Understanding Vaccines What They Are How They Work - VIOLIN

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Bacterium Polysaccharide coating Polysaccharide molecule Toxoid Linked toxoid and polysaccharide Conjugate vaccines link antigens or toxoids to the polysaccharide or sugar molecules that certain bacteria use as a protective coating, thereby allowing the immune system to recognize and attack these “disguised” bacteria. A conjugate vaccine contains the molecules shown in the foreground. The bacterium, part of which is shown in the upper left background, is not part of the vaccine. When the immune system receives a vaccine containing a harmless toxoid, it learns how to fight off the natural toxin. The immune system produces antibodies that lock onto and block the toxin. Vaccines against diphtheria and tetanus are examples of toxoid vaccines. Conjugate Vaccines If bacterium X possessed an outer coating of sugar molecules called polysaccharides, as many harmful bacteria do, researchers would try making a conjugate vaccine for X. Polysaccharide coatings disguise a bacterium’s antigens so that the immature immune systems of infants and younger children can’t recognize or respond to them. Conjugate vaccines, a special type of subunit vaccine, get around this problem. UNDERSTANDING VACCINES 27
28 When making a conjugate vaccine, scientists link antigens or toxoids from a microbe that an infant’s immune system can recognize to the polysaccharides. The linkage helps the immature immune system react to polysaccharide coatings and defend against the disease-causing bacterium. The vaccine that protects against Hib is a conjugate vaccine. DNA Vaccines Once the genes from bacterium X had been analyzed, scientists could attempt to create a DNA vaccine against it. Still in the experimental stages, these vaccines show great promise, and several types are being tested in humans. DNA vaccines take immunization to a new technological level. These vaccines dispense with both the whole organism and its parts and get right down to the essentials: the microbe’s genetic material. In particular, DNA vaccines use the genes that code for those all-important antigens.
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 and 26: 22 Live, Attenuated Vaccines Some s
Page 27 and 28: 24 Inactivated Vaccines An inactiva
Page 29: 26 They also could manufacture the
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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