BIOD29 Pathobiology of Human Disease
January 16, 2012
Single-stranded (+) RNA viruses
Pico RNA viruses
Naked icosahedral capsids because only contains a capsid not an envelope
All genes translated into a huge protein (atypical of eukaryote)
Cause of paralytic polio in humans
Death of motor neurons in the spinal cord which leads to paralysis
Serotypes are different antigens on the outside of a virion
This is a pathogen that has co-evolved with us
It has extra cellular domains that are disulphide linked
Unique to virus: viral proteins insert into the host cell membrane, possibly making a pore through which the RNA
genome is injected
IRES present in the 5’ non-coding region of the viral RNA.
o Multiple stem-loop structures
These RNAs do not rely on the 5’ methyl cap, its own RNA do not have the methyl cap.
Cap-dependent translation (which our cells normally do), the virus is going to find a way to stop this from happening.
The virus is going to target a host factor called eIF host complex and destroy it.
Inhibit cellular mRNA translation
o Encoded a protein that will clip 4G
Inhibit secretory pathway
o Normally involved in ER goes to Golgi and makes vesicles release to outside of the cell. The virus encodes
factors which will stop factor from exocytosing and will be stuck within the cell.
Become anchored to cellular vesicles
o The viral RNA in the cytosol is associated with cellular vesicles that are accumulated
3AB is VPg with an extra bit.
The –ve STRANDED RNA is made by the virally encoded RNA-dependent polymerase = 3D polymerase
The viral genome is the positive RNA; the whole point of viral infection is it wants to make more of itself. You need to
make lots of positive RNA to be able to be packed.
Initial positive strand, make one negative strand, then use that one negative strand 40 times before you use another
negative strand. Really good at making positively RNA that can be packaged.
Two hypotheses of how to end up with fully packaged