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15 Cards in this Set
- Front
- Back
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What are some pathogen defense mechanisms?
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Surface coats, surface receptors, toxins, antigenic variation
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Define antigenic drift
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Mutation that creates new strains. Ex: influenza
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Define antigenic shifts
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Recombination of genomes. Can create pandemics.
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Define gene switching
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Pathogens carry thousands of genes for different surface molecules and switch them on and off frequently. African trypanosomes.
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Define siderophores
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Iron receptors on bacteria. Get iron from host iron-binding proteins like lactoferrin, transferrin, hemoglobin.
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What is the function of polysaccharide capsules
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Antiphagocytic, anti-opsonization. Ex: pneumococcus, waxy capsule of tubercle bacillus
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What is an example of complement activation
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Long M protein on cell wall of streptococcus
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What pathogens proliferate faster than the host can respond
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Cholera (2-3 days), Norwalk virus and rotavirus (v/d in 24-48 hrs), Bunyavirus and hantavirus (hemorrhagic in 24-48 hrs), group A strep (pneumonia in 2 days)
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Define exotoxins
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Enzymes released during bacterial growth. Immunigenic. Elicite production of antibodies known as antitoxins.
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Define endotoxins
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Lipopolysaccharides (LPSs) in cell walls of gram negative bacteria, released with lysis, bacterial growth. Can't be treated with antibiotics.
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What is the disease process of bacteremia
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Usually gram negatives. Toxins released in blood, vasoactive peptides and cytokines, vasodilation, shock
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What are viruses
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Obligate intracellular parasites, usually cause self-resolving infections.
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How do viruses invade cells
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Binds to cell surface with protein receptor binding site; enters cell through receptor mediated endocytosis/envelope fusion/crossing membrane, uncoats, genetic info into cytoplasm, integrate into host DNA
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How do DNA proviruses go into cell DNA
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Enters the nucleus, is transcribed into mRNA, starts production of new viral proteins
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What are cellular effects of viruses
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Inhibition of host cell DNA/RNA/protein synthesis, disruption of lysosomal membranes causing cell digestion, promotion of apoptosis, fusion of infected and adjacent host cells,alteration of antigenic properties of host, changing host to cancer, promotion of secondary bacterial infections
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