Abstract
The hemolytic activity of pneumolysin produced by Streptococcus pneumoniae depends on the culture medium used for bacterial growth. In brain-heart infusion broth, both the culture medium and bacterial cell supernatants from all strains induced erythrocyte lysis and contained pneumolysin, which was detected using sandwich ELISA based on IgM and IgG1-HRP monoclonal antibodies to native pneumolysin. In contrast, samples obtained from strains grown on blood agar exhibited virtually no hemolytic activity, despite the presence of pneumolysin at high concentrations. These findings suggest that the culture medium affects the production of functionally active pneumolysin by pneumococcal strains. The developed sandwich ELISA based on monoclonal antibodies allows detection of pneumolysin that has lost its hemolytic properties.