For the first time, researchers have succeeded in culturing norovirus in human intestinal cells, a breakthrough that could help scientists develop novel therapeutics and vaccines against the debilitating effects of the virus. Intestinal cells are the natural site of norovirus infection, a leading cause of foodborne illness that is highly contagious and can produce sudden onset stomach pain, nausea, diarrhea and vomiting. In the United States, norovirus infection results in about 400,000 emergency department visits and as many as 71,000 hospitalizations annually, mostly among young children and the elderly, according to the U.S. Centers for Disease Control and Prevention. The virus spreads easily in closed and crowded environments such as hospitals, schools and cruise ships.
Norovirus was first identified in 1972 at the National Institutes of Health (NIH) by Albert Z. Kapikian, M.D., and colleagues. However, study of the virus has been difficult because of researchers’ inability to grow the virus outside the human body and the lack of a good animal model to study infection and disease. This has limited knowledge of the basic biology of the virus, including aspects of the molecular mechanisms behind how it causes people to become ill.
To overcome this gap, investigators at Baylor College of Medicine engineered human intestinal tissue from stem cells isolated from the small intestine. When the researchers infected the cultured gut tissue with different strains of norovirus, some virus strains grew well in the cells while others did not. To promote virus growth, the team then tried adding bile from humans and other animals, including cows and pigs, to the intestinal cells. Researchers found that bile was required for replication of some virus strains and enhanced the growth of other strains in the cells. The authors say this new cultivation method could have applications for food safety and the development of new diagnostics, vaccines and therapeutics for norovirus.
Findings from the research, which was supported in part by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, appear in the current issue of the journal Science.
K Ettayebi et al. Replication of human noroviruses in stem cell-derived human enteroids. Science DOI: 10.1126/science.aaf5211 (2016).
NIAID Director Anthony S. Fauci, M.D., and Rodolfo Alarcon, Ph.D., Program Officer, Enteric Viruses, NIAID’s Division of Microbiology and Infectious Diseases, are available for comment.