Coronavirus Reagents

Introduction to Coronaviruses

Coronaviruses (CoV), named after the crown like projections on their surface, are single-stranded RNA viruses that belong to the family Coronaviridae. Coronaviruses were first identified in the 1960’s and there are now six different coronaviruses which are associated with respiratory symptoms and pose a significant risk to public health:

• HCoV-229E (Human coronavirus 229E)
• HCoV-NL63 (Human coronavirus NL63)
• HCoV-OC43 (Human coronavirus OC43)
• CoV-HKU1 (Human coronavirus HKU1)
• MERS-CoV (Middle East Respiratory Syndrome coronavirus)
• SARS-CoV (Severe Acute Respiratory Syndrome coronavirus)
• SARS-CoV-2 (Severe Acute Respiratory Syndrome coronavirus 2)

The novel coronavirus SARS-CoV-2 (previously known as 2019-nCoV), which causes the COVID-19 disease, was first identified in December 2019 in Wuhan (Hubei Province, People's Republic of China).

Classification and Nomenclature of SARS-CoV-2

Coronaviruses are enveloped viruses with a positive, single-stranded RNA genome (~26-32 kb). To date, four coronavirus genera (α, β, γ, δ) have been discovered, with human coronaviruses (HCoVs) belonging to the alpha coronavirus (HCoV-229E and HCoV-NL63) and beta coronavirus (MERS-CoV, SARS-CoV, HCoV-OC43, and HCoV-HKU1) genera.

Viral genome sequencing using samples from patients in Wuhan, presenting with fever, persistent cough, and acute respiratory distress syndrome (ARDS), showed the presence of a novel β-CoV strain. Chinese scientists found that the genome sequence of the novel β-CoV shares 79.5% identity with SARS-CoV and 96.2% identity with bat coronavirus RaTG13. The novel β-CoV was official named as SARS-CoV-2 on the 11th February 2020.

Structural Biology

The SARS-CoV-2 virion is approximately 50-200 nanometers in diameter. It is composed of four structural proteins, identified as the S (spike), E (envelope), M (membrane), and N (nucleocapsid) proteins. The nucleocapsid contains the viral RNA and the spike, envelope, and membrane proteins collectively form the viral envelope. The spike proteins enable the virus to attach to specific cellular receptors on the cell membrane of a host cell. SARS-CoV has been shown to utilize angiotensin converting enzyme 2 (ACE2) as a host cell receptor, which is expressed in both the upper and lower human respiratory tracts, while MERS-CoV utilizes CD26 (also known as DPP4). Recent studies suggest that SARS-CoV-2 can also utilize angiotensin converting enzyme 2 (ACE2), in addition to Basigin (also known as CD147), as a host cell receptor and that it has a higher affinity to human ACE2 than SARS-CoV.