Human nose retains long-term memory of viruses and fights reinfection, study finds

A study by researchers at the La Jolla Institute for Immunology, a biomedical research institute in California, recently highlighted in the journal Nature, provides insight into the nose's role in immune defense. The work, which included contributions from researcher Shane Crotty's teams, analyzed cells in the upper respiratory tract. Scientists found that the nose contains immune cells capable of retaining memory of previously encountered viruses. These cells, located directly in nasal tissues, remain on alert at the entry point for respiratory infections. When a similar virus reappears, they trigger a rapid response, producing antibodies or activating other defense mechanisms to limit infection spread. This finding represents an evolution in understanding immunity. Previously, focus was primarily on cells circulating in the blood. This research highlights the importance of "resident" cells in tissues, which act as a faster, more targeted first line of defense. Researchers also note that this immune memory can persist long-term, sometimes for several years. Vaccines contribute by training these cells to recognize pathogens. However, the effectiveness of this memory also depends on viruses' ability to evolve, as some mutations can partially bypass this recognition. Beyond the fundamental discovery, these results open concrete prospects, according to the researchers. They could guide the development of nasally administered vaccines, capable of strengthening this local immunity