Intro to Virus Flashcards
Viruses rely on what from host
metabolic machinary of host cells
protein biosynthetic machineray of host cell
Intracell phase
replication, transcription, synthesis of proteins and assembly of virons happen inside infected cell
What happens in extracell phase
particles must pass from cell to cell or throughout body o between individuals
any given virus group is described using a collection of individual properties—not necessarily all properties in common
Polythetic
Polytheics key for
idagnosis, idenfificaiton, clarification of life cycle and drug design
classificiation depends on
particle type (what it looks like)
tissue trophism( skin vs respiriorty)
diseae etiology
Serology and genome
Capsids: made from one or few proteins with repeating _____ contacts—these are self assembling
protein-protein
Capsids can form naked viruses or be surrounded by
envelope (matrix proteins lie under envelope)
What are packaging, protection and delivery vehicle during transmission
Capside/envelope
How do neutralizing antiB targed the virus
Exposed proteins on capsid and membrane are the targets of neurtralizing antiB’s; proteins on outside is the source of epitomes that our immune system targets
Whether the virus is naked or enveoloped determines
the virus structure, entry mech and if its suseptible
I:
ds DNA to mRNA
II:
+ ssDNA to dsDNA to mRNA
III:
dsRNA to mRNA
IV:
+ssRNA→ -ssRNA→ +mRNA
V:
-ssRNA→ + mRNA
VI:
+ssRNA → -ssDNA→ dsDNA→ +mRNA
RNA viruses capsids are either
Isocahedral or Helical
Icosahedral RNA viruses are either
while all helical RNA virusese are
naked or enevloped
enveloped`
DNA has three types of capsids:
icosahedral, helical or complex
DNA helical and complex viruses are always
enveloped
DNA icosahedral viuses can be
Naked or enveloped
the viral particle
virion
infectious particle
virus
multiplicity of infection
MOI
cytopathi effect
CPE
Plaque assays titration of # of _______, unit = pfu,
Take a tissue culture assay for ______infectious virus
he plaque or ‘hole’ reflects _______and spread initiated by a single infectious unit (pfu)
infectious progeny
quantitiation
zone of infection
these are intracellular parasites and need to grow INSIDE the cell then you can study what it does to the cell … does it kill it or make it replicate
Cytopathic effect:
DNA/RNA + Stuctual proteins +/- EnZ and nucleic acids =
Nucleocapsid (naked capsid virus)
Nucleocapsid + glycoproteins and membrane =
enveloped membrane
What are components of viral particle
genome (nucleoprotein) Enz (few or none) auxillary proteins (dissasmbly) Strucutal proteins (capsid) Attachment and fusion proteins
During replication… the regulatory phase is ____ while the structual phase is _____
early
late
Goal of infectious virus
hold host at bay long enought to undergo replication rlease at the level of cell’s anitival response and the immune system
6 steps to viral life cycle
- Attachment
- Penetration
- Uncoating:
- Synthesis of components:s
- Assembly of viral components
- exit and maturation
Virion Attachment Both naked and enveloped:
viral surface protein recognized a receptor on the target cell
What happens during uncoating
synthesis of viral mRNA
translation of viral proteins
genome replication
Both naked and enveloped: viral surface protein recognized a ____ on the target cell
receptor
Cell surface receptors (proteins or carbs) often determine
AntiBs that interfere with this intercation can ‘neutralize’ viral infectivity
species or tissue tropism
Receptors may be ubiquitious or cell type specific
Virus recognition of its receptors is important for determing:
host range, (humans vs others) and cell tropism (which cell type it will infect)
Virion Entry:
1. Naked; enter cell via _______ and are surrounded by endosomal membrane (will get taken up into a vesicle)
Endocytosis
Virion entry Enveloped: use their ______to induce fusion of virus and cell→ fusion will release ______into cytoplasm, leaving traces of viral protein in the membrane
glycoprotein
capsid
other enveloped taken up via endocytosis and fusion of their membrane with
membrane of acidic endosomal compartment→ will then release capsid into cytoplasm
Cells do not have enZs that copy RNA→
or RNA→
RNA
DNA
ALL viruses must synthesis _____ to make proteins
+mRNA
ALL viruses use ______ to make viral proteins but viral proteins can modify their translational specificity
host ribs
Viruses can use _____OR _____machinary to modify proteins
host
viral
many viruses______ host macromolecular synthesis; other manipulate cell cycle of host to get the best replicative environment
‘shut off’
proteins are sorted to correct nuclear or cytoplasmic location
capsid proteins must_______
viral genome must be selectively ________
assemble
encapsidated
Viral membrane proteins must be synthesized, modified and trafficked to correct membrane;
- translation (in the \_\_\_\_) - Glycosylation (in \_\_\_\_) - transport to membrane (\_\_\_\_\_\_) by vesicular transport
ER
golgi
internal or lasma
viruses can aquire a membrane in
cytoplasm
viruses can buc:
from nucleuar envelpoe
into compartments of secreatory path
from plasma membrane
once viral proteins replicated, virus replicates its________ and assembles into:
genome
progeny virion
Naked cells rely on ____ for rlease
cell lysis
Enveloped viruses are released by
budding
Capsid assemble and release in
coupled process at the plasma membrane
–capsid has lipid env from cell and has own viral proteins
leads to cytophathi effect with burst of virus produciton
productive infection
on production of infectious particles but genetic information of virust remains
latent infection
chronin virus production
persistant infection
viurs lifecycle incomplete and virus lost
abortive infection
Acute cytopathic effects of virus on host
mmb fusion of adj cells→ get giant multi-nucleated syncytia
shut off host metabolism
induction of apoptosis
Cell death—necorsis
Cell transormation from virus
loss of normal growth = oncogenic potential
Tropism of virus determined by
recepors, tissues specific components, tissue specific restrictions to abort infection, temp or pH
Viruses will cause pathogeneisis by:
destruction of infected cell
modify infected cell function
immune and immlamator response
Innate response
____________ interfeurons, cytokines, chemokines, antiviral response in infected cell
-makes surrounding cells resistant to infection
-recruits effect cells (NK cell or macrophages)
-or apoptosis
Soluble mediators
Adaptive immune response humoral
neutralizing antiB: block entry/attachment
complement fixing: lyse virions or infected cell
Adaptive response: cell mediated
MHC presentation– Cytotoxic T cell
Memory response
B and T cell to reisit infection
