Evasion Of Immune Response Flashcards
How do viruses subverge phagocytes?
Express proteins on the viral surface
How do viruses evade immune system defences?
Subversion of phagocytes Complement inhibition interference with cytokines Blocking of IFNs Suppression of antigen presentation (MHC expression)
How does complement inhibition evade immune responses?
Induce expression of inhibitor proteins
Expression of viral complement inhibitors
Uses complement opsonisation to gain cell entry
In what ways do bacteria evade phagocytosis?
Outer carbohydrate capsule (Cover PAMPs)
Release of exotoxins (block endocytosis)
Escape from phagosome (movement or lysis of phagosome)
Blocking the formation and acidification of phagocytes (resistance to lysis)
How do microbes evade the complement system?
Prevent activation by encapsulation Acceleration of complement breakdown Resistance to membrane attack inhibition of T-cell activation Degradation of immunoglobins Neutralisation of antibodies Secretion of complement inhibitors
How do bacteria manipulate intra and extra cellular bacteria?
Suppression of apoptosis
Initiation of apoptosis in macrophages
Antigenic variation
What is antigenic variation?
Multiple but different copies of the same gene
Highly variable regions in a gene
How do fungi evade host defences?
Mannoprotein coat
Inhibition of phagocytosis
Conversion of yeast to hyphae
How do microbes cause down regulations of responses?
Inhibition of nitric oxide
Release molecules that cause immunosuppression
Change form
How do parasites evade the hosts defences ?
Invade immune privileged sites (eg. Eye, CNS)
Invisibility (shield surface components)
Molecular mimicry (mimic natural molecules)
Perpetual change of antigens over course of infection
Quiescence (temporary inactivation)
Deviation of host immune response
