Flashcards in Viral Pathogenesis Deck (90)
3 ways for viruses to be maintained in nature?
1. shed into environment
2. vector: insect, needle
a systemic viral infection is worse than a local ? T/F?
False. Not correlated with severity
anatomical localization of infection (initially determined by receptor specificity
What's parenteral inoculation?
via mosquito or bite
What determines initial site of virus deposition in the airways? Explain
5-10um = airways
<5um = alveoli
What the body temp in nose vs. lung bases?
33 degrees nose
37 degrees lung bases
Rhinovirus spreads from initial site?
3 viruses that spread from infection site?
MMR baby. and varicella
3 viruses that stay localised?
resp syncytial virus (RSV)
What kind of cytopathic effect could RSV have on lungs?
presence of giant cells
How does measles infect you?
breath it in
replicate in epithelials of URT
infects Macros, lymphos, DCs into lymphnodes
circulate and amplify and go back to lungs and mouth
How are HIV and measles similar?
both cause immunosuppression
What are koplick spots?
measles initial replication causes aggregations of lymphocytes
T/F? Viruses that infect GI have an envelope for more protection?
FALSE YO! are acid and bile resistant, no envelope
What does rotavirus cause?
two viruses that infect GI but spread
HIV and Hep B don't have receptors for epithelial cells, how would they enter?
abrasions/breach via rectal route
What's an M cell?
kinda like a DC cell but in the GI, they're the sentinels in the GI sampling and presenting to underlying lyphoid tissue
how many shells does rotavirus have? why?
triple shelled to withstand the GI environment
What does rotavirus do to you?
infects GI, destroys M cells, epithelial cells, inflammation, gastroenteritis
Rota virus causes diarrhea, how is it amplified or dangerous to children?
NSP4 protein increases fluid secretion
What's the difference between primary and secondary viremia?
primary: in circulation amplifying
secondary: reaches target tissues
Name a systemic virus that infects meninges
Name a systemic virus that infects CNS
Name a systemic virus that infects skin
group A coxsackie (hand/foot/mouth)
Name a systemic virus that infects muscle
Group B coxsackieviruses
What virus enters transcutaneously?
What viruses from insect/animal bites?
dengue virus - fever, rash, poly arthritis
conjunctiva route is rare, what viruses can enter this way?
What's the mechnism of spread of a virus?
in primary viremia, where is the virus
free in plasma
in secondary viremia, it infects vascular endothelium or release in large amount from what two organs?
How is viremia managed by the immune system? how long?
macrophages to the rescue! take 1-2 weeks
What is cell-associated viremia?
spread via the immune system
HIV - CD4
what does smallpox do to a fetus?
it's cytocidal, death and abortion
what do non cytocidal viruses do to foetuses? 2 examples?
developmental abnormalities: rubella, cytomegalovirus
what can infect a baby in the birth canal? 4 things:
herpes simplex, varicella, CMV
coxsackie B from faeces
What does congenital rubella syndrome do?
slows down cell division
4 consequences of congenital rubella syndrome?
2. heart defects
How does polarized release determine tropism of viruses?
those viruses that prefer apical release are less likely to infect deep layers
What virus needs tryptase from Clara cells?
what is a cytocidal virus? 2 examples
death from direct viral replication
what can rhinovirus do to lungs in terms of affecting their function?
cilial stasis can predispose to second bacterial infection
What is immunopathology in terms of viruses?
immune system collateral damage
2 kinds of antibody mediated pathology:
1. Ab-dependent enhancement of infection
2. antigen-Ab complexes
What is Ab-dependent enhancement of infection? example?
Dengue hemorrhagic, infects macrophages
What is antigen-Ab complexes? how is it bad?
big ass complexes deposit in kidney causing glomerulonephritis/vasculitis
what can cause antigen-Ab complexes?
Measles rash is cause by what mediated pathology?
CD4 T-cell-mediated responses
CD4 T-cell-mediated responses for viral immunopathology. What happens?
Cytokines and eosinophils recruitment can cause bronchiolitis in infants with RSV
What is RSV?
respiratory syncytial virus
What virus causes CD8 T-cell mediated responses?
HepB does what in terms of CD8 T-cell mediated response?
What are signs of liver damage in hep B?
yellow eyes, skin
How does the eyes and skin turn yellow in liver damage with Hep B?
excess bilirubin in tissues as it's not secreted into bile from old heme
Can viruses cause autoimmunity? how?
yes via molecular mimicry
2 examples of a virus mediated autoimmunity?
Guillain-Barre syndrome for nerves
coxsackie B4 for heart muscle
What Interleukin does measles suppress?
What does Type 1 IFN a/B mainly target? what does it activate?
target dsRNA viruses
What does Type 2 IFN-y come from? what does it do?
made by NK cells
enhance MHC class I and II
How would a virus evade T or B-cells? examples?
HSV in T-cells
EBV in B-cells
How would a virus evade antibodies? examples?
antigenic drift like flu and HIV
How would a virus evade T-cell recognition? 3 things
inhibit viral peptide presentation
decrease MHC class I (HIV, RSV, adeno)
How does viral antigenic drift happen?
spontaneously through RNA errors
How would HIV evade CD8 recognition?
induces endocytosis of MHC class I and mess with the CTL epitope
What viral protein binds to cytosolic side of TAP transporter to evade CD8?
HSV (herpes simplex)
What viral protein binds to luminal side of TAP transporter to evade CD8?
What is TAP?
transporter of antigen and peptides
What does adenovirus do to MHC peptide complex?
anchors in the ER so it can't do diddly squat
what virus inhibits proteosomes?
Is NK cell a B-cell? or a T-cell?
Neither, own distinct lineage
NK cells are a major source of what?
What cytokines activated NK cells?
I'm getting a lot of varicella and CMV infections... what's up doc?
you might have a NK cell deficiency
NK cells are part of innate or adaptive immune system?
Do NK cells need an antigen to activate?
Nope, could be stress protein or heat shock proteins too
How many signals do NK cells need to kill?
1. first is the check
2. 2nd is the inhibitory (without it, it will kill)
NK cell inhibitory receptor binds to what?
MHC class I of target cell
What happens to viruses that cause reduction of MHC class I expression?
evade CD8 but more susceptible to NK killing
What virus encodes an MHC class I-like molecule to avoid NK cell killing?
Human CMV cytomegalovirus
What is PKR? how is it activated?
activated by IFN, helps to inhibit translation of viral proteins
What does PKR need to be activated? 2 things
viral dsRNA (long enough)
what is a viral evasion technique to get around IFN and PKR? which viruses?
abundant small bits of RNA that bind to PKR but not lengthy enough to activate PKR
What does vaccinia and reovirus do to avoid PKR activation?
Virus proteins bind to dsRNA to prevent PKR activation
What competes with PKR for eIF2a activation to stop viral translation of proteins?
If you are resistant to HIV, what could be causing it?
You may be missing the CCR5 secondary binding receptor
What Ig class are viruses susceptible to?
4 kinds of genetic factors influencing susceptibility to viral infections?
inherited defects (no Ig class)
4 kinds of non-genetic factors influencing susceptibility to viral infections?