Data Validates the World’s First Single Molecule Sequencing of an Organism

CAMBRIDGE, Mass.–Helicos BioSciences (NASDAQ: HLCS), a life science company focused on innovative genetic analysis technologies, today announced the publication of a report in Science Magazine demonstrating the first single molecule sequencing of an organism. The report depicts the use of Helicos’ proprietary True Single Molecule Sequencing (tSMS)™ technology to re-sequence the M13 viral genome. The report will appear in the April 4, 2008 print issue of Science Magazine.

The report demonstrates that the tSMS technology can reliably re-sequence a moderately complex genome without the associated errors, cost, and experimental complexity of amplification. The tSMS process captures images of single dye labeled nucleotides as they are incorporated to determine the sequence of the individual DNA strands. In addition, the tSMS method simplifies the DNA sample preparation process and maximizes throughput by packing individual strands of DNA at high densities onto the sequencing surface.

“The ability to sequence individual strands of genomic DNA has been a goal of the scientific community for more than 20 years,” said Timothy Harris, PhD, senior director of research at Helicos BioSciences and the report’s corresponding author. “The data in Science Magazine demonstrate the robustness of our single molecule method and demonstrate our ability to accurately detect single base mutations. Not only does this data represent the first of its kind, but a significant milestone in the genomics revolution.”

To validate its technology, Helicos scientists sequenced the M13 virus genome, examining more than 280,000 strands of captured DNA, directly visualizing the sequential incorporation of individual labeled nucleotides. Overall per-base accuracy was better than 99% and the accuracy of the consensus sequence was 100%. To assess accuracy and robustness of mutation detection, Helicos’ scientists introduced in silico single nucleotide changes into the reference M13 virus genome sequence and compared them to Helicos DNA sequences. The tSMS technology correctly found 98% of 500 simulated mutations with zero false positive errors.

“This data, remarkable as it is, was based on the first generation of our tSMS chemistry,” said Bill Efcavitch, PhD, senior vice president for product R&D at Helicos BioSciences. “We have since developed new generations of ‘one-base-at-a-time’ nucleotides which allow more accurate homopolymer sequencing, and lower overall error rates.”

The report published in Science Magazine initiates the path to many other scientific reports Helicos plans to publish in the upcoming months. These reports will highlight data recently announced at the AGBT meeting in Marco Island further demonstrating single molecule sequencing being applied to both BAC sequencing accuracy, and the ability to count microRNAs as well as identify putative novel miRNAs.

About Helicos BioSciences

Helicos BioSciences is a life science company focused on innovative genetic analysis technologies for the research, drug discovery, and diagnostic markets. Helicos’ proprietary True Single Molecule Sequencing, tSMSTM, technology allows direct measurement of billions of strands of DNA enabling scientists to perform experiments and ask questions never before possible. Helicos is a recipient of the $1,000 genome grant and is committed to providing scientists the tools to unlock the era of genomic medicine. The company’s corporate headquarters are located at One Kendall Square, Building 700, Cambridge, MA 02139, and its telephone number is (617) 264-1800.

Certain statements made in this press release that are not based on historical information are forward-looking statements which are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. This press release contains express or implied forward-looking statements relating to, among other things, Helicos’ expectations concerning the value of the report and data published in Science Magazine that are discussed in this press release, Helicos’ plans to make future scientific publications and management’s plans, objectives and strategies. These statements are neither promises nor guarantees, but are subject to a variety of risks and uncertainties, many of which are beyond Helicos’ control, which could cause actual results to differ materially from those contemplated in these forward-looking statements. In particular, the risks and uncertainties include, among other things, our ability to successfully complete the manufacturing process and commercialize the Helicos™ Genetic Analysis System; competition; changing technology and customer acceptance requirements; our ability to operate in an emerging market; market acceptance of our technology; our ability to retain our personnel and hire additional skilled personnel; our ability to manage our rapid growth and our ability to obtain capital when desired on favorable terms. Existing and prospective investors are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. Helicos undertakes no obligation to update or revise the information contained in this press release, whether as a result of new information, future events or circumstances or otherwise. For additional disclosure regarding these and other risks faced by Helicos, see the disclosure contained in Helicos’ public filings with the Securities and Exchange Commission.