Download MadCow

First of all!
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DISIDERIO J MENDOZA,
FAMILY OF SIMILAR DISEASES:
Tramsmissible spongiform encephalopathy (TSE)
LISA SOETANTO,
EUNAH CHOI
NOT well understood yet.
Bovine spongiform encephalopathy (BSE), or ``mad cow disease,''
was first recognized in the United Kingdom in 1986.
Bovine spongiform encephalopathy (BSE) commonly known as
"mad cow disease", is a fatal, neurodegenerative disease of cattle.
Mass research started after 1986, mostly into finding the cause of
the disease.
Government implemented rules and regulations to prevent the
spread of the disease.
Next..
Causes of BSE
•
Exact cause not known
•
Mostly attributed to an infectious form of protein
called prions
Recycling diseased animal protein in feed
containing meat and bone meal esp. brain and
spinal chord
Healthy Cows
Infected Cows
» Scrapie
» Bovine Spongiform Encephalopathy
» Variant Creutzfeld-Jakob Disease
•
Transmissions occurs when cattle are fed with
scrapie-infected sheep meat
Feeding of infected
body parts
Symptoms of BSE
• Incubation period: 2-8
years
• Change in behavior and
attitudes
• Abnormal posture
• Weight loss and
decreased milk production
Symptoms of BSE
(cont’d)
Further progression of the disease causes
• Apprehension
• Hyperaesthesia
» Abnormal increase in sensory organ’s
sensitivity
• Frequent licking
• Uncoordinated movements and trouble in standing
and moving
• Progressive paresis or paralysis
• Death
Effects on humans
• Causes variant
Creutzfeldt-Jakob
disease (vCJD)
• Human form of BSE
• Undetected by any
current medical
technology before
onset of symptoms
vCJD
• Incubation period:
10-15 years
• Not contagious
• Fatal, untreatable
neurodegenerative
disease
• Younger people are
more prone to
develop it
157 cases reported cases in UK, France,
Canada, Ireland, Italy, and the United States
Symptoms of vCJD
• Psychiatric/behavioral symptoms
» Depression
» Schizophrenia-like psychosis
• Painful dysesthesias
» Dysesthesias- Pain or uncomfortable sensations
• Unusual sensory symptoms
» Stickiness of the skin
www.commondreams.org
Symptoms of vCJD (cont’d)
Classical v. Variant CJD
• Neurological signs
» unsteadiness, difficulty walking and involuntary
movements
Transmission
• Dementia
• Paralysis and muteness
• Coma and death
Median age at
death
Median duration
of illness
Classical
CJD
Variant CJD
Hereditary,
spontaneous,
infection
65 years
Linked to BSE
4-5 months
13-14 months
29 years
NEXT..
MAD COW DISEASE
STRUCTURE AND FUNCTION
Normal vs. infected
Why do they act so differently?
Why do they act so differently?
• The cow must have been hungry?
Why do they act so differently?
• The cow must have been hungry?
• Tired of eating grass, grass and grass?
Why do they act so differently?
Why do they act so differently?
• The cow must have been hungry?
• Tired of eating grass, grass and grass?
• The cow saw its cowfriend get butchered?
• The cow must have been hungry?
• Tired of eating grass, grass and grass?
• The cow saw its cowfriend get butchered?
None of the above.
What are Prions?
Why do they act so differently?
The name prion was given in 1981 by Dr. Stanley Prusiner, nobel prize
winner for his research in prion proteins.
• The cow must have been hungry?
• Tired of eating grass, grass and grass?
• The cow saw its cowfriend get butchered?
There has been speculation and debate about the cause of the disease.
The most accepted from the scientific community is the protein-only
hypothesis, which discribes what prions are and how they reproduce.
None of the above.
• It is due to a Prion Protein that all animals
carry.
Protein-only Hypothesis
Protein-only Hypothesis
PrPc
PrPsc
PrPc
PrPsc
“NORMAL”
“BAD”
“NORMAL”
“BAD”
conformation
conformation
conformation
conformation
The abnormal protein itself directs the conversion of the normal
host protein to the abnormal form. In other words, PrPSc converts
PrPC into PrPSc.
What is PrPC ?
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• resides on nerve cell surfaces...
What is PrPSc?
• a defective protein agent
(PrPsc) due to a gene
(PRNPc)
• Is extremely resistant to heat,
ultraviolet light, ionizing
radiation, normal sterilization
processes, and common
disinfectants that normally
inactivate viruses and bacteria.
• Same amino acid sequence
and primary structure as
normal protein.
Can we trust the model?
Can we trust the model?
Based
on NMR
results
Nuclear
magnetic
resonance (NMR)
spectroscopy
Proposed
based on
lowresolution
structural
studies
Reproduction
•
•
Physicist J.S. Griffith first proposed the protein-only theory in 1967
to explain how prions could replicate if they were made of protein
but did not contain nucleic acids. He did this fifteen years before the
discovery of PrPSc and PrPC.
Many have called the theory heretical because it describes
replication of a pathogenic agent without a nucleic acid genome.
Reproduction
•
•
Physicist J.S. Griffith first proposed the protein-only theory in 1967
to explain how prions could replicate if they were made of protein
but did not contain nucleic acids. He did this fifteen years before the
discovery of PrPSc and PrPC.
Many have called the theory heretical because it describes
replication of a pathogenic agent without a nucleic acid genome.
To better understand the process, study the
background of a protein.
BACKGROUND
•Proteins are chains of chemicals called
amino acids linked together like beads on
a string.
BACKGROUND
•There are 20 different amino acids
(imagine 20 differently colored beads)
and each amino acid has a different
chemical behavior.
BACKGROUND
BACKGROUND
•The amino acid string does not remain
linear once it is made, however, and the
properties of the different amino acids
make the protein fold into a specific
shape or conformation.
•The prion protein has about 250 amino
acids.
BACKGROUND
•The conformation of a protein
determines its function.
BACKGROUND
•Different amino acid sequences produce
proteins with different conformations and
functions.
BACKGROUND
BACKGROUND
•Changes in the gene (mutations) can
change the amino acid sequence of the
protein and alter its conformation and
function.
•Genes determine the sequence of amino
acids in a protein.
PROCESS
PrPc
•PRPsc
converts PrPc
to the
abnormal form.
PrPc
PrPc
PrPsc
PrPc
PrPc
PrPc
PrPc
PrPc
PrPc
PrPc
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PrPc
PrPc
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PrPC
PrPC
PrPsc fibrils
PrPSC
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Result
! Spongiform
changes in gray matter
Plaque
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NEXT..
What have we learned?
Protein only-hypothesis is currently used to explain the disease.
PrPSc converts PrPC into PrPSc.
Prions have no genetic material (no nucleic acids) –DNA nor RNA.
PrPsc is extremely resistant.
Creates spongiform in brain.
Can BSE be transmitted from one cow to
another cow?
NO! BSE is not a contagious disease.
There is neither any treatment nor a
vaccine to prevent the disease!
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-
disease is NOT
transmitted through
direct contact or animalto-animal spread.
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Animals get infected
through consumption of
feed contaminated with
the infectious BSE agent.
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How can we protect our cows from
getting BSE?
1.
What is the U.S. government doing to
protect the public from BSE?
Feeding the right food.
- banning the use of animal by-product.
Lists of organization:
- feeding cows high protein meal made from nonanimal by product
2.
-U.S. Department of Agriculture’
Agriculture’s Animal (USDA) ,
-Plant Health Inspection Service (APHIS)
-Food and Drug Administration (FDA)
-USDA’
-USDA’s Food Safety and Inspection Service (FSIS)
Enhance the technology.
- Detect their health problems earlier
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Healthy Cows = Healthy US
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NAIS
National Animal Identification System
Surveillance
Information system that
helps producers and
animal health officials
respond quickly and
effectively to animal
disease event in the
U.S.
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Protect yourself, your
animal, and your
community against the
impact of a disease
outbreak.
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APHIS conducts BSE surveillance since 1990,
including four new rules added in Dec. 30, 2003.
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USDA’s Four new rules
enhancing its BSE safeguard
3. Specified Risk Material(SRMs)
Material(SRMs) – Skull, brain,
trigeminal ganglia, eyes, vertebral column, spinal cord and
dorsal root ganglia of cattle >= 30 months of age, tonsils
and the small intestine of all cattle are banned from the
human food supply.
( announced by Secretary Veneman on Dec. 30, 2003 )
1.
Product Holding – FSIS inspectors no longer mark
cattle tested for BSE as “inspected and passed”
passed”, holding
until the test is confirmed negative
4. Advanced Meat Recovery(AMR)
- FSIS expanded a prior
2. Air-Injection Stunning – FSIS banned the practice
prohibition on spinal
of air-injection stunning to ensure that portions of the
brain are not dislocated into the tissues of the carcass as
a consequence of humanely stunning cattle during the
slaughter process.
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cord from being allowed in
product produced from
a technology called AMR.
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No. The only USDA approved testing for the
agent is post-mortem analyses of brain tissue.
This is a laboratory screening test for BSE.
Inspection from FSIS
- Cattle slaughtered in the U.S. are subject to
Japan
inspection.
- Cattle that show signs of illness, disease, or
central nervous system impairment are condemned
and not allowed into the human food supply.
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Is there a BSE test for meat?
Monitoring
!
Effective Dec. 30, 2003, USDA will not allow non-ambulatory
disabled cattle to be slaughtered for human food.
100% of cattle tested
Germany
75%
France
75%
U.K.
100% of cattle over 36 months
United Stated 0.05%.
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“ 36 million cattle were slaughtered in U.S. in
yet only less
2002,
than 20,000
were tested for BSE ! ”
Other ways to prevent BSE
- Scientists try to come up
with a clone cow which is
resistant to BSE
(if we get a clone cow, is
it safe to eat a clone cow?
)
- In WA, no cattle were tested in the first 7
months of 2003.
- At WA’
WA’s largest slaughterhouse, there were
no BSE tests in 2002 and 2003
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“ I’
I’ll have a
clone burger,
medium rare ”
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Organic vs. Non-organic feed
!
Organic meat production
- They are “vegetarian”
vegetarian” !
- feed with pasture, hay,
silage, and grain
concentrates
What can we do to protect
our selves from BSE ?
- absolute ban on feeding
animal by-product to
minimize risks of BSE
!
Non-organic meat
production
- feed with gelatin, fats,
oils, grease, tallow ,
poultry and poultry byproducts
also feed with rendered
pork protein and rendered
horse protein
Non-Organic feed cows have higher risk of getting BSE
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Should Americans fear our beef supply?
Consumer Choices
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One clear option : stop eating beef
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At least avoid burger chains.
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Know the farmers who raise your meat.
!
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Know how the animals were raised and what
they were fed with.
YES
!
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Look for local, grass fed meats.
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Extra Information
BSE has not been fully discovered
yet.
We have no vaccine or treatment.
Easy access of Non-organic meat
from fast food chains.
Increase in number of people eating
meat regularly.
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“We are working together to prevent BSE
reaching to consumers since reduced beef
intake translates into millions of dollars in
lost $$$.” - USDA, FDA, NIH, CDCP, and
U.S. beef industry
“rate of surveillance in U.S. for each of t
he last 5years has been at leat double the
amount recommended. In 2001, the rate w
as ten times. In 2000, the number of brai
ns examined was more than five times” APHIS
“cattle less than 20 months of age make u
p 88% of slaughter population and no whe
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re in the world has a case of BSE been dia
gnosed in cattle less than 20 moths of ag
e.” - APHIS
The End.
Q. Can BSE be transmitted to milk and other dairy
products?
There is no scientific evidence to suggest that milk and
dairy products carry the agent that causes BSE.
Q. Will cooking (including microwave cooking) kill the
BSE agent?
Current scientific research indicates that cooking will
not kill the BSE agent.
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NO
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