title: Comparison of Biological and Immunological Characterization of Lipopolysaccharides From Brucella abortus RB51 and S19.
abstract: BACKGROUND
  Brucella abortus RB51 is a rough stable mutant strain, which has been widely used as a live vaccine for prevention of brucellosis in cattle instead of B. abortus strain S19. B. abortus lipopolysaccharide (LPS) has unique properties in comparison to other bacterial LPS.
  
  
  OBJECTIVE
  In the current study, two types of LPS, smooth (S-LPS) and rough (R-LPS) were purified from B. abortus S19 and RB51, respectively. The aim of this study was to evaluate biological and immunological properties of purified LPS as an immunogenical determinant.
  
  
  METHODS
  Primarily, S19 and RB51 LPS were extracted and purified by two different modifications of the phenol water method. The final purity of LPS was determined by chemical analysis (2-keto-3-deoxyoctonate (KDO), glycan, phosphate and protein content) and different staining methods, following sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). C57BL/6 mice were immunized subcutaneously three times at biweekly intervals with the same amount of purified LPSs. The humoral immunity was evaluated by measuring specific IgG levels and also different cytokine levels, such as IFN-γ, TNF-α, IL-4 and IL-10, were determined for assessing T-cell immune response.
  
  
  RESULTS
  Biochemical analysis data and SDS-PAGE profile showed that the chemical nature of S19 LPS is different from RB51 LPS. Both S and R-LPS induce an immune response. T-cell immune response induced by both S and R-LPS had almost the same pattern whereas S19 LPS elicited humoral immunity, which was higher than RB51 LPS.
  
  
  CONCLUSIONS
  Purified LPS can be considered as a safe adjuvant and can be used as a component in prophylactic and therapeutic vaccines targeting infectious disease, cancer and allergies.
authors: Immunology Lab, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, IR Iran.
authors: Zahra
authors: Z
authors: Kianmehr
authors: Immunology Lab, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, IR Iran.
authors: Sussan
authors: S
authors: Kaboudanian Ardestani
authors: Department of Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran.
authors: Hoorieh
authors: H
authors: Soleimanjahi
authors: Department of Influenza, Pasteur Institute of Iran, Tehran, IR Iran.
authors: Fatemeh
authors: F
authors: Fotouhi
authors: Department of Brucellosis, Razi Vaccine and Serum Research Institute, Karaj, IR Iran.
authors: Saeed
authors: S
authors: Alamian
authors: Department of Biochemistry, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, IR Iran.
authors: Shahin
authors: S
authors: Ahmadian
keywords: Adjuvant; Brucella abortus; Immune System; Lipopolysaccharide