An Indirect Enzyme-Linked Immunosorbent Assay to Detect Antibodies against Brucellosis in Cattle or Humans

Brucellosis is a zoonotic disease with global spread. It is also a well-known endemic infectious disease in Iran. Therefore، its appropriate and rapid diagnosis has a critical role in public health improvement. The purpose of this research was to design an indirect enzyme-linked immunosorbent assay (ELISA) kit for detection of brucellosis in humans or animals. Such a kit can replace serum agglutination test (SAT) and kits imported from foreign countries. Smooth lipopolysaccharide (S-LPS) of Brucella melitensis and Brucella abortus were used as antigens to coat ELISA microplates. Indirect ELISA was performed on 51 human serum samples (10 positive and 41 negative samples) from patients who had referred to laboratories in Tehran، Sari and Hamadan (Iran). It was also performed on 78 bovine serum samples (30 positive and 48 negative samples) that had been sent to veterinary laboratories in Alborz Province (Iran). All samples were also evaluated by SAT. The designed ELISA kit could detect all 40 positive serum samples (10 human and 30 bovine samples) as positive and all 89 negative serum samples (41 human and 48 bovine samples) as negative. The sensitivity and specificity of the bovine kit were thus determined as 100% and 95. 83%، respectively. The corresponding values for the human kit were 100% and 97. 56%. On the other hand، the combined kit had a sensitivity of 100% and a specificity of 96. 73%. The estimated cutoff point was calculated as 0. 13. The designed ELISA kit uses two conjugates and is hence able to detect brucellosis in animals or humans at the same time. In general، high sensitivity and specificity and shorter required time are among the superiorities of our kit over similar ELISA kits.