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Targeting the virus’s stem, not the head, could be the answer.
Investigators at MIT and the Ragon Institute of MIT, MGH, and Harvard have designed a vaccine that triggers an immune response against an influenza protein segment that rarely mutates, but is not normally targeted by the immune system, according to a study published in Cell Systems. According to the authors, this vaccine marks one step closer towards the development of a universal flu vaccine.
The flu vaccine has to be redesigned annually in order to account for mutations that the virus accumulates. However, even with the yearly redesign, the vaccine often does not fully protect everyone.
The vaccine candidate offers nanoparticles coated with flu proteins that teach the immune system to create desired antibodies. In testing with mice, the vaccine elicited an antibody response targeted the protein segment. This means that the vaccine could potentially be effective against any flu strain.
According to the study, the immune system targets the head of the HA Protein and not the stem. The head of the protein tends to mutate rapidly, but the HA stem very rarely mutates. This makes the stem a prime target for a universal flu vaccine.
"We don't understand the complete picture yet, but for many reasons, the immune system is intrinsically not good at seeing the conserved parts of these proteins, which if effectively targeted would elicit an antibody response that would neutralize multiple influenza types," said Daniel Lingwood, PhD of Harvard Medical School, in a prepared statement.
According to study authors, developing a universal flu vaccine can help minimize pandemic threats. Refocusing immunity can help in its development.
"When there's a refocusing event, that means we can swing the antibody response against that target, which under other conditions is simply not seen. We have shown in previous studies that when you're able to elicit this kind of response, it's protective against flu strains that mimic pandemic threats,” Lingwood said.
Trafton A. A step toward a universal flu vaccine. MIT News. Published October 7, 2002. Accessed October 23, 2020. https://news.mit.edu/2020/universal-flu-vaccine-1007