Production of Antisera Against Brucella Abortus in Rabbits and Its Use in Immunohistochemistry to Detect Brucella Abortus Antigen in Spleen of Aborted Bovine Fetus in Bangladesh

Background: Brucellosis is one of the most important emerging zoonotic chronic diseases distributed worldwide since the discovery of Brucella melitensis by Bruce in 1887. This disease is specifically hindering animal productivity and human health in developing countries, which has led the WHO to classify it as one of the world's most important neglected zoonotic diseases. The isolation of Brucella from host tissues, milk, vaginal exudates, etc. continues to be the “gold standard”, followed by bacteriological characterization. However, it is time-consuming and has low sensitivity because Brucella is a fastidious microorganism that can easily be overgrown by other contaminating bacteria. To overcome these adversities, visualization of antigen-antibody interaction assays has been tried for safe and timely diagnosis ahead of conventional isolation. Immunocytochemistry and immunohistochemistry techniques have been used to detect Brucella abortus antigen and it is mainly based upon staining with species-specific monoclonal or polyclonal antibodies. Objective: The main objective of this study is to produce polyclonal antisera against Brucella abortus and its use in immunocytochemistry for the detection of Brucella isolates in clinical samples. Materials and Methods: A total of 10 rabbits were selected for 2 groups consisting of 7 tests and 3 controls. From 7 test samples pooled polyclonal antisera against Brucella abortus was prepared in the same way pooled sera was prepared from control. Brucella abortus strain RB 51 was administered subcutaneously at 21-day intervals on rabbits three times. Blood samples were collected at 21-day intervals and antisera were prepared by centrifugation of the sera at 20000 rpm for 15 minutes and preserved in a deep freezer in the laboratory. Sections of the spleen from aborted fetuses clinically suspected of brucellosis were processed and immunohistochemistry (ICH) was performed. Results: The sample was immune stained with a developed polyclonal Brucella antibody. It gave a brown color positive reaction in the macrophage of the spleen. The immune-stained slides were visualized using a photographic microscope. The results of this study showed that the immunohistochemical technique was sufficiently sensitive for detecting B. abortus antigens in formalin-fixed tissues of artificially inoculated B. abortus RB 51 strain in rabbits. Conclusions: Further studies are necessary to detect the sensitivity of this test for the diagnosis of brucellosis abortion cases in ruminant animals and to find the possibility of using this immunochemical technique as a complementary tool to serology and bacteriology for the diagnosis of brucellosis.