Epidemiology of human noroviruses and updates on vaccine development.
OBJECTIVE
Noroviruses (NoVs) are the most common cause of epidemic and sporadic cases of acute gastroenteritis worldwide. This review summarizes recent NoV disease burden estimates, epidemiology findings and provides an update on virus-like particle (VLP) vaccine studies.


RESULTS
NoVs are the leading cause of food-borne gastroenteritis and are replacing rotavirus as the predominant gastrointestinal pathogen in pediatric populations. Genogroup II, genotype 4 NoVs (GII.4) remain the dominant genotype worldwide. Increased NoV activity reported in late 2012 was associated with the emergence of a new GII.4 variant called Sydney 2012. New studies suggest that human NoVs can bind a larger range of histoblood group antigens, a susceptibility factor for NoV illness, thus expanding the susceptible population pool for infection. Intranasal immunization with a monovalent GI NoV VLP vaccine showed proof-of-concept efficacy. Studies using intramuscular immunization with a bivalent formulation including GII.4 VLPs are now underway.


CONCLUSIONS
The importance of NoVs as a major gastrointestinal pathogen underscores the need for well tolerated and effective vaccines. Results of VLP vaccine trials appear promising. However, the rapid evolution of NoV genotypes through antigenic drift and changing glycan specificities provide new challenges to epidemiology studies and vaccine trials.
aDepartment of Molecular Virology and Microbiology bDepartment of Medicine, Baylor College of Medicine, Houston, Texas, USA.
Sasirekha
S
Ramani
Robert L
RL
Atmar
Mary K
MK
Estes
D000208:Acute Disease; D017250:Caliciviridae Infections / Q000453:epidemiology*; D005759:Gastroenteritis / Q000453:epidemiology* / Q000821:virology; D005838:Genotype; D006801:Humans; D029322:Norovirus / Q000145:classification / Q000235:genetics; D010802:Phylogeny; D058425:Vaccines, Virus-Like Particle
D058425:Vaccines, Virus-Like Particle