microbial pathogenic mechanisms Flashcards
how do microbes evade innate immunity
killing or avoiding being killed by microbes, interfering with ciliary action, interfering with complements alternative pathway, making iron binding molecules, blocking interferons
how do microbes evade phagocytosis
inhibit lysosomal fusion, escape lysosome and grow in plasma, block interferon, inhibit opsonization and chemotaxis
how can viruses thwart immune defneses
they invade tissues silently
what viruses can infect cells for a long amt of time without adverse effects on cell viability
rubella, HPV, hep B, and EBV
what viruses are shed consistently
EBV in saliva, hep b in blood, and egg feces in worm infections
what viruses are shed intermittently
HSV, polymaviruses, typhoid bacilli, tuberle bacilli, malaria parasites
how do microbes evade lymphocytes in adaptive immunity
conceal antigens, antigenic variation (change strands), and immunosuppression
antigenic variation?
genetic changes in microbe like when the flu changes its strain every yr
what are sequestered antigens
when viruses hide their antigens so we dont recognize them as a virus and fight them off
ex of sequestered antigen
persistent latent viruses such as HSV in sensory neurons and HIV
immune priviledged sites?
CNS, joints, testes and placenta where lymphocyte circulation is reduced and antibody complement is limited
a hydatid cyst is an ____
immune privedaged site
hydatid cyst?
cyst in lungs, liver, or brain where echinococcus granulosus live
molecular mimicry?
when something in the body looks like a microbe so they body kills it but its not harmful so the host damages itself ex: gluten
3 mechanisms for antigenic variation
mutation, recombination and gene switching
major surface antigens of flu?
hemagglutinin and neuraminidase
which surface ag of the flu is better at inducing innate immunity
HA
why do viruses cause immunosuppression
unknown maybe allows it to invade the host easier
how do microbes immunosuppress?
infect T cells, B cells,, macrophages, and dendritic cells
EBV infects
b cells
CMV and leischmania infect
macrophages
immunosuppression results in
impaired cell function, reduced cell division, block cytokines, and apoptosis
superantigens?
bind mhc class 2 and tlr
nonspecific polyclonal activators of t cells
superantigens
nonspecific polyclonal activators of B cells
b cell mitogens
when a microbe has a superantigen, the immune response is
unproductive and has poor antimicrobial value
why are persistent infections important
latent viruses can be reactivated
may be associated with chronic disease
may be assoc with cancers
infectious agent persists in host community
viruses assoc. with chronic disease?
hep B and AIDS
acute self limited infection
disease peaks then is gone ex: flu, rotavirus, whooping cough
persistent infection with shedding
disease peaks then continues shedding over time ex: EBV and tapeworms
persistent latent infection
disease peaks, recovers, then reactivates ex: HSV, zoster, tb, malaria
persisten slow infection
slowed microbial growth then the disease with 0 inflammatory component
who is reactivation important in
immunocompromised ppl such as aids, tumor, transplant, pregnancy, old age, stress
what cancer does EBV cause
burkitt lymphoma, nasopharyngeal CA, hodgkin
what cancer does human papilloma virus cause
cervical ca and skin cancer
what cancer does hep b and c cause
liver
HSV2 causes
cervical ca
how do we get successfu vaccines
inactivation of toxins without changing antigenicity
c diptheria inhibits
protein synthesis
v cholerae causes
hyperactivation and diarrhea
what is diarrhea caused by
toxins, damage to epithelial cells, and changes in ETC
toxins in food and sx are quick
food poisoning
c tetani and c botulinism effects
nerve-muscle transmission
LPS is made of
lipid A, polysaccharide core, and variable O polysaccharide
lipid a?
does toxic activity
polysaccharide o?
serologic diversity
fever is due to
IL1 and TNF
how are cytokines made
antigen binds to lps and macrophages release them
endotoxic shock?
systemic spread of organisms
example of endotoxic shock
septicemia and gram - bacteria like e coli and nisseria meningidis
pyrogenic exotoxins are released by the bacteria in ____ inf.
spreptococcal
TNF alpha serum correlates with severity of disease in
septic shock
TSS?
staphlococcal infections of genital tract
mediator of TSS
TSST1
TSST1 acts as a
superantigen
what happens when complement is activated in the pulmonary capilllaries and edema results
ARDS
DIC is a feature of
bacterial septicemia
tissue damaging effects of hypersensitivity are called?
immunopathologic
