Coronaviruses (CoVs) were identified in 1965 to infect birds and mammals. They were so named because of the spike proteins emanated from these viruses which gave them a crownlikeappearence.
Coronaviruses are known to be 20 nm long and are recognised by club shaped surface projections and resemble like solar coronas. These viruses are characterized by their ability to Cause the common cold especially in older children and adults.They represent order nidovirals, family coronaviridae, subfamily coronavirinae.
They are relatively large (120-150 nm), composed of ive strand RNA varying in length from 26 to 32 kilobases (kb) (largest genome for RNA viuses) within the helical nucleocapside, surrounded by the envelope.
The envelope proteins are coded by The CoV E protein that has recently been found to contain a binding motif known as the postsynaptic density protein 95 (PSD95). Thisdomain is a protein-protein interaction module that can bind to the target proteins such as the cellular adapter proteins involved in host-cell processes important for viral infection.
Corona viruses have been classified into three main categories based on the antigenic criteria; α-CoVs, β-CoVs, and μCoVs. Large peplomers (spikes) come out of the envelope in order to help bind and enter the virus in the host cell.
The protruding peplomers extend from the oval to spherical virion to give the illusion of a halo, or corona, around the virus. The peplomer protein mediates viral attachment and fusion to the host cell membrane.
A new type of corona virus has emerged from the city of Wuhan in china named as 2019 Novel Coronavirus (2019-nCoV). Within weeks, it has spread to the several countries and has killed many people.
As an RNA virus, 2019-nCoV still has the inherentfeature of a high mutation rate. This aspect provides thepossibility for this newly introduced zoonotic viralpathogen to adapt to become more efficientlytransmitted from person to person and possibly becomemore virulent.
Infection of this novel coronavirus causes respiratory illness among humans. Patients with 2019-nCoV have reportedly had shortness of breath, fever, cough and severe complications include pneumonia in both lungs.
Coronaviruses are a large group among bird and mammals but in rare cases like this one, theyare transmitted between humans- a process known as zoonosis but it is still unclear whether this happens routinely.
This new virus is the seventh known corona virus but is considered not as deadly as SARS that killed 11%of people it infected.
Though there are several human CoV responsible for a mild respiratory disease, most notable are the highly pathogenic human CoVs: SARS-CoV and MERS-CoV capable of causing a severe respiratory disease
The initial outbreak of SARS originated in China in late 2002, and it spread rapidly to atleast 29 other countries by summer 2003.
The outbreak resulted in 8098 persons with possible SARS, including 744 deaths being reported by WHO. There were 373 possible SARS cases in the United States; however, SARS-CoV identification has been confirmed only in 8 of them. Seven of the eight cases were likely due exposure to one of the other seven.
The 2003 SARS epidemic demonstrated to the world the ease with which a virus can spread. SARS-CoVvirions use the angiotensin-converting enzyme 2 (ACE2) on the host cells as the virus receptor.
A receptor-binding domain of the peplomer is complementary to the ACE2 receptor creating a binding interface.
The virus causes a lower respiratory tract disease which is febrile (100.4, 38oc).Sudden, fatal illness is a characteristic of the disease in people who are otherwise healthy. Other signs may include headache, pain with the flulike discomfort; and body aches. After a couple of days, patients may develop a dry cough, and most will develop pneumonia.
Approximately 10-20 per cent has diarrhoea. If not detected early, even with supportive care, this illness can be fatal.
Rapid detection and prevention measures were pursued during and after the outbreak. Diligent screening for signs of fever or respiratory disease at airports and the initiation of SARS-CoV vaccine trails are two examples of protective measures.
Table: The clinical features of 2019-nCoV, in comparison with SARS-CoV and Middle East respiratory syndrome (MERS)-CoV
The researchers believe that the novel coronavirus (2019-nCoV) was orginated in the Wuhan market by an unknown species. Identifying that animal could help control the current outbreak.
No known medicines are currently approved which can effectively treat infections of Coronavirus in humans and no vaccines are currently licensed.It could be helpful to prevent infection by blocking the receptor used by the virus to infect the cell.
The high mortality rates of novel coronavirus (2019-nCoV) and their effective transmission underline the need for further research to highlight the specific structural requirements for its function in the life cycle and mechanisms behind their pathogensis. This will help in the production effective anti-coronaviral agents.
Author is a research scholar at Department Of Zoology, Maulana Azad National UniversityHyderabad