PARTIAL CHARACTERIZATION OF STREPTOCOCCUS-SUIS TYPE-2 HEMOLYSIN

Streptococcus suis type 2 was evaluated for hemolysin production. Supe rnatants of S. suis type 2 grown in Todd-Hewitt broth were assayed for hemolytic activity by a photometric assay. Twenty-two additional sero types of S. suis (1, 3 to 22, and 1/2) were evaluated for hemolysin pr oduction; nine of them (1/2, 1, 4, 5, 14, 15, 17, 19, and 20) were pos itive. The effects of temperature, atmosphere, centrifugation, sonicat ion, chemicals, bovine serum albumin, fetal calf serum, and enzymes on S. suis type 2 hemolysin activity were studied. Maximum hemolysis occ urred after incubation in RPMI 1640 medium at 40 degrees C in 6% CO2 a nd after growth in Todd-Hewitt broth at 37 degrees C under anaerobic c onditions. Hemolytic activity was absent after the addition of fetal c alf serum and decreased after the addition of trypsin or amylase. Howe ver, treatment of erythrocytes with amylase or trypsin prior to incuba tion with supernatant also resulted in a decrease in hemolytic activit y. The addition of bovine serum albumin caused increased hemolytic act ivity. Dipyridyl and EDTA had negligible effects on hemolysis. Hemolyt ic S. suis type 2 culture supernatant injected intraperitoneally faile d to cause death in BALB/c mice. Data from our study indicate that S. suis type 2 hemolysin is a secreted or loosely cell bound, thermolabil e molecule whose activity is growth condition dependent.