1. BIOE 301 Lecture Nine

2. Engineering Design Method Designing a product to meet a practical goal in the presence of constraints Six design steps: 1. Identify a need 2. Define the problem (goals, constraints) 3. Gather information 4. Develop solutions 5. Evaluate solutions 6. Communicate results Papers, patents, marketing Refine Design SPECS

3. Three Case Studies Prevention of infectious disease Early detection of cancer Treatment of heart disease

4. Outline: Prevention of ID Science Organisms that cause disease Immunity Engineering How to make a vaccine Vaccines: From idea to product Societal Impact Health and economics Ethics of clinical trials Developed world/Developing world

5. Pathogens How They Cause Disease

6. Types of Pathogens Bacteria Cells with membrane and cell wall (usually) Can survive outside host Can reproduce without a host Can be killed or inhibited by antibiotics Viruses Nucleic acid core with protein envelope Use host intracellular machinery to reproduce Cannot be killed with antibiotics >50 different viruses that can infect humans

7. Bacteria

8. How do Bacteria Cause Disease? Invade host Reproduce Produce toxins which disturb function of normal cells

9. Virus

10. How do Viruses Cause Disease? Virus invades host cell Binds to cell membrane receptors Endocytosis brings virus into cell Virus takes over cell Use viral nucleic acid and host cell resources to make new viral nucleic acid and proteins More virus is released from host cell Virus causes host cell to lyse OR Viral particles bud from host cell surface

11. Pathophysiology of HIV/AIDS

12. Viruses Three basic problems each must solve How to reproduce inside a human cell How to spread from one person to another Inhale Eat During birth Intimate physical contact How to evade the immune system

13. Influenza Viral Reproduction - 1 Must get inside human cell to use cell’s biosynthetic machinery Influenza virus binds to cell receptor Induces receptor mediated endocytosis

14. Influenza Viral Reproduction - 2 pH slowly reduced in endosome, virus releases its single stranded RNA and polymerase proteins RNA segments and polymerase proteins enter nucleus of infected cell Cell begins to make many copies of the viral RNA and viral coat proteins

15. Influenza Viral Reproduction - 3 New viral particles exit nucleus and bud from cell Viral polymerase proteins don’t proofread reproduction Nearly every virus produced in an influenza infected cell is a mutant

16. Influenza Viral Spread Infected person sneezes or coughs Micro-droplets containing viral particles inhaled by another person Penetrates epithelial cells lining respiratory tract Influenza kills cells that it infects Can only cause acute infections Cannot establish latent or chronic infections How does it evade immune extinction? Antigenic drift Caused by point mutations Yearly vaccination http://www.cdc.gov/flu/weekly/usmap.htm http://students.washington.edu/grant/rand om/sneeze.jpg

17. Influenza How does the virus cause symptoms? Cells of respiratory tract are killed by virus or immune system Resulting inflammation triggers cough reflex to clear airways of foreign invaders Influenza infection results in production of large quantities of interferon Fever Muscle aches Headaches Fatigue

18. The Immune System How Are We Protected Against Pathogens?

19. Types of Immunity Three layers of immunity: Physical Barriers Innate Immune System All animals possess Adaptive Immune System Vertebrates possess Keep pathogens out Kill them if they get in

20. Types of Immunity Physical Barriers Skin (2 square meters) Mucous Membranes (400 square meters) Innate Immune System Produces general inflammatory response when pathogens penetrate physical barriers Adaptive Immune System Can adapt to defend against any invader Important when innate immune system cannot defend against attack Provides immune system with “memory”

21. White Blood Cells NeutrophilLymphocyteMacrophage

22. What happens when you get a splinter? Pathogen makes it past a physical barrier Symptoms? Red, swollen, hot, pus What causes these symptoms? Innate immune system is kicking into gear Usually innate immune system can take care of it

23. Innate Immune System Macrophages eat bacteria on splinter Phagocytosis Produce chemicals which: Increase local blood flow Redness Heat Increase permeability of blood vessels Swelling Recruit other phagocytes to site of infection Pus

25. Adaptive Immune System Two main components Fight pathogens outside of cells: 1) Antibodies Fight pathogens inside of cells: 2) Killer T cells

26. What is an antibody? Bridge between: Pathogen Tool to kill it Antibodies have two important regions: Fab region: Binds antigen Binds surface of virus infected cell Fc region: Binds macrophages and neutrophils, induces phagocytosis Binds natural killer cell, induces killing

28. Antibodies How are antibodies made? B cells Lymphocytes that make antibodies Have B cell receptors on surface 100 million different types of B cells, each with different surface receptors B cell receptors are so diverse they can recognize every organic molecule When a B cell binds antigen: Proliferates - In one week, clone of 20,000 identical B cells Secretes antibody

30. Adaptive Immune System How do we kill virus once inside the cell? Antibodies cannot get to it Need T cells T Cells Recognize protein antigens When bind antigen, undergo clonal selection Three types of T Cells: Killer T Cells (Cytotoxic T Lymphocytes – CTLs) Helper T Cells Regulatory T Cells

31. How do T Cells ID Virus Infected Cells? Antigen Presentation All cells have MHC molecules on surface When virus invades cell, fragments of viral protein are loaded onto MHC proteins T Cells inspect MHC proteins and use this as a signal to identify infected cells

34. Immunologic Memory First time adaptive immune system is activated by an antigen: Build up a clone of B cells and T cells Takes about a week After infection is over, most die off Some remain – memory cells Second time adaptive immune system is activated by that antigen: Memory cells are easier to activate Response is much faster – no symptoms

37. Summary Pathogens: Bacteria and Virus Levels of Immunity: Barriers  First line of defense Innate  Inflammation Adaptive  Immunologic memory Antibody mediated immunity Cell mediated immunity  Pathogens within cells Diversity to recognize 100 million antigens

38. Vaccines How Are They Made?

39. Vaccination Vaccination: Practice of artificially inducing immunity Goal of vaccination: Make memory T helper cells, memory killer T cells, and memory B cells that will protect the vaccinated person against future exposure to pathogen Want the vaccine to have: Maximum realism Minimum danger

40. What is needed to make memory cells? Memory B Cells & Memory Helper T Cells: B and T cell receptors must see virus or viral debris Memory Killer T Cells: Antigen Presenting Cells must be infected with virus

41. Types of Vaccines Non-infectious vaccines DTaP Pneumococcus Live, attenuated bacterial or viral vaccines Chicken Pox Carrier Vaccines DNA Vaccines

42. Non-infectious vaccines Killed bacterial or inactivated viral vaccines Treat pathogen with chemicals (like formaldehyde) Impossible to guarantee that you have killed all the pathogen Salk (inactivated) Polio vaccine, rabies vaccine Subunit vaccines Use part of pathogen OR Use genetic engineering to manufacture pathogen protein No danger of infection Hepatitis A & B, Haemophilus influenza type b, pneumonoccocal conjugate vaccinespneumonoccocal Toxoid vaccines Bacterial toxins that have been made harmless Diphtheria, tetanus and pertussis vaccines Diphtheria, tetanus and pertussis This approach will make memory B cells and memory helper T cells, but NOT memory killer T cells Booster vaccines usually required

43. Live, attenuated vaccines Grow pathogen in host cells Produces mutations which: Weaken pathogen so it cannot produce disease in healthy people Pathogen still produces strong immune response that protects against future infection Sabin Polio vaccine (oral Polio) Measles, mumps, rubella, varicella vaccinesvaricella This approach makes memory B cells, memory helper T cells, AND memory killer T cells Usually provide life-long immunity Can produce disease in immuno-compromised host

44. Carrier Vaccines Use virus or bacterium that does not cause disease to carry viral genes to APCs e.g. vaccinia for Smallpox vaccine http://www.bt.cdc.gov/agent/smallpox/vaccination/facts.asp This approach makes memory B cells, memory helper T cells, AND memory killer T cells Does not pose danger of real infection Immuno-compromised individuals can get infection from carrier Carrier must be one that individuals are not already immune to Cannot make booster vaccines with carrier (must use different carrier for booster)

45. DNA Vaccines DNA injections can produce memory B cells and memory T killer cells Reasons are not fully understood Make a DNA vaccine from a few viral genes No danger that it would cause infection

46. Types of Vaccines Non-infectious vaccines No danger of infection Does not stimulate cell mediated immunity Usually need booster vaccines Live, attenuated bacterial or viral vaccines Makes memory B cells, memory helper T cells, AND memory killer T cells Usually provides life-long immunity Can produce disease in immuno-compromised host Carrier Vaccines Makes memory B cells, memory helper T cells, AND memory killer T cells Does not pose danger of real infection Immuno-compromised individuals can get infection from carrier DNA Vaccines

47. Effectiveness of Vaccines Vaccination Effectiveness About 1-2 of every 20 people immunized will not have an adequate immune response to a vaccine Herd Immunity Vaccinated people have antibodies against a pathogen They are much less likely to transmit that germ to other people Even people that have not been vaccinated are protected About 95% of community must be vaccinated to achieve herd immunity Does not provide protection against non-contagious diseases – eg tetanus

48. Vaccines How Are They Tested?

49. Vaccine Testing Laboratory testing Animal Model Animal must be susceptible to infection by agent against which vaccine is directed Animal should develop same symptoms as humans

50. Vaccine Testing Human Trials Phase I Small number of volunteers (20-100) Usually healthy adults Last few months Determine vaccine dosages that produce levels of memory B or T cells that are likely to be protective Evaluate side effects at these dosages FDA must approve the vaccine as an Investigational New Drug (IND) NPR Story – Ebola Vaccine TrialsEbola Vaccine Trials http://www.npr.org/rundowns/segment.php?wfId =1513230 http://www.npr.org/rundowns/segment.php?wfId =1513230

51. Vaccine Testing Human Trials Phase II Larger number of volunteers (several hundred) Last few months to few years Controlled study, with some volunteers receiving: Vaccine Placebo (or existing vaccine) Endpoints: Effectiveness, safety

52. Vaccine Testing Human Trials Phase III Large number of volunteers (several hundred to several thousand) Last years Controlled double blind study, with some volunteers receiving: Vaccine Placebo (or existing vaccine) Neither patients nor physicians know which was given

53. Vaccine Testing Role of the FDA: Licensure by FDA required before a company can market the vaccine (about a decade) Each batch of vaccine must be tested for safety, potency, purity and sample lot must be sent to FDA Post-licensure surveillance Doctors must report adverse reactions after vaccination to FDA and CDC Vaccine Adverse Events Reporting System (VAERS) As many as 12,000 reports per year, 2,000 serious Most are unrelated to the vaccine

54. Vaccine Testing Recommendations by health departments and expert physician groups When should vaccine be used Who should receive it Weigh: risks and benefits of the vaccine, costs of vaccination Legislation: States determine which vaccines are required by law All 50 states have school immunization laws Can be exempted based on: Medical reasons (50 states) Religious reasons (48 states) Philosophical reasons (15 states)

55. Recommended Vaccine Schedule

56. History of the Rotavirus Vaccine Withdrawn from the market after post-licensure surveillance indicated small number of adverse effects http://www.npr.org/templates/story/story.php?storyId=3262013

57. Vaccines Are They Effective?

58. Effects of Vaccination in US DiseaseMax # of Cases# Cases in 2000 %  Diphtheria206,929 (1921)2-99.99 Measles894,134 (1941)63-99.99 Mumps152,209 (1968)315-99.80 Pertussis265,269 (1952)6,755-97.73 Polio21,269 (1952)0-100 Rubella57,686 (1969)152-99.84 Tetanus1,560 (1923)26-98.44 HiB~20,000 (1984)1,212- 93.14 Hep B26,611 (1985)6,646-75.03

59. Effects of Vaccination Smallpox First human disease eradicated from the face of the earth by a global immunization campaign 1974 Only 5% of the world’s children received 6 vaccines recommended by WHO 1994 >80% of the world’s children receive basic vaccines Each year: 3 million lives saved

60. Childhood Immunization 1977: Goal to immunize at least 80% of world’s children against six antigens by 1990

63. http://www.npr.org/templates/story/story.php?storyId=849775 http://www.npr.org/templates/story/story.php?storyId=3870193

64. Vaccines What is Still Needed?

65. What Vaccines are needed? The big three: HIV Malaria Tuberculosis

66. Summary How do vaccines work? Stimulate immunity without causing disease How are vaccines made? Non-infectious vaccines Live, attenuated bacterial or viral vaccines Carrier Vaccines DNA Vaccines How are vaccines tested? Lab/Animal testing Phase I-III human testing Post-licensure surveillance Impact of vaccines

67. Assignments Due Next Time None