Development and evaluation of aptamer magnetic capture assay in conjunction with real-time PCR for detection of Campylobacter jejuni

A prototype method for the concentration and detection of Campylobacter jejuni was developed using a previously reported biotinylated DNA aptamer in conjunction with qPCR. The so-called aptamer-based magnetic capture-qPCR (AMC-qPCR) assay was compared to a similar immuno-magnetic separation (IMS)-qPCR assay. In small volume experiments (300 mu l) applied to serially diluted C. jejuni suspended in buffer containing a mixed culture of other common food borne pathogens, the lower detection limit of the AMC-qPCR method was 1.1 log(10)/300 mu l C. jejuni cells, one log(10) better (lower) than that of IMS-qPCR (2.1 log(10) CFU/300 mu l). AMC-qPCR capture efficiency was 10-13% at assay detection limit. In 10 ml scale-up experiments, the lower detection limit of AMC-qPCR was 2.0 log(10) CFU/10 ml with corresponding capture efficiency of 4-7%. Nucleic acid aptamers are promising alternatives to antibodies for magnetic bead-based capture followed by qPCR detection. (C) 2013 Elsevier Ltd. All rights reserved.