Bovine Respiratory Disease Associated Mannheimia haemolytica Serotype A:1 Outer Membrane Vesicles Immunogenicity
Bovine Respiratory Disease Associated Mannheimia haemolytica Serotype A:1 Outer Membrane Vesicles Immunogenicity
Mirtneh Akalu1,2*, Takele Abayneh2, Esayas Gelaye2, Behailu Tefera2, Teferi Degefa2, Vemulapati Bhadra Murthy1
ABSTRACT
Outer membrane vesicles (OMVs) of Mannheimia haemolytica present a wide range of surface antigens. This study was designed to evaluate the immunogenic potential of M. haemolytica serotype A:1 OMVs (MH-OMVs). Fifteen calves were divided randomly into three groups of five calves and immunized with single-dose and booster-dose of 0.15 mg/ml vesicle preparation. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) assay of the partially purified MH-OMVs revealed approximately ten protein bands ranging from 25 to 104 kDa. Hemagglutination inhibition (HI) assay confirmed that the immune response was significantly increased in both single-dose and booster-dose immunized groups as compared to calves in the control group. Calves in booster-dose group reach its peak geometric mean (GM) log10 HI antibody titer (3.46 ± 0.06) at the 42nd day. Whereas calves in the single-dose immunized group reach the peak GM 1og10 HI titer (2.79 ± 0.13) at day 28th post immunization (p < 0.05). Challenged calves showed the lowest mean clinical respiratory sign score in booster-dose immunized calves (1.2 ± 0.35) than in the single-dose group (4.2 ± 0.51) but the highest score was noted in the control group (6.2 ± 1.01). Hence, the current finding revealed that booster-dose-based immunization was found to induce protective level of immune response to protect calves from infection. Therefore, the booster-dose immunization schedule may be useful in inducing higher and maintaining longer protective antibody titer in calves.
Keywords | Calve, HI antibody titer, Immunization, M. haemolytica, Outer membrane vesicle
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