Intro to viruses Flashcards
two forms of a virus
- virion (infetious) (metabollically inert
- replicative
components of a virus
- envelope
- genome
- matric
- capsid
- nucleoprotein
how can a capsod be constructed
- it can only contain a certain amount of DNA
- must be constructed of one or only a few proteins repeated many times
- capsids must have symmetrical structure
- two types of symmetry are obsevered
types of symmetry
- helically symmetrical
- icosahedral
what can the viral genome be composed of
- DNA: ss, ds, circular single
- RNA: linear plus stranded, linear minus stranded, segmented minus stranded, segmented double strnaded
how to produce different viral proteins
- polyprotein
- segemented genome
- nested mRNA’s
- differential splicing
adsorption
interaction between virus protein and cell surface receptors
penetration
- receptor mediated endocytosis ot direct interaction at the cell surface
- fucion of the virus and cell membranes
uncoating
- release of nuceic acid with or without enymes
- allows for expression
early events
- depend on crus group
- prepare for nucleic acid replication
late events
- nucleic acid replication
- virion protein synthesis
- virion assembly and release
polyprotein
-a linear DNA is transcribed and then the protein is split later down the road
segmented genome
-each segment is a different protein
nested mRNA’s
one transcript is trancribed in different segments in order to get different proteins proteins
differential slicing
-trancripts made and spliced differently
dsDNA transcription
- early mRNA synthesis and viral protein synthesis
- uses RNa pol and cell ribosomes
- papillomavirus
+RNA virus transcription
- immediate viral protein synthesis
- cell ribosomes used
- picornavirus (polio)
-RNA minus transcription
- mRNA synthesis and viral protein synthesis
- virion enzyme used to do so, (transcriptase)
- translated on cellular ribosomes myxovirus
retro virus transcription
- plus strand RNA
- virion contains the reverse trranscriptase so it can synth its own DNA
- this is the initial event after infection
- plus RNa gets converted to dsDNA
transfection
- genomes from a virus are introduced into cells by one of a variety of tricks
- with viruses that do no require a virion trancriptase (DNA/+RNA), a complete infection cycle can be done this way
