Norwalk virus vaccines: challenges and progress.

Human caliciviruses (HuCVs) are the major cause of outbreaks of acute nonbacterial gastroenteritis throughout the world. An increasing recognition of the clinical significance of these viruses as human pathogens causing foodborne and waterborne disease indicates that an effective vaccine would be useful. This article reviews the current challenges that exist for the development of a vaccine for the HuCVs as well as the status of development of a candidate vaccine. HuCVs are viruses that exhibit a restricted tropism for infection of the gastrointestinal tract of humans, and a volunteer model of infection and disease is available. As pathogens with a restricted host range, the HuCVs are excellent models for understanding the mechanisms that mediate and regulate viral infection of the gastrointestinal tract and mucosal immunity in humans.