BIOE 301 Lecture Nine

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BIOE 301 Lecture Nine

• Amit Mistry
• Feb 8, 2007

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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
• Youre exposed to chicken pox (you already had it
  as a kid)

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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

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Q3 How can technology solve health care
problems?

• CS1 Prevention of infectious disease

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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

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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

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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
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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
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Influenza

• Viral Reproduction - 1
• Must get inside human cell to use cells
  biosynthetic machinery
• Influenza virus binds to cell receptor
• Induces receptor mediated endocytosis

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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

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Influenza

• Viral Reproduction - 3
• New viral particles exit nucleus and bud from
  cell
• Viral polymerase proteins dont proofread
  reproduction
• Nearly every virus produced in an influenza
  infected cell is a mutant

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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

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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
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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

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Why do we need vaccines?
Pathogen Offense Immune System
Defense Vaccines ? Stealing the
playbook
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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

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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

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History of Vaccination

• Seventh Century
• Indian Buddhists drank snake venom to induce
  immunity (through toxoid effect)
• 1700s
• Variolation against smallpox

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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
• Jenners (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

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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

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Types of Vaccines

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

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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

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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?

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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

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Passaging Cells
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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/f
  acts.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 cant you make a booster vaccine with carrier?

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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

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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

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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

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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 seasonWhy?

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Vaccines

• How Are They Tested?

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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

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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?wfId15132
  30

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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

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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

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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

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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)

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Vaccine Schedule

• 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

By age two 20 shots!! Single visit Up to 5
shots!!
http//www.christianpoint.org/inspiration/images/c
rying_baby.jpg
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Recommended Vaccine Schedule
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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?story
Id3262013 http//www.npr.org/templates/story/stor
y.php?storyId5126636
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Vaccines

• Are They Effective?

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Effects of Vaccination in US
Disease Max of Cases Cases in 2000 D
Diphtheria 206,929 (1921) 2 -99.99
Measles 894,134 (1941) 63 -99.99
Mumps 152,209 (1968) 315 -99.80
Pertussis 265,269 (1952) 6,755 -97.73
Polio 21,269 (1952) 0 -100
Rubella 57,686 (1969) 152 -99.84
Tetanus 1,560 (1923) 26 -98.44
HiB 20,000 (1984) 1,212 - 93.14
Hep B 26,611 (1985) 6,646 -75.03
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Effects of Vaccination

• Smallpox
• First human disease eradicated from the face of
  the earth by a global immunization campaign
• 1974
• Only 5 of the worlds children received 6
  vaccines recommended by WHO
• 1994
• gt80 of the worlds children receive basic
  vaccines
• Each year 3 million lives saved

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Smallpox

• One of worlds 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

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Childhood Immunization

• 1977
• Goal to immunize at least 80 of worlds children
  against six antigens by 1990
• Measles
• Diphtheria
• Pertussis
• Tetanus
• Polio
• Tuberculosis

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Measles
Pertussis
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Diptheria
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http//www.npr.org/templates/story/story.php?story
Id849775
http//www.npr.org/templates/story/story.php?story
Id3870193
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Vaccines

• What is Still Needed?

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What Vaccines are needed?

• The big three
• HIV
• Malaria
• Tuberculosis

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Summary of Lecture 9

• 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

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• Turn in Project Task 2 today
• Next Time
• HW 5 due on 2/13/07
• HIV/AIDS vaccine development

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To learn more

• Influenza
• http//www.cdc.gov/mmwr/mguide_flu.html
• Avian Flu
• http//www.cdc.gov/flu/avian/
• http//www.pandemicflu.gov/
• Original Antigenic Sin
• http//www.rice.edu/sallyport/2003/fall/sallyport/
  flu.html
• An overview of vaccines
• http//www.accessexcellence.org/AE/AEC/CC/vaccines
  _how_why.html