Advances in laboratory methods for detection and typing of norovirus

Abstract

Human noroviruses are the leading cause of epidemic and sporadic gastroenteritis across all age groups. Although the disease is usually self-limiting, in the United States norovirus gastroenteritis causes an estimated 56,000 to 71,000 hospitalizations and 570 to 800 deaths each year. This minireview describes the latest data on laboratory methods (molecular, immunological) for norovirus detection, including real-time reverse transcription-quantitative PCR (RT-qPCR) and commercially available immunological assays as well as the latest FDA-cleared multi-gastrointestinal-pathogen platforms. In addition, an overview is provided on the latest nomenclature and molecular epidemiology of human noroviruses.

FIG 1

Classification of noroviruses into 7 genogroups (GI to GVII) based on amino acid sequence diversity in the complete VP1 capsid protein. To build the phylogenetic tree, capsid sequences from 105 strains representing the spatial and temporal sequence diversity of noroviruses from diverse geographic regions across the world were selected. Viruses belonging to GI, GII, and GIV infect humans, except GII.11, GII.18, and GII.19 viruses, which infect porcine species, and GIV.2 viruses, which infect canine species. GII.15 viruses, which have been detected only in humans, form a tentative new genogroup (dotted circle). GIII viruses infect cows and sheep, GIV.2 infects canines, GV.1 and GV.2 infect mice and rats, respectively, and GVI and GVII infect canine species. GII.4 viruses (arrow) are responsible for the majority of norovirus infections worldwide. The scale bar reflects the number of amino acid substitutions per site.

FIG 2

GII.4 norovirus variants with a global distribution and the first season in which they emerged. New GII.4 variants emerge approximately every 2 to 3 years and replace the previously predominant strains. They include US95_96 in 1995, Farmington Hills in 2002, Hunter in 2004, Yerseke in 2006, Den Haag in 2006, New Orleans in 2009, and Sydney in 2012.