A quick one-tube nested PCR-protocol for EPO transgene detection

The practice of doping threatens fair competition in sports. With the very recent reports on successful gene therapies for several diseases, the likelihood for abuse of gene transfer techniques in elite sports is rapidly increasing. It is therefore very important to develop valid detection techniques for transgenic DNA (tDNA) with ultimate sensitivity and specificity. To date, three slightly different procedures have been reported to reliably detect tDNA with sufficiently high sensitivity. Two utilize a real-time PCR-based approach and one uses a primer-internal, intron-spanning PCR approach (spiPCR). The specificity and sensitivity of these techniques, however, is still a matter of debate. Based on spiPCR, here we present a novel one-tube nested PCR approach that minimizes the chances for cross-contamination and shows increased sensitivity compared to non-nested PCR techniques. To further reduce the occurrence of false-positives based on cross-contamination, a multi-functional 19bp extended erythropoietin standard (EPO) was cloned which can be easily differentiated from transgenic EPO DNA (tEPO) and can be used as an internal or external positive control in PCR-based applications. We found that one-tube nested PCR is superior in terms of sensitivity and specificity compared to conventional PCR, and shows similar sensitivity compared to real-time based PCR assays. Although it did not reach sensitivity of spiPCR, the one-tube nested PCR technique described here is less laborious, less expensive and much faster than spiPCR. This technique might therefore be useful as a pre-screening tool for gene doping in the future.