Rotaviruses

Human rotavirus was first discovered in 1973 by R. Bishop and co-authors during an electron microscopic study of enterocytes of the duodenum in children with gastroenteritis and in their feces using the method of immune electron microscopy (sera of convalescents with known antibodies were used), and their etiological role was proven in experiments on volunteers.

In 1978, the International Committee on Taxonomy of Viruses classified human and animal rotaviruses (in which they were also found) as a separate genus, Rotavirus, of the Reoviridae family. The generic name comes from the Latin word rota, meaning wheel, since the shape of the virion is similar to a wheel. This is due to the fact that the virion is spherical, 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 is in contact with a thin outer layer of the capsid, resulting in a structure resembling a wheel: a hub, spokes, and a rim.

In the patient's secretions, single-capsid (60-65 nm) and double-capsid virions (70-75 nm) are usually found. Complete double-capsid virions are infectious.

The virion genome is represented by double-stranded fragmented RNA (11 fragments); in the core, in addition to genomic RNA, there is virion RNA polymerase. There is no supercapsid. The virion contains 8 proteins (VP1-VP8). The UR3 protein of the outer capsid is especially important. It is responsible for the penetration of the virus into the cell and its virulence. In addition, it has a hemagglutinating property. According to the VP3 and VP7 proteins, rotaviruses are divided into 4 serovariants.

Human and animal rotaviruses are divided into 6 serogroups according to group antigens: A, B, C, D, E, F. Their representatives have no antigen relationship and differ in the electrophoretic properties of genomic RNA. Each serogroup is characterized by its own fragment migration profile, consisting of 4 classes. The following have been identified:

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

Electrophoresis is used to detect and differentiate viruses of different serogroups.

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

[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ]

Pathogenesis and symptoms of rotavirus infection

The virus multiplies in the epithelial cells of the duodenum, causing various lesions. The incubation period varies from 1 to 7 days, but is usually less than 2 days. In a typical rotavirus infection, the main early symptom is vomiting, which occurs earlier than diarrhea and lasts from 2 to 6 days. A slight increase in temperature is noted. Diarrhea manifests itself in the form of frequent urges, the stool is liquid or semi-liquid, the frequency of urges 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 continues up to 10 days. Vomiting reaches a maximum in the first 2 days of the disease, diarrhea lasts longer.

Epidemiology of rotavirus infection

The source of infection is humans. Children under 4 years of age are mostly affected. Rotaviruses cause over 130 million cases of diarrhea annually, resulting in up to 600,000 deaths annually.

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

Diagnosis of rotavirus diarrhea

1. Detection of the virus in feces using electron and immune electron microscopy, enzyme immunoassay in a solid-phase version, counter immunoelectrophoresis, immunodiffusion precipitation in agar, RSC, coagglutination reaction, cloned RNA probes.
2. Specific antibodies are detected using various serological reactions, including enzyme-linked immunosorbent assay, complete immunofluorescence, neutralization reaction, and immunofluorescence.

In our country, the following methods are proposed for diagnosing rotavirus infection:

• RPGA using antibody rotavirus diagnosticum;
• coagglutination reaction;
• test systems for detecting antigen using IFM.

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

A highly effective vaccine against rotavirus infection has been developed in the USA.

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

Treatment of rotavirus infection

Treatment of rotavirus diarrhea has three main goals:

• stopping dehydration;
• restoration and maintenance of normal water-salt metabolism;
• ensuring normal nutrition.

Rotavirus diarrhea is successfully treated by rehydration with oral saline solution (NaCl - 3.5 g; NaHC03 - 2.5 g; KCl - 1.5 g; glucose - 20.0 g per 1 liter of water).