Block D 1 Flashcards
virology
what are the 5 classes of viruses
-respiratory viruses
-enteric viruses
-arboviruses
-hepatitis viruses
-sexually transmitted viruses
examples of respiratory viruses
influenza
rhinovirus
adenovirus
coronavirus
how are respiratory viruses usually acquired
inhalation of droplets and replicated in the respiratory tract
examples of enteric viruses
polio
rotavirus
reovirus
some adenovirus
where do enteric viruses replicate
in the gut
how are enteric viruses acquired
ingestion of faecal-contaminated material
examples of arboviruses
flaviruses
bunyaviruses
some rhabdoviruses
what do arboviruses infect
infects insects that ingest vertebrate blood
where do arboviruses replicate
in the tissue of the insect and then transmitted to vertebrate host
what are hepatitis viruses
all viruses that cause liver disease
examples of sexually transmitted viruses
herpes simplex
papilloma viruses
what is the easiest virus to grow
bacterial viruses
why are plant viruses the most difficult to cultivate
often requires growth of the whole plant
what can animal viruses (and some plant viruses) be cultivated in
tissue/cell cultues
what does titer mean
number of infectious units per volume of fluid
what is a plaque assay
analogous to the bacterial colony
one way to measure virus infectivity
what are the 2 symmetries of capsid
helical
icosohedral
what are capsids formed from
structural subunits
what are large assemblies of capsids referred to as
capsomers
what is the term given to viruses without membranes
naked
what does virion consist of
nucleic acid packaged into a protein coat (capsid)
what is a nucleocapsid
nucleic acid and protein packaged into a virus
what do some virions contain making them critical to infection
enzymes
what are the 3 enzymes that some virions contain
lysozyme
nucleic acid polymerases
neuraminidases
function of lysozymes
makes hole in cell wall
lyses bacterial cell
what do neuraminidases do
cleave glycosidic bonds
allows liberation of viruses from cell
what is the Baltimore classification system
used to classify viruses based on their manner of mRNA synthesis
3 stages of virus replication
initiation
replication
release
what are the 4 stages of the initiation phase of virus rep
recognition
attachment
penetration
uncoating
what are the 4 stages of the replication stage of virus rep
transcription
protein synthesis
genome replication
assembly
what are the 2 stages of the release stage of virus rep
lysis and release
budding and release
in virus replication what may receptors be
proteins
carbohydrates
glycoproteins
glycolipids
in virus replication what may viral attachment be
capsid
protein that extends from capsid
glycoproteins of enveloped viruses
what type of penetration occurs with naked viruses
pore mediated
(viropexis)
in virus replication what occurs when the virus is naked and enveloped
endocytosis
in virus replication what occurs when the virus is enveloped
membrane fusion
what does size have to do with host dependency
smaller the virus the more dependent on host
what do many viruses promote
cell growth
where does transcription occur in DNA viruses
nucleus
what is transcription regulated by (DNA viruses)
by interaction of DNA binding proteins wth regions of viral genome
what is transcribed first (DNA viruses)
mRNA for nonstructural proteins
(early proteins)
where is DNA replication initiated at (DNA viruses)
origin
what is DNA rep said to be (DNA viruses)
semi conservative
what is always formed in replication of RNA viruses
DSRNA replicative intermediate
what must polymerases MUST be (RNA viruses)
virus encoded
where does RNA replication occur
cytoplasm
what type of viruses are more prone to mutation
RNA viruses
what strand of virus is rabies
-ve RNA
what does translation of viral mRNA depend on
host cell functions
what can eukaryotic ribosomes not translate
polycistronic mRNA
what do viruses promote (viral protein synthesis)
preferential translation of their mRNA
