Pathogen_Project

Report
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SARS, also known as Severe Acute
Respiratory Syndrome, is a dangerous virus
that can cause several symptoms and even
death. Scientists believe that SARS was
started in an animal, and that infection
spread from the animal to many humans
and 25 countries in just half a year. It was
first described on the 26th of February in
Hanoi, Vietnam in a 48 year old business
man with high fever and atypical
pneumonia that was getting worse
extremely fast.
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SARS is a disease that is and was very
easy to spread and obtain. Unlike other
coronaviruses, SARS has low infectivity
and high virulence or threat to patient
organs. However, an infected person
would be able to spread the contagious
disease through speech because the
virus is air-borne. By breathing in the virus,
you would be infected as the virus would
penetrate and enter the immune system.
SARS is known for its rapid transmission
 Infectious agent, which is possibly new
 The potential of becoming a pandemic
 Global Alert on the 12th of March
 Is known for its rapid death toll in Asia,
esp. China in which thousands of lives
were taken.
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SARS is a part of the Coronavirus Family,
which is a subdivision of the Coronaviridae
Family.
 They are enveloped viruses that have
positive single-stranded RNA genome along
with helical symmetry.
 SARS contains Single-strand RNA that is nonsegmented and enveloped
 The serotype or serogroups associated with
this virus are 229E and OC43 in human
beings
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When a person is infected, the main
symptom is body temperature.
 The normal body temperature is 98.6 F, but
the average temperature for patients with
SARS is usually 100.4 or higher.
 Another symptom is headache. The
infection can start with fever, and can even
lead to severe diarrhea, and pneumonia.
When people get pneumonia, it causes
respiratory failure, which is where most
people encounter death.
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The initial symptoms of SARS include flu,
fever, gastrointestinal symptoms, cough,
and sore throat.
 Also, some symptoms are lethargy, which
means drowsiness or being dull,
unenergetic, and, overall an overpowering
sleep.
 And Myalgia which is pain in the muscles.
 SARS pathogen can lead to illnesses such as
pneumonia and influenza.
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Although the most common symptom to all
patients is fever, shortness of breath also occurs
later .
Symptoms can appear anytime between 2-10
days after you are exposed to the disease, but
even up to 13 days has been noted for
symptoms after exposure.
In many cases, symptoms can be seen 2-3
days after exposure
10-20%of all cases require mechanical
ventilation, which is a method in medicine that
assists natural breathing impulses in humans via
machines.
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SARS goes through the lytic cycle when it
replicates. Therefore, the virus exits the
cell when the cell dies or bursts as the
virus takes over. Because dormant
diseases are relatively rare in animals, it is
safe to say that SARS is not a retrovirus
that goes through a lysogenic cycle. The
viruses also can exit the cell through
exocytosis or active transport
When the SARS pathogen replicates, it is
aided by the protein enzyme protease.
 The transcription of coronaviruses involves
RNA synthesis during the extension of
negative copies of mRNAs.
 Protease is enzyme that conducts
proteolysis that begins protein catabolism
by the hydrolyzing of peptide bonds.
 Proteolysis speeds the process of mRNA and
furthermore, viral replication.
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Replication of the virus is done inside the
nucleus of the cell
This is known by the name of the disease of
SARS or Severe Acute Respiratory Syndrome.
Because it is a syndrome along with the many
famous chromosomal disorders such as Down
Syndrome or Patau Syndrome, we know it is in
relevance to the chromosomes of a cell or
furthermore the DNA and nucleus of that cell.
Earlier, it was explained that the replication of
this pathogen is catalyzed by protease, which
aids in proteolysis and overall the replication of
the disease.
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SARS is a coronavirus that gets its name from their
crown-like spikes, which are made of S glycoprotein.
Also, the virus is enveloped, which means it is cloaked
in a membrane that is derived from a host cell.
The virus binds to receptor sites on the host cell
through the S glycoproteins.
SARS is a virus that enters the host cell by a fusion
called “membrane fusion”. This is when the SARS virus
binds with the outer side of the host cell’s receptor,
and enters the host cell.
The virus enters the cell by injecting part of its RNA
complex into the host cell to replicate inside stored in
the capsid or protein coat of the virus.
The worldwide death rate of SARS has
increased up to, 14-15%, which is almost
double the latest measurement.
 If older than 65 years old, more than half
are likely to die, very dangerous for
elders.
 Currently, there are 5600 SARS cases of
the syndrome with 3647 of these cases in
China.
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http://www.nejm.org/earlyrelease/SARS.jpg
According to a June 10 study in 2003:
 There have been 8430 cases of SARS
reported around the world
 There have been 789 deaths
 5937 recovered patients
 1184 currently with the disease
 With a 9.4% fatality percentage
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Out of the 8430 total cases reported:
China had 5328 incidents of SARS patients, which is
63.2% of the total
Hong Kong had 1754 cases which is 20.8% of the total
Taiwan had 686 cases which is 8.1% of the total
Canada had 229 cases which is 2.7 % of the total
Singapore had 206 cases which is 2.4% of the total
the USA had 69 cases which is 0.8% of the total
Vietnam had 63 cases which is 0.7% of the total
And the rest of the world had 95 cases which makes
1.1% of the total reported cases of SARS.
The goals of the treatment are to:
 Block the binding to the receptor by the S
protein or restrain “receptor-induced
conformational change” or in other words,
stop the changing of the disease through
the receptor
 Hinder the cleave of the SARS-CoV
polymerase and viral RNA synthesis noted
that the polymerase gene of the CoV has
to be degraded or digested by the viral
protein enzymes or proteases to be active.
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Block the interrupted RNA transcription
 Block assembly of viruses in that the virus
buds into pre-Golgi membranes.
 Inhibit the process of exocytosis or active
transport of transferring waste out of the
cell through phagocytosis and
pinocytosis.
 Inhibit serine proteases to block the
cleave of spike glycoproteins
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Through clinical trials, we know that SARS develops in
stages, which includes acute constitutional symptoms,
acute viral pneumonitis, acute lung injury, and acute
respiratory distress syndrome.
Corticosteroids are used to help lung damage from
inflammatory response
Also, ribavirin is an antimetabolite antrival that blocks
nucleic acid synthesis and it is used for both RNA and
DNA. Interestingly, recent studies have found ribavirin is
ineffective.
Mechanical ventilation is used to aid in spontaneous
breathing
Glycyrrhizin that is extracted from liquorice roots can be
used to treat the virus as it inhibits its replication.
Overall, treatment of SARS is done through antipyretics or
fever treatment along with ventilator support.
In order to diagnose this disease, two
tests are performed
 First, the ELISA Test is used. If negative Ab
on acute serum with a positive Ab test
on healing serum. To diagnose SARS
there must be seroconversion by the
ELISA Test
 Also PCR test must be confirmed positive
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Our nature as human beings effects our
chances of getting such a disease.
 Human demographics or population along
with behavior, susceptibility to disease,
economic development and land use,
altering ecosystems, international travel
and commerce, microbial evolution and a
breakdown of health measure all will affect
the emergence of SARS as a pandemic to
fear.
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Campbell Textbook
 http://www.scidev.net/en/health/sars/n
ews/scientists-shed-light-on-sars-virus-cellentry.html
 http://en.wikipedia.org/wiki/SARS
 http://www.cdc.gov/ncidod/sars/
 http://www.who.int/csr/sars/en/
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*http://www.uleth.ca/bio/bio4110/olga15.
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