Caliciviridae

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Cryo-electron microscopy shows the three-dimensional structure of Norwalk virus, a strain of norovirus. Courtesy of Baylor College of Medicine

The family Caliciviridae is composed of small (27 to 40 nm), nonenveloped, icosahedral viruses that possess a linear, positive-sense, single-stranded RNA (ssRNA) genome. The four genera of the family are Norovirus, Sapovirus, Vesivirus, and Lagovirus. The major medical pathogens in the family are the noroviruses and sapoviruses, which cause acute gastroenteritis. Important veterinary pathogens include vesiviruses such as feline calicivirus (FCV), which causes a respiratory disease in cats, and lagoviruses such as rabbit hemorrhagic disease virus (RHDV), which causes an often fatal hemorrhagic disease in rabbits (Green et al., 2007). Noroviruses are the major cause of nonbacterial epidemic gastroenteritis, a disease that usually occurs in family or community-wide outbreaks. Noroviruses and sapoviruses have been associated with gastroenteritis in infants and young children, but the predominant etiologic agent of severe diarrheal illness in this young age group is the 70-nm rotavirus in the family Reoviridae (Green et al., 2007)

For references and expanded information, please refer to the Norovirus and Sapovirus PathInfo documents.

Norovirus

Pathogen and Disease

Norovirus (NV) (formerly called Norwalk-like virus) is a member of the family Caliciviridae and causes acute nonbacterial gastroenteritis in humans worldwide. NV is highly infectious and spreads by ingestion of contaminated food, such as oysters and water. NV also spreads by person-to-person transmission through the fecal-oral route in semiclosed communities, such as hospitals, schools, nursing homes, and cruise ships. These characteristics make NV a major public health concern. Within the last decade molecular analyses of the genome of Norwalk-like viruses (NLVs) have confirmed that this important group of infectious agents belongs to the Caliciviridae family. NLVs have a positive-sense, single-stranded RNA genome of approximately 7700 nucleotides excluding the polyadenylated tail (Clark and Lambden, 2002).

For references and expanded Norovirus information, please refer to the Norovirus PathInfo document.

Sapovirus

Pathogen and Disease

Human sapoviruses (SVs), formerly known as Sapporo-like viruses, are single-stranded positive sense RNA viruses in the family Caliciviridae. Genetically, SV is divided into five genogroups (genogroup I [GI], GII, GIII, GIV, and GV). GI, GII, GIV and GV infect humans while GIII infects porcine species (Chan et al., 2006). The Sapporo virus (SV) was one of the first HuCVs with classical morphology to be characterized as antigenically distinct from NV and to be partially characterized at the sequence level (Green et al., 2000).

For references and expanded Sapovirus information, please refer to the Sapovirus PathInfo document.