Proteomic Analysis and Protective Effects of Outer Membrane Proteins from Salmonella Gallinarum in Chickens

Abstract

Salmonella Gallinarum (SG) is known as an important pathogen that causes fowl typhoid in chickens. To investigate SG outer-membrane proteins (OMPs) as a vaccine candidate, we used proteomic mapping and database analysis techniques with extracted OMPs. Also, extracted OMPs were evaluated in several aspects to their safety, immune response in their host and protective effects. Our research has established a proteomic map and database of immunogenic SG-OMPs used as inactive vaccine against salmonellosis in chickens. A total of 22 spots were detected by 2-dimensional gel electrophoresis and immunogenic protein analysis. Eight spots were identified by Matrix-Assisted Laser Desorption/Ionization-Time of FlightMass spectrometry (MALDI-TOF-MS) and peptide mass fingerprinting (PMF) and categorized into four different types of proteins. Among these proteins, OmpA is considered to be an immunogenic protein and involved in the hosts' immune system. To estimate the minimum safety dose in chickens, 35 brown layers were immunized with various concentrations of OMPs, respectively. Consequently, all chickens immunized with more than a 50 µg dose were protected against challenges. Moreover, intramuscular administration of OMPs to chickens was more effective compared to subcutaneous administration. These results suggest that the adjuvanted SG-OMP vaccine not only induces both the humoral and cellular immune response in the host but also highly protects the hosts' exposed to virulent SG with 50 µg OMPs extracted by our method.