What causes rotavirus

Rotavirus is a common virus. When a person is infected with rotavirus, it can induce acute viral enteritis. Infants and young children often suffer from this viral infection, especially in spring when the incidence rate is relatively high. This is also an infectious disease that can be transmitted through saliva and feces. With good treatment, it will not cause further harm to the health of the child and will not leave any sequelae.

1. Causes

Rotavirus belongs to the Reoviridae family. It is a double-stranded RNA virus with a diameter of about 70nm and a spherical shape. Under an electron microscope, rotavirus has a unique shape, like a wheel, hence the name. Its two-layer shell wraps around the central protein core, and the outer shell is rim-shaped, surrounding the core gene-encoding protein, vp1~vp7 and five non-structural proteins (nspi~4). The particles with a single-layer shell are incomplete viruses and are not contagious.

According to the different capsid protein group-specific antigen vp6, it can be divided into seven serotypes (a~g). Children's infections are mostly caused by type a, while types b and c mainly infect adults. The others are pathogens that infect animals. Non-group a rotavirus is also called atypical rotavirus or pararotavirus. Infection can be seen in humans, pigs, cattle, sheep, chickens, etc.

Rotavirus has strong resistance to the outside world and can survive for 7 months at room temperature and for several days or weeks in feces. It is acid-resistant and alkali-resistant and can be inactivated by heating at 55°C for 30 minutes or using formaldehyde.

Pathogenesis

Whether rotavirus can cause disease after entering the body depends on the amount of infected virus, the body's immune status and the body's physiological characteristics. When the amount of invading virus is large and the immune function is low, it is helpful for the virus to invade. When the body's intestinal epithelial brush border contains a lot of lactase (a rotavirus receptor), such as in infancy, it is easy to be infected with rotavirus. With age, the amount of this enzyme decreases and susceptibility decreases.

After rotavirus enters the body, it causes diarrhea through two pathways: first, rotavirus directly damages the villus epithelial cells of the small intestine, causing pathological changes; second, the metabolites of rotavirus during the replication process act on the endothelial cells of the small intestine, destroying the normal physiological functions of the intestinal cells and causing diarrhea.

After rotavirus invades the human body and reaches the small intestine, it enters the epithelial cells through its outer shell protein vp4 (adsorption protein) binding to the lactase on the intestinal mucosal villus epithelial cells, proliferates in the epithelial cytoplasm and causes them to be damaged and fall off. As the villus epithelial cells are damaged, the amount of disaccharidases such as lactase is reduced, resulting in the obstruction of the conversion of lactose to other monosaccharides. Lactose accumulates in the intestinal cavity, causing high osmotic pressure in the small intestine and colon cavity, causing water to move into the intestinal cavity, leading to diarrhea and vomiting.