Background: Brucellosis is one of the five common bacterial zoonoses caused by a gram negative, non-spore forming, and facultative intracellular bacterial organism belonging to the genus Brucella. Although brucellosis is considered as a health problem for both men and domestic animals in many countries, any licensed human vaccine has not been designed and produced for it yet. To overcome the problem, currently, antigenic determinants of Brucella cell wall e.g. outer membrane proteins [OMPs] and lipopolysaccharide [LPS] are considered as potential candidates to develop subunit vaccines.

Materials and Methods: Brucella abortus S99 used in the present study is obtained from the standard bacterial collection of Institute Pasteur of Iran. OMPs were extracted by deoxycholate extraction technique and further purification performed by sequential centrifugation and ultracentrifugation. Protein concentration was determined using the Nanodrop ND–10000 spectrophotometery. SDS-polyacrylamied gel electrophoresis (SDS–PAGE) was performed to determine the electerophoretic pattern and the molecular weight of the extracted OMP samples. Results: OMPs concentration of B.abortus S99 has been measured and reported as 6.27 mg/ml. SDS-PAGE analysis indicated one protein band in the range of 36-38 kDa which would be classified as the porins of B.abortus S99.

Conclusion: Extraction of B.abortus S99 OMPs with the applied method in the present study produced a satisfactory yield of OMPs. These proteins belonging to the second group of OMPs, called porins.