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.
Human noroviruses (NoVs) of genogroup II, genotype 4 (GII.4) are the most common strains detected in outbreaks of acute gastroenteritis worldwide. To gain insight into the epidemiology and genetic ...variation of GII.4 strains, we analyzed 773 NoV outbreaks reported to the CDC from 1994 to 2006. Of these NoV outbreaks, 629 (81.4%) were caused by GII viruses and 342 (44.2%) were caused by GII.4 strains. The proportion of GII.4 outbreaks increased from 5% in 1994 to 85% in 2006, but distinct annual differences were noted, including sharp increases in 1996, 2003, and 2006 each associated with newly emerging GII.4 strains. Sequence analysis of the full-length VP1 gene of GII.4 strains identified in this study and from GenBank segregated these viruses into at least 9 distinct subclusters which had 1.3 to 3.2% amino acid variation between strains in different subclusters. We propose that GII.4 subclusters be defined as having >5% sequence variation between strains. Our data confirm other studies on the rapid emergence and displacement of highly virulent GII.4 strains.
Noroviruses are genetically diverse RNA viruses associated with acute gastroenteritis in mammalian hosts. Phylogenetically, they can be segregated into different genogroups as well as P ...(polymerase)-groups and further into genotypes and P-types based on amino acid diversity of the complete VP1 gene and nucleotide diversity of the RNA-dependent RNA polymerase (RdRp) region of ORF1, respectively. In recent years, several new noroviruses have been reported that warrant an update of the existing classification scheme. Using previously described 2× standard deviation (sd) criteria to group sequences into separate clusters, we expanded the number of genogroups to 10 (GI-GX) and the number of genotypes to 48 (9 GI, 27 GII, 3 GIII, 2 GIV, 2 GV, 2 GVI and 1 genotype each for GVII, GVIII, GIX formerly GII.15 and GX). Viruses for which currently only one sequence is available in public databases were classified into tentative new genogroups (GNA1 and GNA2) and genotypes (GII.NA1, GII.NA2 and GIV.NA1) with their definitive assignment awaiting additional related sequences. Based on nucleotide diversity in the RdRp region, noroviruses can be divided into 60 P-types (14 GI, 37 GII, 2 GIII, 1 GIV, 2 GV, 2 GVI, 1 GVII and 1 GX), 2 tentative P-groups and 14 tentative P-types. Future classification and nomenclature updates will be based on complete genome sequences and will be coordinated and disseminated by the international norovirus classification-working group.
With the advent of the rotavirus vaccine, the causes of acute gastroenteritis in children are evolving. In this report from three sentinel U.S. sites, norovirus is identified as a leading causal ...organism in acute gastroenteritis in children.
Norovirus-associated acute gastroenteritis is characterized by the sudden onset of intense vomiting and dehydrating diarrhea, typically lasting 1 to 3 days, with high rates of transmission to persons of all ages.
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Norovirus is a leading etiologic pathogen implicated in severe gastroenteritis outbreaks in the United States.
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However, the endemic burden of norovirus-associated acute gastroenteritis identified through active, laboratory-confirmed surveillance of U.S. pediatric populations has not been fully characterized.
Given the substantial decline in pediatric rotavirus-associated acute gastroenteritis in the United States since the introduction of rotavirus vaccines,
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and given recent advances in the development of candidate norovirus vaccines, . . .
We report a norovirus GIV outbreak in the United States, 15 years after the last reported outbreak. During May 2016 in Wisconsin, 53 persons, including 4 food handlers, reported being ill. The ...outbreak was linked to individually prepared fruit consumed as a fruit salad. The virus was phylogenetically classified as a novel GIV genotype.
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DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Human noroviruses are a leading cause of epidemic and endemic acute gastroenteritis worldwide and a leading cause of foodborne illness in the United States. Recently, human intestinal enteroids ...(HIEs) derived from human small intestinal tissue have been shown to support human norovirus replication. We implemented the HIE system in our laboratory and tested the effect of chlorine and alcohols on human norovirus infectivity. Successful replication was observed for 6 norovirus GII genotypes and was dependent on viral load and genotype of the inoculum. GII.4 viruses had higher replication levels than other genotypes. Regardless of concentration or exposure time, alcohols slightly reduced, but did not completely inactivate, human norovirus. In contrast, complete inactivation of the 3 GII.4 viruses occurred at concentrations as low as 50 ppm of chlorine. Taken together, our data confirm the successful replication of human noroviruses in HIEs and their utility as tools to study norovirus inactivation strategies.
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DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Although recognized as the leading cause of epidemic acute gastroenteritis across all age groups, norovirus has remained poorly characterized with respect to its endemic disease incidence. Use of ...different methods, including attributable proportion extrapolation, population-based surveillance, and indirect modeling, in several recent studies has considerably improved norovirus disease incidence estimates for the United States. Norovirus causes an average of 570-800 deaths, 56,000-71,000 hospitalizations, 400,000 emergency department visits, 1.7-1.9 million outpatient visits, and 19-21 million total illnesses per year. Persons >65 years of age are at greatest risk for norovirus-associated death, and children <5 years of age have the highest rates of norovirus-associated medical care visits. Endemic norovirus disease occurs year round but exhibits a pronounced winter peak and increases by ≤ 50% during years in which pandemic strains emerge. These findings support continued development and targeting of appropriate interventions, including vaccines, for norovirus disease.
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DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The cell tropism of human noroviruses and the development of an in vitro infection model remain elusive. Although susceptibility to individual human norovirus strains correlates with an individual’s ...histo-blood group antigen (HBGA) profile, the biological basis of this restriction is unknown. We demonstrate that human and mouse noroviruses infected B cells in vitro and likely in vivo. Human norovirus infection of B cells required the presence of HBGA-expressing enteric bacteria. Furthermore, mouse norovirus replication was reduced in vivo when the intestinal microbiota was depleted by means of oral antibiotic administration. Thus, we have identified B cells as a cellular target of noroviruses and enteric bacteria as a stimulatory factor for norovirus infection, leading to the development of an in vitro infection model for human noroviruses.
CaliciNet, the outbreak surveillance network for noroviruses in the United States, was launched in March 2009. As of January 2011, twenty state and local health laboratories had been certified to ...submit norovirus sequences and epidemiologic outbreak data to CaliciNet. During the network's first year, 552 outbreaks were submitted to CaliciNet, of which 78 (14%) were associated with foodborne transmission. A total of 395 (72%) outbreaks were typed as GII.4, of which 298 (75%) belonged to a new variant, GII.4 New Orleans, which first emerged in October 2009. Analysis of the complete capsid and P2 region sequences confirmed that GII.4 New Orleans is distinct from previous GII.4 variants, including GII.4 Minerva (2006b).
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DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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