ALL ABOUT CORONAVIRUS:what is it?where did it come from?how to protect yourself? скачать в хорошем качестве

ALL ABOUT CORONAVIRUS:what is it?where did it come from?how to protect yourself?

Coronaviruses are a group of viruses that cause diseases in mammals, including humans, and birds. In humans, the virus causes respiratory infections which are typically mild but, in rare cases, can be lethal. In cows and pigs they may cause diarrhea, while in chickens it can cause an upper respiratory disease. There are no vaccines or antiviral drugs that are approved for prevention or treatment. Coronaviruses are viruses in the subfamily Orthocoronavirinae in the family Coronaviridae, in the order Nidovirales.[4][5] Coronaviruses are enveloped viruses with a positive-sense single-stranded RNA genome and with a nucleocapsid of helical symmetry. The genomic size of coronaviruses ranges from approximately 26 to 32 kilobases, the largest for an RNA virus. The name "coronavirus" is derived from the Latin corona and the Greek κορώνη (korṓnē, "garland, wreath"), meaning crown or halo. This refers to the characteristic appearance of virions (the infective form of the virus) by electron microscopy, which have a fringe of large, bulbous surface projections creating an image reminiscent of a royal crown or of the solar corona. This morphology is created by the viral spike (S) peplomers, which are proteins that populate the surface of the virus and determine host tropism. Proteins that contribute to the overall structure of all coronaviruses are the spike (S), envelope (E), membrane (M) and nucleocapsid (N). In the specific case of the SARS coronavirus (see below), a defined receptor-binding domain on S mediates the attachment of the virus to its cellular receptor, angiotensin-converting enzyme 2 (ACE2).[6] Some coronaviruses (specifically the members of Betacoronavirus subgroup A) also have a shorter spike-like protein called hemagglutinin esterase (HE).[4]