ABSTRACT. Salmonella Enteritidis is the most common cause of salmonellosis in humans in South Korea. It has been recognized that the principal source of human infection with S. Enteritidis is chickens and their products such as meat and eggs. A total of 173 S. Enteritidis isolates from humans (65 isolates) and chickens or their products (108 isolates) were analyzed by antibiotic susceptibility assay, phage typing, and pulsed-field gel electrophoresis (PFGE). Drug resistance was found to streptomycin (32.3%), ampicillin (30.6%), nalidixic acid (30.1%), ticarcillin (30.1%), and tetracycline (28.3%). More than 70% of the isolates were found to be resistant to one or more antibiotics tested. The most frequent patterns of resistant isolates were resistance to nalidixic acid only (28.3%) and resistance to two antibiotics (four combinations; 20.2%). The most predominant phage type (PT) was PT1 (27.2%) followed by PT21 (20.8%) and PT4 (8.7%) in chicken and human isolates. Nineteen different PFGE patterns were found among the 173 isolates, and A1 was the most common PFGE pattern, followed by A6 (17.3%). Most S. Enteritis isolates (except two isolates with patterns B and C) showed similar PFGE patterns that differed by only a few bands. These results show that 2 or 3 subtypes of S. Enteritidis are shared to a large extent by humans and chickens. This implies the possibility of the spread of chicken S. Enteritidis to humans.
: This study was focusing on evaluating the protection of polyphosphate kinase (ppk) deleted and/or temperature-sensitive (ts) Salmonella Enteritidis (SE) as an attenuated vaccine in chickens. We constructed SEppk, SEts and SEppk::ts mutants and screened those mutants by growth capability in vitro, protection study in mice model and antibody response in chickens. Among the mutants, SEppk::ts-3 was selected because it showed higher growth capability, good protection against highly virulent SE in mice model, and good antibody response in chickens. SEppk::ts-3 also showed good protection against highly virulent SE isolate because it decreased colonization of virulent SE challenge strain in spleen, liver and cecum compared with the non-vaccinated control. The SEppk::ts-3 mutant showed crossprotection against S. Gallinarum (SG) challenge although the its cross-protection rate was a little lower than that of SG9R, a commercial vaccine against SG infection. To use for live attenuated vaccine in chickens, it should further be characterized.
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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.
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