Chapter 17: IR to Infectious Disease • In BIOL 304, we examined how pathogens can establish an infection in a susceptible host • Re: the 7 components of pathogenicity!! • On the other hand, humans are defended by: • Physical barriers of epithelia and skin • Surface chemicals, enzymes, acids • Competitive flora • Complement and sIg • Phagocytic cells • Specific/Adaptive IR
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Chapter 17: IR to Infectious Disease In BIOL 304, we examined how pathogens can establish an infection in a susceptible host Re: the 7 components of pathogenicity!!
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Chapter 17: IR to Infectious Disease
• In BIOL 304, we examined how pathogens can establish an infection in a susceptible host
• Re: the 7 components of pathogenicity!!
• On the other hand, humans are defended by:• Physical barriers of epithelia and skin
• Surface chemicals, enzymes, acids
• Competitive flora
• Complement and sIg
• Phagocytic cells
• Specific/Adaptive IR
Still, infectious disease kills millions each year
*Mostly, from bacterial and viral diseases
Anti-viral protection: Innate
• Type I IFN’s (α & β) are triggered from infected cells
• IFN’s bind to nearby cells and activate JAK-STAT pathway
• Induces several gene products which function to:– Degrade viral RNA
– Shuts down PS in infected cells
Anti-viral protection: Adaptive
Neutralization by Ab’s• If Ig can bind to viral
surface, prevents binding to target cell
• Or Ig can trigger Complement cascade
• Or bound Ig can agglutinate viruses to be phagocytized
• Within 7-10 days, most virions are elim; parallels the development of Tc’s vs the virus
Evasion of Host defenses
• Block intracellular effects of IFN’s (Hep C)• Block TAP function for Ag delivery to MHC I
(HSV1 and 2) prevents lysis by Tc’s• Block formation of MHC I (Adenovirus, CMV)• Block formation of MHC II (CMV, measles, HIV)• Block complement fixation (Vaccinia binds to