Inhibition of C. perfringens sialidase activity by sialidase inhibitors NADNA and SB. Supernatants were removed from five independent cultures (wild-type CN3718 expresses all three sialidase genes; BMC205 has null mutations in all three sialidase genes [17]; ENanJ expresses only the nanJ gene, ENanI expresses only the nanI gene, and ENanH expresses only the nanH gene) grown for 16 h at 37°C in TH broth. (A) Sialidase activity of wild-type CN3718, ENanJ, ENanI, ENanH, and BMC205 supernatants in the presence of the NADNA sialidase inhibitor (0, 8, 16, and 24 μM). (B) Sialidase activity of wild-type CN3718, ENanJ, ENanI, ENanH, and BMC205 supernatants in the presence of the SB sialidase inhibitor (0, 27.5, 55, 110 μM). All experiments were repeated three times, and mean values are shown. The error bars indicate standard deviations.