Two international research groups have sequenced the entire genetic blueprint of the SARS virus. Access to the viral genome helps expose its strengths and weaknesses, knowledge which could lead to vaccines against it.
The separate groups produced almost identical genomes for the coronavirus responsible for SARS. Both teams discovered that it is a unique form, significantly different from other known human, avian or animal coronaviruses.
Both sequences are published this morning in the journal Science. A Canadian team was the first to sequence the full genome using samples taken from patients in Toronto. A US-based team also involving Dutch and German researchers then sequenced the so-called urbani strain which Dutch researchers had linked directly to lung disease.
Having the full sequence immediately opens up opportunities to develop new treatments and faster diagnostic methods against SARS, said Prof William Hall, director of the virus reference laboratory at University College Dublin. "We will now be able to make recombinant proteins with potential use in vaccines."
The SARS virus, with about 30,000 steps, is unusually large so sequencing it so quickly was exceptional, Prof Hall said. "It is quite a remarkable achievement given the genome's size. The speed of this was extraordinary."
There are three known groups of coronaviruses, the first two including viruses which affect humans and a third which only affects birds. Most cause only minor illnesses in humans and about 30 per cent of common colds are caused by coronavirus forms.
This new type was very different, however, and "does not closely resemble any of the three previously known groups of coronaviruses", the Canadian authors write.
The US-based team compared the urbani SARS strain to other coronavirus sequences. While the overall structure of the viruses was similar, the researchers found key differences, showing it was a new form and not just a recently-mutated virus derived from a known variety.
"This seems to be a really different virus falling between groups two and three," Prof Hall said. "I think it will be put into a new group four."
Having the sequence "allows you to establish the genetic relationships with other coronaviruses", he said. It can be tracked back to animals and birds by looking for signs of previous infection to discover its origins.
Prof Hall said it should quickly lead to new, faster diagnostic systems to test for the disease. There would also be immediate efforts to identify targets for existing antiviral drugs which could be used against it.