Temperature-dependent Variation in the Synthesis of Group-specific Carbohydrate by Streptococcal Variant Strains

A temperature-dependent alteration in the synthesis of the group-specific polysaccharide was found to occur in two "variant" streptococcal strains, A-486-Var and C 121/46/4. These strains synthesize a polysaccharide with variant immunochemical characteristics when grown at 37 degrees C. However, when these organisms are grown at lower temperatures, 22 degrees C, an enhanced synthesis of Group A carbohydrate occurs. Other variant strains show no appreciable alteration of the cell wall carbohydrate composition when grown at lower temperatures. Studies on an intermediate strain show that this organism has a propensity for the synthesis of a polysaccharide with higher glucosamine content and enhanced Group A serological reactivity when grown at 22 degrees C. Immunochemical studies performed on the carbohydrates produced by the A-486-Var at various temperatures revealed that the appearance of Group A serological reactivity at lower temperatures is due to the additional synthesis of a polysaccharide with Group A specificity along with the continued synthesis of a variant carbohydrate. This finding contrasts with data obtained on the carbohydrate produced by the intermediate organisms that appears to consist predominently of one molecule bearing dual A and variant antigenic determinants.