An Introduction To The 2019 Novel Coronavirus

Introduction 

 

In December 2019, there was a cluster of pneumonia cases in Wuhan, China. Investigations found that it was being caused by a previously unknown virus, now named the 2019 novel coronavirus (2019-nCoV). Coronaviruses are a large group of viruses that can cause respiratory and gastrointestinal symptoms. A coronaviral particle envelope has protein spikes, giving it the appearance of a crown. The name ‘corona’ originates from this microscopic appearance, meaning ‘crown’ in Latin. Other examples of coronaviruses are the Severe Acute Respiratory Syndrome   coronavirus (SARS) and the Middle East Respiratory Syndrome coronavirus (MARS). There is a ~70% genetic similarity between 2019-nCoV and SARS-CoV. 

 

 

Origin 

 

Coronaviruses are known to circulate in a number of animals. When the virus makes a transition from these animals to humans it is called a spillover. This may occur through mutations in the viral genome or through increased contact between humans and animals. The first cases of pneumonia linked to the 2019 novel coronavirus were associated with a seafood and live animal market in Wuhan. The disease has since spread through close human contact and, as of today (09/02/2020), there have been 814 confirmed deaths and more than 37,590 confirmed cases (2-3% death rate). The animal of origin is still unknown, although it has been widely suspected that bats may carry this virus. SARS was first identified in China in 2003 and is known to have been transmitted to humans from civet cats, while MARS was first identified in Saudi Arabia in 2012 and is known to have been transmitted to humans from camels. 

 

 

Pathogenesis 

 

When coronaviruses enter a host cell, the viral particle is uncoated and the RNA genome enters the host cell cytoplasm. Coronaviral genomes have a 5’ methylated cap and a 3’ polyadenylated tail. This mimics a fully processed host mature RNA sequence, enabling translation of viral proteins at the host cell ribosomes. Coronavirus genomes also encode replicase, a protein that catalyses the the replication of the RNA genome using host cell machinery. Coronaviruses contain a non-structural protein with a proofreading function which provides extra fidelity in replication. This is beneficial to us humans, as it reduces the viral mutation rate and hence the generation of new (and potentially more dangerous) strains of the virus. 

 

 

Symptoms

 

The symptoms of the 2019-nCoV can range from mild to severe. Mild symptoms include fever and respiratory problems such as coughing and shortness of breath. More severe symptoms include pneumonia, kidney failure and death. 

 

 

Transmission 

 

Coronaviruses are transmitted through droplets when an infected person coughs or sneezes, or through objects contaminated by the virus. People at highest risk are those who come into close contact with animals, or with people suffering from the virus, such as healthcare workers and family members. 

 

Standard practises to prevent transmission of the virus are: 

• Covering nose and mouth with a medical mask or tissue when coughing or sneezing.
• Avoiding close contact with those who are unwell.
• Washing hands regularly with soap and water or alcohol based hand sanitiser.
• Appropriate use of medical masks in a health care setting.
• Avoiding unnecessary contact with animals.
• Washing your hands after contact with animal products.
• Ensuring animal products are cooked thoroughly before consumption.
  
  

Diagnosis and Treatment 

 

The 2019-nCoV is diagnosed by performing a RT-PCR (Reverse Transcriptase Polymerase Chain Reaction) on blood or respiratory samples to detect the viral fingerprint. There is currently no specific medication for the virus, so the current treatment is in supportive care. Specific treatments and vaccines are in development.