BIOE 301 Lecture Nine

1. BIOE 301 Lecture Nine Amit Mistry Feb 8, 2007

2. BIOE 301 – Lecture 9 WARM-UP • What type of immune defense is involved in each of the following: • A flu virus infects your cells • You step on a rusty nail and it pierces your skin • You’re exposed to chicken pox (you already had it as a kid)

3. Summary of Lecture 8 • Pathogens: Bacteria and Virus • Levels of Immunity: • Barriers  First line of defense • Innate  Inflammation • Phagocytes • Complement • Adaptive  Immunologic memory • Antibody mediated immunity • Cell mediated immunity  Pathogens within cells

4. Q3: How can technology solve health care problems? CS1: Prevention of infectious disease

5. Outline • Pathogens: How They Cause Disease • The Immune System: How We Fight Disease • How Vaccines Work • The Power of Vaccines: Childhood Illnesses • Designing a New Vaccine: HIV/AIDS

6. Roadmap of CS 1 • 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

7. Influenza Pandemic • CDC Public Service Announcement http://www.pandemicflu.gov/ • 1918-19: Spanish Flu • 50-100 million deaths • 1957-58: Asian Flu • 1-4 million deaths • 1968-69: Hong Kong Flu • 750,000 deaths www.cdc.gov http://en.wikipedia.org/wiki/Pandemic

8. 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 http://students.washington.edu/grant/random/sneeze.jpg

9. 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

10. Influenza • Viral Reproduction - 2 • pH slowly reduced in endosome, due to proton pump in membrane • 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

11. 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

12. 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 • http://www.cdc.gov/flu/weekly/usmap.htm

13. 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 • Interferon – protein that fights infection, but also causes: • Fever • Muscle aches • Headaches • Fatigue

14. Genetic Shift and Flu Pandemics • Genetic Shift • Animals co-infected by different strains of virus • Viral gene segments randomly reassociate • Reassortment of virus segments from birds, pigs, etc is source of new strains that infect humans • How does this happen? • Virus shed in bird feces, gets into pigs' drinking water • Humans handle and/or cough on the pig • New virus - segments from humans, birds & pigs • China: • Breeding ground for new influenzas strains • Proximity of humans, pigs, and ducks in China • Asian flu, Hong Kong flu, etc. • http://www.cdc.gov/flu/avian/facts.htm

15. Why do we need vaccines? Pathogen = Offense Immune System = Defense Vaccines  “Stealing the playbook”

16. Vaccination • Vaccination: • Practice of artificially inducing immunity • Goal of vaccination: • Stimulate both cell mediated and antibody mediated immunity that will protect the vaccinated person against future exposure to pathogen • Want the vaccine to have: • Maximum realism • Minimum danger

17. 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

18. History of Vaccination • Seventh Century • Indian Buddhists drank snake venom to induce immunity (through toxoid effect) • 1700’s • Variolation against smallpox

19. History of Vaccination • 1798 - Edward Jenner noted: • Smallpox and Cowpox: • Milkmaids frequently contracted cowpox which caused lesions similar to that smallpox • Milkmaids who had cowpox almost never got smallpox • Jenner’s (unethical) experiment: • Collected pus from cowpox sores • Injected cowpox pus into boy named James Phipps • Then injected Phipps with pus from smallpox sores • Phipps did not contract smallpox • First to introduce large scale, systematic immunization against smallpox

20. History of Vaccination • 1885: Attenuation • Louis Pasteur - first vaccine against rabies • Early 1900s: Toxoids • Diphtheria, tetanus • 1936 • Influenza • 1950s: Tissue Culture • Polio (Nobel Prize for Enders, Robbins, Weller) • 1960s: • Measles, Mumps, Rubella

21. Types of Vaccines • Non-infectious vaccines • Flu, plague • DTaP, Pneumococcus • Live, attenuated bacterial or viral vaccines • Chicken Pox, MMR • Carrier Vaccines • DNA Vaccines • Experimental

22. 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 vaccines • Toxoid vaccines • Bacterial toxins that have been made harmless • Diphtheria, tetanus and pertussis vaccines • This approach will make memory B cells and memory helper T cells, but NOT memory killer T cells • Booster vaccines usually required

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

24. Cell culture allows development of: live, attenuated vaccine • Grow cells: • Removed from tissue • In vitro (in glass) • By supplying nutrients and other factors • Specific O2 and CO2 (pH level) • Glucose, ions • Serum from blood: proteins

25. Dissection/ Breakdown… Organ Primary Cell Line Secondary Cell Line Add media for growth Incubate Divide -> transferred Passaging Cells

26. 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 • Why can’t you make a booster vaccine with carrier?

27. 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

28. 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 • Experimental…

29. 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

30. Your Flu Shot • If you got your flu shot this season, and skip it next season, you are more likely to get the flu next season…Why?

31. Vaccines How Are They Tested?

32. 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

33. 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 Trials • http://www.npr.org/rundowns/segment.php?wfId=1513230

34. 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

35. 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

36. 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

37. 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)

38. Birth Hepatitis B 2 Months DTap #1 Polio #1 Hib #1 Hepatits B #2 Pneumococcus #1 4 months DTaP #2 Polio #2 Hib #2 Pneumococcus #2 6 months DTaP #3 Hib #3 Pneumococcus #3 12 months MMR #1 Varicella 15 months Hib #4 Polio #3 Hepatitis B #3 Pneumococcus #4 DTap #4 4-6 years MMR #2 Polio #4 DTaP #5 11-12 years Tetanus, Diphtheria Vaccine Schedule By age two: 20 shots!! Single visit: Up to 5 shots!! http://www.christianpoint.org/inspiration/images/crying_baby.jpg

39. Recommended Vaccine Schedule

40. 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 http://www.npr.org/templates/story/story.php?storyId=5126636

41. Vaccines Are They Effective?

42. Effects of Vaccination in US

43. 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

44. Smallpox • One of world’s deadliest diseases • Vaccine available in early 1800s • Difficult to keep vaccine viable enough to deliver in developing world • Elimination of smallpox • 1950: stable, freeze dried vaccine • 1950: Goal  Eradicate smallpox from western hemisphere • 1967: Goal achieved except for Brazil • 1959: Goal  Eradicate smallpox from globe • Little progress made until 1967 when resources dedicated, 10-15 million cases per year at this time • Strategies: • Vaccinate 80% of population • Surveillance and containment of outbreaks • May 8, 1980: world certified as smallpox free

45. Childhood Immunization • 1977: • Goal to immunize at least 80% of world’s children against six antigens by 1990 • Measles • Diphtheria • Pertussis • Tetanus • Polio • Tuberculosis

46. Measles Pertussis

47. Diptheria

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

49. Vaccines What is Still Needed?

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