A Guide to COVID-19: a global pandemic caused by the novel coronavirus SARS-CoV-2

Abstract

The emergence of the SARS-CoV-2 strain of the human coronavirus has thrown the world into the midst of a new pandemic. In the human body, the virus causes COVID-19, a disease characterized by shortness of breath, fever, and pneumonia, which can be fatal in vulnerable individuals. SARS-CoV-2 has characteristics of past human coronaviruses, with close genomic similarities to SARS-CoV, the virus that causes the disease SARS. Like these related coronaviruses, SARS-CoV-2 is transmitted through the inhalation of droplets and interaction with contaminated surfaces. Across the world, laboratories are developing candidate vaccines for the virus - with vaccine trials underway in the United States and the United Kingdom - and considering various drugs for possible treatments and prophylaxis. Here, we provide an overview of SARS-CoV-2 by analyzing its virology, epidemiology, and modes of transmission while examining the current progress of testing procedures and possible treatments through drugs and vaccines.

Keywords: ACE2; COVID-19; CRISPR; MERS; MERS-CoV; SARS; SARS-CoV; SARS-CoV-2; coronavirus; vaccine.

Fig. 1

Reported cases of COVID‐19 by country adapted from CDC. Red represents China, the SARS‐CoV‐2 origin. Orange represents countries reporting COVID‐19 cases. Green represents major countries reporting no cases of COVID‐19 and includes Lesotho, North Korea, and Turkmenistan. Figure reproduced from [155].

Fig. 2

Diagram of SARS‐CoV‐2 virus structure. The spike glycoprotein (red) is the protein that binds to the ACE2 receptor of host cells and mediates viral entry. Additionally, this protein is what gives the virus its crown‐like (Latin ‘corona’) appearance. The membrane proteins (yellow) and the envelope small membrane proteins (blue) are important structurally as well as mechanistically. The genomic RNA (white) comprises the genetic material that the virus uses to propagate itself once inside its host.

Fig. 3

Diagram of SARS‐CoV‐2 entry into host cell. The spike glycoprotein (red), which consists of two subunits, binds to the ACE2 receptor (green) of host cells to merge the viral and cellular membranes and insert the viral genomic RNA (white) into the host cell. This induces endocytosis and the merging of the viral and cellular membranes, causing the viral genomic RNA to be inserted into the host cell and thus allowing the virus to replicate. The binding of SARS‐CoV‐2 to the ACE2 receptor causes a downregulation of this receptor, disrupting its normal function in maintaining immune homeostasis and leading to pro‐inflammatory effects that can cause lung injury.

Fig. 4

The top of the drawing represents the DNA encoding for the Cas 13 protein and the CRISPR array, which contains the targets for Cas13 cleavage and subsequent degradation. This array is transcribed into pre‐crRNA. The Cas13 protein turns this transcript into mature crRNAs, forming a crRNA‐Cas13 complex that in turns searches along existing RNA transcripts for matching sequences known as protospacers. Once this complementary protospacer is found, Cas13 undergoes a conformational change to enhance binding and activates the RNA cleavage activity of Cas13, which can then be used to degrade foreign viral RNA entering the cell as shown on the right side of the image. Adapted from [156].