorescein-labeled antibody. J. Bacteriol.87:1377–1382. 1964.—Unadsorbed, fluorescein-labeled globulins derived from rabbits immunized with acid-extracted M-protein of type 1 streptococci (plus adjuvant) were found to have high fluorescent-antibody (FA) staining titers and to be considerably more type-specific than were similar preparations derived from whole-cell immunization. Appropriate adsorption rendered the anti-M reagent entirely type-specific without appreciable loss of titer; whole-cell reagent was appreciably weakened in FA titer by comparable adsorption. Type-specificity was confirmed by parallel bactericidal, long-chain, and precipitin studies. Removal of reactivity by adsorption with homologous M protein was complete, confirming that the FA reaction was truly a manifestation of an M anti-M protein system. The data indicate that the development of FA reagents specific for the streptococcal types is feasible.