Reminder: Celiac is that autoimmune disorder where the body improperly freaks out over the protein gluten, which is found in wheat, rye, and barley, and the immune response leads to inflammation and damage in the small intestine. The only treatment is a strict gluten-free diet. (This is not to be confused with people who think gluten is bad for their overall health; they've just read one too many poorly researched wellness articles.)
For the study, researchers from the University of Chicago and the University of Pittsburgh School of Medicine found that giving mice an intestinal pathogen called a reovirus made their immune systems overreact to gluten and become intolerant to it, effectively triggering celiac disease to develop. They also looked at blood samples from people with celiac and found much higher levels of reovirus antibodies than those without the disease, which suggest that they'd been infected with the virus. Celiac patients also had higher expression levels of the IRF1 gene, which plays a role in losing tolerance to gluten. They said it's possible that the virus leaves a permanent mark on the immune system, like a scar.
The authors certainly aren't suggesting that everyone with celiac got the disease from a virus—others are just genetically predisposed—but it's just more evidence that viruses can cause autoimmune diseases, including celiac and type 1 diabetes. This may mean that in the future vaccines could help prevent some cases of such chronic illnesses.