Researchers Grow Human Norovirus Culture

Hoping their discovery will lead to novel treatments, University of Florida (UF) researchers successfully manufactured the human norovirus in a cell culture dish.

The norovirus, which rapidly spreads through schools, hotels and cruise ships, infects millions worldwide, a UF statement pointed out. While vaccines to combat norovirus are being tested, there are no readily available medications due to the lack of the virus to test it on, until now.

“The biggest hurdle to doing norovirus research for its entire history — it was discovered in 1972 – has been that we can’t culture the human viruses in a cell culture dish,” said Stephanie Karst, the study’s author, UF Health researcher and an associate professor in the department of molecular genetics and microbiology in the UF College of Medicine. Karst continued, “That complicates every aspect of research. We can’t study how it replicates, we can’t test therapeutics and we can’t generate live virus vaccines.”

UF investigators’ study published in Science had implicated white cells common to the intestine, or targets B cells role in norovirus infection, contradicting previous belief that intestinal epithelial cells, which line the intestine and protect it from pathogens, were the target for the virus.

The researchers also noted the norovirus’ infection B cells, a key immune cell, was dependent on the person having histo-blood group antigen (HBGA)-expressing enteric bacteria in their bodies. Present in the gut and commensal, HBGA-expressing enteric bacteria’s role in infection was surprising to researchers.

According to Karst, “What we’ve shown is that noroviruses attach to that carbohydrate expressed on commensal bacteria, and that this interaction stimulates viral infection of the B cell.” Karst remarked, “This is a really exciting, emerging theme. A variety of intestinal viruses seem to exploit the bacteria that are present in our intestines all the time. These viral infections are enhanced by the presence of bacteria in the gut.”

“We have identified B cells as a cellular target of noroviruses and enteric bacteria as a stimulatory factor for norovirus infection, leading to the development of an in vitro infection model for human noroviruses,” the authors concluded.