105231
Description
Flashcards by tanitia.dooley, updated more than 1 year ago
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Created by tanitia.dooley
almost 11 years ago
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| Question | Answer |
| What is the effect of IFNa and b activated by ds DNA? | synthesis of oligoadenylate synthase-adenine synthesis-activates endonuclease and degrades viral RNA/ synthesis of protein kinase which phosphorylates and activates elF-2a inhibits protein sun-cant translate viral RNA |
| What cytokines are secreted by cells infected with virus? | IFN a & b |
| What do NK cells do? | reocgnise cells that dont express MHC class I and kill them by lysis |
| what antibody classes are involved in viral immunity? | IgG, IgA, IgM |
| What is the effect of antibodies in virus immunity? | recognise Ags on virus or virally infected cells-neutralise infectivity of free virus and activate lysis by complement, NK cells and macrophages |
| Describe antigenic drift in influenza? | has haemagluttin and neuraminidase on cell surface which is recognised by Ab- can have mutations so cant be recognised |
| How does HIV avoid CD8+ T cell recognition? | mutations in viral geneome-Ags constantly changing- peptide from HIV envelope presented to CD8+- escapres recognition |
| How does herpes virus invade the immune system? | blocks transport of peptides from cytosol to ER via TAP |
| How does epstein barr virus evade host cells? | prevent degradation of Ag by proteosome- but kills host cell so rarely used by virus |
| What does Herpes virus US3 do? | retains class I in ER |
| What does herpes virus US2 and US11 do? | targets MHC class I for degradation |
| What does human cytomeglovirus US2 do to evade immune system? | targets class II HLA DR & DMalpha for degradation |
| What does HIV Naf do to evade host? | interferes with class II MHC processing |
| What does HIV vpu & net do to evade immune system? | target CD4 for down reg from cell surface |
| What is vaccina virus protein K3L? | elf-2a homologue prevents phosphorylation of elF2a so isnt activated |
| What does protein E3L do? | bind dsRNA & inhibits 2' 5' oligoadenylate synthase pathway |
| What is UL18? | inhibitory signal expressed by herpes virus that down reg's MHC class I cells |
| What does poxvirus have to evade immune system?? | vIL-1b receptor that binds IL-1b |
| How do leishmania major parasites invade the hosT? | live in macrophages, surface glycoproteins make them resistant to lysosomal enzymes, survive at low pH, sometimes produces IL-4 by TH2 which decrease TGFa and IFNy |
| What is the role of interferons? | antiviral resistant in unifected cells, enhancement of mechs: NK, macrophages, MHC class I & II |
| What parasite causes malaria? | p.falciparium and p.vivax |
| What parasite causes sleeping sickness? | trapanosoma brucei |
| What parasite causes changas disease? | T-cruzi |
| What parasite causes Lymphatic filarasis? | wucheria bancrofti |
| Describe the immunity against malaria? | CD8+ against liver stages, CD4+ against erythrocytes, Ab mediated- Abs against merozoite- causes agglutination of them and infected cells= killed by spleen |
| How do malaria parasites evade the immune system? | live intracellularly, RBC can't present Ags because no MHC, sporozoites shed surface coat if Ab binds them when entering hepatocyte, merozoite polymorphic, erythrocytes have cytoadherance molecules which enable sequesteration in capillary and avoid removal by spleen |
| How does the parasites of sleeping sickness avoid the host? | Have variant surface glycoproteins which there are about 1000 of and it changes its expression of them- masks all other Ags and protects against lysis via the alternative pathway. Ab-mediated immunity takes time and may change variant in that time |
| How does the immune system kill sleeping sickness parasites? | Ab mediated mechanisms-IgM-direct lysis via classical pathway, Ab mediated phagocytosis cant eradicate them just control it |
| What is the immune systems response to chagas disease parasites? | acute caused by trapanosoma in blood-mech unclear-can supress but not eliminate. Chronic- due to cross reactivity and autoimmunity= damage to heart oesophagus and colon |
| How do T.cruzi evade the host? | complement resistant as express DAF. Invade host cells by phagocytosis in cells that arent usually involved- taken up by macrophages and therefore escape phagosomes- express Ags which mimic host. Induces IL-10 and TGfb |
| What is the immune response against leishmania major? | increased TH1 cytokine production |
| How does the immune system respond to schistosomiasis? | produces abs to worm excretions and secretions- kills them by ADCC via IgE/eosinophils and IgM/macrophages. eggs cause granulomas |
| How do schistosomiasis parasites invade host cells? | larvae in skin shed surface coat after penetration and absorb host Abs so disguised. Release soluble Ags which decrease Ag binding to worm surface and block cytotoxic cells |
| How do wucheria bancrofti in lympathic filirasis invade host cells? | netomtode worm has thick cuticle, produces antioxidants and protease inhibitors which neutralise cytotoxic killing mechs. Microfilia have decreased TH1 responsiveness as non Ag specific and secrete TGFb and IL-10. Also have TNFb and MIf homologues |
| How does the immune system protect against wusteria bancrofti? | microfilia killing via ADCC- requires TH1 and TH2- can cause obstruction of lymphoctes by adult worms |
| What is the disease transmitted by in changas disease? | kissing bug |
| What organism is responsible for leichmania major? | sandfly |
| What illness are snails and worms (termatodes) associated with? | schistomiasis |
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