The development of indirect and sandwich ELISA-based detection methods for the detection of Campylobacter jejuni using monoclonal and polyclonal antibody preparations

Aims: The current gold standard method for the detection of Campylobacter jejuni is the culturing method followed up by immuno-based detection method, of which, the ELISA is the most often used. Many commercial detection methods based on ELISA use monoclonal antibody preparations although polyclonal antibody can be more sensitive and cheaper to produce. In this study, a comparison of indirect and sandwich ELISA-based detection methods for the detection of C. jejuni using a commercial monoclonal and polyclonal antibody preparations was explored. Methodology and results: An indirect and sandwich ELISA-based methods for the detection of C. jejuni was carried out using the same concentration of antibody (5 mu g/mL) and the same concentration of the bacterium at 1x10(9) CFU/mL. At the pre-screening for optimum concentration of antibody to be used for both assay formats, the commercial monoclonal preparation gave a poor absorbance value of about 0.112 compared to 1.582 for the polyclonal antibody preparation. Hence, the use of the monoclonal antibody was not pursued further. Using the polyclonal antibody, the calculated Limits of Detection (LOD) value obtained for the indirect and sandwich ELISA methods were at 1.6x10(4) CFU/mL and at 1.29x10(4) CFU/mL, respectively, which are more sensitive than commercially used methods. The results of the specificity test obtained from the developed polyclonal antibody were then tested against other common food borne bacterial pathogens such as Salmonella Typhimurium, Listeria monocytogenes and Escherichia coli tested using the sandwich ELISA format indicated that the responses by other bacterial genus were relatively low with the translated cross-reactivity percentages of 1.78, 2.36, and 6.87%, respectively. Conclusion, significance and impact of study: The results indicated that the developed system using a polyclonal antibody preparation can be more sensitive than monoclonal preparation. In addition, it is also specific towards Campylobacter while the monoclonal antibody preparation fares poorly.