mcd cram Flashcards
type one interferons
polypeptides
induce antimicrobial state locally
modulate immune responses by promoting antigen presentation but antiinflammatory
activate adaptive
alpha (all cells first induced by irf 3)
plasmacytoid cells produce alpha and irf 7
ifnar is receptor
plasmacytoid cells
produce ifn alpha and express irf 7
irf genes
interferon regulatory factor
type two and three interferon
gamma and lambda
two is t cells and nk ifngr
three is il28r il10beta
resp tract and liver infection
stimulation of ifn production
pamps such as drna for viruses activate prrs - tlrs rlrs nlrs
prrs interferons
rlrs - beta
tlrs alpha
nlrs
how are viruses detected in cell
cGAS = enzyme detects dsDNA in cytoplasm
causes cGAMP production
passes to sting on er which follows same pathway as prrs with pamps
ifn type one signalling
ifnar1 dimerises with ar2 causing jak1 and tyk2 to cross phosphorylate. STAT proteins are activated which cause inflammatory through gas, antiviral through isre and inflammatory repressor through gas
hundreds of antiviral mediators released like pkr mx ifitm3
interferon response
ifitm3 stops virus entering through endosomes
mx1/2 are gtpases that wrap form multimers and wrap around nucelocapsids of viruses
ifitm3
stops virus entering through endosomes by stopping escape so broken down by acidic endosome
mx1
mx2
GTPases that form multimers that wrap around the nucleocapsids of viruses
duration of ifn response?
few hours, can’t last due to negative regulation mediated by suppressor of cytokine signalling SOCS which turns the genes off.
What is viral ifn evasion mediated by
HIBIBAR Hide pamps Interfere with host gene expression Block IFN induction cascades Inhibit ifn signalling directly Block ifn induced antiviral enzymes Activate SOCS Replicate in a manner insensitive to IFN
How does hep c evade ifn
NS3/4 Protease production cleaves MAVS which is the protein on the mitochondria that is activated by RLRs hence ifn beta cant be produced
how does flu evade ifn
NS1 protein binds to rig/trim/rna complex preventing ifn signalling activation
how does pox and herpes evade ifn
pox genome is hugely anti-ifn. soluble cytokine receptors produced that incapacitate immune mediators.
how does ebola evade ifn
VP35, 24, 30
Respectively blcok rig 1 complexes and rnai expression
block rnai expression
block ifn signalling.
Consequences of viral evasion
both the virus and immune system damage the body
hence can be pathalogical or immunopathological.
more ifn is needed for more severe responses like fever than for localised responses like mx induction
cytokine storm if too much ifn is made, worse in healthier people as better at making ifn
uses of viral evasion tactics
live attenuated viruses - can be made if u put viruses that cant control ifn in cells that cant make ifn. lots of replication
anti-virals, ifn used as treatment but with se’s
ifn lambda stimulates antiviral state but not inflammatory or immune response so good for treating flu.
cancercells dficient inifn can be attacked by viruses whilst normal cells produce ifn so they dot get hurt.
staph aureus
gram +ve most common skin infeciton causes scalded skin toxic shock food poisioning necrotising soft tissue infections treat with antibiotics no vaccine
treponema pallidum
syphilis
painless ulcers to rash lymphadenopathy to asymptomatic to lesions on skin bone vascular neuro manifestations
can be vertically transmitted
no vaccine antibiotics
Herpes
simplex 1&2
dna viruses
painful rash, eczema, herpeticum, encephalitis
no vaccine, antivirals
Varicella Zoster
pox, human herpes virus again
fever malaise rash becomes latent after two weeks still there can cause shingles
herpes zoster shingles painful rash
vaccine and antiviral
Trichophytum
superficial fungal infections dermatophyte, affects keratin areas name is tinea and body part yeasts as well like candida scaly rash crumbly nails antifungals like terbinafine
scabies
sarcoptes scabei ite burrows lays eggs faeces delayed type reaction type four eczematous rash can cause secondary bacterial infection topical systemic insecticides
viral evasion of immune response
mhc 1
internal viral proteins dont vary much so good targets.
includes - evading loading to tap
modulation of tapasin function and prevention of loading to mhc
interfering with mhc presentation at cell surface.
viral methods evading mhc
loading to tap
EBV - ebna1 cant be processed by proteasome
HSV icp47 blocks peptide access to tap
CMV US6 stops atp binding to tap and translocation
modulation of tapasin function and prevention of mhc transport
CMV US3 binds to tapasin and prevents peptide loading to mhc
Adenovirus E3-19k prevents recruitment of TAP to tapasin and retains the MHC in ER
interfering with mhc presentation at cell surface
KSHV kK3 protein induces polyubiquitinylation and internalisation of MHC then endosome to lysosome
how does ebv evade mhc
ebna1 cant be processed by proteasome, only processed peptides get put on mhc 1
How does hsv evade mhc
icp47 blocks peptide access to tap
how does cmv evade mhc
US6 stops atp binding to tap and translocation
and
US3 binds to tapasin and prevents peptide loading to mhc
how does adenovirus evade mhc
E3-19k prevents recruitment of TAP to tapasin and retains the MHC in ER
how does KSHV evade mhc
kK3 protein induces polyubiquitinylation and internalisation of MHC then endosome to lysosome
how do viruses evade nk cells
if in cell that doesnt show mhc class one it will be killed encode mhc class one analgoue to prevent this like cmv or upregulate mhc
cmv in the clinic
most infected, only issue in immunocmpromised like during transfusions, needs elimination before procedure
produces protein ul138 that removes mrp1 (removes toxins from cells). treat with toxic drugs to stop this.
antigenic variation methods
drift is mutating to have different antigens
shift is new subtypes from animals
different serotypes are all stable and cocirculate. Polio, dengue, rhinovirus.
can be consequence of vaccine
how does hiv resist abs
gp120 large gaps between spikes so no cross linking of ab glycosylation masks ab epitopes poorly accessible important bits of ag BNABS can control load
dengue
leakage of plasma from capillaries
high haematocrit and rbc count decreased protein count
bleeding and bruising
treat with iv.
dengue ag variation
four serotypes
abs from last response bind dont neutralise so haemorrhagic fever and could lead to shock.
monocytes bound could be used for replication by virus.
evasion of ab response
glycoprotein antigen ab cant access
can make them look like apoptotic bodies so uptaken and hidden
viral filaments mean glps inaccessible in packets
why is measles vaccine important
infection erases immuno memory so raises morbidity and mortality of other diseases.
main bacterial virulence factors
flagella movement attachment pill adherence capsule protect against phagocytes endospores are metabolically dormant biofilms aggregates embedded in polysaccharide so antibiotic resistant
endotoxins exotoxins
exo damage bio systems neurotoxins enterotoxins pyrogenic exotoxins stimulate cytokine release tissue invasive allow bacteria to tunnel can be other
endo lipids gram -ve released steadily so sudden antibiotic and cell death can release loads leading to septic shock
outbreaks
lots of cases short time
need to isolate strain with pcr, surveillance, reporting system
eu communicable resp
Legionnaire amoeba in lakes inhalation type iv secretion tb, extra lipid layer can be dormant treatment good
eu communicable sti
chlamydia trachomatis
neisseria gonorrhoeae
pili antigen variation
eu food waterborne
campylobacteriosis gi uncooke dpultry adhesion, invasion, flagella etc
salmonella tthree secretion
cholera
listeriosis
eu vector borne
plague yersina pestis
q fever coxiella burnetti
smallpox
eu vaccine preventable
clostridium diptheriae haemophilus influenze neisseria meningitides streptococcus pneumnie bordetella pertussis clostridium tetani
hospital acquire
nosocomial
escape
nosocomial causes
catheters intubation chemo prosthetics lines prophylactic antibiotics inappropriate prescribing
dissemination carriers
concentration is density of people
escape
resistant Enterococcus faecium + vancomycin Staoh aureus mrsa + Clostridium difficile + Acinobacter baumanii - Pseudomonas aeruginosa - mdr Enterobacteriacae - mdr
pathogenic e coli
common gram -ve bacteraemia utis
cephalosporin and carbapenem resistance
others nosocmial
klebsiella pneumoniae
pseudomonias aeruginosa
mrsa
clinical significance of nosocomial infection and reistance
morbidity cost clinicians need to use old more toxic drugs to treat
immunity to fungi
phagocytes then nk which give ifn gamma then dendritic which cause t cells to differentiate then th1/17
fungal virulence
candida spores dimorphism so allows for tissue invasion
Cryptococcus capsule evades phagocytosis
aspergillus conidia inhaled invades as hyphae
what required for innate immunity to fungal infection?
Flies is a prr needed
human deficiencies leading to fungal infection
dectin 1, deficiency leads to mucocutaneous infection as impaired macrophage il6 production and binding in response.
card 9 causes chronic mucocutaneous candidiasis
card9 needed for tnf alpha responding to beta glucan and t cell th17 differentiation
tlr4 polymorphism lead to risk of aspergillosis in transplant.
plasminogen mutation
defence against fungus
neutrophils important
throw nets of chromatin to capture spores act as danger molecules to recruit effector cells
fungal morphogenesis can transition between hyphae yeast candida to modulate dendritic cell response confuses immune response
innate - mucosal immunity
treatment - adoptive immunotherapy make lots of fungal t cells in a sample and give to patients needing to fight infection
gene therapy like restoring genes that fight fungal spores. can be ifn gamma