BioWorld International Correspondent

LONDON - PowderMed Ltd. is lining up to bid for a UK government contract to supply 2 million doses of vaccine to protect against the avian influenza that has caused 53 deaths in Southeast Asia since the first infection was reported in December 2003. The company's DNA-based vaccine against the H5N1 strain of flu has reached the final stages of preclinical development and will enter clinical trials next year.

PowderMed's vaccines consist of a standard DNA backbone, which is loaded with an immunologically active gene specific to each viral strain. In the case of avian flu, that is the H5 Vietnam gene. The technology could be applied to develop vaccines against potential bioterrorism agents, also.

Clive Dix, PowderMed CEO, told BioWorld International the technique of plugging the active gene into a standard backbone enables rapid development of new vaccines. Currently avian flu can be passed only from birds to humans, but in the event that it becomes able to move human to human and causes a pandemic, the company would be able to produce enough vaccine to protect everyone in the UK within three months.

"Everyone is aware of the potential threat from avian flu. While existing manufacturing processes can produce vaccines against the strain that is currently causing infection in Southeast Asia, it may not be that strain that causes a pandemic," Dix said.

Cambridge-based PowderMed's technology has been validated in the clinic through its DNA vaccine against annual influenza, which is ready to enter Phase IIb.

"This has proved we get the immune response we require. Of course we still need to get approval for DNA vaccines, but the same is true for other companies that are using cell-based manufacturing to produce vaccines for stockpiles," Dix said.

If and when the emergence of a pandemic strain of flu is confirmed, conventional egg-based manufacturing would take nine months to produce a vaccine. "In the event of a pandemic most deaths will occur in the first six months of an outbreak, so egg-based manufacturing would not work in time," Dix said.

Apart from speed of development, DNA vaccines offer other advantages over their conventional counterparts in that they can be stored at ambient temperatures and cost less to produce.

DNA vaccines are administered in a powdered form using PowderMed's gas-powered needle-free injection device. That directs the DNA directly to antigen-presenting cells (APC) in the epidermis. Once inside the APCs the DNA produces the encoded protein, which when presented by the APCs to lymphocytes initiates a T-cell mediated immune response.

PowderMed has a clinical trials manufacturing unit that would be capable of producing the 2 million doses requested by the UK government. The company has carried out detailed feasibility studies with its manufacturing partners and Dix said that it would be possible to produce 150 million doses of a vaccine and the accompanying delivery device within three months of a pandemic strain being identified.

In the absence of an avian flu pandemic, PowderMed expects its annual flu product to be the first to reach the market. "We are going to go ahead with the avian flu vaccine, both to prove it is effective and to demonstrate that we can respond rapidly to emerging diseases and bioterrorism threats, and will then look to get government contracts to supply [products] for stockpiling," Dix said.

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