Chinese scientists have sequenced the genetic code of at least four samples of the SARS virus from different patients. Comparison of these genomes will determine whether the virus is mutating rapidly, which in turn will determine how difficult it will be to develop tests and vaccines based on the virus鈥檚 genes.
The outbreak of Severe Acute Respiratory Syndrome (SARS) began in China in November, but was not made public until March. Now, 243 people have died and over 4200 infected in 26 countries around the world. Some experts fear it may already be too late to contain SARS, for which there is currently no cure.
The biggest challenge facing health officials is the lack of information from China. The country, home to about half the SARS cases, has been severely and widely castigated for its secrecy, but the criticism appears finally to be making an impact.
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China has admitted that the virus is spreading into more remote provinces and has dispatched emergency SARS teams. On Sunday, the government raised the official number of SARS cases in Beijing from 37 to 358 and fired the health minister and the mayor of Beijing for covering up the crisis. By Tuesday, suspected cases of SARS in the capital had reached 602.
Nose and throat swabs
The latest gene sequences of the SARS virus were obtained by scientist at the Beijing Genomics Institute and the Institute of Microbiology and Epidemiology of the Academy of Military Medical Sciences. They have now released five sequences on the internet.
A short report on four of the coronavirus samples was also published. The samples came from nose and throat swabs, as well as lung, liver and lymph node tissue removed during autopsies. Three samples were from Beijing patients, with the fourth from a patient from Guangdong, the province where SARS originated.
Four other code sequences have been released by scientists in Canada, the US, Hong Kong and Singapore. All differ by up to 15 鈥渓etters鈥� in the 30,000 that comprise the virus. The Chinese scientists note the differences and write that 鈥渢he virus is expected to mutate very fast and easily鈥�. Such slight differences could also be explained by errors in the sequencing process.
However, most of the variations seen so far seem to affect one gene in particular, while 12 more genes show no changes between non-Chinese sequences. This suggests the variants may genuine mutations.
快猫短视频s will now be working to determine whether different strains produce different symptoms in patients and are spread in different ways. In Hong Kong, the group of patients from the now infamous Amoy Gardens tower block were much more likely to suffer diarrhoea and the virus鈥檚 spread there has been linked to the sewer system. 快猫短视频s at Hong Kong University are now sequencing key regions of the virus.
鈥淒ark misgivings鈥�
China鈥檚 increased openness has given a cautious welcome by the World Health Organization. 鈥淲e鈥檙e now much closer to what we always thought was the reality in Beijing,鈥� says Peter Cordingley, spokesman at the WHO鈥檚 Western Pacific headquarters in Manila. 鈥淏ut as for the rest of the country, we have dark misgivings.鈥�
New data reveals that SARS now ranges from the densely populated Sichuan province in the southwest to Liaoning in the northeast. 鈥淲e鈥檙e very worried about the less accessible provinces, where there is poor health care and poor resources,鈥� Cordingley says.
But another WHO official says China is still not revealing some key data. 鈥淲ithout the date of onset for patients, you can鈥檛 say what the trend of the disease is,鈥� Jeff McFarland, a WHO virologist, told AFP. 鈥淭his is the data that we need to have to fully understand the epidemic.鈥�
鈥淭o be able to contain SARS, we have to know what is happening in China,鈥� says microbiologist John MacKenzie at the University of Queensland, Australia, and a SARS investigator for WHO. 鈥淯ntil the Chinese authorities come totally and utterly clean, they will maintain a sink that will carry on affecting us globally,鈥� he told 快猫短视频.
MacKenzie adds that problems with the flow of information between authorities and the WHO have also been a problem in Hong Kong, particularly in relation to the spread of SARS in the Amoy Gardens housing block. 鈥淒etails of work on transmission, on what animals, if any, might be involved is still to come out,鈥� he says.
On a more positive note, MacKenzie says the draconian quarantine measures have had an impact in Hong Kong and Singapore, the worst affected places after China. Most secondary schools re-opened on Tuesday after weeks of being closed.