For the passive immunization, the 200 μL of antiserum was injected intraperitoneally into naïve mice (n = 3 per group). Control group received the serum obtained from mice, immunized with PBS and Freund’s adjuvant. After 6 h, 5 × 107 CFU of AbIC I bacteria were injected intraperitoneally. After experiments mice were sacrificed using cervical dislocation.