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Order Picornavirales
Published in Paul Pumpens, Peter Pushko, Philippe Le Mercier, Virus-Like Particles, 2022
Paul Pumpens, Peter Pushko, Philippe Le Mercier
The family Caliciviridae joined the order Picornavirales in 2019 and includes, under the current official ICTV view (Vinjé et al. 2019; ICTV 2020), 11 genera and 13 species. The genus Lagovirus that includes the well-studied rabbit hemorrhagic disease virus (RHDV) causing a highly contagious disease in rabbits and is thus an economically important pathogen for commercial rabbit production, as well as European brown hare syndrome virus (EBHSV) and the genus Norovirus with Norwalk virus (NoV), are especially essential for the VLP nanotechnologies. Some representatives of the genera Sapovirus and Vesivirus also played a remarkable role in this field. Generally, the Caliciviridae members infect mammals, birds, and fish (Vinjé et al. 2019). The most clinically important representatives are human noroviruses, which remain a leading cause of acute gastroenteritis in humans (Green 1997).
Noroviruses: Laboratory Surrogates for Determining Survival and Inactivation
Published in Dongyou Liu, Laboratory Models for Foodborne Infections, 2017
Doris H. D’Souza, Snehal S. Joshi
HNoVs are a worldwide public health and food safety concern. However, in the absence of reproducible cell-culture-based infectivity assays and due to the lack of available vaccines to date, cultivable surrogates and model systems are used in order to determine survival, transmission, and inactivation methods to prevent outbreaks and minimize the risk of HNoV contamination. Typically, cultivable surrogates that mimic the characteristics of HNoVs are genetically related and are used in laboratory settings. These surrogates include cultivable animal viruses from the Caliciviridae family as well as bacteriophages and noroviral-like particles. The application of these surrogates in environmental studies and to enhance food safety remains ongoing. However, the ideal situation of having reproducible infectivity assays for HNoVs appears to be a challenge and research efforts continue to be made toward attaining this goal.
Common Viral Infections
Published in Thomas T. Yoshikawa, Shobita Rajagopalan, Antibiotic Therapy for Geriatric Patients, 2005
After respiratory viruses, GI viruses are the leading causes of serious viral illnesses in the elderly. Although deaths related to diarrhea have traditionally been thought to be a problem of young children in developing countries, 51% of the 28,000 diarrhea-related deaths in the United States from 1979 to 1987 occurred in adults >74 years of age compared with 11% in children <5 years old (28). The odds ratio of dying during a hospitalization involving gastroenteritis for adults aged >70 years was 52.6 compared with children <5 years of age. Residents of nursing homes are at particular risk of infectious diarrhea illness because of the potential for spread in closed populations. The majority of nursing home outbreaks of gastroenteritis are probably viral in origin since bacterial causes are not usually identified. These agents include rotavirus, enteric adenoviruses, calicivirus, Norwalk-like virus (NLV), Snow Mountain agent, and small round viruses (29). NLV are a group of antigenically distinct RNA viruses of the Caliciviridae family. Recent reports indicate that NLV have a major role in the etiology of gastroenteritis in nursing homes and are implicated in 59-86% of outbreaks. Rotaviruses are the second most commonly identified gastroenteritis virus in older persons and have been implicated in several outbreaks in elderly residents of long-term care facilities (30). The mode of transmission is assumed to be fecal-oral for most viruses, and viruses are relatively resistant to common disinfectants facilitating nosocomial dissemination. Attack rates have ranged from 36% to 66% with mortality rates of 1-10%. The typical illness includes voluminous vomiting and watery diarrhea with low-grade fever. Bloody stools are not usually seen and diarrhea typically lasts 2-3 days. Death may result from dehydration, progressing to oliguria and acidosis (28,30). A commercial rapid EIA test is available for the diagnosis of rotavirus and is available in many microbiology laboratories. Most often the diagnosis of viral gastroenteritis is made based on clinical features. However, it is important to exclude bacterial pathogens and antibiotic-associated diarrhea which may require specific antimicrobial treatment. The mainstay of treatment for viral gastroenteritis is replacement of fluid losses. In the absence of vomiting, oral rehydration therapy may be used with intravenous fluids reserved for those unable to take oral fluids.
cGAS-STING effectively restricts murine norovirus infection but antagonizes the antiviral action of N-terminus of RIG-I in mouse macrophages
Published in Gut Microbes, 2021
Peifa Yu, Zhijiang Miao, Yang Li, Ruchi Bansal, Maikel P. Peppelenbosch, Qiuwei Pan
Noroviruses are positive sense single-stranded RNA viruses belonging to the Caliciviridae family.1 The lack of robust cell culture system for human norovirus (HuNV) impedes development of effective antiviral therapeutics. The closely related murine norovirus (MNV) shares similar structural and genetic features with HuNV and efficiently propagates in vitro and in vivo, representing as a useful model for studying norovirus biology.2 The MNV genome is approximately 7.5 kilo bases in length, consisting of four open reading frames (ORFs). ORF1 encodes a polyprotein that is post-translationally cleaved into six non-structural proteins (NS1/2 to NS7), while ORF2 and ORF3 encode the major and minor structural viral proteins as VP1 and VP2, respectively. ORF4 overlaps with ORF2, and encodes the virulence factor (VF1), which has been reported to antagonize innate immune response.3
Vaccines against gastroenteritis, current progress and challenges
Published in Gut Microbes, 2020
Hyesuk Seo, Qiangde Duan, Weiping Zhang
Progress has been also made in vaccine development for the other enteric viruses including astroviruses (Astroviridae), adenoviruses (Adenoviridae), and sapoviruses (Caliciviridae). Other Astroviridae members such as VA-Like and MLB-like astroviruses, Picornaviridae (silivirus, cosavirus), and Parvoviridae families (bocaviruses, bufaviruses) are also isolated from patients (usually in infants and children) with gastroenteritis. Several subunit vaccines have been investigated for prevention against astrovirus infections. In particular, a trivalent subunit vaccine for hepatitis E virus, norovirus, and astrovirus was generated by fusing together the dimeric P domains of the three viruses to form a tetramer.93 When intranasally administered to mice, this trivalent product induced significant neutralizing antibody responses to the P domains of all three viruses. Another subunit astrovirus vaccine candidate used the capsid protein (CP) of mink astrovirus elicited high levels of serum anti-CP antib odies and lymphoproliferation responses and also stimulated IFN-γ levels in mice.94 Importantly, it was observed that virus shedding was suppressed and clinical signs including severe diarrhea were reduced in the litters born to the immunized mink mothers when challenged with a heterogeneous astrovirus strain.94 Future human volunteer studies and clinical trials are needed to assess the efficacy of these vaccine candidates against viral gastroenteritis.
Progress on norovirus vaccine research: public health considerations and future directions
Published in Expert Review of Vaccines, 2018
Claire P. Mattison, Cristina V. Cardemil, Aron J. Hall
The genus Norovirus includes a genetically and antigenically diverse group of viruses within the family Caliciviridae (i.e. caliciviruses) and consist of at least seven genogroups, three of which – GI, GII, and GIV – infect humans [4]. Genotype GII.4 causes the majority of norovirus outbreaks worldwide, and until 2012 new GII.4 variants emerged every 2–4 years [5,6]. The norovirus genome has three open reading frames (ORFs) of which ORF2 and ORF3 encode the major capsid protein (VP1) that determines the antigenicity of the virus, as well as the minor capsid protein (VP2). ORF1 encodes a large polyprotein that is cleaved by the viral protease in mature nonstructural proteins, including the RNA-dependent RNA polymerase [7]. To date, all norovirus vaccine candidates contain noninfectious recombinant VP1 proteins, either as virus-like particles (VLP), as P-particles, or as recombinant adenoviruses.