Smiley-3 Flashcards
(30 cards)
What must viruses do to initiate infection?
- attach to host cell
- uncoat genome
- deliver genome to appropriate location
Virus-attachment proteins
Proteins located on outer membrane of virus used to attach to host cell receptors
viral attachment molecules are always _____, but cell receptors can be ____, or a _____ linked to protein or lipid
protein, protein, or carbohydrate
Cell receptors
- have normal host functions other functions besides viral entry
Which viruses use sialic acid as their receptors?
Influenza, reovirus, and rotaviruses
Why are mouse fibroblasts expressing human CD4 resistant to HIV infection?
They do not have the coreceptors for HIV
Co-receptor
cellular chemokine receptor (normally detects chemokine)
fibroblast
cell that produces collagen and extracellular matrix (for structure)
HIV coreceptor that is implicated in human resistance to HIV
CCR5
Examples of viruses that need co-receptors
herpes simplex virus and HIV
Receptor for herpes virus
heparan sulfate of cell surface proteoglycans
Parts of T4 bacteriophage
head, contractile tube, tail and tail fibers
Where is DNA genome located in bacteriophage T4?
Head
What are the protein components of “molecular machine” released by bacteriophage T4?
gp5 and gp27
Function of bacteriophage molecular machine
- penetrate outer membrane of host cell
- has lysozyme activity to degrade peptidoglycan and allow DNA to be injected into cytoplasm
Differences between animal cell and bacterial cell
animal cells have nuclei and have compartmentalized organelles
mechanisms of entry to animal cells (x3)
- direct fusion of envelope with host plasma membrane
- pore-mediated penetration
- escape from endosomes
how do viruses escape from endosomes? (x3)
- fusion at endosomal membrane
- lysis of endosomal membrane
- local permeabilization of endosomal membrane
what type of viruses use direct fusion w/ host cell membrane technique?
enveloped
What viruses use direct fusion w/ host cell membrane method?
herpesvirus retrovirus, paramyxovirus
What type of viruses use pore-mediated penetration?
Non-enveloped
Which virus use pore-mediated penetration?
picornaviruses
What type of viruses use fusion at endosomal membrane?
enveloped
Which virus uses fusion at endosomal membrane?
influenza
