Evaluation of a competitive immunochromatographic strip based on B. neotomae LPS for detecting antibodies against B. melitensis and B. abortus in cattle and goats.

Effective brucellosis control necessitates rapid serological screening assays suitable for on-site deployment. B. neotomae, a smooth Brucella species handled under lower-containment conditions, is a potential alternative source of lipopolysaccharide (LPS) antigen. This study aimed to develop and evaluate a competitive colloidal gold immunochromatographic strip based on B. neotomae LPS for detecting antibodies against B. melitensis and B. abortus in cattle and goats. A screened LPS-reactive monoclonal antibody, mAb 1B4, was incorporated into a dual-label format with an independent control line. The strip detected Brucella Positive National Standard Antiserum at 5.0 IU/mL, whereas the detection limit of the Rose Bengal test (RBT) exceeded 20 IU/mL. No cross-reactivity was observed with the limited panel of sera positive for Escherichia coli O157, Salmonella Dublin, Yersinia enterocolitica O:9, or rough Brucella. The strip also showed good repeatability and stability. Using commercial competitive ELISA (cELISA) as the confirmatory method, overall agreement was 97.37% ((kappa = 0.94) for goat sera and 98.75% ((kappa = 0.98) for cattle sera, both higher than the corresponding values for RBT. These findings indicate that the B. neotomae LPS-based strip has the potential to serve as a rapid preliminary screening assay for detecting antibodies against B. melitensis and B. abortus in cattle and goats. Further validation using larger, geographically diverse serum panels with well-defined infection and vaccination status is warranted before broader field application.