What is Rotavirus?

Rotavirus is one of the main pathogens that cause diarrhea in infants and young children. It mainly infects small intestinal epithelial cells, causing cell damage and diarrhea. Rotavirus is epidemic every year in summer, autumn, and winter. The infection route is fecal-oral route. The clinical manifestations are acute gastroenteritis and osmotic diarrhea. The course of disease is generally 6-7 days. Days, 5 days of diarrhea, severe symptoms of dehydration.

Rotavirus

Around 900,000 infant and child deaths are caused by rotavirus infections worldwide each year, most of which occur in developing countries. In our country, people under 0 ~ 2 years old

Rotavirus infection ranges from asymptomatic, mild to severe, and fatal if severe

Spherical, 70nm, nucleic acid, segmented double-stranded RNA, stable structure, heat resistance, acid and alkali resistance on the surface of hemagglutinin, inhibit V and cell contact, trypsin can be used to destroy hemagglutinin, difficult to culture MA-104 Rhesus monkey passage cell culture causes children

In 1943, Jacob Light and Horace Hodes demonstrated that there is a filter vector in children infected with infectious diarrhea, which can also cause diarrhea in livestock. . Thirty years later, a preserved vector sample proved that the vector was rotavirus. During the intervention years, the virus in mice showed a correlation with the virus that causes diarrhea. Ruth Bishop in Australia in 1973

Rotavirus

Rotaviruses are transmitted by the fecal-oral route. They are transmitted by contact with soiled hands, soiled surfaces, and soiled objects, and may be transmitted through the respiratory path [1]. The faeces of infected patients can contain more than 100 billion billion per gram [data is problematic, the total weight of 10E19 viruses is greater than 1 gram] infectious virus particles; and only 10 to 100 of them can be transmitted through And infect another person.

Rotavirus is stable in the natural environment, and can also be found in samples from estuaries, whose samples can find 1 to 5 infectious rotavirus particles per US gallon. Sanitary equipment that eliminates bacteria and parasites appears to be ineffective in controlling rotavirus because the incidence of rotavirus infections is similar in countries with high and low levels of health.

Diarrhea is a multiple activity caused by rotavirus. Because it is called the intestine

Rotavirus infection is diagnosed normally

In 2006, two vaccines against rotavirus A infection have proven safe for children and

Rotavirus can also infect young animals and cause diarrhea. Various studies have shown that rotaviruses can infect mammals (such as apes, cows, pigs, sheep, voles, cats and dogs, house mice, horses and rabbits, etc.) and birds (chickens and turkeys). These rotaviruses in infected animals are produced by rotaviruses that infect humans.

Rotavirus Rotavirus

There are seven types of rotaviruses, which are numbered A, B, C, D, E, F, and G, etc. Humans are mainly infected by Rotavirus A, B, and C, and the most common of these is Rotavirus A. All seven of these rotaviruses cause disease in other animals.

There are different strains of rotavirus A, called serovar. Similar to influenza viruses, rotavirus uses a dual classification system, so the classification is based on two structural proteins on the surface of the virion. The glycoprotein VP7 defines the G-type and the protease-sensitive protein VP4 defines the P-type (see below for details of these proteins). P-type will mark the P serotype with a number, and use a number inside the square brackets to indicate the corresponding P genotype. The expression of G serotype is similar, but the number of G genotype will be the same as the number of G serotype. For example, "rotavirus strain Wa" will be labeled "P1A [8] G1". Because these two genes that determine the G and P types can be transmitted separately to produce offspring, different combinations of the two genes will produce different virus strains.

Rotavirus structure

The rotavirus genome contains 11 unique ribonucleic acid double helix molecules, of which there are a total of 18,555 nucleobase pairs. Each spiral or segment is a gene, and is numbered 1 to 11 according to the size of the molecule. Each gene can be encoded as a protein, and the 9th gene is more special than the 11th gene, and they can be encoded as two kinds of proteins. The outer periphery of the RNA is a protein shell that encloses a three-layered icosahedron. The virus particles are approximately 76.5 nm in diameter and do not have a viral envelope.

Rotavirus protein

There are six viral proteins (VPs) that frame the entire virus particle (virion). These "structural" proteins are called VP1, VP2, VP3, VP4, VP6 and VP7. In addition to these structural proteins, there are six non-structural proteins (NSP), which are produced only in cells infected by rotavirus, without the structure of the virion. These six non-structural proteins are called NSP1, NSP2, NSP3, NSP4, NSP5, and NSP6.

Of the 12 proteins encoded by the rotavirus genome, at least six will bind to RNA. The role these proteins play in rotavirus replication is not fully understood; their function is thought to be related to the synthesis and packaging of the virion's internal ribonucleic acid, or the delivery of messenger RNA to the genome for replication Field-related, or messenger RNA translation and gene expression regulation.

Structural protein

The VP1 protein is a ribonucleic acid polymerase located in the core of the virion. In infected cells, the enzyme produces copies of messenger RNA transcripts needed for viral protein synthesis, as well as copies of the rotavirus genome ribonucleic acid fragment to provide for the use of newly generated virions.

The VP2 protein forms the core layer of the virion and binds to the ribosome.

The VP3 protein is part of the virion's core and is an enzyme called guanylyl transferase. This enzyme is a capping enzyme, which is the enzyme used to make a 5 'end cap for post-transcriptional modification of messenger RNA. This 5 'end cap protects the viral messenger ribonucleic acid from nucleases (hydrolytic enzymes that use nucleic acid as a substrate) to keep them stable.

The VP4 protein is located on the surface of the virion and protrudes into a spike. It connects receptor molecules on the cell surface and drives the virus into that cell. Before the virus is contagious, the VP4 protein is changed to VP5 * and VP8 * proteins by a protease that can be found in the internal organs. The VP4 protein determines the virus's toxicity (Virulence), and it also determines the P type of the virus.

The VP6 protein forms the volume of the shell. It is a highly antigenic protein and can be used to distinguish between rotavirus species. This protein is used by laboratories to perform various tests for rotavirus A infection.

VP7 protein is a glycoprotein that establishes the outer surface of the virus. Excluding its function on the structure of the virus, it also determines the G-type of the virus bead. VP7 protein, like VP4 protein, is used by immunity as a way to prevent infection.

Nonstructural protein

The NSP1 protein is the product of the No. 5 gene, a non-structural protein, and also a RNA-binding protein.

NSP2 protein is a ribonucleotide binding protein that accumulates in the cytoplasmic contents (ie, viroplasm) and is a protein required for genome replication.

The NSP3 protein is affected by viral messenger RNA in infected cells, which is responsible for stopping cellular protein synthesis.

NSP4 protein is a viral enterotoxin that can cause symptoms of diarrhea. This protein is the first viral enterotoxin found.

The NSP5 protein is a product encoded by the 11th gene of the rotavirus A genome. In virus-infected cells, NSP5 protein accumulates in the virions.

The NSP6 protein is a nucleic acid-binding protein and is the coding product of gene 11 at the open reading frame stage.

Rotavirus genes and proteins

RNA fragment (gene)	Size (base pairs)	protein	Molecular weight (kDa)	location	function
1	3302	VP1	125	At the apex of the core	RNA-dependent RNA polymerase (RdRp)
2	2690	VP2	102	Inner shell forming the core	RNA-replicating enzyme
3	2591	VP3	88	At the apex of the core	Guanylate transferase, messenger RNA capping enzyme
4	2362	VP4	87	Surface spikes	Cell attachment, toxicity
5	1611	NSP1	59	Unstructured	Not necessary for virus growth
6	1356	VP6	45	Inner shell	Structural and species-specific antigens
7	1104	NSP3	37	Unstructured	Strengthens viral messenger RNA activity and stops protein synthesis in infected cells
8	1059	NSP2	35	Unstructured	Nucleoside triphosphatase (NTPase) contained in the RNA packaging
9	1062	VP7 VP7	38 34	surface	Structural and neutralizing antigens
10	751	NSP4	20	Unstructured	Enterotoxin
11	667	NSP5 NSP6	twenty two	Unstructured	Single-stranded RNA and double-stranded RNA that combine NSP2 regulators

The information in this table is based on the rotavirus SA11 strain that infects apes. ^[4] The encoding predictions between ribonucleic acid and protein will vary among different strains of the virus.

Rotavirus replication

Rotavirus infects the intestinal mucosal cells of the villi of the small intestine and changes the structure and function of epithelial tissues. ^[5] The triple protein outer layer of rotavirus makes them resistant to gastric acid in the stomach and digestive enzymes in the digestive system.

The virus enters the cell by endocytosis of the receptor medium and forms a vesicle called an endosome. Rotavirus third-layer proteins (ie, VP7 and VP4 spikes) break down the outer membrane of the endosome and create an outer membrane with different calcium concentrations. This change caused the VP7 protein trimer to break into subunits of a single protein, leaving behind the VP2 and VP6 proteins surrounding the viral double-stranded RNA, forming a double-layered virus particle (DLP).

Seven double-stranded RNA strands still maintain two protein layers and provide viral RNA-dependent RNA polymerase (RNA replicase or RNA-dependent RNA polymerase (RdRp)) to create a messenger RNA transcription copy of the double-stranded virus genome protection of. By keeping viral RNA at the core of the virus, viral RNA evades the immune response of the innate host. This immune response is called RNA interference and is triggered by the performance of double-stranded RNA strands.

During the infection, rotaviruses produce messenger RNA to biosynthesize proteins and perform gene replication. Most of the rotavirus proteins are accumulated in the virions, which are also where the RNA replicates and where the double-layered virus particles assemble. Viral mass will rapidly form around the nucleus within about two hours of virus-infected cells, forming what is called a "virus factory". This virus factory is made of two viral non-structural proteins (NSP5 and NSP2) . If NSP5 protein is suppressed due to RNA interference, it will significantly reduce the rotavirus replication function. The newly formed double-layered virus particles will move to the endoplasmic reticulum, where they will obtain their third outer layer (consisting of VP7 and VP4 proteins). In the end, these progeny viruses are released outside the cell via lysis. ^[6]