9.3 - poxvirus Flashcards
what family of viruses is poxvirus from
family of large dsDNA
- can infect insects, animals, humans
egs of poxviruses
small pox (varoila virus ), moonkey virus,
what is small pox
pus filled lesions on the skin
how to get small pox from the infected person
direct contact with the infected person
- very contgaoius
how does smallpox vaccine work and stages of it to gain immunity
- dip the needle in the vaccinia virus
- jab the arm
- strong immunological response to the virus
- lesion formed then scab formed after days
- scab falls and forms a scar
- immunity produced
why does the vaccine work against smallpox
- the vaccine contains vaccinia virus which is similar to the smallpox virus
- vaccinia gives a strong immune response but doesn’t kill the cells
is there transmission between humans and animals
no only human to human
structure of vaccinia
- enveloped
- dumbbell shape
- has 2 proteinacaeous structures which are lateral bodies
- flank core
- membrane
what familt is vaccinaia part of
nucleocytoplasmic large DNA viruses
functions of core and lateral bodies
contain proteins important for processes in the virus
- like core has proteins for transcription
where does the replication vaccinia takes place in the host cell
cytoplasm
-use host organelles like golgi, ER
how many forms does vaccinaia make and what are they
2 forms of this virus
- mature virions
- extracellular virions
how does vaccinaia enter the cells
binds to glycoproteins and trigger endocytosis of macropinocytosis
- gets inside of macropinosomes
what is macropinocytosis
engulfment and uptake process of large amounts of fluids and membranes
how does the virus leave the macropinosome and what does it leave behind
by fusion
- membrane which is then degraded
what is dispered into the cytoplasm after virus leaving the macripinosome
core and the lateral bodies in
stages of vaccinia virus replication
- early gene replication happen where it makes proteins for DNA replication of the virus
- viral genome uncoated
- viral genome replicated
- replication for intermediate and late gene expression
how does mature virions (MVs) come about after the repilcation
cresents (open membrane) grow contaning viral factory and proteins > immature virions
- go through maturation like cleavage and structural changes
becomes infectious
how does the vaccinia exit the cell
MV transported to golgi to be wrapped in the golgi cisternae
- then transported to cell surface
- virus fuses with the plasma membrane
how does the virus get to other cells
actin rails push the virus to surrounding cells
how does the virus evade the immune system
- molecular mimicry > mimics the self AGs so IS not activated
- inhibition or activation of cell processes
alternative immune evasion strategies
- apoptotic mimicry
extracellular enveloped virions (EEVs)
-lateral bodies
what does dead cell and cell debris express on their surfaces
PS - phosphatidylserine
- signal to engulf the cells
all cells have this receptor
how does the virus use apoptotic mimicry
the virus is enriched in PS layer and expresses PS receptors
- tricks the cells to take it up as debris
- the virus can then infect the that cell
why else is apoptotic mimicry good
suppresses inflammation and immune system response
two infectious particles of vaccinia virus
MV and EEVs
- the virus presents two forms of these > forms 2 different immune responses
features of MVs
single lipid bilayer
- very stable
features of EEVs
like MVs but has extra 9 proteins
- have glycocylated proteins and glyco shielidng
- travel in blood stream
what is F17
phosphoprotein
- major core component
DNA binding protein
-associated with lateral bodies
