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24 Cards in this Set
- Front
- Back
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seroconversion
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the production of antibodies to the infecting pathogen
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give 2 examples of where innate immunity in host defense systems may vary in effectiveness of immune response
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1)histocompatibility complex (MHC)
2)Toll-Like Receptors (TLR) |
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In general, pathogens need their host for reproductive success, so they are selected for mild virulence. The exeptions to this rule are:
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1) Hosts are abundant and abnormally crouded. e.g., prison refuge camp
2) pathogen jumps from another species e.g., SARS |
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endogenous disease
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our flora leaves its normal location and is introduced into an area where it causes harm. e.g., urinary tract infection
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Exogenous infections
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acquired from other people, from animals e.g., legionaires disease
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fomites
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e.g., towel- use towel someone else uses towel),
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reservoirs
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which are sources of the pathogen in nature that do not directly transmit the infection to humans
e.g., deer or white mice as a resevour for lyme spiruchette and ticks |
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steps typically followed in the pathogenic process
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adherence
colonization invasion disruption or avoidance of host defenses production of damage to the host. |
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ADHERENCE AND COLONIZATION
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microbe must attach itself to a tissue surface and avoid being washed away by secretions
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Bacteria use virulence factors called ______ located on or near their surface to attach to specific receptors on the membranes of host cells.
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adhesins
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What are the two forms of invasiveness
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1) Invasion at cellular level
-microbe uses type III & IV secretion systems to trick cell into letting it inside 2)gross destruction of tissue at the macroscopic level -caused by the secretion of large amounts of histolytic enzymes, such as phospholipase, hyaluronidase, collagenase, and other proteases |
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OVERCOMING HOST DEFENSES INSIDE THE BODY
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bacteria have virulence factors to avoid or overcome host defenses as phagocytes, complement, and the adaptive immune response
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AVOIDING OR SURVIVING PHAGOCYTOSIS
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Some bacterial capsuls or cell wall components are antiphagocytotic.
Some bacteria have the ability to survive macrophage phagocytosis by (1) preventing acidification of the phagosome (2) preventing phagolysosomal fusion, or (3) escaping from the phagosome into the cytoplasm of the macrophage where it can live safely inside the phagosome |
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serum resistance
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outer membrane proteins on bacteria that afford resistance to complement
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IgA protease
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enzyme secreted by pathogen that that degrades IgA
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antigenic variation
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e.g. Neisseria gonorrhoeae
Has ability to change at a high frequency it's pilli which affords it different antigenicity |
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leukocidins
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toxins produced by bacteria that lyse and kill white blood cells like phagocytes and lymphocytes
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superantigens
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toxins secreted by microbes that overactivate immune system in an antigen indipendant manner
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Damaging the host
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Microbe achieves this by production of toxins, or by eliciting an inflammatory or hypersensitivity reaction
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Exotoxins
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-are secreted proteins
-have a subunit structure called A-B, where the A subunit contains the toxic activity (A=ACTIVE), and the B subunit binds to the receptor on the target tissue and is involved in delivering the A subunit across the cell membrane into the cytoplasm of the target cell (B=BINDING). |
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True endotoxin
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-LPS or LOS from the Gram-negative outer membrane
-has multiple activities, including fever, hypotension, and activation of complement and coagulation |
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ADP-ribosylation
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to the activation of adenylate cyclase and the overproduction of cyclic AMP
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HYPERSENSITIVITY
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Way bacteria damages it's host basically by causing the host defense systems to over-react
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toll-like receptors (TLR’s)
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-located on macrophages, B-cells, and other cell types
-pattern-recognition receptors -detect characteristically microbial molecular patterns and sound the alarm -part of innate immunity -work immediately to inform the body that a microbial invader is present and to activate the innate host defenses -. Through the macrophage, etc. they induce the production of cytokines, such as tumor necrosis factor (TNF) and interleukin-1 (IL-1), and the synthesis of nitric oxide, which lead to inflammation, fever, hypotension, and sometimes septic shock |
