Noroviruses inflict diarrhoea and vomiting on hundreds of millions of people worldwide every year. Now, the gut cells targeted by the virus have finally been identified in mice.
Noroviruses are known to infect the immune cells of mice by binding to a receptor called CD300lf, but that receptor has never been found in the cells lining the gut. Craig Wilen at Washington University School of Medicine in St. Louis, Missouri, and his colleagues used a fluorescent marker to identify mouse gut cells that express CD300lf. The tags revealed that noroviruses infect tuft cells, a rare type of cell in the gut lining.
This also explains a puzzling observation from previous studies: why mice infested with intestinal worms tend to experience worse norovirus symptoms than mice without worms. Worm infestation leads to a proliferation of tuft cells, providing more cells for the virus to infect. The finding also offers an explanation for why antibiotics that reduce tuft-cell proliferation alleviate norovirus infection.