Hemolysin production by Vibrio cholerae as examined by hemolytic and antigenic activities.

Abstract

The hemolytic and antigenic activities of 36 strains of Vibrio cholerae O1 biotype El Tor, and 63 strains of Vibrio cholerae non-O1 isolated in Argentina were studied. Only 8% in stationary culture and 11% in shaking culture were hemolytic when the heart infusion broth (HIB) culture supernatants of V. cholerae O1 were examined. However, these percentages increased to 94% and 22% respectively when the strains were grown in HIB supplemented with 1% glycerol. On the other hand, most strains of V. cholerae non-O1 (97%) were hemolytic in both stationary and shaking HIB culture supernatants. The antigenic activity detected by reversed passive latex agglutination method (RPLA) varied markedly from strains and culture conditions; ranging from below the detection limit to 16, 000 ng/ml. The optimal condition of hemolysin production varied with the strain, but a stationary culture was preferable to obtain high hemolytic activity and shaking culture to obtain a large amount of hemolysin antigen. The comparison of the hemolytic and antigenic activities showed that the hemolysin is readily inactivated in the culture supernatant, especially in the case of V. cholerae O1. These findings suggested the presence of some potent inactivation factor (s) in El Tor vibrios.