Lecture 11 Flashcards
Intro Virology
baltimore classification
viral genomes must make mRNA that can be read by host ribosomes
reverse complement
has to be coped into a positive strand to be read by a ribosome
non-enveloped viruses
very stable in the environment
minute mouse virus
coxsackievirus B4… poliovirus
enveloped viruses
fragile in the environment
influenza A virus
herpesvirus
how do bacteria divide
binary fission
how do viruses proliferate
by assembly
virus replication cycle
Attachment
Penetration
Uncoating
Transcription
Translation
Genome Replication
Assembly
Release
attachment is done through
viral attachment proteins (VAP)
what are viral attachment proteins (VAP)
viral proteins that bind receptors
glycoproteins (enveloped), fibers or canyons (non-enveloped)
can have multiple, redundant VAPs (Herpes)
how does attachment evolve
attachment is first weak, reversible electrostatic binding
attachment is strengthened by irreversible interactions (sometimes to a second receptor)
what prevents viral attachment
antibodies binding to VAPs
viral receptors vary _____
widely
permissive cell
allow for productive virus replication
resistant cell
does not express the virus receptor
penetration and uncoating
most viruses must escape endosomes before fusion with the lysosome, others fuse at the plasma membrane
nothing large diffuses fast in cytoplasm, virions require active transport on microtubules
penetration of a virus
a virus particle reaches the cytoplasm
uncoating of a virus
a virus sheds its capsid
the genome must be delivered to
the correct subcellular compartment
enveloped virus entry
virions enter by endocytosis
acidification changes conformation of VAP
reveals a hydrophobic fusion peptide
fusion peptide penetrates host membrane
further conformational change fuses membranes
influenza A VAP is
Haemagglutinin (HA)
non-enveloped virus entry
makes a large hole in cell membrane
initial binding to CAR by adenovirus fiber
secondary binding to integrin
acidification in endosome degrades capsid
structural protein (Protein VI) penetrates endosomal membrane
membrane disruption allows remaining capsid to associate with microtubules and traffic nucleus
example of non-enveloped virus
adenovirus
