Coronaviruses (CoVs) are a highly diverse family of enveloped, single-stranded RNA viruses.The Coronavirus Disease 2019 (COVID-19) is a new viral infection caused by the severe acute respiratory coronavirus 2 (SARS-CoV-2). Genomic analyses have revealed that SARS-CoV-2 is related to Pangolin and Bat coronaviruses

  • They infect humans, other mammals and avian species, including livestock and companion animals, and are therefore not only a challenge for public health but also a veterinary and economic concern.
  • The family Coronaviridae is further specified into the subfamily of Orthocoronavirinae, which consists of four genera: alphacoronavirus, betacoronavirus, gammacoronavirus and deltacoronavirus.
  • Whereas alphacoronaviruses and betacoronaviruses exclusively infect mammalian species, gammacoronaviruses and deltacoronaviruses have a wider host range that includes avian species. Human and animal coronavirus infections mainly result in respiratory and enteric diseases.
  • Human coronaviruses, such as HCoV, have long been known to circulate in the population and they, together with the more recently identified HCoV-NL63 cause seasonal and usually mild respiratory tract infections associated with symptoms of the ‘common cold’.
  • In strong contrast, severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV) and SARS-CoV-2, which have emerged in the human population over the past 20 years, are highly pathogenic.
  • By infecting bronchial epithelial cells, pneumocytes and upper respiratory tract cells in humans, SARS-CoV, MERS-CoV and SARS-CoV-2 infections can develop into severe, life-threatening respiratory pathologies and lung injuries for which no specific prophylactic or therapeutic treatment has been approved to date.


The coronavirus virion consists of structural proteins, namely spike (S), envelope (E), membrane (M), nucleocapsid (N).

Coronavirus particles bind to cellular attachment factors and specific S interactions with the cellular receptors (such as angiotensin-converting enzyme 2 (ACE2))

Spike Protein:

The spike (S) protein of SARS-CoV-2, plays a key role in the receptor recognition and cell membrane fusion process, is composed of two subunits, S1 and S2. The S1 subunit contains a receptor-binding domain that recognizes and binds to the host receptor angiotensin-converting enzyme 2, while the S2 subunit mediates viral cell membrane fusion.


COVID 19 Symptoms:

Signs and symptoms of coronavirus disease 2019 (COVID-19) may appear two to 14 days after exposure. This time after exposure and before having symptoms is called the incubation period. Common signs and symptoms can include:

  • Fever
  • Cough
  • Tiredness

Early symptoms of COVID-19 may include a loss of taste or smell.

Other symptoms can include:

  • Shortness of breath or difficulty breathing
  • Muscle aches
  • Chills
  • Sore throat
  • Runny nose
  • Headache
  • Chest pain
  • Pink eye (conjunctivitis)
  • Nausea
  • Vomiting
  • Diarrhea
  • Rash

Risk factors for COVID 19

Risk factors for COVID-19 appear to include:

  • Close contact (within 6 feet, or 2 meters) with someone who has COVID-19
  • Being coughed or sneezed on by an infected person


Although most people with COVID-19 have mild to moderate symptoms, the disease can cause severe medical complications and lead to death in some people. Older adults or people with existing medical conditions are at greater risk of becoming seriously ill with COVID-19.

Complications can include:

  • Pneumonia and trouble breathing
  • Organ failure in several organs
  • Heart problems
  • A severe lung condition that causes a low amount of oxygen to go through your bloodstream to your organs (acute respiratory distress syndrome)
  • Blood clots
  • Acute kidney injury
  • Additional viral and bacterial infections


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