As reported cases of swine flu continue to accumulate (as of today, 40 had been reported in the US) and mainstream media outlets dust off their foreboding music tracks and positively scary taglines, a biotechnology company in Maryland says that its approach may speed development of a successful vaccine.

Influenza A/South Carolina/1918 (H1N1) VLPs Image: Novavax, Inc.

Researchers at Novavax have been developing vaccines for the H5N1 strain of avian flu, along with other strains of influenza, over the past few years using an approach built around virus-like particles (VLP)--viral membrane proteins in a matrix of lipids. Researchers from the company, with scientists from the Centers for Disease Control and Prevention (CDC), published a study last month in which they successfully protected mice against a reconstructed virus from the 1918 Spanish flu outbreak through intranasal immunization with H1N1 VLPs.

A new strain of H1N1 is likely causing the current outbreak of swine flu in North America, which this weekend led both the World Health Organization and the CDC to declare a public health emergency.

Gregory Poland, an immunologist and head of the Vaccine Research Group at the Mayo Clinic in Minnesota, said VLPs and other novel approaches to vaccine development, for combating influenza are exciting but untested. "The issue, from the perspective of influenza, is that none of these is approved," he said. In fact, the only FDA-approved VLP-based vaccines on the market are those developed to protect women from human papillomavirus.

Novavax's typical timeframe, going from DNA sequence to a testable product based on VLPs, is 10 to 12 weeks, according to the company's vice president for strategy, Thomas Johnston. "The way we develop vaccines allows us to move pretty quickly once DNA sequences are known," Johnston told The Scientist, adding that Novavax--like scores of other biotechs and pharmaceutical companies--received the sequence data for the new H1N1 strain of swine flu late last week. "We have begun our process for developing a vaccine."

Novavax's approach--which clones key viral genes, and uses insect cell cultures to produce the virus-like particles--is faster and safer than approaches that utilize live viruses, said Gale Smith, Novavax's vice president for vaccine development. Because the latest strain of H1N1 is transmittable from human to human, manufacturing a live virus vaccine represents significant safety risks, he added.

But so might a relatively untested strategy. Novavax has two vaccine candidates in clinical trials: One, for H5N1, just completed Phase IIa trials, and a seasonal vaccine candidate is in Phase IIa trials now.

According to Andrea Sant, an immunologist at the University of Rochester, traditional approaches, such as the commonly used subunit vaccines that consist of non-viable viral protein extracts, could be enough. "I think it's not impossible to make a conventional vaccine for next fall," at the typical start of the flu season, she said.

Hildegund Ertl, an immunologist at the Wistar Institute in Philadelphia, cautioned that going the VLP route may be tricky because the approach is so new and relatively untested. "For a company that's in a pre-clinical stage for a new vaccine to think that their vaccine is going to help in this situation is very optimistic indeed," she told The Scientist. "I would stick to what we know about in case time is of the essence."

Ertl and Sant agreed that how swine flu plays out in the human population--how the virus mutates, moves between hosts, etc--over the next couple weeks will determine which vaccine development strategy will be most effective. "A lot will depend on what happens over the next month," Sant said.

Correction (April 28): The original version of this story mistakenly mentioned vaccines that use live virus cells. Viruses, of course, are not composed of cells. The Scientist regrets the error.


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