- Hello, Jeff - One thing that should be considered is
the fact that this time SARS was contracted by a researcher. It is therefore
a possibility that the pathogen was altered in some way, i.e. it was a
lab pathogen. I am not sure whether it was being studied in the context
of vaccine or how it was being genetically manipulated. This could account
for the pathogen's proclivity toward infecting humans this time around.
-
- In fact, scientists fear that the greatest risk for SARS
outbreak is from "BIOLABS"
-
- Exerpt: He noted that the single case of SARS reported
in China last December [2003] was associated with a virus whose genome
sequence was distinct from that seen in the epidemic, and more like that
of virus isolated from civets.
-
- "This suggests a new host interaction, that it was
not the old virus that was still kicking around." It probably would
not have been recognized as SARS if healthcare providers had not been sensitized
to recognize the syndrome, he suggested. "It would have been seen
as just another pneumonia." In fact, this last case may represent
a common spontaneous event, Dr. Brown said, where isolated cases come from
virus that is not well adapted for human hosts, resulting in "a flare
of cases followed by burnout."
-
- On the other hand, the possibility exists that a new
SARS coronavirus could adapt to humans so well "that it would cause
a sustained epidemic in human populations that would persist for perpetuity."
Dr. Brown believes that this paper highlights "the big frontier for
microbiologists, which is to interpret genotypes of viruses [as they are
identified] so we can say where they come from and what their properties
are."
-
- SARS - WORLDWIDE MOLECULAR EPIDEMIOLOGY, 2003
-
- A ProMED-mail post ProMED-mail is a program of the International
Society for Infectious Diseases http://www.isid.org
-
- SARS Epidemic Caused By Evolution Of Single Coronavirus
Lineage
-
- By Karla Gale 1-30-4
-
- (Reuters) -- During the 2003 SARS epidemic in China,
SARS coronavirus (SARS-CoV) isolates obtained during different phases appear
to represent different evolutionary stages of the same viral lineage. To
investigate SARS-CoV adaptation to humans, Dr. Guo-Ping Zhao and members
of the Chinese SARS Molecular Epidemiology Consortium analyzed viral genomic
sequences of isolates obtained throughout the epidemic. Their findings
were published 0n 29 Jan 2004 on the Sciencexpress site http://www.sciencexpress.org/29.
-
- [The full article is published in Science: Molecular
Evolution of the SARS Coronavirus During the Course of the SARS Epidemic
in China. By the Chinese SARS Molecular Epidemiology Consortium. Published
online 30 Jan 2004, 10.1126/science.1092002].
-
- The early phase of the epidemic involved 11 individuals
from different geographical locations within Guangdong Province, where
exotic animals are part of the diet. 7 of these cases had documented contact
with wild animals. 2 major genotypes predominated, whose sequences were
similar to those of coronaviruses infecting other mammalian hosts. He noted
that the single case of SARS reported in China last December [2003] was
associated with a virus whose genome sequence was distinct from that seen
in the epidemic, and more like that of virus isolated from civets.
-
- "This suggests a new host interaction, that it was
not the old virus that was still kicking around." It probably would
not have been recognized as SARS if healthcare providers had not been sensitized
to recognize the syndrome, he suggested. "It would have been seen
as just another pneumonia." In fact, this last case may represent
a common spontaneous event, Dr. Brown said, where isolated cases come from
virus that is not well adapted for human hosts, resulting in "a flare
of cases followed by burnout."
-
- On the other hand, the possibility exists that a new
SARS coronavirus could adapt to humans so well "that it would cause
a sustained epidemic in human populations that would persist for perpetuity."
Dr. Brown believes that this paper highlights "the big frontier for
microbiologists, which is to interpret genotypes of viruses [as they are
identified] so we can say where they come from and what their properties
are."
-
- The second phase started with the first "super-spreader
event (SSE)", associated with more than 130 primary and secondary
infections in the city of Guangzhou.
-
- The late phase involved an outbreak in Hong Kong, traced
to a physician who worked with patients in Guangzhou who visited Hotel
M.
-
- During the second phase, the authors found that the SARS-CoV
sequences contained a new 29-nucleotide deletion that dominated the viral
population for the rest of the epidemic. The deletion affected the S protein,
which is responsible for virus-host interactions, the report indicates.
"We observed that the epidemic started and ended with deletion events,"
Dr. Zhou's group writes, "together with a progressive slowing of the
non-synonymous mutation rates and a common genotype that predominated during
the latter part of the epidemic."
-
- Dr. Earl G. Brown, a microbiologist at the University
of Ottawa whose research encompasses viral evolution, virulence, and virus-host
interactions, discussed the report with Reuters Health. "Their findings
point to the fact that SARS was a focal event, something that happened
once," he said. The observed genome deletions "can only go in
one direction," thus proving that all the isolates evolved from the
same viral lineage.
-
- -- ProMED-mail <promed@promedmail.org>
-
- [The important conclusion from these data is the inference
that the 11 isolates represent a single lineage. Hence it is probable that
the 2002/2003 SARS outbreak may have been a focal event (i.e. had a single
source). One expectation might be that future outbreaks of SARS-like coronaviruses
might have significantly different epidemiological characteristics depending
on the initial source (e.g. a different animal species). The data are consistent
with derivation of the epidemic virus from an animal source, but they do
not prove this. - Mod.CP]
-
- [see also: SARS - Worldwide (11): molecular epidemiology,
2003 20040130.0358 2003 ---- SARS - worldwide (180): epidemiology, Guangdong
20031027.2681 SARS - worldwide (13): etiology 20030327.0758 SARS - worldwide
(16): etiology 20030328.0774 SARS - worldwide (26): etiology 20030403.0819
SARS - worldwide (42): WHO historical overview 20030411.0878 SARS - worldwide
(48): etiology 20030414.0909] ............................mpp/dk/cp/pg/jw
-
-
- Patricia A. Doyle, PhD Please visit my "Emerging
Diseases" message board at: http://www.clickitnews.com/ubbthreads/postlist.php?Cat=&Board=emergingdiseases
Zhan le Devlesa tai sastimasa Go with God and in Good Health
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