Abstract
On typing of 90 strains of bovine Group-B streptococci (B-str.) from 21 herds, NT1, NT2 and NT3 antigens were found in 30 %, viz., NT1 in 14.4 %, NT2 in 3.3 %, and NT3 in 12.2 %. In 9 of the 21 herds examined (43 %) one or other of these antigens was found. Among 8 strains from 4 herds of Herd type NT the NT1 antigen was demonstrated once. In 5 herds of Herd type X, 20 strains were typed, and 9 isolates (45 %) from 3 herds (60 %) carried one or other of the three antigens. Among herds in which the herd type was referable to polysaccharide antigens of the accepted set, NT3 antigen was present in 1 herd of Herd type Ia, namely along with IaX antigens in two strains, and with Ia antigen in one. In 3 herds of Herd type Ibc and in 2 herds of Herd type Ib no NT1, NT2, or NT3 antigen was demonstrated. On the other hand, such antigens were found in all of 4 herds of Herd type III, being present in 50 % of the strains (14/28) examined, and the frequency of NT1, NT2, and NT3 antigens was only slightly higher among NT and X strains (10/19 or 53 %) than among III and IIIX strains (4/9 or 44 %). The NT2 reference strain carried the Ibc protein antigen. In addition to strong homologous reactions, NT1 antiserum reacted with B-str. group antigen, NT2 antiserum with Ibc antigen, and NT3 antiserum with the NT1 reference strain. It is concluded that the NT1, NT2, and NT3 antigens are of doubtful value in epidemiological studies on bovine infections with group-B streptococci.