According to a new study, the virus responsible for the common cold, the rhinovirus, reproduces more easily in the cool, in the nasal cavities, than in the warm, in the lungs.
Why do colds find refuge in our noses? This is the question that American researchers from theYale University (New Haven). The goal of their mission: to try to understand the reasons why respiratory viruses seem to prefer the upper airways (nose, mouth, throat…) to the lower airways (trachea and lungs). Unpublished results published in the scientific journal Proceedings of the National Academy of Sciences (PNAS).
The virus prefers the cold
To reach this conclusion, the study’s lead author, Ellen Foxman, a member of Prof. Akiko Iwasaki’s immunology lab, infected mouse nasal cells and observed their immune response at various temperatures.
And the results reported by the researchers are clear, the common cold likes the cold. In Le Figaro, Bruno Lina, head of the national influenza reference center confides: “At 37 ° C, the activation of immune processes was faster after exposure to the virus than at 33 ° C, where there was a” delay on ignition ”which gave the virus more time to replicate. “
And this is what happens in practice since our nose, in contact with the outside air, is often between 33 and 35 ° C. For their part, the lungs are rather at 37 ° C, which allows them to perform their function correctly.
Host biology
In addition, these scientists reveal that in mouse cells with deficient immunity, the rhinovirus multiplied as much at 37 ° C as at 33 ° C. The team’s conclusion, “the common cold would therefore prefer the nose also because the antiviral response is less effective. “For the researchers, if the common cold is located in the nose it is partly due” to the biology of the host “, they conclude.
Our grandmothers’ expression of telling toddlers to “cover your nose well before going out” suddenly seems very relevant.
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