Chinese researchers searching for the causative agent of severe
acute respiratory syndrome (SARS) have narrowed their focus to
chlamydia-like agents.
Their on-going efforts to identify the causative agent have been
integrated into a global network of laboratories racing to find the
origin.
While scientists outside China have hypothesized that SARS is
caused by a new virus belonging to the coronavirus family, Chinese
scientists say they have obtained a great deal of evidence in
support of their hypothesis.
"A
new chlamydia-like agent or a mutation of chlamydia could very
possibly be one of the causes of SARS," Prof. Li Liming, director
of the Chinese Center for Disease Prevention and Control, told the
press Friday afternoon.
He
said the hypothesis was based on the results of observation under
an electron microscope, tissue cultivation in labs, and serological
studies carried out since February.
Since Feb. 18, researchers at Li's center have discovered
chlamydia-like agents in five tissue samples taken from people who
died of SARS.
Li
said the tissue samples were taken in several different hospitals
in different areas of the country.
"The agent is clearly similar to chlamydia, though not common
chlamydia, which usually causes pneumonia, trachoma or ornithosis.
We have thus decided to use the term "chlamydia-like agent," Li
said.
He
added that further research would be necessary, including
experiments on lab animals and studies on more serum samples,
before a final conclusion could be reached.
"We think it could be the cause, or one of the causes of SARS," Li
said, although we haven't ruled out the possibility that other
causes may exist."
Several of the experts from the Chinese disease prevention and
control center are currently in Guangdong, accompanying a team of
World Health Organization experts who are searching for clues to
the origin of SARS.
The WHO said Friday that SARS "is thought to be caused by a new
virus in the coronavirus family," though the exact identity of the
virus has proved elusive.
Virologist Hong Tao, a member of the national disease prevention
and control center, said they had detected traces of coronavirus
from three tissue samples. However, the team has not conducted
follow-up research because it does not consider it a research
focus, Hong said.
The Chinese researchers have joined a WHO-initiated global network
of laboratory experts and have exchanged their latest findings with
their international colleagues through teleconferences.
Henk Bekedam, WHO representative in Beijing, said the international
community should remain open-minded about the cause of SARS until a
final conclusion is reached.
Most importantly, Chinese scientists have joined the global network
of laboratory experts to share information to find the cause as
soon as possible, Bekedam said. "We're very pleased (about
it)."
(Xinhua News Agency April 5, 2003)