Taking the RAP
“Rapid pathogen testing is an unmet clinical need that PCR combined with microarrays can fill,” says Christof Henne, Ph.D., key account manager for diagnostics at Eppendorf Diagnostics. To address this void, the company has developed the RAP™ (Real-Time Array PCR) that it believes combines the advantages of qPCR and those of microarrays.
According to Dr. Henne, RAP technology brings together the sensitivity and reproducibility of PCR with the rapid multiplexing capability of microarrays.
A critical feature in the construction of the Eppendorf platform was the genetic engineering of the active site of the polymerase enzyme so it would function at high salt concentrations. This allows stable surface binding under conditions that would ordinarily be nonpermissible. Microarrays do not lend themselves to quantification, and they have a low dynamic range, but these drawbacks can be overcome when they are combined with effective PCR.
Dr. Henne mentions that the Eppendorf platform can be coupled to commercial systems for PCR-based DNA testing. “This is a niche market that is rapidly expanding with an increasing number of assays,” he notes. One example of an integrated commercial system for PCR-based DNA testing is designed by Cepheid, combining sample preparation, DNA amplification, and detection. “The system was originally developed for anthrax testing, but the company is now expanding its diagnostic offerings,” Dr. Henne comments.
“For a point-of-care test for infectious disease diagnosis to be acceptable, it must have robustness and it must have built-in controls that inform the user of his mistakes, with clear positive and negative controls,” he continues. “The more automated the platform is, the better for the patient, so the only remaining variable is the sample quality.”
Personalized medicine is a rapidly developing area to which the RAP technology lends itself, Dr. Henne notes. Voluminous information is generated per patient, and it will be necessary to describe the patient in much more individualized terms, taking into account genetic subtypes that describe sensitivity to cancer and other disease processes.
“The combination of multiplexing ability with rapid testing will be essential in building of personalized medicine platforms,” he concludes.