Acquired Immunity Aims: Must be able to state the different ways that immunity can be acquired, with examples. Should be able to explain the differences between the main types of acquired immunity. Could be able to outline how vaccination works and describe the different types.

Acquiring Specific Immunity Immunity involves a specific defense response by the host to invasion by foreign organisms or substances: Acquired immunity is the protection that develops against specific microbes or foreign substances. Active immunity develops after exposure to microorganisms or foreign substances. Passive immunity is acquired when antibodies are transferred from one person to another. Active and passive immunity may be naturally acquired or artificially (induced) acquired as a result of medical treatment.

Active Immunity (antibodies produced within the person) Induced Active Antigens (weakened or dead microbes or their fragments) are introduced in vaccines. The body produces and specialized lymphocytes and antibodies. Natural Active Antigens enter the body naturally, as when: • Microbes cause the person to catch the disease. • There is a sub-clinical infection (one that produces no evident symptoms). The body produces specialized lymphocytes and antibodies.

Passive Immunity (antibodies are received from an outside source) Natural Passive Antibodies pass from the mother to the fetus via the placenta during pregnancy or to her infant through her milk. The infant's body does not produce any antibodies of its own. Induced Passive Preformed antibodies in an immune serum are introduced into the body by injection (e.g. anti-venom used to treat snake bites). The body does not produce any antibodies.

Activity Read the information and answers the questions from page 149 in the Biozone book.

Vaccination

Activity Read the information and answers the questions from pages 150 to 152 in the Biozone book.