SARS coronavirus

The Severe acute respiratory syndrome-related coronavirus, sometimes shortened to SARS-CoV, is the virus that causes severe acute respiratory syndrome (SARS). 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 Severe acute respiratory syndrome-related coronavirus, sometimes shortened to SARS-CoV, is the virus that causes severe acute respiratory syndrome (SARS). 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. On April 12, 2003, scientists working at the Michael Smith Genome Sciences Centre in Vancouver, British Columbia 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'. The sequence of the SARS coronavirus has since been confirmed by other independent groups. The SARS coronavirus is one of several viruses identified by WHO as a likely cause of a future epidemic in a new plan developed after the Ebola epidemic for urgent research and development before and during an epidemic toward new diagnostic tests, vaccines and medicines. SARS, or Severe Acute Respiratory Syndrome, is the disease caused by SARS coronavirus. 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, mainly cough, dyspnea, and pneumonia. Another common finding in SARS patients is a decrease in the number of lymphocytes circulating in the blood. In the SARS outbreak of 2003, about 9% of patients with confirmed SARS infection died. The mortality rate was much higher for those over 50 years old, with mortality rates approaching 50% for this subset of patients. The CDC and Canada's National Microbiology Laboratory identified the SARS 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, macaques infected with the virus developed the same symptoms as human SARS victims. In late May 2003, studies from samples of wild animals sold as food in the local market in Guangdong, China, found the 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. 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.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. The SARS coronavirus is a positive and single stranded RNA virus belonging to a family of enveloped coronaviruses. Its genome is about 29.7kb, which is one of the largest among RNA viruses. The SARS virus has 13 known genes and 14 known proteins. There are 265 nucleotides in the 5'UTR and 342 nucleotides in the 3'UTR. SARS is similar to other coronaviruses in that its genome expression starts with translation of two large ORFs, 1a and 1b, both of which are polyproteins. The functions of several of these proteins are known: ORFs 1a and 1b encode the replicase and there are four major structural proteins: nucleocapsid, spike, membrane and envelope. It also encodes for eight unique proteins, known as the accessory proteins, all with no known homologues. The function of these accessory proteins remains unknown.