Chapter 3.5 - Molecular Epidemiology and Evolution of Noroviruses

Abstract

Noroviruses are a major cause of acute gastroenteritis and belong to the family Caliciviridae. Replication of the positive-sense single-stranded RNA genome is carried out by an error-prone RNA-dependent RNA polymerase (RdRp) that drives adaptation and evolution. The noroviruses are remarkably diverse, with seven major phylogenetic genogroups (G) each comprised of one or more genotypes. Among the human norovirus pathogens, multiple genotypes within GI, GII, and GIV, as well as variants of these genotypes, can be detected in epidemiologic surveys, with genotype GII.4 predominating globally as the major cause of infectious diarrheal disease. The marked diversity as well as the ability of strains to undergo recombination have led to the development of a unified dual nomenclature system that defines both RNA-dependent RNA polymerase (P) and capsid protein (C) genotypes. This chapter provides a summary of norovirus epidemiology and evolution, and ongoing efforts to translate this knowledge into the development of effective vaccines.