A new process for manufacturing flu vaccines in baker's yeast might someday replace the current 80-year-old process that uses chicken eggs while offering potentially significant advantages as well, researchers say.
Not only would such vaccines be cheaper, but they might make yearly flu shots obsolete by providing long-lasting protection against multiple influenza strains, the researchers said at the American Chemical Society meeting in Chicago.
Most vaccines target hemagglutinin, a viral surface protein that triggers a strong immune response. But hemagglutinin mutates rapidly, requiring the design of a new vaccine — and another shot in the arm — each year.
The new vaccines target a different viral protein known as M2, which is far less prone to mutation. It has hardly changed since the 1918 flu pandemic, the researchers said.
By targeting a highly conserved viral protein such as M2, the researchers hoped the resulting vaccine would provide broad protection that lasts longer than a year, perhaps even a lifetime.
Along with targeting M2, they aimed to develop a more cost-effective, rapid system for manufacturing at large scale that doesn’t require incubation in chicken eggs. Their approach uses baker’s yeast (Saccharomyces cerevisiae) to produce virus-like particles that display the M2 protein on their surface but do not contain the genetic viral material that causes infection.
Mice vaccinated with the purified M2 virus-like particles were protected against infection from three different influenza strains, the researchers found.
Although the findings in mice are promising, work still needs to be done before it is ready for human trials, the researchers say.
“I would definitely anticipate that the M2 vaccine provides broader and longer protection than the current HA-focused vaccines,” senior researcher Fei Wen of the University of Michigan said in a statement.
“Can it be even longer than that, like once in a lifetime? Possibly, or maybe people will need a booster when they get older.”
The team has licensed the technology to a company developing yeast systems to produce oral vaccines. Wen speculates that someday, engineered yeast strains could be “brewed” as oral vaccines for influenza and other diseases.
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