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BUFFALO, NY – Anyone who has undergone a nasal swab or saliva test for COVID-19 knows that the virus is more easily detected in the nose and mouth. That’s why, University of Buffalo researchers argue in a new paper, more COVID-19 studies should be devoted to how immunity to SARS-CoV-2 emerges in the mucous membranes of the nose and mouth.
The document was published on November 30 in Frontiers in immunology.
Noting that the mucosal immune system is the largest component of the immune system, the researchers expressed concern that it has not been the focus of much research on COVID-19 to date.
“We believe it is a grave omission to ignore the mucosal immune response to SARS-CoV-2, given its initial sites of infection,” said Michael W. Russell, PhD, professor emeritus, Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences at the UB and senior author of the article. “Clearly the systemic immunoglobulin G antibody response [the most abundant circulating antibody] it is important – we do not deny it – but in itself it is insufficient “.
Russell noted that, of course, the initial focus of the disease research was on cases of severe disease when the virus descends into the lower respiratory tract, particularly the lungs, where cellular immune responses exacerbate inflammation rather than fight infection.
But since the upper respiratory tract, including the nose, tonsils, and adenoids are the starting point of infection of the SARS-CoV-2 virus, the immune responses that are activated are of particular concern.
Additionally, the high asymptomatic transmission rate of COVID-19, which the Centers for Disease Control and Prevention recently estimated to be above 50 percent, is another reason mucosal immunity is so important, according to the authors.
“Something, somewhere, does a pretty good job of controlling the virus”
“Given that many infected people remain asymptomatic and a large number of those who develop symptoms only suffer from mild to moderate illness, this suggests that something, somewhere, is doing a pretty good job of controlling the virus,” Russell said. .
“Could it be that this is due to the early mucosal immune responses that manage to contain and eliminate the infection before it becomes severe?” churches. “We won’t know unless these questions are addressed.”
The paper recommends that studies be needed to determine the nature of mucosal immunoglobulin A (SIgA) antibody responses during infection, including asymptomatic or pre-symptomatic infections and mild and moderate cases of COVID-19 disease. Furthermore, the authors point out that mucosal immune responses may vary according to different age groups and populations.
A focus on mucosal immunity could also make it possible to develop a type of vaccine, such as a nasal vaccine, which may be easier to store, transport and administer. Many of these vaccines are currently in development for COVID-19, but it is unknown how long they are.
Russell added that these vaccines may not have special temperature requirements and may be more palatable to large sections of the population, particularly children, because they would not require an injection.
Potential benefits of a mucosal vaccine
“The potential advantage of a mucosal vaccine, especially intranasal vaccine, is that it should induce immune responses, including SIgA antibodies, in the mucous passages, in this case especially in the upper respiratory tract, where the coronavirus makes first contact,” he explained Russell, adding that injected vaccines usually don’t.
Among the study areas that the authors suggest would be constructive are molecular studies of IgA antibodies and their relationship to the disease stage of COVID-19 and the determination of the characteristics of cells that secrete IgA antibodies and other induced mucosal immune cells. by infection or by vaccination.
“As mucosal immunologists with several decades of experience, we have been troubled by the lack of focus on this, and we hope to draw attention to this glaring omission,” Russell said. “After all, the mucosal immune system is by far the most important component of the entire immune system and has evolved to protect the mucosal surfaces where most infections arise.”
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Co-authors with Russell are Pearay L. Ogra of UB and Zina Moldoveanu and Jiri Mestecky of the University of Alabama in Birmingham.
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