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VACCINES

VACCINES . Caleb Aswegen & Ilene Tsui. 11-14-12. Learning Objectives. Describe the importance of vaccines in preventing infectious diseases Describe the basic concept of how vaccines provide immunity Describe why you need to get a tetanus vaccine every 10 years.

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VACCINES

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  1. VACCINES Caleb Aswegen & Ilene Tsui 11-14-12

  2. Learning Objectives • Describe the importance of vaccines in preventing infectious diseases • Describe the basic concept of how vaccines provide immunity • Describe why you need to get a tetanus vaccine every 10 years

  3. Part I: Immune System Basics

  4. Immune System Basics • Skin • Innate immune system -White blood cells • Adaptive immune system -Cell and Antibody mediate (t, b cell) • Vaccines, memory cell formation

  5. IMMUNE SYSTEM BASICS • SKIN -1st line of defense- acts a barrier -Keeps water in and bacteria out -Harsh environment for some bacteria-antibacterial molecules (antimicrobial proteins) -Skin pH is acidic -Current colonization (of relatively harmless bacteria)

  6. IMMUNE SYSTEM BASICS • 2ND LINE OF DEFENSE- INNATE IMMUNE SYSTEM -Consists of white blood cells (leukocytes) -Different types -Recognize bacteria By general bacterial markers (PAMPs) Ex- a bacteria cell wall protein

  7. IMMUNE SYSTEM BASICS • 2ND LINE OF DEFENSE-INNATE IMMUNE SYSTEM -Once recognized, phagocytosis (engulfment) of bacteria and “digestion” of bacteria (mostly by neutrophil and monocyte/macrophages) -Signaling and recruitment/migration after local infection like a cut (causing inflammation)

  8. IMMUNE SYSTEM BASICS • 2ND LINE OF DEFENSE AGAINST VIRUSES -Viruses spend time within host cell -Can’t really perform phagocytosis on own cells -Natural Killer cells(NK cell)- scan body cells, recognize some abnormal cells that are infected, and kill them.(Many viruses can evade this non-specific technique)

  9. IMMUNE SYSTEM BASICS • 3RD LINE OF DEFENSE – ADAPTIVE IMMUNE SYSTEM (acquired) (MOST SPECIFIC) -Not born with it -Developed through body “learning” -Mediated through lymphocytes- (NK cell is considered a lymphocyte, but not part of adaptive immune system) -B and T cells- Both called lymphocytes (sometimes referred to as a type of white blood cell)

  10. IMMUNE SYSTEM BASICS • 3RD LINE OF DEFENSE- ADAPTIVE IMMUNE SYSTEM -T cells- Cell mediated immunity (because the immune system goes after our own infected cells) • Two main types- Helper T cells and Cytotoxic T cells (scientifically called CD4, CD8, respectively) • Helper T cells activated through specific piece of a pathogen (virus recognized by CD8 T cells)

  11. IMMUNE SYSTEM BASICS • T Cell jobs -Helper T cell (CD4)- job is to help activate Cytotoxic T cell (CD8) and B cells. -Each T cell is looking for a different shaped piece of a pathogen. -Once Cytotoxic T cells are activated- they clone themselves, and search for any of our cells carrying that specific VIRUS. Then kills those cells specifically.

  12. -Basically, bacteria or virus is taken up by leukocyte, and shows a unique piece of the pathogen to the matching T cell, which is then turned on. -T cells are very very specific!!! each one has its own unique receptor. Having many Helper T cells is kind of like a giant ring of keys, and the bacteria antigen is a specific keyhole- probably only a handful of T cell receptors will fit!! -When the helper T cell is activated, it can help activate the corresponding Cytotoxic T cell (with the same receptor) and cause those cells to proliferate and attack virus-infected cells

  13. IMMUNE SYSTEM BASICS • 3RD LINE OF DEFENSE- ADAPTIVE IMMUNE SYSTEM • Humoral (or antibody mediated) immunity-goes after things outside of our cells- ex.- in our blood • B Cells- respond to an antigen • -Piece of a virus or bacteria – like the ones that activate the T cells(can be an allergen like pollen) • ANTIGEN- Triggers an immune system response to form an antibody (anti+gen=antibody+generator)

  14. IMMUNE SYSTEM BASICS • ANTIBODY- produced by B cells (when they are activated by helper T cells they are called plasma cells) -Like the T cell receptor- very specific for a certain antigen- (like a lock and key) -Antibodies are a Y shape, and have two binding sites for antigens. -Each B cell can produce one “key” or one shape of antibody

  15. IMMUNE SYSTEM BASICS • Once the B cell is activated by the helper T cell (and it “sees” the antigen itself) it then matures into a plasma cell • It then divides rapidly (proliferates) and produces lots of one antibody type (like making a million copies of a single key at the hardware store) • Antibody can then stick to the invader (often to something like a bacterial wall)

  16. IMMUNE SYSTEM BASICS • Once the antibody coats the invader, like a bacteria or a virus (before it enters the cell), it can do a few things -signal leukocytes to phagocytose the bacteria- make it more visible to them “opsonization” -can coat a bacteria so it can’t attach to anything -can deactivate toxins- antivenom -can signal an event that “pops” the bacteria (called complement)

  17. IMMUNE SYSTEM BASICS • Why do we get some illnesses only one time? -IMMUNE SYSTEM “MEMORY”! -After an infection is over, the activated T or B cells begin to die. -A few remain dormant, waiting to be reactivated- memory cells! -These react quickly to the same antigens, and mount a much faster immune response the second time around. -This is where we get the term “acquired immunity”

  18. Memory cells can live for years, giving us an acquired immunity to infection Titer basically means the amount of a specific antibody produced With memory B cells, a second exposure to the same pathogen allows the immune system to react much faster and much stronger than the first time- preventing us from feeling sick

  19. REVIEW • 1st line of defense- SKIN • 2nd line of defense: INNATE IMMUNTE SYSTEM • White blood cells (leukocytes) • 3rd line of defense-ADAPTIVE (acquired) IMMUNE SYSTEM • Specific, memory • T cells: cell mediated immunity • B cells: humoral (antibody) mediated immunity • specific for certain pathogenic antigens

  20. Review Questions • 1. What’s the difference between a T and B cell? • 2. What are two different types of T cells? What are their different functions? • 3. Why do we only get chickenpox once? • 4. What is adaptive immunity?

  21. Part II: Vaccines

  22. Why Do We Vaccinate? • Why get vaccinated? • Prevent life-threatening or debilitating diseases • Meningitis • Polio- can cause paralysis • Pertussis- can cause fatal whooping cough in infants -Influenza- contagious and can be spread to very old or very sick people and can be fatal.

  23. Are all vaccines something we get in shot/nasal spray form? • Passive immunity- We don’t make antibodies against pathogens ourselves, but we get them from somewhere else- Ex- breast feeding- antibodies in breast milk (temporary, since we don’t keep making them) Ex- antivenom- horse specific antibodies • Active immunity- We “actively” make our own memory cells from the bacteria or viruses we see -natural immunization- getting sick and becoming immune -vaccination- exposure to microorganism or antigenic pieces of the microorganism

  24. How Vaccines Work • Take the infectious agent of interest, and weaken it or kill it • Introduce it (or pieces of it) to the body- so that it can cause an adaptive immune response without causing illness • Memory cells are formed from the vaccine- so it can rapidly and powerfully respond to the real thing later • Video • BBC: http://www.youtube.com/watch?v=Syz0RWe-x20&feature=related

  25. What are some common vaccines?

  26. Growth medium (Egg) Virus Antibodies + Memory Cells

  27. The Flu Vaccine: Preventing Infectious Disease • What is the flu? • Contagious respiratory disease • Influenza Virus (A or B strand) • Flu vaccine – 3 most common strands • Why do we need a new flu vaccine every year? • Mutations • Flu vaccine is different every year • Vaccines and the law: A New Hampshire Case Study • Bill exempts parents from vaccinating children • Consequences? • Public Health and “herd immunity”

  28. How Vaccines Provide Immunity • What does a vaccine contain? • What does it help the body produce? • Antibodies are proteins that destroy toxins • Are disease-specific • Two types of immunity: • Active immunity • Natural or vaccine-induced • Passive immunity

  29. Tetanus Shot (Tdap) • What is tetanus? • Not contagious, due to wound contamination • Combination of Diptheria, Tetanus, Pertussis toxins • 4 vaccine combos depending on age, need • DTap vs. Tdap • Why do we get multiple doses on a schedule? • Why do we get boosters every 10 years? Which vaccine do you get?

  30. Concerns with Vaccination • “I don’t want the flu vaccine because I might get the flu!” • Autism • No scientific link • Suspected correlation with MMR vaccine • Thimersol • Vaccines and Autism

  31. HIV: The Problem with Vaccine Development • Why is it so difficult to make an HIV vaccine? • 1. Viral escape • 2. Rapid mutations and human variation to response • 3. Variation in vaccine targets • 4. Vaccination against disease vs. infection

  32. New Terms • Active versus passive immunization • Live vs. attenuated vaccine • T cell • B cell • Innate immunity • Cell-mediated immunity (v antibody mediated) • Antibody • Antigen

  33. Questions?

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