Norovirus

Abstract Norovirus infections are the leading cause of acute gastroenteritis globally. Despite the increasing recognition of norovirus infections in various animal species, there is to date no evidence of an animal reservoir for human norovirus, and transmission of norovirus is primarily person‐to‐person. Contaminated food, water and environment act as important amplifiers for infection. Human noroviruses are very diverse; however, one genotype GII‐4 predominates globally and is responsible for nearly half of all the infections and for a higher proportion of the outbreaks. Recently, in vitro systems for the propagation of human noroviruses have been developed, and there is an expectation that in the coming years, these will provide new insights into the molecular biology of human noroviruses and a better understanding of factors that determine susceptibility to and protection form infection. Host genetic factors and comorbidities in addition to potentially modifiable factors such as microbiome and use of certain treatment and drugs are increasingly recognised as important drivers of susceptibility to infection. Key Concepts Norovirus is the leading cause of acute gastroenteritis in humans. Transmission of norovirus is predominantly person‐to‐person and is greatly amplified via contaminated food, water and environment. Glycans act as attachment factors that mediate viral infection and cell entry and potentially drive host restriction. New in vitro systems have recently been developed for human norovirus replication: B cell‐ and stem cell‐derived enteroids. Virus diversity and host genetic and acquired factors are important drivers of susceptibility to infection. The host microbiome has been recognised as an important factor for susceptibility to norovirus infection and clearance.