Fig: Schematic diagram of SARS-CoV-2
Corona virus is scientifically known as Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is the strain of coronavirus that causes coronavirus disease 2019 (COVID-19). SARS-CoV-2 is a positive-sense single-stranded RNA virus and is the successor to SARS-CoV-1, the strain that caused the 2002–2004 SARS outbreak.
Each SARS-CoV-2 virion is 50–200 nanometres in diameter.Like other coronaviruses, SARS-CoV-2 has four structural proteins, known as the S (spike), E (envelope), M (membrane), and N (nucleocapsid) proteins; the N protein holds the RNA genome, and the S, E, and M proteins together create the viral envelope. The spike protein, which has been imaged at the atomic level using cryogenic electron microscopy, is the protein responsible for allowing the virus to attach to and fuse with the membrane of a host cell; specifically, its S1 subunit catalyzes attachment, the S2 subunit fusion.Like other coronaviruses, SARS-CoV-2 particles are spherical and have proteins called spikes protruding from their surface. These spikes latch onto human cells, then undergo a structural change that allows the viral membrane to fuse with the cell membrane. The viral genes can then enter the host cell to be copied, producing more viruses. Recent work shows that, like the virus that caused the 2002 SARS outbreak, SARS-CoV-2 spikes bind to receptors on the human cell surface called angiotensin-converting enzyme 2 (ACE2). The researchers found that the SARS-CoV-2 spike was 10 to 20 times more likely to bind ACE2 on human cells than the spike from the SARS virus from 2002. This may enable SARS-CoV-2 to spread more easily from person to person than the earlier virus.
Despite similarities in sequence and structure between the spikes of the two viruses, three different antibodies against the 2002 SARS virus could not successfully bind to the SARS-CoV-2 spike protein. This suggests that potential vaccine and antibody-based treatment strategies will need to be unique to the new virus. The researchers are currently working on vaccine candidates targeting the SARS-CoV-2 spike protein. They also hope to use the spike protein to isolate antibodies from people who have recovered from infection by the new coronavirus. If produced in large quantities, such antibodies could potentially be used to treat new infections before a vaccine is available.
