Sometimes molecular diagnostics doesn’t have to involve highly complex assays or sophisticated instrumentation.
Timothy Stenzel, M.D., Ph.D., CSO of Quidel, discussed his company’s collaboration with BioHelix to develop isothermal amplification tests using the latter’s helicase-dependent amplification (HDA).
With this technology, designed for resource-poor areas in the developing world, or simply where capital expense budgets are low or being slashed (even in the U.S.), “you don’t need a thermocycler, just a heat block,” he says.
“I think there are untapped markets out there,” Dr. Stenzel confided. “It’s our understanding that there are nonmolecular labs that can’t afford to get into molecular diagnostics, because they either can’t afford to hire the personnel, set up a high-complexity lab, or buy the current integrated systems right now. If there were a lower cost option where they didn’t have to make a capital outlay, they would get into molecular now.”
In the developing world, right now molecular testing is a challenge. And because it’s mainly done in centralized locations, the turnaround to get results back to patients can be months, and many patients are lost to follow-up as a result.
The Quidel-BioHelix system makes use of capillary flow on nitrocellulose membranes, similar to that of over-the-counter home pregnancy tests. It’s easy to use, high performing, and uses a visual read: you see a line develop and the target is there; you don’t see a line and it’s not there. Because this type of technology is less prone to inhibition, it’s often not necessary to perform an up-front nucleic acid extraction (or to make the large capital expense for an extractor).
Another attractive thing is that the technology can be multiplexed—even allowing for an internal control to be placed in the same tube with the target—he noted, but it won’t be as highly multiplexed as arrays.
The first menu is in the area of infectious disease, offering up some fairly obvious targets that labs are expecting, Dr. Stenzel said. One of the top priority targets is C. difficile testing, especially in U.S. where it is an important pathogen for hospitals to get control of. “The whole area of hospital-acquired infections is still growing and is very interesting.”
Dr. Stenzel predicts that much of the C. difficile testing currently being done by EIA “will move to molecular as soon as labs can get up and going with a method that works for them.”