Remember those B-flicks where researchers ran from their labs as experiments came to life and burst messily from test tubes? The latest is brought to you by Amersham Pharmacia Biotech — call it Revenge of the Blob.
TempliPhi is a new DNA amplification polymerase that will outproduce PCR techniques, according to AP Biotech developer John Nelson. It’s not just exponential like PCR, he says: “It’s exponentially exponential.” The process is based on Molecular Staging’s rolling circle technology (licensed exclusively to AP Biotech), and its value is that each strand of DNA produced by amplification can also be amplified, and each strand gets longer and longer as the enzyme works its way around the circle. Every double strand is displaced into single strands, which are then replicated, and the process begins again. The technology eliminates the need for all but the first boiling step required by PCR.
“I’ve never had any DNA polymerase that works like this,” Nelson says. In one experiment, “the enzyme went around the circle for 700,000 bases.” There are no exact figures yet for TempliPhi’s amplification capacity. AP Bio- tech is just starting, hindered by the lack of tools available to measure DNA almost a million bases long.
Despite panicky rumors, Nelson says there’s no way this polymerase will replace PCR. “It has the potential to be faster than PCR, but it doesn’t have the specificity of PCR,” he explains. “It’ll have its own niche of uses that PCR could never do.”
Nelson is proud of his accomplishment, but AP Biotech must be kicking itself. Phi 29, the enzyme used for this reaction, has been sitting in the company’s enzyme library for five years. “We never knew what we could do with it,” Nelson says.
TempliPhi, currently in beta testing at the Sanger Centre, the Washington University Genome Sequencing Center, and the Joint Genome Institute, should be released in second quarter 2001. Pricing information has not been released, but AP Biotech says it will be competitive with other template prep kits.
— Marian Moser Jones and Meredith Salisbury