CORONA VIRUS -19

1. CORONA VIRUS PRAKASHBAJAGAIN Msc.Microbiology Central Campus of Technology +977-9842526957

2. VIRUS • A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. •  Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. • A virus is made up of a core of genetic material, either DNA or RNA, surrounded by a protective coat called a capsid which is made up of protein. • Sometimes the capsid is surrounded by an additional spikey coat called the envelope

3. CORONA VIRUS • Structure Spherical or pleomorphic enveloped particles containing single-stranded (positive-sense) RNA associated with a nucleoprotein within a capsid comprised of matrix protein. The envelope bears club-shaped glycoprotein projections

6. Classification Coronaviruses(and toroviruses) are classified together on the basis of the crown or halo-like appearance of the envelope glycoproteins, and on characteristic features of chemistry and replication. Most human coronaviruses fall into one of two serotypes: OC43-like and 229E-like.

7. Multiplication • The virus enters the host cell, and the uncoated genome is transcribed and translated. • The mRNAs form a unique “nested set” sharing a common 3′ end. • New virions form by budding from host cell membranes.

8. Pathogenesis • Transmission is usually via airborne droplets to the nasal mucosa. • Virus replicates locally in cells of the ciliated epithelium, causing cell damage and inflammation.

9. Host Defenses(Immunity) • The appearance of antibody in serum and nasal secretions is followed by resolution of the infection. • Immunity wanes within a year or two.

10. Epidemiology • Incidence peaks in the winter, taking the form of local epidemics lasting a few weeks or months. • The same serotype may return to an area after several years.

11. seven strains of coronavirus • Scientists have identified seven strains of coronavirus that infect humans. • These cause illness, ranging from common cold to more severe diseases such as Middle East Respiratory Syndrome or MERS.

12. Harmless strains of coronavirus • The harmless strains of coronavirus are • Serotype 229E, • Serotype OC43, • Serotype NL63and • Serotype HUK1. • These cause symptoms of common cold and rarely cause severe pneumonia

13. More dangerous strains • Sars-CoV which causes Severe Acute Respiratory Syndrome or SARS, • Mers-CoV which Middle East Respiratory Syndrome or MERS and Deadly Mutated • Sars-CoV2that causes the coronavirus disease Covid-19.

14. Sars-CoV2 • Sars-CoV2 is closely associated to two bat-drivedSars-like coronaviruses (bat-SL-Cov-ZC45 and bat-SL-Cov-ZXC21) collected in 2018 in Zhoushan, eastern China. • It has 79 per cent genetic affinity with Sars-CoV and 50 per cent with Mers-CoV.

15. Diagnosis • Colds caused by coronaviruses cannot be distinguished clinically from other colds in any one individual. • Laboratory diagnosis may be made on the basis of antibody titers in paired sera. The virus is difficult to isolate. • Nucleic acid hybridization tests (including PCR) are now being introduced

17. PCR • PCR(Polymerase Chain reactions) tests work by detecting specific genetic material within the virus. Depending on the type of PCR on hand, health care workers might swab the back of the throat; take a saliva sample; collect a liquid sample from the lower respiratory tract; or secure a stool sample. • Once a sample arrives at the lab, researchers extract its nucleic acid, which holds the virus' genome. Then, researchers can amplify certain regions of the genome by using a technique known as reverse transcription polymerase chain reaction. This, in effect, gives researchers a large sample that they can then compare to the new coronavirus, known as SARS-CoV-2.

18. Symptoms • The most common symptoms of COVID-19 are fever, tiredness, and dry cough. • Some patients may have aches and pains, • nasal congestion, • runny nose, or sore throat. • These symptoms are usually mild and begin gradually..

20. Control • Treatment of common colds is symptomatic; no vaccines or specific drugs are available. • Research Going ON. • Hygiene measures reduce the rate of transmission. • Follow WHO guidelines for the Prevention.

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