Antigenic analysis of pasteurella multocida mutant strains by SDS-PAGE and Western blot

Abstract

The study of virulence and protective immunity in ducks against challenge with p. multocida strain Pm-vac showed that p. multocida mutant strains 2T35, 2/1U3 and 1S24 were low virulent, but 3T5, 2/1U2 and 1S15 were high virulent. p. multocida 2T35, 3T5 and 2/1U2 were high protection and 2/1U3, 1S15 and 1S24 were low protection. Analysis of antigen extracts by SDS-PAGE of strains Pm-vac, 3005, 2T35, 2/1U2 and 1S24 revealed their differences in intensities and in major and minor protein patterns among antigen extracts and strains of p. multocida. The similar protein bands of their KSCN antigen extracts were observed at 36, 38, 58, 60, 61, 63, 77, and 80 kDa. Protein profiles of capsule were similar at 36, 38, 58, 60 and 63 kDa. Similar outer membrane proteins (OMP) at 29, 31, 38 and 48 kDa were observed. All strains expressed lipopolysaccharide (LPS) at 7 kDa. The immune response of rabbit against various antigens of p. multocida were analyzed by ELISA. The antibody titers were detectable at day 21 after first immunization and had high antibody titers of 103-106 at days 35-49. The titers were gradually decreased with times, but the titers of 103-105 were still observed at days 70-90. The sonicated cells of Pm-vac, 3005, 2T35 produced higher antibody titers than that of whole cell antigen, KSCN antigen extract and capsule showed similar immune response. The study of specificity of antigen extract to rabbit immune sera by western blot showed that KSCN antigen extract, capsule, OMP and LPS extract showed differences as strong and weak reactions. The immune sera recognized various antigens in each antigen extract at 7, 36, 38, 45, 48, 52, 55 and 77 kDa