Severe acute respiratory syndrome coronavirus 1 ( SARS-CoV-1), previously known as severe acute respiratory syndrome coronavirus ( SARS-CoV), is a strain of coronavirus that causes severe acute respiratory syndrome (SARS), the respiratory illness responsible for the 2002–2004 SARS outbreak.
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. The Centers for Disease Control and Prevention (CDC) in the United States and the National Microbiology Laboratory (NML) in Canada identified the SARS-CoV-1 genome in April 2003. 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, infected with the virus developed the same symptoms as human SARS patients.
A virus similar to SARS-CoV-1 was discovered in late 2019. This virus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is the causative pathogen of COVID-19, the propagation of which started the COVID-19 pandemic. The spike protein responsible for viral entry differs by 24% between the two viruses, and the genome differs by approximately 20%, indicating that the two do not share a very recent common ancestor.
In the SARS outbreak of 2003, about 9% of patients with confirmed SARS-CoV-1 infection died. The mortality rate was much higher for those over 60 years old, with mortality rates approaching 50% for this subset of patients.
This outbreak led to many research programs, such as Predict and the Understanding the Risk of Bat Coronavirus Emergence grant, which aimed to identify zoonotic risks prior to spillover in humans, but ultimately failed to prevent the SARS-CoV-2 pandemic.
Epidemiological evidence suggested a Zoonosis origin of the virus: more than 33% of the first detected cases of SARS in Guangdong corresponded to animal or food handlers. Seroprevalence studies reinforced this zoonotic link (a high proportion of asymptomatic animal handlers at markets in Guangdong Province had antibodies against SARS-CoV).
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 Marco Marra and Caroline Astell 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 is shared with scientists worldwide via the GSC website. Donald Low of Mount Sinai Hospital in Toronto described the discovery as having been made with "unprecedented speed". The sequence of the SARS coronavirus has since been confirmed by other independent groups.
Molecular epidemiological research demonstrated the virus isolated in 2002–2003 in south China and the virus isolated in the same area in late 2003 and early 2004 are different, indicating separate species-crossing events. The phylogeny of the outbreak strains shows that the southwestern provinces including Yunnan, Guizhou and Guangxi compare to the human SARS-CoV-1 better than those of the other provinces, but the viruses' evolution is a product of the host interaction and particularity.
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 species 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 ( Nyctereuteus sp.), ( Melogale spp.), and domestic cats. In 2004, scientists from the Chinese Center for Disease Control and Prevention of the University of Hong Kong and the Guangzhou Center for Disease Control and Prevention established a genetic link between the SARS coronavirus appearing in civets and humans, confirming claims that the virus might have transmitted from the animal species to humans. Infected palm civets at the market were traced to farms where no infected animals were found. It is unknown whether the virus was originally introduced to the market by civets, humans, or another animal.
In 2005, two studies identified a number of SARS-like coronaviruses in Chinese . Although the bat SARS virus did not replicate in cell culture, in 2008, American researchers altered the genetic structure of bat SARS virus with the human receptor binding domain both in the bat virus and in the mice which demonstrated how zoonosis might occur in evolution.
Human SARS-CoV-1 appears to have had a complex history of recombination between ancestral that were hosted in several different animal groups. In order for recombination to happen at least two SARS-CoV-1 must be present in the same host cell. Recombination may occur during genome replication when the RNA polymerase switches from one template to another (copy choice recombination).
SARS-CoV-1 is one of seven known coronaviruses to infect humans. The other six are:
Notably, SARS-CoV-1 is the second of three coronaviruses known to infect humans and use ACE2 (the others being HCoV-NL63 and SARS-CoV-2).
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