The Occurrence of Two M Antigens in Certain Group a Streptococci Related to Type 14

Abstract

The type classification of Group A streptococci depends upon the M proteins, which are imrnunologically different for each type. These antigens are of special importance among the several well studied antigens of this group of streptococci because of their dose association with virulence. They are demonstrable by precipitin tests, and antibodies to them react type-specifically in active and passive animal protection tests and in ingestion and bactericidal tests. There have been described, up to the present time, some 45 types of streptococci, and in each type the determinant has been a single M antigen characteristic of the type.The work reported here shows that most Type 14 streptococci possess two M antigens, the presently recognized M antigen of Type 14 and another M designated here Type 51. A few strains have been encountered possessing the Type 51 M antigen without the Type 14 M antigen and one strain possessed the Type 14 M antigen alone. Mthough it has previously been shown that Group A streptococci may possess more than one T antigen (1), the present work is the first demonstration that strains may have two distinct M antigens. Materials and MahodsStreptococcal Strains.raThe principle strains used in this work are listed in Table I. In addition to these, 34 strains obtained from many sources and covering a wide geographical distribution were tested for their M antigen composition. All strains were preserved by freezing and drying. For routine work strains were grown in neopeptone--sheep blood broth and maintained in the refrigerator at approximately 4°C. To roa~ntaln cultures capable of vigorous multiplication in normal human blood, strains were recovered approximately once a month from the dried state, or as an alternative method, stock blood broth cultures were sometimes given a single intraperitoneal mouse passage.Precipitin tests were performed by the capillary precipitin method using crude acid extracts (2) or M extracts (3).Antlsera were prepared by injecting rabbits three times weekly with heat-killed bacterial suspensions, and collecting serum when adequate antibody content had been achieved. Sera were absorbed with packed hcat-ldlled cells in the desired proportions. We are indebted to the Commtmicable Disease Center, Chamblee, Georgia for absorbed typing sera for many streptococcal types and to Dr. Rebecca C. Lancefield for a generous supply of antiserum prepared against strain Type 14146.

Nucleotide substitutions and small‐scale insertion produce size and antigenic variation in group A streptococcal M1 protein

“…There have been reports of a few strains of GAS which appear to express two M antigenic determinants according to immunological and biological studies. One study reported that most of the M14 strains examined also had the M51 antigen (Wiley and Wilson, 1960). Another study described a strain that possessed a second non-typable M protein in addition to Ml (El Kholy etai., 1975).…”

Cross-Protective Antigens of Group A Streptococci Types 3 and 31 and Types 46 and 51

“…Antigens that stimulate cross-productive antibodies which act in only one direction have been reported in types 13 and 48 (6), types 14 and 51 (11), types 43 and 41 (12), and, in this paper, in types 46 and 51. The presence of bactericidal antibodies for type 46 and type 51 cocci in unabsorbed type 46 antiserum and the absence of reciprocal bactericidal antibodies in type 51 antiserum are analogous to the one-way cross reported by Wiley and Wilson for types 14 and 51 (11). Thus, although one can conclude that both types 14 and 46 cocci may contain type 51 M protein in addition to their homologous M protein, its presence in the two types appears to be dependent upon different factors.…”

“…Thus, although one can conclude that both types 14 and 46 cocci may contain type 51 M protein in addition to their homologous M protein, its presence in the two types appears to be dependent upon different factors. In a study of 42 strains previously identified as type 14, Wiley and Wilson (11) found that 37 of the strains possessed both type 14 and type 51 M protein, 4 strains had only type 51 M protein, and 1 strain had only type 14 M protein. Representive strains of each type, that is, types 14, 14-51, and 51, were isolated from patients with streptococcal infections.…”

“…In addition, Fox and Wittner (2) reported cross-protective antibodies in serum from children with upper respiratory infections caused by either types 3 or 12 group A streptococci. Common protective antigens have been reported between the following established types: types 2 and 48 (9), 3 and 12 (2), 13 and 48 (6), 14 and 51 (11), and 33, 41, 43, 52, and 53 (12). In addition, Wiley and Bruno (12,13) have described cross-protective antigens between established types and several uncertain types of group A streptococci.…”

Cross-Reactions Among Group a Streptococci

“…Indirect Bactericidal Tests.--The details of this test are given in another publication from this laboratory (7). Briefly, it consists of rotating mixtures of dilutions of streptococci grown in filtered beef heart infusion broth (0.1 ml), normal rabbit serum or antiserum (0.05 ml), and heparinized normal human blood (0.25 ml) in silicone-stoppered, 7 X 10 mm glass test tubes for 3 hr at 37°C.…”