June 2, 2010 |
By Kevin Davies
BOSTON – The latest entry in the next-generation sequencing sweepstakes made its public debut at the Consumer Genetics Show today, offering the prospect of a $30 human genome.
GnuBio is a company based on the technology of David Weitz, a physics professor at Harvard University. Weitz did not unveil an instrument or even any detailed sequencing data – “I’m just a physics professor across the river,” he said modestly. But he did outline a microfluidics platform that could have instrumentation available by the end of 2010 for some very affordable DNA sequencing.
The Weitz group uses microdroplets as microreactors in a way quite similar to the commercially available RainDance platform. The drops are surrounded by inert oil which provides a measure of fluidics control. A droplet of 10 microns in diameter can contain 10-14 grams reagent.
“We process drops at 1 million/second,” said Weitz. The droplets can be formed, broken apart, sorted, and the contents detected. “The size of the device is roughly the thickness of a human hair, so they can be stacked and run in parallel.”
For the sequencing application, Weitz takes DNA templates and reagents, and puts them into larger drops (nanoliter volumes). In principle, many sequencing assays could be performed in these miniature drops, such as sequencing by ligation. “You can do it in these drops, just using very small amount of reagent and fluid,” said Weitz. A typical workflow would be to amplify the DNA template, inject in the oligonucleotide probes, read the hybridization signal and reconstruct the sequence
Weitz said the spherical microdroplets act like tiny lenses, focusing the camera to make the relevant interpretation. “We can produce drops at 1 million/second, and we think we can read the drops at 1 million/second.” Weitz says arranging 1000 channels per device is “easily achievable,” and the camera system is working.
Weitz presented some fairly provocative figures for the cost of DNA sequencing using his technology. With an estimated sequencing cost per base of just $10-9, a 30-fold human genome sequence would cost a mere $30 and take about 10 hours. “You can quibble about the details of these calculations but the orders of magnitude are not that far off. That’s what makes us want to pursue it,” said Weitz.
Since the Weitz team is “just a group of postdocs and grad students,” Weitz has co-founded a start-up biotech called GnuBio Corporation. Advisors on the “convergence board” include George Church, Dietrich Stephan, and Affomix founders Michael Weiner and John Boyce.
Weitz said he hopes to have beta systems ready by the end of 2010. There are already commitments to purchase instruments from the Beaulieu-Saucier Universite de Montreal pharmacogenomics center and Stephan’s Ignite Institute.