The influenza viruses that cause flu in people have high rates of mutation that allows them to evolve quickly. That means a flu vaccine has to be designed for three or four viral strains that are suspected to be most likely to spread and sicken people, and redesigned every year or so. To make a better flu vaccine, it would benefit scientists greatly to know how these viruses are mutating. Research reported in the journal eLife has revealed new details about how flu viruses change frequently.
Scientists at MIT have found that invading viruses use a group of proteins called chaperones that are present in cells infected with the virus, whether human or animal. These proteins normally have a critical function in making sure other proteins are properly folded, a vital step to ensure they function correctly.
Flu viruses don’t have their own chaperones, so they take over the ones in the host cell. Now for the first time, it has been shown that the host chaperones are not only crucial to the ability of the virus to replicate, they are also a part of viral mutation or evolution.
“Viral proteins are known to interact with host chaperones, so we suspected that this interplay could have a major impact on what evolutionary pathways are available to the virus,” explained the senior author of the study, Matthew Shoulders, an Associate Professor of Chemistry.
For this work, the scientists used cells they had engineered to have either a high or low level of active chaperones and cells with inactive chaperones. Then they assessed how much a flu virus mutated in these different cells. Not only did the chaperone level affect the mutation rate of the virus, it also impacted the types of changes that occurred in the viral genome.
These results have suggested that the chaperone effect on the evolution of the flu virus is very complex. However, the researchers have suggested that by stopping the flu virus from hijacking host chaperones, it may make it much harder for the virus gain resistance to vaccines and drugs.
"It's relatively easy to make a drug that kills a virus, or an antibody that stops a virus from propagating, but it's very hard to make one that the virus doesn't promptly escape from once you start using it," said Shoulders.
"Our data suggest that, at some point in the future, targeting host chaperones might restrict the ability of a virus to evolve and allow us to kill viruses before they become drug-resistant," he concluded.
The Centers for Disease Control and Prevention has more information about why it is so important to get a flu vaccine, and they offer tips for preventing flu infection in the video.
They have also addressed misconceptions about the flu vaccine.