Virus/cell interactions Flashcards
what are permissive cells?
cells supporting viral infection and this leads to productive infection
what effects to productive infections usually have?
cytopathic
what are non permissive cells?
if the virus does manage to get in it leads to abortive or restrictive infection
What are persistent infections?
infections that last for long periods of time and occur when primary infection is not cleared by the adaptive immune response. Two types-chronic and latent
what are chronic infections?
infections where there are low levels of virus to escape immune (can be reactivated)
define a latent infection?
the virus has the ability to lie dormant within a cell and this is denoted at lysogenic part of the viral infection
How can viruses transform cells?
abortive/restrictive infection and/or oncogenesis
what is an acute viral infection?
short term infection no more than 6 months in which lots of viruses are present and leads to the death of many cells.
how long can an acute infection be up to?
6 months
are all effects intended and beneficial to viruses?
no for example polio and cervical cancer (but most effects are intended)
What main 4 effects can viruses have on cells?
1) morphological effects
2) Syncitia/giant cell formation
3) Biochemistry effects
4) genetic effects`
why are physical effects useful for detection?
they are visible under a microscope so allow quick detection, the cell looks visibly different
How can viruses affect the cytoskeleton?
virus factors with associated tubules can change the cytoskeleton enough to bend it and therefore cause a change in cell shape
how can viruses affect the nucleus?
can cause perinuclear inclusions with microtubule bundles
what are inclusion bodies?
Nuclear or cytoplasmic aggregates of stainable substances, usually proteins. They typically represent sites of viral multiplication.
Where are inclusion bodies usually for DNA virus and RNA?
in nucleus for DNA virus and in cytoplasm for RNA virus
what was the cauliflower mosaic virus?
the first DNA plant virus to be reported
how is the CAMV transmitted?
CaMV is transmitted between host plants by several aphid species
CAMV is “circulative”, what does this mean?
to viruses that are transmitted only if the virus is transported across cell membranes and carried internally within the vector body cavity or fungal cells
what are syncitia?
they are giant cells with many nuceli caused by fusion of a viral envelope with infected cells e.g measles and retroviruses (proteins on membrane can act as viral fusion ones and fuse cells together)
what are giant cells called?
syncitia
what effects do viruses have on cell biochemistry?(3)
a) activation of cellular protein
kinases and transcription
factors
b) activation of cellular
oncogenes, cell cycle arrest
c) inhibition of DNA synthesis as switching host DNA replication and synthesis to virus synthesis etc
what type of effect on cells is activation of cellular
oncogenes, cell cycle arrest
and inhibition of DNA synthesis ?
biochemical
What genetic effects do viruses have on cells? (3)
1) chromosome rearrangement and mutations
2) generalised chromosomal damage
3) transformation
what are 2 morphological affects viruses can have on cells? and due to what?
effects on cytoskeleton and nucleus due to virus factors and inclusion bodies
what viruses produce syncitia?
measle virus and retoviruses
define briefly latent,chronic and acute.
Acute is sudden and severe, latent is dormant or recessive and chronic is on-going and long term.
