Pathogenesis of Noroviruses, Emerging RNA Viruses

Abstract

Human noroviruses in the family Caliciviridae are a major cause of epidemic gastroenteritis. They are responsible for at least 95% of viral outbreaks and over 50% of all outbreaks worldwide. Transmission of these highly infectious plus-stranded RNA viruses occurs primarily through contaminated food or water, but also through person-to-person contact and exposure to fomites. Norovirus infections are typically acute and self-limited. However, disease can be much more severe and prolonged in infants, elderly, and immunocompromised individuals. Norovirus outbreaks frequently occur in semi-closed communities such as nursing homes, military settings, schools, hospitals, cruise ships, and disaster relief situations. Noroviruses are classified as Category B biodefense agents because they are highly contagious, extremely stable in the environment, resistant to common disinfectants, and associated with debilitating illness. The number of reported norovirus outbreaks has risen sharply since 2002 suggesting the emergence of more infectious strains. There has also been increased recognition that noroviruses are important causes of childhood hospitalization. Moreover, noroviruses have recently been associated with multiple clinical outcomes other than gastroenteritis. It is unclear whether these new observations are due to improved norovirus diagnostics or to the emergence of more virulent norovirus strains. Regardless, it is clear that human noroviruses cause considerable morbidity worldwide, have significant economic impact, and are clinically important emerging pathogens. Despite the impact of human norovirus-induced disease and the potential for emergence of highly virulent strains, the pathogenic features of infection are not well understood due to the lack of a cell culture system and previous lack of animal models. This review summarizes the current understanding of norovirus pathogenesis from the histological to the molecular level, including contributions from new model systems.

High prevalence of noroviruses among hospitalized diarrheal patients in Bangladesh, 2011

“…Samples were transported in temperature controlled boxes (2)(3)(4)(5)(6)(7)(8) o C) to the Virology Laboratory of icddr,b in Dhaka and stored at -20°C until tested.…”

“…Recent reports from around the world indicate that NoV has become one of the most commonly identified pathogens and is responsible for the hospitalization for severe gastroenteritis of 12% of children less than 5 years of age (range 4.4-30.7%) [1,2,3,4]. NoV is associated with nausea, vomiting, and diarrhea with abdominal cramps and is sometimes accompanied by malaise and low grade fever [5]. The disease is self-limiting; however, it can be severe in the elderly, very young or immune-compromised patients [5].…”

“…NoV is associated with nausea, vomiting, and diarrhea with abdominal cramps and is sometimes accompanied by malaise and low grade fever [5]. The disease is self-limiting; however, it can be severe in the elderly, very young or immune-compromised patients [5].…”

Detection of GI and GII noroviruses in drinking water and vegetables using filtration and real-time RT-PCR

“…Indeed, NoVs cause at least 95 % of all non-bacterial gastroenteritis outbreaks and 50 % of all gastroenteritis outbreaks [13]. Moreover, waterborne transmission is a significant route of exposure, as contaminated water also serves as a vehicle for outbreaks of food poisoning by foods such as vegetables and shellfish.…”

Targeting Norovirus: Strategies for the Discovery of New Antiviral Drugs

“…Its function in viral replication is currently undefined but there is evidence that it increases the level of expression of VP1 and stabilizes virus-like particles (VLPs, generated through expression of the VP1) (Bertolotti-Ciarlet et al, 2003). The basic charge of VP2 suggests that it may function in encapsidation of the viral genome (Karst, 2010).…”