Memory and Escape Flashcards
(27 cards)
what is immunological memory caused by?
long lived antibodies and memory cells, re-exposure, affinity maturation, class switches
what are the infection processes of bacteria?
attaching to host cells, proliferation, invasion of host tissues
how does the host defend against bacteria attachment?
blocked by secretory IgA
how does bacteria evade IgA secretion?
protease splits the IgA dimers, antigenic variation
how does the host defend against proliferation?
phagocytosis, complement-mediated lysis
how do bacteria try and evade phagocytosis?
surface inhibitors, survive within the phagocytic cell, causes apoptosis within macrophages
how do bacteria try and evade compliment-mediated lysis?
resistance of gram-positive bacteria as they don’t allow compliment protein to bind to its surface
how does bacteria prevent MAC forming?
inserting long side chains which interfere with compliment proteins
how does the host cell try and protect invasion of host tissues?
Ab-mediated agglutination
how do bacteria evade ab-mediated agglutination?
secrete elastase with inactivates agglutination, release hyaluronidase which enhances invasiveness
what are some other bacterial escape strategies?
cell wall resistant to enzymes, secreted toxins to repel phagocytes, enzymes secreted to inhibit host response
how do bacteria interfere with the host response?
inhibit inflammatory response, break cement between cells, coat bacterium with fibrin layer
what does IgA do in response to viruses?
blocks binding to cells
what antibodies block the fusion of viral envelope and cell membrane?
IgG, IgM, IgA
what antibodies cause agglutination of a virus?
IgM
what does complement do in response to viruses?
assist opsonisation, produces MACs which kills infected host cells
what responses to viruses are involved in the humoral response?
antibodies and complement
what responses to viruses are cell mediated?
gamma interferon, Tc cells, NK cells and macrophages
what does the gamma interferon do in response to viruses?
stops viral infected cells from producing new copies
what do Tc cells do in response to viruses?
kill cells which have been infected with the virus
what do NK cells and macrophages do in response to viruses?
kill cells that have been infected by the virus
how does hepatitis C survive?
blocks protein kinase and alpha and beta interferons
how does the herpes simple survive?
early protein inhibits transporter molecules for antigen processing to MHC-I receptors
how do adenoviruses survive?
reduce expression of MHC-I and so reduced presentation with CD8 to T cells
