A study published in ACS Nano describes a vaccine platform that uses cell-derived extracellular vesicles (EVs) displaying inverted hemagglutinins (HAs) on their surface. The goal is a mucosal vaccine that protects the respiratory tract and helps prevent virus spread during epidemics or pandemics.
With the inverted arrangement the HA stalk becomes more exposed to the immune system while the variable HA head is less visible. The stalk contains conserved structures shared by many influenza strains, so targeting it can produce broader protection than strain-specific vaccines.
In mice, multiple HA-EV vaccines given intranasally elicited cross-reactive antibodies to HA stalks, robust virus-specific cellular immune responses and a balanced Th1/Th2 profile. Intranasal immunization with these vaccines provided complete protection against lethal heterosubtypic challenges with H7N9 and H5N1 reassortants. The authors note that EVs are a biocompatible delivery platform and that more mucosal vaccine strategies are needed.
Difficult words
- extracellular vesicle — a small membrane particle released by cellsextracellular vesicles
- hemagglutinin — a viral surface protein on influenza viruseshemagglutinins
- invert — to put something in the opposite positioninverted
- stalk — a supporting or connecting part of a proteinstalks
- cross-reactive — able to react with different but related targets
- mucosal — relating to the moist lining of body passages
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Discussion questions
- Would you prefer a mucosal vaccine given through the nose rather than an injection? Why or why not?
- What are the possible advantages of targeting the HA stalk instead of the HA head in influenza vaccines?
- What practical challenges might scientists face when developing more mucosal vaccine strategies?
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