WHAT IS CORONA VIRUS ?

WHAT IS CORONA VIRUS ?

PAIN: BODY AND MENTAL ?

viruses that combine pleomorphic viruses that contain medium-sized RNAs. The diameter of different viruses is about 80-220 nm. Viruses reproduce in the cytoplasm of infected cells. Basically, bird-borne infectious bronchitis is considered coronavirus, although this family also includes human coronaviruses. Some coronaviruses are capable of causing fatal TGR, BCRS and a new coronavirus respiratory disease, which appears as a serious outbreak of international concern.

Morphology of virions

Virions with a diameter of 75-160 nm. They are surrounded by projections in the form of surface rock 12–24 nm long and resemble the shape of a solar corona. The protrusions are twice as rare as the spine on the surface of the influenza virus, easily broken during storage and purification of the virus, destroyed by bromelain and trypsin.

In the core of the virion the central body and the matrix are distinguished. The central body is a central nucleocapsid with a diameter of 14-16 nm, consisting of filaments with a diameter of 9 nm. The matrix is   located between the nucleocapsid and the lipoprotein sheath.

Physico-chemical and physical properties

The floating density in cesium chloride is 1.18 g / cm3, the density of floating nucleocapid is 1.31 g / cm3. The virus is sensitive to ether and detergents, unstable at pH 3.0, warming to 56 ° C, UV rays.

genome

It is represented by single-stranded linear RNA, with a molecular weight of 5 × 106 - 7 × 106 and a sedimentation factor of 60-70S. When heated, RNA dissociates into fragments with a sedimentation factor of 35S and 4S. RNA contains up to 70 polyadenylate sequences at the 3 'end. The coronavirus genome has a positive polarity. The genome size is 27-32kb.

Strategy for replication of the cytoplasmic type

Attachment of the viral S protein to the host receptors, which mediates endocytosis of the virus in the host cell.
Fusion of the viral membrane with the endosomal membrane, ssRNA () is released into the cytoplasm.
Proteolytic synthesis and cleavage of polyprotein replicase.
Replication occurs in virus factories. The dsRNA gene is synthesized from ssRNA ().
The dsRNA gene is transcribed / replicated thus ensuring mRNA genome formation / new ssRNA ().
Synthesis of structural proteins encoded by subgenomic mRNA.
Assembly and flowering on the membrane of the endoplasmic reticulum, intermediate compartment and Golgi complex.
Release of new virions.

Proteins, lipids, carbohydrates

The composition of the virion includes RNA, proteins, lipids, carbohydrates. Lipids are in the lipoprotein membrane, carbohydrates are in the glycoproteins.

Corona viruses contain three groups of nucleocapsid proteins with a molecular weight of 50 × 103 - 60 × 103, which are associated with the genome and form a helical RNP; membrane proteins, which are glycoproteins with a molecular weight of 90 × 103-180 × 103, which ensure the adsorption and penetration of the virus into the cell and cause fusion of the viral and cellular membranes; a matrix protein with a molecular weight of 20 × 103 - 35 × 103, which is part of the viral envelope and is glycosylated to a different extent.

Human corona viruses share a common antigen with animal corona viruses (cattle, mice, pigs), with the exception of the infectious virus with chicken bronchitis and others.

Biological properties

Coronaviruses infect birds and many mammals, causing a coronavirus infection. The main targets of the virus are the respiratory tract, digestive system and nervous tissue, which often suffer from the liver, kidneys, heart and eyes. Coronaviruses also infect epithelial cells and macrophages. In nature, coronaviruses have a much wider host spectrum than anticipated in the laboratory. Severe acute respiratory syndrome (SARS) causes a specific coronavirus, which is thought to be transmitted to humans from another animal species. Infection occurs through unknown fecal-oral vectors transmitted through the air.

Although coronaviruses can interact with a large number of cellular receptors, specific interaction is required for the development of infection. Depending on the receptors used by the virus, they are divided into 3 groups. Since in every country where serological and virological studies are carried out, there is evidence of coronavirus infection, the spread of coronaviruses is common.

Coronavirus infections are seasonal and spread especially in autumn and winter. The source of infection is a sick person, an air control mechanism. The disease is very contagious.

Coronaviruses cause colds in humans; the most common symptoms are usually a runny nose, with the exception of TGRS and BCRS, which cause acute endemic acute respiratory infections and create a public health emergency on the Arabian Peninsula and in some neighboring countries. In 2015, South Koreans recorded a short-term outbreak of BCRS.

In January 2020, a new 2019-nCoV / SARS-CoV-2 coronavirus was discovered in China, causing an acute respiratory disease, which is now widespread in China.