General virology 2 - Tesse Flashcards
what is viral replication
the formation of virions (extracellular or intracellular infectious form of a virus) during the infection process in the target host cells
what is a viral factory
locations where the virus replicates (ie cytoplasm of mitochondria, endosomes, ER, etc)
what is an example of a non-productive stage
herpesvirus latency
Viral spread is through two methods:
Lymphatics
Circulation
How can you demonstrate the viral DNA?
PCR
what is the only method you can use to see the whole viral protein
electron microscopy
how to see viral proteins
staining
what are the six steps of viral infection and replication
- viral attachment/endocytosis
- penetration
- uncoating
- genome replication, mRNA production and translation
- assembly
- virion release
what is the eclipse period
2-12 hours. Replication occurs.
what is the latent period
the period between attachment until release (uncoating, replication, and maturation)
what is tissue tropism
the capacity of a virus to infect cells selectively in particular organs
what two things does tissue tropism rely on
susceptibility (suitable surface receptors)
Permissivity (cellular machinery must be able to support viral replication and release of new infectious particles)
T/F: different viruses can bind the same receptor
true
T/f some viruses may have more than one receptor
true
how do enveloped viruses enter cells
- bind receptor
- direct membrane fusion (enveloped viruses have lipid membrane)
- endocytosis of nucleocapsid
t/f naked viruses can fuse directly to a cell membrane
false. only enveloped viruses can do this because they have a lipid membrane (naked ones do not)
how do naked viruses enter cells
receptor mediated endocytosis, membrane bound vesicles, pore forming peptides that penetrate the cell membrane
how does adenovirus enter cell
receptor mediated endocytosis / membrane bound vesicles
how does picornavirus enter the cell
via pores from viral pore forming peptide. only the genome goes through the pore, not the whole capsid
which step is used by all viruses
translation
all DNA viruses but ___ virus go into the nucleus
pox
all the RNA viruses replicate in the ___ except for the retroviruses, that go to the ___
cytoplasm, nucleus
alpha mRNA from herpesvirus
blocks immune response, induces B mRNA production
beta mRNA from herpesvirus
genome replication, induces gamma mRNA production
GAMMA mRNA from herpesvirus
initiates production of structural proteins (capsid, glycoprotein)
The retrovirus RNA is converted into DNA by
viral reverse transcriptase and intergrase
retrovirus DNA integrates itself into the
host genome (host cell DNA)
is a nascent virion infective
no. not until it’s Gag-Pol precursor protein is cleaved by viral protease
T/F retroviruses are lifelong
true
What are two main differences with the retrovirus replication cycle
- integrates into host DNA
- produces nascent (non-infective) virion that must be cleaved by viral proteases to become infectious
Naked virus release causes:
host cell lysis
Enveloped virus release causes:
budding
influenza, rabies and paramyxoviruses exit via
mucosal surface of cell
alphavirus, vesicular stomatitis virus, lentivirus exit via
basal surface of cell
