Steps of Viral Infection of a Host Cell Flashcards
What are the steps of viral infection of host cell?
Attachment to the host cell
Entry of virus into the host cell
Synthesis of viral proteins and genome
Assembly and release
What is the most important determinant for host specificity?
viral receptors
viruses are very host and tissue specific due to the presence of receptors on host
Which virus is CD4 receptor for
HIV-1
On which cells is CD4 present on?
macrophages and Tcells
It normally binds to MHC class II and mediates the T-cell response
What are coreceptors Cxcr4 and Ccr5 for?
HIV-1
normally chemokine receptors present on immune cells
which proteins on HIV bind to CD4 and Cxcr4/Ccr5 co receptors?
SU
TM
What is the mode of entry into host cells for non enveloped viruses?
1) Bind to host cell at surface and rearrangement of capsid protein.
2) viruses engulfed by receptor mediated endocytosis. There is partial breakup of the capsid in the vacuole, followed by migration into the cytoplasm for further uncoating.
What is the mode of entry into host cells for enveloped viruses?
1) Fusion of viral membrane and cell membrane mediated by a viral F protein (fusion protein).
2) Phagocytosis and fusion of viral membrane with membrane of phagosome mediated by a viral F protein.
Why is the F protein important for functioning of enveloped viruses?
the F protein or fusion protein is present in those membranes. Without the F protein, the virus cannot enter the host cell and has not evolved the mechanisms that unenveloped viruses possess to enter host cells.
Which part of the F protein inserts into the host cell?
The F protein has a hydrophobic domain that can insert into the host cell membrane.
The viral and host cell membrane are brought into juxtaposition and are ready to fuse.
What is a syncytium?
multinucleated viral cell formation (giant cell formation) is catalyzed by the F protein.
What are the parts of the growth curve for viruses/’
eclipse period
latent period
What is the eclipse period in a growth curve of a virus?
period-nucleic acid uncoated from its protective capsid, no infectious particles in host cell
What is a latent period in the growth curve of a virus?
no extracellular virus can be detected. Virus is making mature particles inside and none outside
