SARS-CoV-2

This transmission electron microscope image shows SARS-CoV-2 isolated from a patient in the U.S. Virus particles are shown emerging from the surface of cells cultured in the lab. The spikes on the outer edge of the virus particles give coronaviruses their name, crown-like. Image captured and colourised at NIAID's Rocky Mountain Laboratories (RML) in Hamilton, Montana.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease (COVID-19) which has resulted in the human COVID-19 pandemic. SARS-CoV-2 is an RNA virus which belongs to the coronavirus family (Coronaviridae), which is further split into four groups: Alphacoronavirus, Betacoronavirus, Gammacoronavirus and Deltacoronavirus. SARS-CoV-2 is a Betacoronavirus. Coronaviruses are named for the crown-like spikes on their surface which resemble the corona of the sun and contain an RNA genome which is protected by an outer envelope with protruding proteins. SARS-CoV-2 is the seventh coronavirus to emerge and cause respiratory disease in humans.

  • COVID-19 is a notifiable disease and should be reported.
    Please visit the World Health Organization (WHO) website for advice on symptoms and how to prevent its spread. 

Associated diseases:

SARS-CoV-2 causes COVID-19, a disease that can vary enormously in severity and in the symptoms displayed. Huge global research efforts are underway to understand more about the virus and how it infects humans. There is currently no treatment or vaccine available and therefore biosecurity measures are essential to prevent the spread of the virus.

Symptoms typically occur five to six days after infection, but can take up to 14 days. Most people that become infected will develop mild to moderate illness and recover without hospitalisation. The elderly and those with underlying health conditions are at greater risk from developing serious symptoms. WHO defines the symptoms as below.

Most common symptoms:

  • fever
  • dry cough
  • tiredness

Less common symptoms:

  • loss of taste or smell
  • aches and pains
  • sore throat
  • diarrhoea
  • conjunctivitis
  • headache
  • a rash on skin, or discolouration of fingers or toes

Serious symptoms:

  • difficulty breathing or shortness of breath
  • chest pain or pressure
  • loss of speech or movement

For advice on what you should do if you have any of these symptoms, please visit the NHS website (for those in the UK) or consult your local health care provider in your country.

Disease transmission:

COVID-19 can be spread from human-to-human via small droplets that are expelled when an infected individual coughs, sneezes or speaks. People can become infected if they inhale these droplets or transfer them to their face after touching a contaminated surface.

It is accepted that bats are most likely the original host of SARS-CoV-2, as closely related viruses were previously isolated in horseshoe bats. Similarly, close relatives in bats were also found for severe acute respiratory syndrome (SARS-CoV-1) following its emergence in 2003. Like SARS-CoV-1 it is expected that there may have been an intermediate host for SARS-CoV-2, however the identity of this animal species remains unclear. Other animals such as cats, dogs and mink have been shown to be infected by SARS-CoV-2, and there have been reported cases of mink transmitting the virus to humans; however, the significance of these infections to the ongoing human pandemic is unclear. Research is ongoing in this area.

Disease prevalence:

COVID-19 was first reported in Wuhan, China, in December 2019. Since then, the disease has spread to over 190 countries and regions, resulting in around 196 million confirmed cases and more than 4.1 million deaths. Unprecedented control measures have been taken to prevent the spread of COVID-19, with many countries resorting to lockdowns to reduce case numbers but which have also prevented many from working. This has caused worldwide economic disruption. The pandemic is still ongoing - for up to date information on the spread of COVID-19, visit the WHO website.

Impact for Society – what are we doing?

The Pirbright Institute has a history of working with livestock coronaviruses, primarily focused on studying how coronaviruses replicate and interact with their host cell and developing effective vaccines for infectious bronchitis virus (IBV), a poultry disease that has a huge financial impact on the UK poultry industry.

Our scientists are now applying their expertise to help with the COVID-19 research effort. In collaboration with the University of Oxford, Pirbright has successfully shown that two doses of the ChAdOx1 nCoV-19 (AZD1222) vaccine produce a greater antibody response than a single dose in pigs. Pirbright is using the same pig model to establish the immune response generated by Imperial College London’s RNA vaccine and Oxford's new potential vaccine, as well as establishing the dosage size that may be needed in order to protect humans. Using the pig model will help to inform the development of vaccines that are both effective and safe for humans.

Other Pirbright COVID-19 research projects have explored the mechanisms SARS-CoV-2 uses to enters cells, which have recently demonstrated how SARS-CoV-2 could have adapted to jump the species barrier and which animals could potentially be infected. Work generating reagents and tests to explore diagnostic options for SARS-CoV-2 is also ongoing.

Pirbright is assisting the UK Government during the pandemic by supporting the NHS Berkshire and Surrey Pathology Services (BSPS) and the national NHS Test and Trace programme by providing induction and training for staff joining the new Lighthouse Laboratory in Bracknell. The Institute has also supplied 13 of its high-throughput testing instruments to the UK’s National Coronavirus Testing Centre in Milton Keynes. Over 60 of Pirbright’s diagnostic staff and scientists have also volunteered to join the testing effort at seven Public Health England testing sites across the country and at Pirbright’s local NHS hospital to increase the UK’s diagnostic capacity.

Announced in January 2021, virologists at Pirbright have taken a lead role in a new national research project to study the effects of emerging mutations in SARS-CoV-2. The ‘G2P-UK’ National Virology Consortium with £2.5 million of funding from UK Research and Innovation (UKRI) will study how mutations in the virus affect key outcomes such as how transmissible it is, the severity of COVID-19 it causes, and the effectiveness of vaccines and treatments.

Working with lead researchers at the University of Cambridge, our scientists have helped to demonstrate that one of the key mutations seen in the ‘Alpha variant’ of SARS-CoV-2 makes the virus better at escaping immunity and more infectious. This is likely to explain why these deletions are now so widespread.

Pirbright’s research into IBV and other coronaviruses such as porcine deltacoronavirus will continue to further expand our knowledge of how this family of viruses infect hosts and replicate within cells. Building upon this coronavirus expertise, Pirbright scientists will investigate how SARS-CoV-2 replicates and incorporate this into comparisons between other coronaviruses, which could provide vital insights for vaccine and antiviral development. Testing potential antivirals will also form an important part of Pirbright’s SARS-CoV-2 research programme.

Research papers

Lee B, Echavarría-Consuegra L, Cook G M, Busnadiego I, Lefèvre C, Keep S, Brown K, Doyle N, Dowgier G, Franaszek K, Moore N A, Siddell S G, Bickerton E, Hale B G, Firth A E, Brierley I, Irigoyen N (2021)

PLOS Pathogens 17 (6)
Meng B, Kemp S A, Papa G, Datir R, Ferreira I A T M, Marelli S, Harvey W T, Lytras S, Mohamed A, Gallo G, Thakur N, Collier D A, Mlcochova P, Duncan L M, Carabelli A M, Kenyon J C, Lever A M, De Marco A, Saliba C, Culap K, Cameroni E, Matheson N J, Piccoli L, Corti D, James L C, Robertson D L, Bailey D, Gupta R K (2021)

Cell Reports 35 (13) , 109292
Al-Beltagi S, Preda C A, Goulding L V, James J, Pu J, Skinner P, Jiang Z, Wang B L, Yang J, Banyard A C, Mellits K H, Gershkovich P, Hayes C J, Nguyen-Van-Tam J, Brown I H, Liu J, Chang K C (2021)

Viruses 13 (2) , 234
Publisher’s version: https://doi.org/10.3390/v13020234
Thakur N, Conceicao C, Isaacs A, Human S, Modhiran N, McLean R K, Pedrera M, Tan T K, Rijal P, Townsend A, Taylor G, Young P R, Watterson D, Chappell K J, Graham S P, Bailey D (2021)

Journal of General Virology 102 (1) , 1506
Lulla V, Wandel M P, Bandyra K J, Ulferts R, Wu M, Dendooven T, Yang X, Doyle N, Oerum S, Beale R, O'Rourke S M, Randow F, Maier H J, Scott W, Ding Y, Firth A E, Bloznelyte K, Luisi B F (2021)

Journal of Virology

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