Caliciviridae
المؤلف:
Cornelissen, C. N., Harvey, R. A., & Fisher, B. D
المصدر:
Lippincott Illustrated Reviews Microbiology
الجزء والصفحة:
3rd edition , p287
2025-09-01
328
Caliciviruses are small, nonenveloped, spherical particles. Each contains a single-stranded, nonsegmented RNA genome, and a single species of capsid protein. In contrast to the picornaviruses, the calici viruses genome contains three open reading frames. Norovirus is the prototype human calicivirus. There are at least four strains of human caliciviruses.
A. Caliciviruses
Norovirus (formerly known as Norwalk-like virus) replicates in the GI tract and is shed in the stool. Infection by the Norovirus is by the fecal–oral route, following ingestion of contaminated food or water, by person-to-person contact, or by contact with contaminated surfaces. Norovirus is a major cause of epidemic acute gastroenteritis, particularly at schools, camps, military bases, prisons, and other closed environments such as cruise ships. It affects primarily adults and school-age children but not infants. The clinical presentation is characterized by nausea, vomiting, and diarrhea. Symptoms last 24 to 48 hours, and the disease is self-limited. Radioimmunoassays and ELISA (enzyme-linked immunosorbent assay) tests are available for the detection of antiviral antibodies . No specific antiviral treatment is available. Careful attention to hand washing and measures to prevent contamination of food and water supplies should reduce the incidence of these infections.
B. Hepatitis E virus (HEV)
HEV is a nonenveloped, single-stranded RNA virus. It is a major cause of enterically transmitted, waterborne hepatitis in developing countries. The peak incidence is in young adults, and the disease is especially severe in pregnant women, in whom death can result from HEV infection. Viral RNA can be detected in the feces of infected individuals by RT-PCR , and nearly all serologically confirmed epidemics of HEV can be attributed to fecally contaminated water. Apart from epidemic situations, the diagnosis of HEV cannot be made in an infected individual solely on clinical grounds. However, specific tests are available to detect antibodies to HEV. The signs and symptoms are similar to those seen with other forms of acute viral hepatitis, but, as with hepatitis A, progression to chronic hepatitis is not seen. Interestingly, in regions of the world where HEV is rarely, if ever, diagnosed, antibodies to HEV can still be found. Neither antiviral treatment nor vaccine is currently available.
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