A team of researchers has developed technology that could improve the production of Influenza B vaccines by allowing producers to grow vaccine viruses at high yield in mammalian cell culture rather than in eggs.
Led by Yoshihiro Kawaoka, professor of pathobiological sciences at the University of Wisconsin-Madison School of Veterinary Medicine, the approach should improve the ability of seasonal vaccines to protect against influenza A and B because vaccine viruses grown in mammalian cell culture are less likely to mutate compared to those grown in eggs. Mutations can lead to vaccine viruses that no longer match the intended strains of influenza.
“We want to provide a system that produces influenza vaccines that are more efficacious,” says Kawaoka. “It is better to produce influenza viruses for vaccine production in cells instead of eggs, but the problem is that influenza virus does not grow well in cell culture compared with embryonated eggs.”
The new technology may overcome that challenge. Kawaoka’s team first screened influenza B viruses for random genetic mutations that led to improved replication. Using these mutants as templates, the researchers attached the genes that code for the surface proteins that trigger the human immune response (and thus offer protection in vaccinated individuals) — HA (hemagglutinin) and NA (neuraminidase).
They then selected the combinations of backbone mutations that supported better growth in cell culture, identifying two candidate backbones that led to higher amounts of vaccine virus.
“It may still not be perfect, but it will at least be substantially better than current vaccines,” says Kawaoka, who notes no one else has successfully tried to produce high-yield influenza B vaccine virus before now.
Last year, his research team created a high-yield influenza A vaccine virus candidate for cell culture production.
Kawaoka points out that more testing is required to discern whether these results would translate to increased vaccine virus yield under industrial conditions.
Several companies and federal agencies have already contacted him about the influenza A and influenza B backbones, Kawaoka says, and he is hopeful the systems can be adopted by vaccine manufacturers and grown in cell culture facilities already available in the United States and Japan.