Rotaviruses

Rotavirus was first discovered in 1973 by R. Bishop and co-authors in electron microscopic examination of duodenal enterocytes in patients with gastroenteritis of children and in their feces using the method of immune electron microscopy (serum of convalescents with known antibodies was used), and in experiments on volunteers have been proven their etiological role.

In 1978, the International Committee on Taxonomy of Viruses isolated rotaviruses of humans and animals (in which they were also found) into the independent genus Rotavirus of the family Reoviridae. The generic name comes from the Latin word rota - the wheel, since the shape of the virion is similar to the wheel. This is due to the fact that the virion has a spherical shape and its genome is surrounded by a nucleocapsid consisting of two layers: the inner layer tightly surrounds the core, has the shape of an icosahedron and contacts the thin outer layer of the capsid, resulting in a structure resembling a wheel: a bush, spokes and bezel.

Isolations of the patient usually meet single-cap (60-65 nm) and two-capsid virions (70-75 nm). Infectious are full two-capsid virions.

The virion genome is represented by double-stranded fragmented RNA (11 fragments); In the core, in addition to genomic RNA, a virion RNA polymerase is located. Supercapsid is absent. The virion contains 8 proteins (VP1-VP8). Especially important is the URZ protein of the outer capsid. He is responsible for the penetration of the virus into the cell and its virulence. In addition, it has a hemagglutinating property. For VP3 and VP7 proteins, rotaviruses are divided into 4 serovariants.

Rotaviruses of humans and animals by group antigens are divided into 6 serogroups: A, B, C, D, E, F. Their representatives do not have antigenic relationship and differ according to the electrophoretic properties of genomic RNA. Each serogroup has its own fragment migration profile, which consists of 4 classes. Identified by:

A = 4, 2, 3, 2; B = 4, 2, 2, 2; C = 4, 3, 2, 2.

With the help of electrophoresis, viruses of different serogroups are identified and differentiated.

A feature of human rotaviruses is that they reproduce poorly in the laboratory, and therefore a long time is required to adapt them to growth in cell cultures.

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Pathogenesis and symptoms of rotavirus infection

The virus multiplies in the epithelial cells of the duodenum, causing various injuries. The incubation period varies from 1 to 7 days, but usually less than 2 days. With a typical rotavirus infection, the main early symptom is vomiting, which occurs earlier than diarrhea, and lasts from 2 to 6 days. There is a slight increase in temperature. Diarrhea manifests itself in the form of frequent desires, the stool is liquid or semi-liquid, the frequency of desires is up to 20 times a day. Dehydration is observed in 83% of patients. The duration of the disease varies from 4 to 7 days, the release of the virus lasts up to 10 days. Vomiting peaks in the first 2 days of the illness, the diarrhea lasts longer.

Epidemiology of rotavirus infection

The source of infection is a person. Mostly children under 4 years old are ill. Rotaviruses cause more than 130 million cases of diarrhea every year, resulting in 600,000 deaths each year.

[6], [7], [8], [9], [10], [11], [12], [13], [14], [15]

Diagnosis of rotavirus diarrhea

1. Detection of the virus in feces by electron and immune electron microscopy, enzyme-linked immunosorbent assay, reverse immunoelectrophoresis, immunodiffusion precipitation in agar, RSK, coagglutination reaction, cloned RNA probes.
2. Specific antibodies are detected by various serological reactions, including by means of an enzyme immunoassay, DSC, neutralization reaction and immunofluorescence.

In our country for the diagnosis of rotavirus infection the following methods are suggested:

• RPGA with the use of an antiviral rotavirus diagnosticum;
• coagglutination reaction;
• test systems for antigen detection with the help of IFM.

These methods are designed to quickly detect rotavirus in the patient's bowel movements. To detect specific antibodies to rotaviruses, the inhibition of indirect (passive) hemagglutination is used.

In the US, a highly effective vaccine against rotavirus infection has been established.

[16], [17], [18], [19], [20], [21], [22], [23], [24], [25],

Treatment of rotavirus infection

Treatment of rotavirus diarrhea has three main objectives:

• cessation of dehydration;
• restoration and maintenance of normal water-salt metabolism;
• provision of normal nutrition.

Rotavirus diarrhea is successfully cured by rehydration with an oral saline solution (NaCl 3.5 g, NaHC03 2.5 g, KC1 1.5 g, glucose 20.0 g per 1 liter of water).