title: Comparison and transfer testing of multiplex ligation detection methods for GM plants.
abstract: BACKGROUND
  With the increasing number of GMOs on the global market the maintenance of European GMO regulations is becoming more complex. For the analysis of a single food or feed sample it is necessary to assess the sample for the presence of many GMO-targets simultaneously at a sensitive level. Several methods have been published regarding DNA-based multidetection. Multiplex ligation detection methods have been described that use the same basic approach: i) hybridisation and ligation of specific probes, ii) amplification of the ligated probes and iii) detection and identification of the amplified products. Despite they all have this same basis, the published ligation methods differ radically. The present study investigated with real-time PCR whether these different ligation methods have any influence on the performance of the probes. Sensitivity and the specificity of the padlock probes (PLPs) with the ligation protocol with the best performance were also tested and the selected method was initially validated in a laboratory exchange study.
  
  
  RESULTS
  Of the ligation protocols tested in this study, the best results were obtained with the PPLMD I and PPLMD II protocols and no consistent differences between these two protocols were observed. Both protocols are based on padlock probe ligation combined with microarray detection. Twenty PLPs were tested for specificity and the best probes were subjected to further evaluation. Up to 13 targets were detected specifically and simultaneously. During the interlaboratory exchange study similar results were achieved by the two participating institutes (NIB, Slovenia, and RIKILT, the Netherlands).
  
  
  CONCLUSIONS
  From the comparison of ligation protocols it can be concluded that two protocols perform equally well on the basis of the selected set of PLPs. Using the most ideal parameters the multiplicity of one of the methods was tested and 13 targets were successfully and specifically detected. In the interlaboratory exchange study it was shown that the selected method meets the 0.1% sensitivity criterion. The present study thus shows that specific and sensitive multidetection of GMO targets is now feasible.
authors.affiliation: RIKILT-Institute of Food Safety (WUR), Akkermaalsbos 2, 6708 WB Wageningen, the Netherlands.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Ujhelyi
authors.forename: Jeroen P van
authors.initials: JP
authors.lastname: Dijk
authors.forename: Theo W
authors.initials: TW
authors.lastname: Prins
authors.forename: Marleen M
authors.initials: MM
authors.lastname: Voorhuijzen
authors.forename: A M Angeline Van
authors.initials: AM
authors.lastname: Hoef
authors.forename: Henriek G
authors.initials: HG
authors.lastname: Beenen
authors.forename: Dany
authors.initials: D
authors.lastname: Morisset
authors.forename: Kristina
authors.initials: K
authors.lastname: Gruden
authors.forename: Esther J
authors.initials: EJ
authors.lastname: Kok
mesh_terms: D001483:Base Sequence; D018744:DNA, Plant / Q000032:analysis; D005524:Food Technology / Q000379:methods*; D021141:Nucleic Acid Amplification Techniques; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D015345:Oligonucleotide Probes / Q000737:chemistry; D030821:Plants, Genetically Modified / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D018744:DNA, Plant; D015345:Oligonucleotide Probes