Experimental Intranasal Booster Uses Virus Spike to Enhance Immunity

(Reuters) – Once the body has been “primed” by mRNA vaccines to recognize and attack the coronavirus, a booster containing purified versions of virus’ spike protein that could be given intranasally would have many advantages, researchers believe.

Their “Prime and Spike” strategy employs a booster vaccine currently being tested in animals. In mice with waning immunity after two doses of the Pfizer/BioNTech shot, the purified spike protein vaccine strongly boosted first- and second-line immune responses to the virus in the nose, lungs and blood and protected against lethal doses of the virus, researchers reported on bioRxiv ahead of peer review. Furthermore, the mice had lower-than-expected viral loads, which would likely reduce transmission.

In mice whose immune systems had not been “primed” with the mRNA vaccine, the spike protein vaccine had no effect, however, because it takes advantage of the body’s adaptive immunity, building on what the immune system has learned from the mRNA vaccine.

“This strategy is likely to confer long-lasting and cross-reactive memory that can be quickly restimulated to prevent viral spread,” study leader Akiko Iwasaki of Yale University explained on Twitter. “The intranasal spike protein booster will also be much easier to administer (via nasal spray) … and is much more likely to be accepted by people who are hesitant of mRNA or those with needle phobia.”

SOURCE: https://bit.ly/3Ga5sZ9 bioRxiv, online January 26, 2022.

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