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Page No. : 19-25

ABSTRACT

Listeria monocytogenes is an important food borne pathogen with very high case fatality rate, thus drawing the attention for its rapid detection in foods, especially of animal origin for safeguarding the public health. A Competitive-ELISA (c-ELISA) using polyclonal antibody directed against specific cell surface proteins (75 and 60 kDa) was developed for rapid detec-tion of Listeria monocytogenes. The minimum detection limits of the assay were 5x104 cells and 1x108 cells for anti-75 kDa and anti-60 kDa sera, respectively. Both the polyclonal antibodies showed cross-reactions with E. coli and V. cholera. However, both of these pathogens were unable to grow in the enrichment media i.e. modified University of Vermont broth and Listeria enrichment broth used for isolation of Listeria spp. Among listerial species tested for cross-reactions, L. ivanovii and L. siligeri showed slight cross-reactions with anti-75 kDa serum, whereas L. welshimeri, L. innocua, L. seeligeri, cross-reacted with anti-60 kDa serum. The storage life of pre-coated and blocked ELISA plates at 4°C was found to be 4 months.

Keywords: C-ELISA, Cross-reaction, CSP, Listeria, Minimum detection