Virus Plus Gene Mutation Spurs Crohn's Disease in Mice

THURSDAY, June 24 (HealthDay News) -- Mice with a gene variant linked to Crohn's disease only develop the inflammatory bowel disorder if they are infected by a common norovirus called MNV, finds a new study.

Noroviruses are a group of viruses that cause gastroenteritis, an inflammation of the stomach lining.

Two years ago, the researchers at Washington University School of Medicine in St. Louis and others discovered that mice with an ATG16L1 gene variant associated with Crohn's disease in humans develop similar abnormalities in gut immune cells called Paneth cells. But the mutation alone wasn't enough to trigger Crohn's disease.

In a routine screening, the team later found that mice with the gene variant developed Crohn's disease symptoms within seven days after exposure to the MNV norovirus.

The study appears in the June 25 issue of the journal Cell.

It's been suspected that autoimmune and other diseases might be influenced by viral infections, but "this is the first really clear indication of a disease caused by a susceptibility gene and a specific virus," study co-leader Thaddeus Stappenback said in a journal news release.

This particular ATG16L1 gene variant is found in about half of all people of European descent, but is just one of more than 30 genes that may be associated with Crohn's disease. In addition, the ATG16L1 variant only increases a person's risk of the disease by two-fold. The findings of this study may explain why, the researchers said.

-- Robert Preidt

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SOURCE: Cell Press, June 24, 2010, news release.