Monoclonal antibody-based cross-reactive sandwich ELISA for the detection of Salmonella spp. in milk samples

Abstract

An immunogen consisting of Salmonella lipopolysaccharide and bovine serum albumin was prepared by periodate oxidation. Mice sera cross-reacted with strains of the genus Salmonella. Monoclonal antibodies (mAbs) against the Salmonella lipopolysaccharide core structure were obtained after cell fusion. Based on mAb 6E8, a cross-reactive sandwich enzyme-linked immunosorbent assay was developed. The detection limit of different strains in the genus Salmonella ranged from 1.56 × 10⁶ to 1.25 × 10⁷ colony-forming units ml⁻¹. No cross-reactivity was observed with other bacterial strains tested, including Cronobacter sakazakii, Escherichia coli O6, E. coli strain O157 : H7, Campylobacter jejuni and Listeria monocytogenes. Samples of bovine milk spiked with 1 colony-forming unit ml⁻¹Salmonella spp. were analysed following enrichment for 24 h.