Respiratory coronaviruses (Coronaviridae)
Last reviewed: 23.04.2024
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To the family Coronaviridae with two genera, Coronavirus (which also includes pathogens of gastroenteritis in children) and Torovirus, include round-shaped viruses with a diameter of 50-220 nm. Virions have a supercapsid, over which protrude spikes 12-24 nm in length, they consist of a thin neck and a massive globular or pear-shaped head and resemble a figure of the solar corona, which is why the family has been called coronavirus. The nucleocapsid is located in the core of the virion. Of all RNA viruses KopoHaj viruses have the largest genome in the form of single-stranded unfragmented positive RNA from 27 000-32 000 bp. The virion contains 3 groups of proteins: a nucleocapsid protein bound to RNA; matrix protein and empowering the virus to adsorb on cell receptors and to penetrate into it the glycosylated proteins of the supercapsid. The natural hosts of coronaviruses are man, domestic and wild animals, in which they cause widespread diseases.
Respiratory coronaviruses are divided into 3 serogroups. Infection from a sick person occurs by airborne droplets; incidence of sporadic. Epidemic outbreaks of coronavirus infections in the form of fever, runny nose, bronchitis and pneumonia are noted mainly during the cold season. Prior to SARS, these outbreaks were most often caused by the coronavirus HCV-209E.
In November 2002, an outbreak of the disease, called SARS (English Severe Acute Respiratory Syndrome), or severe acute respiratory syndrome (SARS), or SARS, occurred in China; it was described in Hong Kong by K. Urbani. The disease spread rapidly and, according to WHO, as of June 19, 2003, 8,462 SARS cases were registered in 32 countries (most in China (7058)). Killed 804 people (the lethality about 9.5%). In Russia, 1 case is registered. Thanks to strong preventive measures initiated by WHO (compulsory hospitalization, isolation, quarantine, widespread use of cotton-gauze masks, etc.), the SARS epidemic was eliminated by June 2003, but a few more cases were later identified and the risk of recurrence epidemic is not excluded. The causative agent of SARS was detected in April 2003. He was a coronavirus, not related to any of the known strains of this virus. Its genomic RNA consists of 29 727-29 736 bp. According to the nucleotide sequences, the SARS virus differs by 50-60% from the three known serogroups of coronaviruses.
Natural carriers of the virus have not yet been clearly established. They can be rats, other rodents, insects. In China, it is believed that the main bearer of it is the small predator viverra Asiatic, or eastern (Viverra zibetha). It is bred in aviaries for sale, since meat is highly valued by gourmets. The main biological feature of the virus is high contagiousness, which is many times higher than that of viruses of pathogens of various ARI, including influenza. The reason for it is also not clear.
[Diagnostics of SARS
Laboratory diagnostics of coronavirus infections, including SARS, is carried out by isolating virus cultures and identifying them, either by detecting virus-specific antibodies and increasing their titer in paired sera with various serological reactions or using DNA and RNA probes, PCR. In particular, several types of primers have already been proposed for the diagnosis of SARS by PCR. Any biological material can be used for the detection of RNA virus by PCR: blood, sputum, urine, feces, etc. However, all the proposed test systems for SARS Diagnostics need additional study of the degree of their specificity.
Treatment of SARS
The treatment of coronavirus diseases, including SARS, is based on the use of antiviral drugs: ribavirin, interferons, specific immunoglobulins (plasma of people who have had SARS); to prevent bacterial complications - antibiotics (beta-lactam, fluoroquinolones, cephalosporins, tetracyclines).