Scientists control characteristics Attenuated by growing generations of them so

Scientists control characteristics attenuated by

This preview shows page 10 - 12 out of 12 pages.

Scientists control characteristics - Attenuated by growing generations of them, so they don’t reproduce well in human body because they aren’t use to the conditions - Evolve to new environment → weaker to natural hosts (humans) - Difficult to make for bacteria - More genes and hard to control - Use recombinant DNA technology to remove key genes - EXAMPLES - Measles, mumps, chickenpox vaccines Inactivated - Chemicals, heat, or radiation is used to kill pathogen - More stable and safe than live vaccines - Refrigeration NOT required - Easily stored and transported as freeze-dried form - Weaker immune response → several doses and boosters are required Subunit - Includes only antigens that stimulate immune system
Image of page 10
- Use epitopes - Epitopes: specific parts of antigens that antibodies or T cells recognize and bind to - Subunits can be 1 to 20 or more antigens - Make - Grow microbe in lab - Use chemicals to break it apart and gather important antigens - Manufacture antigen molecules from microbes using recombinant DNA - Recombinant subunit vaccines - EXAMPLES - Hepatitis B vaccine Toxoid - Used when bacterial toxin causes illness - Formalin inactivated toxin - Toxoid is safe to use - Toxoid: detoxified toxin - Immune system makes antibodies to block toxin - EXAMPLES - Diphtheria and tetanus vaccine Conjugate Vaccine - Bacteria have outer coat polysaccharides that disguises antigens - Immature immune systems (in infants and young children) can’t recognize them - Antigens or toxoids from the microbe are linked to a polysaccharide that the immature immune system can recognize - EXAMPLE - Haemophilus influenzae (type B) vaccine DNA Vaccines - Analyze genes of microbes - Use genes that code for antigens - When these are introduced to the body, cells will take that DNA - DNA makes the cell make antigen molecules - Cells secrete antigens onto their surface - Antigens stimulate immune system - Strong antibody response to antigen secreted by cells and against microbial antigens on cell surface
Image of page 11
- Won’t cause disease because only a few genes are copied - Easy and inexpensive to design and produce Naked DNA - DNA administered into body - DNA mixed with molecules that facilitate uptake into body cells - EXAMPLES - Tested for influenza and herpes Recombinant Vector Vaccines - Like DNA vaccines but use attenuated virus or bacteria to introduce microbial DNA - Vector: virus or bacteria used as carrier - Because viruses latch onto cells and inject genetic material into them - Genome of weakened viruses insert portions of genetic material from other microbes into them - Recombinant vector vaccines mimic natural infection and stimulate immune system - Inserted DNA causes the bacteria to display the antigens on the surface of the bacteria - EXAMPLES - Working on HIV, rabies, and measles vaccine Potential Risks of Some Vaccines - Pathogen can mutate, so even if a person is immune they won’t be immune to the new strain Herd Immunity - More immune individuals decrease the incidence of the disease and the occurrence of pathogen - Greater numbers immunized → less likely unimmunized person will encounter pathogen - “Herd immunity” → mass vaccination
Image of page 12

You've reached the end of your free preview.

Want to read all 12 pages?

  • Fall '17
  • Cannobio
  • Bacteria, DNA, Sensorineural Hearing Loss

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes