Predicting human norovirus infectivity - Recent advances and continued challenges.

Human norovirus is the leading cause of foodborne illness globally, imposing a considerable public health and economic burden. Historically, one of the major obstacles to the study of human noroviruses has been the lack of an in vitro cultivation system. In addition to hindering elucidation of viral pathogenesis, research efforts have been limited by the inability to discriminate infectious from non-infectious viral particles. Two recent breakthrough human norovirus in vitro cultivation system systems have been reported, but in their current state, may be unsuitable for routine detection or study of human noroviruses in the food and water sciences. More accessible alternative techniques utilizing molecular assays, animal models, and surrogate virus systems for prediction of human norovirus infectivity have been presented. The purpose of this review is to present the multiple recent techniques used to assess human norovirus infectivity, including recently described human norovirus in vitro cultivation systems, cultivable surrogate viruses, animal models, and alternative molecular techniques, and discuss their advantages and disadvantages in the context of determining human norovirus infectivity.