Virology Flashcards
Viruses differ from living cells in what 3 ways
acellular organization
has either DNA or RNA not both
can not produce independently of living cells
the combination of nucleic acid and a capsid is referred to as…
nucleocapsid
If a virus has only a protein capsid covering, it is termed a…
naked capsid virus
some viruses contain an additional component called an envelope which is derived from…
host cell
why aren’t enveloped viruses stable?
destroyed by stomach acid
what are the effects of viral infection on cells?
direct damage of host cells
host defense mechanisms
viral pathogenicity can cause syncytia which is?
giant cell formation
list the cytopathic effect of viruses
cell death
syncytia
roudnign up of cells (change function)
piling up of cells (cancer)
inclusion bodies
viral CPE piling up of cells result in warts
warts
What is the life cycle of viruses
recognition
attachment
penetration
what do naked viruses and enveloped viruses use for for attachment?
capsid protein
viral proteins on membrane envelope
How do naked capsids attach and penetrate cells?
direct penetration or endocytosis
How do enveloped virus attach and penetrate cells?
membrane fusion or endocytosis
this part of the life cycle involves the removal of capsid proteins, usually carried by cellular enzymes that chew off the viral coat by lysosome fusion
uncoating
this part of the viral life cycle makes mRNA which can be recognized by host ribosomes
mRNA transciption
this part of the viral life cycle happens in the cytoplasm; both types of viruses use cellular ribosomes and the rest of the host cell protein synthetic machinery
protein synthesis
replication of DNA virus occurs wher?
nucleus
replication of RNA virus occurs where?
this part of the viral life cycle is where nucleic acid and capsid protein come together and undergo self-assembly which is a spontaneous process
How does the release step of the viral life cycle occur in enveloped viruses?
budding
reverse membrane fussion
How does the release step of the viral life cycle occur in naked capsid viruses?
lysis
host cell breaks open and releases viral particles
how do viruses spread throughout the body?
replicate at site of entry
viremia (spread into blood)
target organ
after exposure to the virus we are ASYMPTOMATIC until the virus reaches…
target organ and cause symptoms
this is the amount of time between infection with a virus or bacteria to the beginnings of the symptoms
incubation period
what does the incubation of viral disease depend on?
distance between site of infection and target organ
growth rate of the virus
