New Brucella Abortus S19 Mutant to Improve Distinction between Infected and Vaccinated Animals

Document Type: Short Paper


1 Department of Microbiology, Faculty of Veterinary Medicine, University of Tehran.

2 Department of Microbiology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.

3 Department of Bioscience and Biotechnology, Malek-Ashtar University of Technology, Tehran, Iran.

4 Department of Brucellosis, Razi Vaccine and Serum Research Institute, Agricultural Research Education and Extension Organization(AREEO), karaj, Iran.

5 department of microbiology,faculty of veterinary medicine,university of tehran iran


Background: Using Brucella abortus Strain 19 (S19) to control bovine brucellosis is restricted due to induce antibodies to the O-side chain of the smooth lipopolysaccharide (LPS) which may be difficult to differentiate vaccinated and infected animals. Furthermore, it is virulent for humans and can induce abortion to cattle. Objectives: The aim of this study was to employ gene knockout B. abortus S19 to eliminate diagnostic defects and obtain the attenuated mutant strain. Materials and Methods: The wbkA gene, which is one of the LPS O-chain coding genes, was knocked out in vaccinal Brucella abortus Strain (S19). The proliferative response and immunoglobulin M production were analyzed in wbkA deletion strain-infected BALB/c mice. Results: The loss of wbkA gene function resulted in induction of the splenocyte proliferative response in mice infected by the mutant S19 strain compare to those induced by parental S19 and RB51 strains. Moreover, wbkA mutant did not induce any IgM antibody response using the enzyme-linked immunosorbent assay. Conclusions: As a result, the new mutant S19 strain had deficiency in its LPS O-chain structure, besides can not induce IgM response then, reduce mistakes to discriminate between vaccinated and infected animal, and also can be considered as a new vaccine candidate.
Keywords: Brucella abortus S19, Mutant S19 strain, WbkA, Gene knock out


Main Subjects