Viral structure and function Flashcards
Virus
infectious, obligate intracellular pathogen that requires host cell machinery for replication
can use DNA or RNA
genetic material of virus enters host cell and directs the production of new virus parcles called virions
Viral components
nucleic acid
capsid
envelope
Virion size correlates with
genome complexity
Host and tissue tropism
virions bind to host cell receptors through attachment proteins in the capsid via glycoproteins embredded in the viral envelope
specificity of binding interaction determines which host species the cell types of the virus can infect (tropism)
The influenza hemagglutinin glycoprotein binds to
sialic acid receptors on target cells
The baltimore classification system uses _ as the primary criterion for classification
nucleic acids
DNA viruses establish
persistent infections
RNA viruses are
prone to mutation
Naked capsid consequence
spread easily
can dry out and retain infectivity
Can service in adverse conditions of the gut
can be resistant to detergents and poor sewage treatment
antibody may be sufficient for immunoprotection
Enveloped virus consequence
may stay wet
cannot survive in GI tract
Spreads in large droplets, secretions, organ transplants, and blood transfusions
does not need to kill cell to spread
Life of a virus
Infect host cell
replicate genome (requires translation of virus encoded genome)
assemble new virions (requires translation of virus encoded genome)
exit host cell
DS or SS DNA virus
DNA dependent RNA polymerase
DNA dependent DNA polymerase
+RNA or -RNA
RNA-dependent RNA polymerase (-RNA only) virus encoded
DSRNA or retro
RNA-dependent DNA polymersase (virus encoded)
DNA-dependent RNA polymerase
Acute disease
brief symptoms, resolution within days
