Midterm%20II%20review - Host responses to different...

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1 Midterm II Review Robert Beatty MCB 50 Host responses to different pathogens Extracellular bacteria usually live in mucosal tissue, or blood. Intracellular bacteria and parasites live in endosome or cytoplasm. Viruses are intracellular pathogens take over host cell machinery for replication. Extracellular parasites can be Protozoa that live in blood or mucosal or helminths (worms) which live throughout body. Location of Pathogen Determines immune response Important to mobilize correct immune defense. Antigen processing ---> CD4 vs CD8 Th1 vs Th2 Antibody Th2 vs Cytokines to activate macrophages/CTLs Th1 Streptococcus pyogenes Extracellular Bacterium One bacteria can cause multiple diseases. •Strep throat- common form. •Skin infections- breaks skin barrier. •Gangrene- Rare virulent form Flesh eating bacteria. •Rheumatic fever-- cross reactive antibodies cause autoimmune disease.
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2 Immune response to S. pyogenes Extracellular bacteria so Th2/B cell/Abs most important!! Has antigenic variation (diff M proteins) between different strains to evade ab response and cause repeated infections! Evades phagocytosis with M proteins that inhibit uptake. RNA vs DNA viruses RNA viruses are primarily fast replicating viruses (exception Rabies) with horizontal transmission. RNA viruses primarily cause acute infections (exception hepatitis C virus). DNA viruses are more highly evolved for host species and often cause chronic disease. DNA virus infections more often chronic, latent,
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This note was uploaded on 05/13/2009 for the course MCB 50 taught by Professor Beatty during the Spring '09 term at University of California, Berkeley.

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Midterm%20II%20review - Host responses to different...

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