Immunization of rabbits and inbred mouse strains with streptococcal vaccines may induce the production of high concentrations of group-specific antibodies that not infrequently show a considerable reduction in molecular heterogeneity (1, 2). Genetically, the degree of heterogeneity and the magnitude of the immune response to the streptococcal Group A and C polysaccharides appear to be independent variables (3). In addition, selective breeding for restricted antibodies is associated with limited idiotypic variability (4)3 Similar studies were now extended to the streptococcal Group A-variant polysaccharide as an antigen that chemically and serologically constitutes the backbone of the Groups A and C carbohydrates (5, 6). A random and a related group of rabbits were used for antibody production. The d a t a suggest that immune responsiveness to the A-variant polysaccharide is also controlled b y genetic factors that again influence the magnitude and the degree of restriction as independent variables. These systems appear to be different from the situation where the pneumococcal Types I I I and V I I I antigens were used for immunization (7,8), although recently suggestive evidence is at hand that in this latter situation genetic factors may be operative as well. 2 Materials and MethodsThe major source of rabbits was the closed colony of the Statens Serum Institute, Copenhagen. A second group of rabbits consisted of progeny bred for high and restricted response to the Group C polysaccharide (3). They all originated from one breeding pair 3 (9).Vaccines from Group A-variant, strain A486 var. M--, and Group C, strain C74, streptococci were prepared as previously described (9). The group polysaccharide concentration 1 Braun, D. G., and A. S. Kelus. 1973. Idiotypic specificity of rabbit antibodies to streptococcal group-polysaccharides.

Antisera raised in rabbits against two nontypable group B streptococci, which were not agglutinable in a specific group B antiserum, were tested with acid extracts of 78 nontypable human group B streptococci. One antiserum (12351) reacted with 15 strains, and the other (7271) reacted with only 2 strains. Antiserum to Wilkinson's strain SS 1169 (NT 1) reacted with three strains. Antiserum against strain 12351 appears to be a useful antiserum against a new type antigen, which is probably polysaccharide in nature.

The main part of strains of Streptococcus mutans isolated from the present Danish material of blood from patients with subacute endocarditis and from human teeth belonged to two of five serotypes established by Bratthall, viz. type c and type e. Two new types were established: type f and type g. Strain SL‐1 seems to constitute a distinct type. Strains of serotypes a and b have not been isolated in Denmark, and strains of serotypes d, g and SL have been isolated from teeth only. The registered differences in biochemical behaviour warrant a proposal of a subdivision into three biotypes.

A total of 252 strains of group B streptococci were serotyped and examined for their ability to ferment lactose (lac+), to hydrolyze salicin (sal+), and to produce hyaluronidase (hy+). Of these strains, 67 had been isolated from bacteremia and meningitis in infants less than 2 months old. Eighty-one strains were isolated from bacteremia and meningitis in adults, and 104 strains were from various other infections. Type III was the most common in neonatal disease, especially if isolates from cases of bacteremia in infants less than 10 days of age were not included. Only 6% of the strains were lac+. Sal+/hy+ strains were never type III, but 91% of the strains belonging to the other serotypes were sal+/hy+. Results showed that 81% of the sal+/hystrains and 95% of the sal-/hy+ strains were type III, and sal-/hy+ strains were more than twice as frequent as sal+/hystrains in serious neonatal infections, in contrast to the other two disease groups, in which the opposite was found to be the case. These reactions may be used as additional markers in epidemiological studies.

Sixty‐six strains of R, S, and RS streptococci could be distinguished from other species of streptococci by their ability to ferment inulin and glycogen and to hydrolyze arginine, combined with resistance to optochin. Likewise, they were easily recognizable serologically. The capsular reaction test is the test of choice.