Severe acute respiratory syndrome coronavirus
electron microscope image of SARS virion
Virus classification
(unranked):	Virus
Realm:	Riboviria
Kingdom:	Orthornavirae
Phylum:	Pisuviricota
Class:	Pisoniviricetes
Order:	Nidovirales
Family:	Coronaviridae
Genus:	Betacoronavirus
Subgenus:	Sarbecovirus
Species:	Severe acute respiratory syndrome-related coronavirus
Strain:	Severe acute respiratory syndrome coronavirus
Synonyms
SARS coronavirus SARS-related coronavirus Severe acute respiratory syndrome coronavirus[1]

Severe acute respiratory syndrome coronavirus (SARS-CoV) is the strain of virus that causes severe acute respiratory syndrome (SARS).^[2] On April 16, 2003, following the outbreak of SARS in Asia and secondary cases elsewhere in the world, the World Health Organization (WHO) issued a press release stating that the coronavirus identified by a number of laboratories was the official cause of SARS. Samples of the virus are being held in laboratories in New York City, San Francisco, Manila, Hong Kong, and Toronto.

The Centers for Disease Control and Prevention (CDC) in the United States and National Microbiology Laboratory (NML) in Canada identified the SARS-CoV genome in April 2003.^[3][4] Scientists at Erasmus University in Rotterdam, the Netherlands demonstrated that the SARS coronavirus fulfilled Koch's postulates thereby confirming it as the causative agent. In the experiments, macaques infected with the virus developed the same symptoms as human SARS victims.^[5]

An outbreak of a novel coronavirus disease in 2019 showed many similarities with the SARS outbreak, and the viral agent was identified as another strain of the SARS coronavirus, SARS-CoV-2. Although the two are strains of the same virus, SARS-CoV-2 is not a direct descendant of SARS-CoV, and made the jump into humans separately.

SARS

SARS, or severe acute respiratory syndrome, is the disease caused by SARS-CoV. It causes an often severe illness marked initially by systemic symptoms of muscle pain, headache, and fever, followed in 2–14 days by the onset of respiratory symptoms,^[6] mainly cough, dyspnea, and pneumonia. Another common finding in SARS patients is a decrease in the number of lymphocytes circulating in the blood.^[7]

In the SARS outbreak of 2003, about 9% of patients with confirmed SARS-CoV infection died.^[8] The mortality rate was much higher for those over 60 years old, with mortality rates approaching 50% for this subset of patients.^[8]

History

On April 12, 2003, scientists working at the Michael Smith Genome Sciences Centre in Vancouver finished mapping the genetic sequence of a coronavirus believed to be linked to SARS. The team was led by Dr. Marco Marra and worked in collaboration with the British Columbia Centre for Disease Control and the National Microbiology Laboratory in Winnipeg, Manitoba, using samples from infected patients in Toronto. The map, hailed by the WHO as an important step forward in fighting SARS, is shared with scientists worldwide via the GSC website (see below). Dr. Donald Low of Mount Sinai Hospital in Toronto described the discovery as having been made with "unprecedented speed".^[9] The sequence of the SARS coronavirus has since been confirmed by other independent groups.

In late May 2003, studies from samples of wild animals sold as food in the local market in Guangdong, China, found a strain of SARS coronavirus could be isolated from masked palm civets (Paguma sp.), but the animals did not always show clinical signs. The preliminary conclusion was the SARS virus crossed the xenographic barrier from palm civet to humans, and more than 10,000 masked palm civets were killed in Guangdong Province. The virus was also later found in raccoon dogs (Nyctereuteus sp.), ferret badgers (Melogale spp.), and domestic cats. In 2005, two studies identified a number of SARS-like coronaviruses in Chinese bats.^[10][11] Phylogenetic analysis of these viruses indicated a high probability that SARS coronavirus originated in bats and spread to humans either directly or through animals held in Chinese markets. The bats did not show any visible signs of disease, but are the likely natural reservoirs of SARS-like coronaviruses. In late 2006, scientists from the Chinese Centre for Disease Control and Prevention of Hong Kong University and the Guangzhou Centre for Disease Control and Prevention established a genetic link between the SARS coronavirus appearing in civets and humans, confirming claims that the disease had jumped across species.^[12]

Virology

SARS-Coronavirus follows the replication strategy typical of the Coronavirus genus. The primary human receptor of the virus is angiotensin-converting enzyme 2 (ACE2), first identified in 2003.^[13]