A previously unknown layer of antiviral defense that exerts its action on epithelial surfaces before an interferon response has been identified by researchers at Aarhus University.

The newly discovered immune reaction is activated when the body’s mucous membranes are disrupted, as they are when viruses and bacteria attempt to establish an infection, according to the study researchers, who reported their findings in Nature Immunology

The immune system recognizes the virus and produces a substance that neutralizes it. If this first immune reaction is not sufficient to suppress the virus, the infection establishes itself in the body. This in turn triggers the next reaction involving interferon, according to the researchers.

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“Our study fundamentally alters our understanding of how the body begins its defense against viruses. This can help to explain how we can be constantly exposed to the viruses and bacteria that always surround us, without activating the entire immune system every time, something that would lead to more frequent influenza-like symptoms,” Søren Riis Paludan, professor at the Department of Biomedicine at Aarhus University, said in a prepared statement about the study.

He has headed the research project in Aarhus, while also collaborating with researchers from the University of Copenhagen as well as from universities in the United States and Germany.

Experiments on mice have shown that mice, lacking this first defense mechanism, become ill if they are exposed to herpes virus, while normal mice remain healthy.

“We do not yet know the precise significance of this mechanism, but it may explain why some people become more ill from viral infections such as influenza than others. The same may apply to other viral infections that are initiated on mucous membranes such as HIV and herpes. We will now begin to map out the molecules that are involved. Once we have done this, it will be possible to identify people with defects in the mechanism, just as there is a potential to develop new forms of treatment. At the same time, the mechanism may turn out to have significance also for non-viral diseases, so continued research into this area shows great potential,” explained Søren Riis Paludan. 


1. Iversen MB, Reinert LS, Thomsen MK, et al. An innate antiviral pathway acting before interferons at epithelial surfacesNat Immunol. 2015;doi:10.1038/ni.3319.