What if the solution is in the nose? More than a year and a half after the start of the Covid-19 pandemic, a new generation of vaccines to be administered by the nasal route is preparing, with the promise of offering sterilizing immunity, that is to say that blocks transmission of the virus through the nasal passages, preventing it from multiplying and then spreading in the body. In France, three vaccine candidates could make this hope a reality. Not immediately, however, as trials are still at the preclinical stage: results have been observed in animals, but not yet in humans.
The intranasal route of administration for respiratory infections theoretically benefits from several advantages. First advantage, the immune response triggered by a vaccine administered into the nose is, it is logical, localized in the nasal mucosa. There, therefore, where the virus enters the body. “We can therefore hope to induce a localized response in the respiratory tract and thus curb the infection more quickly”, estimates Simon Fillatreau, professor of immunology at the Necker-Enfants Malades Institute (Inserm, CNRS, University of Paris).
At the Faculty of Pharmacy in Tours, around twenty researchers from the University of Tours and the National Research Institute for Agriculture, Food and the Environment (Inrae) are thus working on a protein vaccine with nasal instillation. . A protein cocktail is encapsulated in nanoparticles based on starch and lipids completely eliminated by the body in a few hours, without any additional adjuvant. Among these proteins is the “spike”, the main target of neutralizing antibodies, molecules that prevent infection by blocking the entry of the virus into the body. Other virus proteins have been included in the mixture, which they are not subject to mutation. A peculiarity which gives hope for an efficacy of the vaccine against most of the known variants.
According to the head of the research team in charge of the vaccine project, Isabelle Dimier-Poisson, the results of the first tests carried out on genetically modified mice and then on golden hamsters – whose symptoms in the face of SARS-CoV-2 are very similar of those of humans – are “Very encouraging”. Of six golden hamsters vaccinated, none died after coming into contact with the virus. Better still, no viral load was detected in their nasal cavities. It is now for the researchers to found a start-up in order to raise the necessary funds to produce proteins and carry out clinical trials on humans, which could begin in the second half of 2022.
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