Evaluation of antibody response to outer membrane proteins of Brucella abortus S99 by Enzyme Linked Immunosorbent Assay

Currently, antigenic determinants of Brucella cell wall such as outer membrane proteins (OMPs) and lipopolysaccharide (LPS) are considered as potential candidates to develop subunit vaccines. It has been shown that OMPs of Brucella abortus along with other bacterial components could stimulate synthesis of specific IgG antibody in rabbits. The aim of present study was evaluation of antibodyresponse to OMPs of Brucella abortus S99 by ELISA method. OMPs were extracted by deoxycholate extraction technique and further purification performed by sequential centrifugation and ultracentrifugation. Protein concentration determined by using the Nano drop ND – 10000. Sodium dodecyle sulfate polyacryl amid gel electrophoresis (SDS – PAGE) was used toproduce a profile of OMPs proteins which these were further differentiated on the basis of molecular weight.By using this method, the class II proteins belongs to porins, which comprised the major OMPs in B. abortus were purified. The groups consisted of 3 rabbits were immunized with three different compounds comprises of OMPs only, combined with LPS and combined with complete Freund's adjuvant (CFA). Sera from immunized animals were then evaluated for specific antibody response. the most immunogenic compounds were LPS+ porins and CFA+ porins and could promoted specific antibody response in experimental animals. The level of specific antibodies in rabbits immunized with above mentioned combinations was significantly higher compared to immunized rabbits with porins only (P<0.05). Based on the results, the combination of LPS+ porins can produce long term protective immunity against Brucella. So it could be probably considered for developing of subunit vaccine for prevention of human brucellosis.