一篇并不难懂的E文简介……
**********************
Coronaviruses - the cause of SARS
Here's what we know about SARS so far:
SARS is a type of viral pneumonia, with symptoms including fever, a dry cough, d
yspnea (shortness of breath), headache, and hypoxaemia (low blood oxygen concent
ration). Typical laboratory findings include lymphopaenia (reduced lymphocyte nu
mbers) and mildly elevated aminotransferase levels (indicating liver damage). De
ath may result from progressive respiratory failure due to alveolar damage.
E.M of SARS virus
The outbreak is believed to have originated in February 2003 in the Guangdong pr
ovince of China, where 300 people became ill, and at least five died. After init
ial reports that a paramyxovirus was responsible, the true cause appears to be a
novel coronavirus with some unusual properties. For one thing, the SARS virus c
an be grown in Vero cells (a fibroblast cell line isolated in 1962 from a primat
e) - a novel property for HCoV's, most of which cannot be cultivated. In these c
ells, virus infection results in a cytopathic effect, and budding of coronavirus
-like particles from the endoplasmic reticulum within infected cells.
Amplification of short regions of the polymerase gene, (the most strongly conser
ved part of the coronavirus genome) by reverse transcriptase polymerase chain re
action (RT-PCR) and nucleotide sequencing revealed that the SARS virus is a nove
l coronavirus which has not previously been present in human populations. This c
onclusion is confirmed by serological (antigenic) investigations. We now know th
e complete sequence of all 29,736 nucleotides of the SARS virus genome. The sequ
ence appears to be typical of coronaviruses, with no particularly unusual featur
es:
The SARS virus is believed to be spread by droplets produced by coughing and sne
ezing, but other routes of infection may also be involved, such as contamination
of objects by the hands, so wash your hands! The WHO estimates that SARS is fat
al in around 4% of cases, usually where the person has an underlying condition s
uch as diabetes or heart disease, or a weakened immune system. In 90% of cases,
people seem to recover around a week after being infected. This is around the sa
me mortality rate as in other diseases, such as West Nile virus infection. There
are currently no antiviral drugs shown to be consistently successful in treatin
g SARS or any coronavirus infection, nor any vaccine against SARS. Diagnostic te
sts for coronavirus infection fall into two types:
Serological testing for anti-coronavirus antibodies consists of indirect fluores
cent antibody testing and enzyme-linked immunosorbent assays (ELISA) which detec
t antibodies against the virus produced in response to infection. Although some
patients have detectable coronavirus antibody within 14 days of illness onset, d
efinitive interpretation of negative coronavirus antibody tests is possible only
for specimens obtained >21 days after onset of fever.
Molecular testing consists of reverse transcriptase-polymerase chain reaction (R
T-PCR) tests specific for the RNA from this novel coronavirus. This can detect i
nfection within the first 10 days after the onset of fever in some SARS patients
, but the duration of detectable viraemia and virus shedding is unknown, so RT-P
CR tests performed too late could give negative results. Commercial diagnostic t
ests are now available.
From http://www-micro.msb.le.ac.uk/3035/Coronaviruses.html#SARS
~~~~~~~~~~~~~~~~~~~~
知我者谓我心忧
不知我者谓我何求
~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~
※作者已于 2003-04-26 01:02:25 修改本文※
~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~
※作者已于 2003-04-26 01:08:44 修改本文※
~~~~~~~~~~~~~~~~~~~~
|
瞻仰一下SARS的元凶：）[多图]
[转载]
~~~~~~~~~~~~~~~~~~~~
RE:
RE:RE:
Top