Humoral antibody responses of swine infected experimentally with group E streptococcus. II. Antistreptokinase and antistreptodornase responses.

Swine infected experimentally with group E Streptococcus (GES) produced significant antibody titers against streptokinase (streptococcal fibrinolysin, SK) and streptodornase (streptococcal deoxyribonuclease, SD). The antibodies directed against SK (antistreptokinase, ASK) appeared two to nine weeks postexposure and persisted for the duration of the experiment (nearly six months). The ASK inhibited SK produced by GES antigenic types III, IV, and V, by GES devoid of type specific antigen, and by a group P Streptococcus. Selected strains of GES serotypes I and II and group U Streptococcus did not produce detectable SK. The antibodies directed against SD (antistreptodornase, ASD) appeared two to three weeks postexposure, reached a peak about six weeks postexposure, and persisted at high levels for nearly six months (the duration of the experiment). The ASD inhibited SD produced by all known antigenic types of GES, by GES devoid of type specific antigen, and by strains of groups P and U Streptococcus. The antibodies failed to inhibit SD produced by group C Streptococcus. The potential utilization of ASK and ASD titers as serological means of identifying swine infected with GES (carrier swine) is discussed.