Human heat-shock protein 60 receptor-coated paramagnetic beads show improved capture of Listeria monocytogenes in the presence of other Listeria in food.

AIMS

To investigate the suitability of human Hsp60, a receptor for Listeria adhesion protein (LAP), on paramagnetic beads (PMB) to capture Listeria monocytogenes from food in the presence of other Listeria to facilitate rapid and specific detection of this pathogen.

METHODS AND RESULTS

Commercially available streptavidin-coated PMBs were linked with biotinylated Hsp60 (PMB-Hsp60), and the bacterial capture efficiency from pure culture and meat samples was determined. Capture rate was also compared with the monoclonal antibody (MAb)-C11E9-coated beads (PMB-C11E9) and the commercial Dynabeads anti-Listeria. Captured cells were detected and quantified by plating on selective medium, quantitative real-time PCR (qPCR) and a light-scattering sensor. Overall, all ligand-coated beads had similar capture efficiency (varied from 1·8 to 9·2%) for L. monocytogenes under the conditions employed, and the minimum cell number required to achieve such capture was 10³ CFU ml⁻¹. PMB-Hsp60 had significantly greater capture efficiency for pathogenic Listeria (P < 0·0001) than the nonpathogenic Listeria. In contrast, PMB-C11E9 and Dynabeads anti-Listeria had similar capture efficiency for both. The efficacy of all PMBs to capture L. monocytogenes in the presence of Listeria innocua from food matrices was compared. Although Dynabeads anti-Listeria had the overall best capture efficiency, PMB-Hsp60 was able to selectively capture L. monocytogenes even in the presence of 10-100-fold more L. innocua cells from enriched meat samples.

CONCLUSIONS

Data show that the human cell receptor, Hsp60, is suitable for the capture of pathogenic Listeria on PMB in the presence of other Listeria in food.

SIGNIFICANCE AND IMPACT OF THE STUDY

As pathogen interaction with host cells is highly specific, host cell receptors could be used as alternate capture molecules on PMB to aid in specific detection of pathogens.