Serological Evaluation of Brucella abortus S99 Lipopolysaccharide Extracted by an Optimized Method

Hojat Ahmadi,Parichehr Yaghmai,Dariush Norouzian,Ali Sharifat Salmani,Mohammad Reza Aghasadegh,Seyed Davar Siadat,Mohammad Reza Fallahian

doi:10.3844/ajidsp.2009.11.16

Abstract

Problem statement: Brucellosis is a globally found infectious disease and there is no licensed vaccine against human brucellosis. The present study carried-out to evaluate the potency of our modified extracted lipopolysaccharide (LPS) of B. abortus to elicit specific anti-Brucella antibodies in animal model (Rabbit) as a part of a candidate vaccine for brucellosis. Lipopolysaccharide is one of the main virulence factors and the most immunogenic structure of smooth strains of Brucella. Approach: Lipopolysaccharide of B. abortus S99 (S-LPS) initially extracted through an optimized method as described previously. After biochemical and pyrogenicity evaluations of the extracted S-LPS humoral immune response against the extracted LPS analyzed in animal model through serological assays such as Rose Bengal assay, Rapid agglutination (Rapid Wright) test and Standard agglutination test (SAT or Wright test) to demonstrate the specific elicited antibodies against the injected LPS. In addition, the interaction of LPS and anti-LPS antibodies was demonstrated by Agarose Gel Immunodiffusion (AGID) assay. Results: Higher doses of B. abortus S99 LPS caused less or equal body temperature increase in comparison to E. coli LPS doses. Sera of immunized animals had been reported positive by RBT because of B. abortus LPS immunogenicity which we extracted through our optimized method. The highest titer of anti-Brucella antibodies detected two weeks after the third immunization (assayed by rapid slide agglutination and standard agglutination tests). Anti-Brucella antibodies of immunized animals reacted more specifically with the LPS of B. abortus in comparison with E. coli LPS and precipitation lines between B. abortus LPS and immune sera appeared after 30 min while detected after three hours for E. coli LPS. Conclusions/Recommendations: The properties of B. abortus S99 LPS concluded from the present study results, suggest the possible use of this component as a carrier or a part of a sub-unit or conjugated vaccine for human brucellosis.

Highlights

Detection of synthesized antibodies against B. abortus S99 LPS: Presence of Anti-Brucella abortus S99 LPS in the sera of immunized animals demonstrated by Rose Bengal test (RBT), Serum Agglutination Test (SAT) (tube agglutination and rapid slide agglutination) and Agarose Gel-Immuno Diffusion (AGID)[16]
The diagnosis must be confirmed by isolation of Brucella, mostly from blood culture or Brucella abortus is a bacterium that can cause by the detection of an immune response to its antigens abortions in cattle and a debilitating fever (undulant such as lipopolysaccharide (LPS)
Detection of synthesized antibodies against B. abortus S99 LPS: Presence of Anti-Brucella abortus S99 LPS in the sera of immunized animals demonstrated by Rose Bengal test (RBT), Serum Agglutination Test (SAT) and Agarose Gel-Immuno Diffusion (AGID)[16]

Summary

Introduction

Detection of synthesized antibodies against B. abortus S99 LPS: Presence of Anti-Brucella abortus S99 LPS in the sera of immunized animals demonstrated by Rose Bengal test (RBT), SAT (tube agglutination and rapid slide agglutination) and Agarose Gel-Immuno Diffusion (AGID)[16]. Rapid slide agglutination test: Titer of anti-Brucella antibodies in the sera of immunized animals, taken 2 weeks after the first, second and third immunization reported to be 160, 320 and 640, respectively while no agglutination has been observed in the negative control (Table 2).

Results

Conclusion