Understanding Vaccines What They Are How They Work - VIOLIN

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Subunit Vaccines Scientists would certainly look into the possibility of a subunit vaccine for X. Instead of the entire microbe, subunit vaccines include only the antigens that best stimulate the immune system. In some cases, these vaccines use epitopes—the very specific parts of the antigen that antibodies or T cells recognize and bind to. Because subunit vaccines contain only the essential antigens and not all the other molecules that make up the microbe, the chances of adverse reactions to the vaccine are lower. Subunit vaccines can contain anywhere from 1 to 20 or more antigens. Of course, identifying which antigens from bacterium X best stimulate the immune system would be a tricky, time-consuming process. Once scientists did that, however, they could make subunit vaccines against X in one of two ways. They could grow bacterium X in the laboratory, and then use chemicals to break the bacteria apart and gather the important antigens. Subunit vaccines contain just the antigens of the microbe that best stimulate the immune system. This image depicts antigens that have been separated from the rest of the microbe for use in a subunit vaccine. UNDERSTANDING VACCINES 25
26 They also could manufacture the antigen molecules from X using recombinant DNA technology. Vaccines produced this way are called recombinant subunit vaccines. Such a vaccine has been made for the hepatitis B virus. Scientists inserted hepatitis B genes that code for important antigens into common baker’s yeast. The yeast then produced the antigens, which the scientists collected and purified for use in the vaccine. Research is also continuing on a recombinant subunit vaccine against hepatitis C virus. Toxoid Vaccines Because our imaginary bacterium X secretes a toxin, or harmful chemical, a toxoid vaccine might work against it. These vaccines are used when a bacterial toxin is the main cause of illness. Scientists have found they can inactivate toxins by treating them with formalin, a solution of formaldehyde and sterilized water. Such “detoxified” toxins, called toxoids, are safe for use in vaccines. Harmless toxoid molecules (artist’s representation) are used in toxoid vaccines to immunize and protect people against harmful toxins secreted by some microbes.
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: 24 Inactivated Vaccines An inactiva
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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