title: Evaluation of the Immunogenicity of Diphtheria Toxoid Conjugated to Salmonella Typhimurium-Derived OPS in a Mouse Model: A Potential Vaccine Candidate Against Salmonellosis.
abstract: BACKGROUND
  Salmonella enterica serovar Typhimurium (S. Typhimurium) causes gastroenteritis in humans and paratyphoid disease in some animals. Given the emergence of antibiotic resistance, vaccines are more effective than chemotherapy in disease control.
  
  
  OBJECTIVE
  The aim of this experimental study was to evaluate the immunogenicity of diphtheria toxoid (DT) conjugated with S. Typhimurium -derived OPS (O side chain isolation) in mice to determine its potential as a vaccine candidate against salmonellosis.
  
  
  METHODS
  Lipopolysaccharide (LPS) was extracted from the bacterial strain. After isolation of the O side chain of LPS, detoxification, and conjugation of the detoxified OPS samples with DT, pyrogenicity, toxicity, and sterility tests were performed. To vaccination, four groups of female Balb/c mice were used in an immunization test. Antibody responses were measured by the ELISA method. Challenging processes were performed to analyze the efficacy of the OPS-DT compound.
  
  
  RESULTS
  Two weeks after the first vaccination dose, there was no significant difference in the antibody titers of the OPS and OPS-DT groups. However, after the second and third doses, the antibody titers of the OPS-DT group increased significantly compared with those of the control groups (P < 0.001). The induction of anti-OPS antibodies was as follows: OPS-DT>OPS. The most anti-OPS IgG antibody was IgG1. Challenging procedure showed successful protective characteristics in clinical examinations.
  
  
  CONCLUSIONS
  The results indicated that DT increased anti-OPS antibodies against the OPS-DT compound. The antibody response to OPS-DT was greater than that to OPS alone. We conclude that OPS-DT is an appropriate and acceptable vaccine candidate against salmonellosis.
authors.affiliation: Department of Microbiology, Zanjan Branch, Islamic Azad University, Zanjan, IR Iran.
authors.forename: Vahid
authors.initials: V
authors.lastname: Amini
authors.affiliation: Department of Medical Microbiology, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Kazemian
authors.affiliation: Department of Pathobiology, Division of Microbiology, School of Public Health, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Jalil Kardan
authors.initials: JK
authors.lastname: Yamchi
authors.affiliation: Tehran University of Medical Sciences, International Campus (TUMS-IC), Tehran, IR Iran.
authors.forename: Seifu Gizaw
authors.initials: SG
authors.lastname: Feyisa
authors.affiliation: Department of Immunology, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Aslani
authors.affiliation: Department of Medical Microbiology, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran.
authors.forename: Aref
authors.initials: A
authors.lastname: Shavalipour
authors.affiliation: Department of Medical Microbiology, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran.
authors.forename: Hamidreza
authors.initials: H
authors.lastname: Houri
authors.affiliation: Department of Microbiology, Kurdistan Science and Research Branch, Islamic Azad University, Sanandaj, IR Iran.
authors.forename: Mohammadneshvan
authors.initials: M
authors.lastname: Hoorijani
authors.affiliation: Department of Bacteriology and Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran.
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Halaji
authors.affiliation: Department of Bacteriology and Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Heidari
keywords: DT; ELISA; OPS; Salmonella Typhimurium; Vaccine Candidate