The emergence of COVID-19 variants such as delta and omicron has sent scientists to struggle to determine whether existing vaccinations and enhancements are still effective against new SARS-Cov-2 strains.
A new response to the rapidly mutating virus could be found at the door of our lungs, says Akiko Iwasaki of Yale, a professor of immunobiology at Waldemar Von Zedtwitz. In a new study, she and her colleagues found that intranasal vaccination provides broad protection against heterologous respiratory viruses in mice, while so-called systemic immunization, which uses an injection to protect the whole body, does not he did.
His findings are published in the journal on December 10 Science Immunology.
The best immune defense is at the door, protecting itself from viruses trying to get in. “
Akiko Iwasaki, lead author of the study
Mucous membranes contain their own immune defense system that fights airborne or foodborne pathogens. When challenged, these barrier tissues produce B cells which in turn secrete immunoglobulin A (IgA) antibodies. Unlike system-wide immune vaccines, IgA antibodies work locally on the mucous surfaces of the nose, stomach, and lungs.
Although the protective role of IgA-producing cells had been well established in the fight against intestinal pathogens, Iwasaki’s laboratory wondered whether triggering the IgA response could also produce a localized immune response against respiratory viruses.
Working with researchers at Mount Sinai’s Icahn School of Medicine in New York, they tested a protein-based vaccine designed to initiate an IgA immune response by administering it to mice by injection, as is usually done with systemic immunizations. intranasally. They then exposed mice to multiple strains of the flu virus. They found that mice that had received the intranasal vaccine were much better protected against respiratory flu than those who received injections. Nasal vaccines, but not the vaccine, also induced antibodies that protected animals against a variety of influenza strains, not just the strain against which the vaccine was intended to protect.
The Yale team is currently testing nasal vaccine strains against COVID strains in animal models.
Although both vaccine injections and nasal vaccines increased the levels of antibodies in the blood of mice, only the nasal vaccine allowed the secretion of IgA into the lungs, where respiratory viruses must be housed for infect the host, Iwasaki said.
If nasal vaccines prove to be safe and effective in humans, Iwasaki expects them to be used in conjunction with current system-wide vaccines and booster to add immune boosts to the source of the infection.
Other early co-authors of the study are Ji Eun Oh, Eric Song and Miyu Moriyama, all of Yale.
Oh yeah et al. (2021) Intranasal priming induces local populations of resident B cells in the lung that secrete mucosal protective antiviral IgA. Science Immunology. doi.org/10.1126/sciimmunol.abj5129.