Plasmid DNA positive control standards for molecular environments assays

The proliferation of sensitive DNA-based assays for detecting the presence of specific harmful, toxic or invasive organisms, as well as the simple reagent and instrumentation requirements for these assays has made widespread and more frequent testing for these different organisms possible. However, a frequent problem with such assays is the lack of available, well-quantified positive control standards for all laboratories running a particular assay. This lack of standardized positive controls greatly hampers both evaluating the correct performance of the assay and comparing results between samples taken at different times, by different individuals, or tested with different assays. Many laboratories carrying out DNA-based assays make their own standards in small batches. These are generally tedious to make, poorly quantified and hard to reproduce, as well as a source of contamination potentially causing false positive results. We propose that plasmid DNA based positive control standards, containing a synthetic DNA sequence, mimicking, but distinguishable from, the natural target sequence of the organism, and quantified using a simple statistical test can be made accurately, economically and in almost unlimited quantities. Such standards would foster the expanded use of DNAbased detection assays, and equally importantly, facilitate comparison of results between different samples, laboratories and assays.