Section 2: Biology of SARS-CoV-2 (from DOI: 10.1007/s11886-020-01292-3)
From publication: "Cardiovascular Complications in Patients with COVID-19: Consequences of Viral Toxicities and Host Immune Response" published as Curr Cardiol Rep; 2020 04 21 ; 22 (5) 32. DOI: https://doi.org/10.1007/s11886-020-01292-3
Section 2: Biology of SARS-CoV-2
In order to better understand the biology of viral immune response and how it impacts the heart, we explore here the basic biological mechanisms underlying viral entry into the host cells and the subsequent immune response. Coronaviruses are enveloped viruses with a single-strand, positive-sense RNA genome approximately 26-32 kilobases in size, which is the largest known genome for an RNA virus. Six coronaviruses (CoVs) are known to infect humans: 229E, OC43, SARS-CoV, NL63, HKU1, and MERS-CoV. In humans, CoV infections primarily involve the upper respiratory tract and GI tract. Studies have demonstrated that SARS-CoV-2, as well as other corona viruses, requires the angiotensin-converting enzyme 2 (ACE2) for cellular entry. ACE2 is a type I integral membrane protein that serves an important role in cardiorenal homeostasis. It is also highly expressed in lung alveolar cells, providing the main entry site for virus into human hosts. It is plausible that the high expression of ACE2 in the lung, gut, heart, and kidneys may facilitate direct damage by the virus throughout the course of infection. One key protein on the virus:the Spike protein (S):facilitates viral entry into the target cells by the binding of its surface unit, S1, to the ACE2 receptor on the host cell, followed by cleavage by host-cell protease TMPRSS2. Other important SARS-CoV-2 components include the hemagglutinin-esterase protein, the membrane (M) protein, the nucleocapsid protein, the small envelope protein, the internal protein, and group-specific proteins, which could become targets for vaccines in the future. Of note, SARS-CoV-2 also contains an RNA-dependent RNA polymerase which is the target of the anti-viral agent remdesivir, currently being studied randomized clinical trials for use against COVID-19 disease.
