Understanding Vaccines What They Are How They Work - VIOLIN

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Antigens Membrane Genetic material Live, attenuated vaccines use a weakened version of the microbe that has been changed to reduce or eliminate its potential to cause disease. This image shows the live microbe’s antigens, membrane, and genetic material. Viruses are simple microbes containing a small number of genes, and scientists can therefore more readily control their characteristics. Viruses often are attenuated through a method of growing generations of them in cells in which they do not reproduce very well. This hostile environment takes the fight out of viruses: As they evolve to adapt to the new environment, they become weaker with respect to their natural host, human beings. Live, attenuated vaccines are more difficult to create for bacteria. Bacteria have thousands of genes and thus are much harder to control. Scientists working on a live vaccine for bacterium X, however, might be able to use recombinant DNA technology to remove several key genes from X. This approach has been used to create a vaccine against the bacterium that causes cholera, Vibrio cholerae, although the live cholera vaccine has not been licensed in the United States. UNDERSTANDING VACCINES 23
24 Inactivated <strong>Vaccines</strong> An inactivated vaccine, or killed vaccine, might be better for bacterium X. Scientists produce inactivated vaccines by killing the disease-causing microbe with chemicals, heat, or radiation. Such vaccines are more stable and safer than live vaccines: The dead microbes can’t mutate back to their disease-causing state. Inactivated vaccines usually don’t require refrigeration, and they can be easily stored and transported in a freeze-dried form, which makes them accessible to people in developing countries. Most inactivated vaccines, however, stimulate a weaker immune system response than do live vaccines. So it would likely take several additional doses, or booster shots, to maintain a person’s immunity to bacterium X. This quality could be a drawback in areas where people don’t have regular access to health care and can’t get booster shots on time. Inactivated or killed vaccines contain microbes that have been inactivated with chemicals, heat, or radiation. The microbe’s antigens, membrane, and genetic material are still present. Antigens Genetic material Membrane
Page 1 and 2: Understanding nderstanding VACCINES
Page 3 and 4: Contents 1 2 4 6 11 21 36 38 43 47
Page 5 and 6: What Is aVaccine? 2 Chances are you
Page 7 and 8: Vaccine Benefits 4 You and Your Com
Page 9 and 10: Harmful Microbes 6 Vaccines protect
Page 11 and 12: 8 • The toxic bacterium Bordetell
Page 13 and 14: 10 What Do Cows Have to Do with Vac
Page 15 and 16: 12 A mosquito bite transmits the ye
Page 17 and 18: 14 T Cells T cells function either
Page 19 and 20: T cell B cell 16 Virus B cell Antib
Page 21 and 22: 18 fever antibody if needed. Memory
Page 23 and 24: 20 How Viruses Work Viruses such as
Page 25: 22 Live, Attenuated Vaccines Some s
Page 29 and 30: 26 They also could manufacture the
Page 31 and 32: 28 When making a conjugate vaccine,
Page 33 and 34: 30 So-called naked DNA vaccines con
Page 35 and 36: 32 An infant’s immune system cont
Page 37 and 38: Some Vaccine Types and Diseases The
Page 39 and 40: Vaccines of the Future 36 Aside fro
Page 41 and 42: Making Safe Vaccines 38 No vaccine
Page 43 and 44: 40 Because Phase III trials are com
Page 45 and 46: Vaccine Concerns, Myths, and Safety
Page 47 and 48: 44 testing sites are based at unive
Page 49 and 50: 46 system’s response to HIV infec
Page 51 and 52: Glossary 48 adjuvant—a substance
Page 53 and 54: 50 DNA vaccine or naked DNA vaccine
Page 55 and 56: 52 lymph node—a small bean-shaped
Page 57 and 58: 54 recombinant subunit vaccine—a
Page 59: U.S. DEPARTMENT OF HEALTH AND HUMAN

Understanding Vaccines What They Are How They Work - VIOLIN

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