Design and storage stability of reference materials for microfluidic quantitative PCR-based equine gene doping tests

One method of gene doping in horseracing is administering of exogenous genetic materials, known as transgenes. Several polymerase chain reaction (PCR)-based methods have been developed for detecting transgenes with high sensitivity and specificity. However, novel designs for reference materials (RMs) and/or positive template controls (PTCs) are necessary for simultaneous analysis of multiple transgene targets. In this study, we designed and developed a novel RM for simultaneously detecting multiple targets via microfluidic quantitative PCR (MFQPCR). Twelve equine genes were selected as targets in this study. A sequence region including primers and probes for quantitative PCR was designed, and a 10 bp sequence was inserted to allow the RM to be distinguished from the original transgene sequences. The sequences of individual detection sites were then connected for 12 genes and cloned into a single plasmid vector. We performed fragment size analysis to distinguish between the PCR products of the original transgene sequence and those of the RM, enabling identification of RM contamination. PTCs diluted to 10,000, 1,000, 100, and 10 copies/µl with horse genomic DNA from RM were stably stored at 4°C for 1 year. As digital PCR enabled absolute quantification, the designed substances can serve as an RM. These findings indicate that the RM design and storage conditions were suitable for gene doping tests using MFQPCR.