As flu season soon arrives, researchers around the world are pursuing the design of a vaccine against influenza which would protect against all strains of the virus. Indeed, there are many strains of influenza and current vaccines target a particular one each year, previously chosen by experts. Unfortunately, this variability in the virus means that the vaccine is between 40 and 70% effective. A universal vaccine, which can destroy any strain of influenza therefore seems to be the ideal solution to eradicate this virus, on average 400,000 deaths per year. Published in the journal Scientific Report, a new study from the University of Rochester, in the United States, shows that this vaccine is more complex than expected to create.
A virus that constantly mutates
The influenza virus is covered by a hemagglutinin protein similar to a flower. It is made up of a “stem”, which was thought to be constant from one strain to another, and a “petal head” mutating regularly and being specific to each strain. It is the latter which is currently targeted by our vaccines. The most promising strategy for creating a universal one would therefore be to target the stem to provide more protection against the flu. However, by analyzing genetic sequences of H1N1 influenza viruses circulating since 1918, researchers at the University of Rochester have just noticed that this rod can also change, but not as frequently as the head.
The repeated exposure to human antibodies caused mutations in the head of this protein, in order to escape our immune system, but also in the stem, something that we did not know until now. In order to design such a vaccine, this new information will need to be taken into account. Targeting the stem of this protein will, in all cases, protect individuals more widely than with normal vaccines.
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