View source for SARS-CoV-2

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<noglossary><h2>What is SARS-CoV-2? </h2></noglossary>
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<h3>April 2020 </h3>
<p>Coronavirus disease 2019 (COVID-2019) is caused by a novel coronavirus known as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and was identified as a pandemic by the World Health Organization (WHO) on March 11, 2020. As of April 12, 2020, more than 1.8 million people were confirmed to have been infected and tested positive for COVID-19, with over 114,000 deaths worldwide. This virus was first identified in the respiratory tract of patients with pneumonia in Wuhan, Hubei China, in December 2019 which was then indicated as a newly identified β-coronavirus (nCoV).</p>
<p>SAR-CoV2 is an enveloped, non-segmented, positive sense RNA virus that is included in the sarbecovirus, ortho corona virinae subfamily which is broadly distributed in humans and other mammals. Its diameter is about 65-125 nm, containing single strands of RNA and provided with crown-like spikes on the outer surface. SARS-CoV2 is a novel β-coronavirus after the previously identified SARS-CoV and MERS-CoV which led to pulmonary failure and potentially fatal respiratory tract infection and caused outbreaks mainly in Guandong, China and Saudi Arabia. In COVID-19 research, many studies have demonstrated that bats are suspected as the key reservoir of the viruses by finding as much as 96.2% identical genome sequencing of SARS-CoV-2 with bat CoV RaTG13. </p>
<p><u>Source</u>: Indwiani Astuti, Ysrafil, <i>Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): An overview of viral structure and host response</i><ref name="Indwiani" /><br />Note: Each statement in this extract was referenced but the links have been removed. Please refer to the original article for details.</p>
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<h3>Virus and Disease Names</h3>
<p>Viruses are named by the International Committee on Taxonomy of Viruses (ICTV).</p>
<p>In February 2003 an outbreak of a severe acute respiratory syndrome emerged in China and spread to 4 other countries<ref name="WHO_SARS" />. This coronavirus was named Severe Acute Respiratory Syndrome (SARS)  or SARS-CoV.</p>
<p>The novel (new) coronavirus which emerged in Wuhan, China in December 2019 was initially referred to as the 2019 novel coronavirus or 2019-nCoV. However, this new virus is genetically related to the coronavirus responsible for the SARS outbreak of 2003, so the ICTV officially named it <i>severe acute respiratory syndrome coronavirus 2</i> which is abbreviated SARS-CoV-2<ref name="WHO_Naming_Covid" />. For greater detail please refer to the article [[SARS-CoV-2/Taxonomy]].</p>

<p>On 11 February 2020 the  World Health Organisation named the disease caused by the new coronavirus COVID-19<ref name="WHO_Naming_Covid" />, a short form of the descriptor <i>coronavirus disease 2019</i>.</p>
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<h3>Growing the Virus</h3>
<p>In January 2020 The Peter Doherty Institute for Infection and Immunity (Doherty Institute) in Melbourne (Australia) announced that scientists had successfully grown the 2019 novel coronavirus (COVID-19) from a patient sample. This is the first time the virus has been grown in cell culture outside of China.<ref name="Doherty" /> </p>
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<h3>Survival of the Virus</h3>
<p>In October 2020 researchers at CSIRO, Australia's national science agency, published results from a study on the effect of temperature on persistence of SARS-CoV-2 on common surfaces<ref name="CSIRO" />. They found that SARS-CoV-2, the virus responsible for COVID-19, can survive for up to 28 days on common surfaces including banknotes, glass – such as that found on mobile phone screens - and stainless steel. They found that that SARS-CoV-2:</p>
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   <li>survived longer at lower temperatures</li>
   <li>tended to survive longer on non-porous or smooth surfaces such as glass, stainless steel and vinyl, compared to porous complex surfaces such as cotton</li>
   <li>survived longer on paper banknotes than plastic banknotes</li>
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<p>The research was undertaken at the Australian Centre for Disease Preparedness (ACDP)<ref name="CSIRO_ACDP" /> in Geelong.</p>
<p>The CSIRO has been significantly involved in COVID-19 vaccine and antiviral research and a section on their website is very informative.<ref name="CSIRO_COVID-19_Research" />. </p>
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<h3>Structure</h3>
<p>What does SARS-CoV-2 look like?</p>
<p>Three images are reproduced below. The first is obviously a graphic design, a neatly symmetrical, spherical model created to illustrate the important features of the virus, the 'structural proteins'.<br />
The second image is more realistic as it was through an electron microscope, but note that it has been 'colorized' so it is more engaging.<br />
The third image illustrates the whole SARS-CoV-2 virion containing the viral RNA genome.</p>
{{Content:SARS-CoV-2 (CDC-23313)}}

{{Content:SARS-CoV-2 Electron Microscope}}

{{Content:Military Medical 6Jan2021 Image1}}

<h3>Transmission</h3>
<p>The SARS-CoV-2 virus emerged in Wuhan, Hubei China, in December 2019. However, person-to-person transmission of the virus was not acknowledged  until 24 January 2020. In Vietnam a confirmed case who had not travelled to China was a family member of a confirmed case who visited Wuhan; which suggested an instance of human to human transmission. In the Situation Report No 4 on 24 January 2020 the WHO stated:-</p>
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<p>New epidemiological information reinforces the evidence that the 2019-nCoV can be transmitted from one individual to another. During previous outbreaks due to other coronavirus (Middle-East Respiratory Syndrome (MERS) and the Severe Acute Respiratory Syndrome (SARS)), human to human transmission occurred through droplets, contact and fomites, suggesting that the transmission mode of the 2019-nCoV can be similar.  </p>
<p><u>Source</u>: {{Link:UN/WHO/Sitrep-4 Text}}</p>
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<p>The concept of <i>social distancing</i> at 1.5 to 2 metres, six feet, one crocodile or alligator, and other measures is based on the belief that a droplet containing the virus and expressed from a person by a cough, sneeze or outward breath would likely travel no more than about 2 metres before falling to the ground. It took the WHO about a year to acknowledge that the virus could spread as an aerosol:-</p>
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<p>We know that the disease is caused by the SARS-CoV-2 virus, which spreads between people in several different ways. </p>
<p>The virus can spread from an infected person’s mouth or nose in small liquid particles when they cough, sneeze, speak, sing or breathe. These particles range from larger respiratory droplets to smaller aerosols.</p>
<p>Current evidence suggests that the virus spreads mainly between people who are in close contact with each other, typically within 1 metre (short-range). A person can be infected when aerosols or droplets containing the virus are inhaled or come directly into contact with the eyes, nose, or mouth.</p>
<p>The virus can also spread in poorly ventilated and/or crowded indoor settings, where people tend to spend longer periods of time. This is because aerosols remain suspended in the air or travel farther than 1 metre (long-range).</p>
<p>People may also become infected by touching surfaces that have been contaminated by the virus when touching their eyes, nose or mouth without cleaning their hands.</p>
<p><u>Source</u>: {{Link:UN/WHO/How virus is transmitted Text }}</p>
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<h3>Infection</h3>
<p>How does SARS-CoV-2 infect human cells?</p>
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<p>Using the spike-like protein on its surface, the SARS-CoV-2 virus binds to ACE2 – like a key being inserted into a lock – prior to entry and infection of cells. Hence, ACE2 acts as a cellular doorway – a receptor – for the virus that causes COVID-19. </p>
<p><u>Source</u>: {{Link:TheConversation/ACE2 Receptor Text}}</p>
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<p>A diagram illustrating this process is shown below:-</p>

{{Content:ACE Receptor}}
<p>See also {{Link:Reports/Nature/Structure Spike Receptor Text}}<ref name="Nature" /> which describes the processes in more detail.</p>
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<h3>COVID-19 and Angiotensin-converting enzyme 2 (ACE2)</h3>
<p>When infection with SARS-CoV-2 occurs, the spike proteins bind to ACE2 receptors and the disease COVID-19 may progress beyond a mild case. The article [[ACE2]] provides an introduction and three linked articles provide more detail:-</p>
<p><ul>
   <li>[[ACE2/ACE2 and COVID-19|ACE2 and COVID-19]] </li>
   <li>ACE2 and Vaccines, and </li>
   <li>ACE2 and early treatment </li>
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<h3>References</h3>
<references>
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<ref name="Indwiani">{{Link:Reports/Indwiani Astuti and Ysrafil Text}}</ref>
<ref name="Doherty">{{Link:AusDoherty/Grow coronavirus text}}</ref>
<ref name="CSIRO">{{Link:AusCSIRO/Covid on surfaces text}}</ref>
<ref name="CSIRO_ACDP">{{Link:AusCSIRO/ACDP Text}}<br />The Australian Centre for Disease Preparedness (ACDP) is a high-containment facility designed to allow research into the most dangerous infectious agents in the world.</ref>
<ref name="CSIRO_COVID-19_Research">{{Link:AusCSIRO/COVID-19 Research Text}}</ref>
<ref name="WHO_SARS">{{Link:UN/WHO/SARS Text}}</ref>
<ref name="WHO_Naming_Covid">{{Link:UN/WHO/Naming Covid Text}}<br />
The guidelines for naming a disease excludes names that refer to a geographical location, an animal, or an individual or group of people. The name must also be pronounceable and related to the disease. So the new disease could not be officially called the China Virus or the Wuhan Flu, terms used frequently by US President Trump during his term of office.</ref> <!-- WHO Director-General's remarks at the media briefing on 2019-nCoV on 11 February 2020 -->
<ref name="Nature">{{Link:Reports/Nature/Structure Spike Receptor Cite}}</ref>
<ref name="MMR">{{Link:Reports/MMR/Vaccines Pandemic Era Cite}}</ref>
</references>
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