Samenvatting hoorcollege 7

Virusziekten samenvatting HC.7
Membrane function is a key process in cellular life. You have three kinds of membrane
fusion:
1. Intracellular fusion
 Cell secretory pathway
 ER to Golgi and back
 Golgi to plasma membrane and back
 Synaptic transmission
 Organelle fusion
 Mitochondrial fusion
 Endosome-lysosome fusion
 Mostly mediated by SNAREs.
2. Cell-Cell fusion
3. Fusion of virus membrane with host cell membrane
 Enveloped viruses needs to fuse their membrane with that of the host to deliver the
viral content
 Mediated by viral fusion proteins




There are different routes of virus entry. But there are two common things in every entry:
attachment and crossing the host membrane. In all cases, and all steps of the viral entry are
mediated by specialized proteins!!

 Attachment  is mediated by virion protein(s) binding to specific host surface
molecule(s) such as membrane proteins, lipids or the carbohydrate moieties present either
on glycoproteins or glycolipis.




 Crossing the host membrane

,  Pore-mediated entry




 Lysis or membrane permeabilization (many non-enveloped viruses)




 Membrane fusion (enveloped viruses)




Biolayer piophysics
 The intrinsic tendency of a lipid bilayer is to adapt and keep a flat shape (some lipids
spontaneously form monolayers of different curvatures)
 In the lipid bilayer the two monolayers will tend, energetically, to have the same lipid
composition
 The bilayer will be completely symmetric with respect to its mid plane
 Bilayer will oppose curving by external forces