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First of all! • • • • • 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 ? ! "#$%&'()*+,(-,,&()$.)/0(1%&',#+,2($& 3*33*/$*&(,+%/45$%&6(-45(7)%',(84&15$%&($' &%5(7,//(4&2,#'5%%29 ! :),&(*-&%#3*//0(8%/2,26(5),0(1*4',(5), 2$',*',9 ! "#$%&'()*+,(&%(.,&,5$1(3*5,#$*/(;&%(&41/,$1 *1$2'<(=>?@(&%#(A?@9 ! B*'$/0('%/4-/, ! B*'$/0(2$.,'5,2(-0(C#%5,*',' • 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 3/13/07 PrPc PrPc 44 PrPC PrPC PrPsc fibrils PrPSC 3/13/07 45 3/13/07 46 Result ! Spongiform changes in gray matter Plaque 3/13/07 47 3/13/07 48 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! 3/13/07 51 - disease is NOT transmitted through direct contact or animalto-animal spread. - Animals get infected through consumption of feed contaminated with the infectious BSE agent. 3/13/07 52 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 3/13/07 Healthy Cows = Healthy US 53 3/13/07 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. 3/13/07 Protect yourself, your animal, and your community against the impact of a disease outbreak. 54 APHIS conducts BSE surveillance since 1990, including four new rules added in Dec. 30, 2003. 55 3/13/07 56 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. 3/13/07 cord from being allowed in product produced from a technology called AMR. 57 3/13/07 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. 3/13/07 58 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%. 59 3/13/07 60 “ 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 3/13/07 “ I’ I’ll have a clone burger, medium rare ” 61 3/13/07 62 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 3/13/07 63 3/13/07 64 Should Americans fear our beef supply? Consumer Choices - One clear option : stop eating beef - At least avoid burger chains. ! - Know the farmers who raise your meat. ! - Know how the animals were raised and what they were fed with. YES ! ! Look for local, grass fed meats. - 3/13/07 65 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. 3/13/07 “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 66 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. 3/13/07 NO 67