exam 2 Flashcards
Example of a DNA virus that replicates in the cytoplasm
pox virus
why are cytoplasmic dna viruses more independent
don’t rely on cell machinery for replication
why do cytoplasmic dna viruses have large genomes
must encode DdDp and DdRp, don’t use cell machinery
where are the cellular polymerases
the nucleus
what is the largest animal virus (other than girius)
pox virus
why are pox virus morphology complex
contains lateral bodies and core
what virus causes a localized skin infection and can cause a severe systemic disease in immunocompromised
vaccinia
why do we study the structure of vaccinia for understanding small pox
vaccinia is the cousin of small pox virus
how many genes does the vaccinia genome have
200!
1st thing to happen in pox virus after uncoating
early mrna production
how does pox virus avoid the innate immune response
encodes 10 proteins specifically for that (early proteins)
what happens in intermediate transcription
make a bunch of mrnas that support last transcription
what kind of proteins impact the host cell in pox viruses
intermediate proteins
define IMV
intracellular mature virion, brought to golgi
which statement regarding pox viruses is incorrect?
a. they are the largest and most complex of all the animal viruses
b. they multiply in the cytoplasm
c. their sites of multiplication within infected cells appear as inclusion bodies
d. they are non enveloped dna viruses
e. none of the above.
d
list ways that pox viruses evade the immune response/why is variola so nasty
IFN receptor (viroceptor-mimics cell receptor for IFN)
virokine-(mimic chemokines)
chemokine binding protein
dsRNA binding protein (hides it from RIG-I)
homolog to eif-2 (blocks translation)
difference between IEV and CEV
IEV-released by fusion, responsible for host to host transmission, uses microtubules
EEV-actin tails push through the PM and transmit cell to cell
4 types of variola major viruses (virus that causes small pox)
- ordinary-accounts for most cases 30% mortality
- vaccine modified
- flat or malignant pox, 90% mortality rate
- hemorrhagic
describe variola minor
mild
what is the causative agent of small pox
variola virus
how did we eradicate small pox
- narrow host range
- no carriers (all symptomatic)
- no animal reservoirs
- effective attenuated vaccine
- easy to surveillance
what type of vaccine is the smallpox vaccine
live attenuated vaccinia virus
What is better for viruses, treatment or prevention?
treatment is difficult
why is antiviral treatment difficult
most of the damage to cells occurs early and only a few effective antivirals exist
what is passive antibody therapy
normal human igG fraction, heat treated to destroy viruses. creates serum
read in text fig 7.23
list 3 complication of passive immunization that limit it from being used commonly
fever, difficulty breathing, skin lesions
how could you create a perfect vaccine (3)
evoke b and t cell immunity, will not make patient sick, don’t need 100% uptake of vaccine to get immunity
which of the following is true:
a. it is easier to prevent a virus than to treat it
b. the perfect vaccine will invoke a strong immune response
c. the perfect vaccine will not cause disease
d. it is not necessary to get 100% uptake due to herd immunity
e. all of the above
e
what are the two types of traditional vaccines
- live, attenuated
- killed, inactivated
4 steps to producing attenuated vaccines
- pathogenic virus is isolated from host and grown in human cultured cells
- cultured virus is used to infect foreign cells
- pass to other cells, mutates over time and becomes less virulent
- virus no longer grows well in human cells but still looks enough like a pathogen to invoke immune response
list 6 advantages of live attenuated vaccines
strong immune response, long lasting, cross reactive, low cost, quick immunity, don’t require -80 for storage
what are some disadvantages of live attenuated vaccines
problem if not properly attenuated, can revert to virulence, not possible with all viruses, not recommended for immunocompromised people
Viruses that have lost their ability to cause disease are said to be
attenuated
what is one disadvantage of using attenuated vaccines
a. they require fewer doses than other types of vaccines
b. they provide long lasting protection
c. the organisms multiply following vaccination
d. the organisms can mutate back to a virulent form following vaccination
d
How do you produce inactivated viral vaccines
virus is exposed to denaturing agent that results in lost of inefectivity
what is formalin
denaturing agent used in inactivated viral vaccines
are inactivated viral vaccines able to replicate
no
advantages of inactivated vaccines
sufficient humoral immunity, no mutation, little to no risk if inactivated properly because it won’t become virulent suddenly, can be used by immunocompromised
disadvantages of inactivated vaccines
less effective than attenuated, not possible for all viruses, boosters needed, higher cost, must be tested in monkies
list the 5 new approaches to different vaccines
- recombinant subunit 2. synthetic peptides, 3. naked dna vaccines 4. live recombinant vector vaccines 5. mrna vaccines
what approach produces an entire viral protein from plasmid to illicit an immune response
recombinant subunit
what approach produces a peptide to illicit an immune response
synthetic peptides
what approach uses plasmid dnas injected that contain a gene encoding a viral antigen of interest
naked dna vaccines
what approach inserts an antigen of interest into a safe virus and infect with the hybrid virus to illicit an immune response
live recombinant vector vaccines
what approach used mrna coated in a lipid shell
mrna vaccines
general procedure for creating recombinant subunit hbv vaccine
grow in yeast, put cloned for heb b surface protein into the yeast plasmid, transform the yeast, isolate surface protein
how do you produce naked dna vaccines
purify out genetic material that encodes surface protein, incorporate into dna plasmid, forcefully insert it using gene gun into muscle
using a recombinant form of vaccinnia, what virus vaccine is dropped in forests to give immunity to animals
rabies vaccine
what virus uses live recombinant vector vaccines using reassortment
flu
advantages of recombinant subunit vaccines
cheapily manufactured at large quantities, most very stable, can use for wide variety of viruses
disadvantages of recombinant subunit vaccines
delivery is hard, post translational modification can be difficult, poor antigenicity
how do edible vaccines work
cut leaf, expose leaf to bacteria carrying an antigen gene qne qn antibiotic resistant gene. kill cells that dont have the new gene. grow plant
what 2 unwanted immune responses might a vaccine cause
th2 immunopathogy (all and adeergic inflamatory response) and ADE (virus uses antibodies to aid in infection)
stage 1
animal studies
stage 2 phase 1
use healthy volunteers and see if they get sick
3 ways to visualize virus particles
electron microscope, transmission em, scanning em, x ray crystallography
how does negative staining work
molds around virus particle, reveals cavities and internal structures
2 types of animal cell culture
- continuous/immortalized 2. primary cell culture
advantages of immortilized cell lines
powerful tool, drug toxicity testing, antibody production
what is continuous cell lines bad to use to study
subtle effects of virus infection, differentiated cell function
properties of immortalized cells
immortal, grow quick, aneuploidy(wrong number of chromosomes)
what is a primary culture
isolated from embryonic fetal tissue and identical to original tissue
properties of primary cells
normal chromosome number, require growth factors, cannot grow in suspension, finite lifetime, may survive in animal
examples of cytopathic effect (CPE)
cell rounding, cell lysis/apoptosis, accumulation of virus components at site of assembly
what does the plaque assay do
determine how many virion particles you’re iteratively adding
pfu
dilution factor * number of plaques
how many pfu in 1 mL of 10^4 dilution given 33 plaques in .1 mL of 10^4 dilution
330 pfu
what is the titer concentration given 33 plaques in .1 mL of 10^4 dilution
33*10^5 pfu/mL
expected range of pfu and moi
pfu around 10^7, moi less than 100 pfu/cell
diffeerence between em and plaque assay
em counts every particle, plaque assay counts infectious particles
hybridization techniques for characterization of viral genomes
northern, southern blot. in situ hybridization
Hoow big are rna virus genomes
small about 10k nucleotides
why is rna genome so small
don’t have proofreading and rna sucks
what do both positive and negative rna viruses encode
RdRP
which viral genome + or - more closely resembles our rna
+ sense
why most - rna viruses encode RdRP
genome is complementary to rna so must copy rna first with RdRP
does double stranded mrna viruses package a RdRP
yes
which types of rna viruses are non infectious
negative and double stranded
what is the initial event in the cell for + sense rna virus
translation
what is the initial event in the cell for- sense rna virus
transcription
structure of polio and + or - ssRNA
non enveloped icosahedral, +ssRNA
how to disinfect for polio
chlorine, hydrochloric acid, heat
describe the first steps of the polio infectious cycle
- virus attaches to PVR
2.binding=conformational change in capsid VP4 - enters cytoplasm through pore
what is unique bout polio translation
cap independent (IRES)
how does polio create so many proteins
proteases chop it up
how does polio use translation inhibition
degrades initiation factors
how does poliovirus assemble
assemble pentamers around rna
how is polio released
lysis
what is an inclusion body related to polio
naked virions become concnetrated near the site of maturation, leading to lysis
what vaccines exist for polio
salk (inactivated trvalent), sabin (attenuated strains). don’t use salbin anymore to avoid the risk of vaccine polio
roadblocks of polio eradication
contagious, ipv in tropical regions is hard, resistance to mass vax, opv can cause polio
structure and genome of rubella
+ssRNA, enveloped helical
hcv structure and genome
+ ssRNA, enveloped icosahedral
examble of rhabdovirus
rabies virus, vsv
how do -ssrna virus get in cell
clathrin mediated endocytosis
where does replication occur for -ssRNA viruses
cytoplasm
strutcure and genome of paramyxovirus
enveloped helical -ssRNA
how does paramyxovirus get in cell
fusion
role of neuromididase for virion release
stops virions from sticking to each other or the cell theyre budding from
how is flu different in regards to rnps
rnps are brought to the nucleus because it relies on cell machinery
how does flu use cap scavenging in transcription
takcell recognizes cap and begins transcriptiones host cap and binds it to biral genome,
assembly of flu
nucleocapsidis transported to cytoplasm, all the proteins come, bud through plasma membrane
antigenic drift is responsible for…
seasonal strains
antigenic shift is responsible for
pandemic strains
why is antigenic shift a concern
reassortment with a non human host, get new N and H proteins (viral attachment proteins)
which strain of flue is more common in non human hosts
influenza a
what is the standard flu vaccine
inactivated
structure and genome of flu
helical enveloped, -ssRNA
does flu or mumps require a rna primer
flu
is flu or mumps nonsegmented
mumps
what polymerase replicate and transcribe rna nuclear viruses
DdDP and DdRP
why is there a risk of dna nuclar viruses integrating into the host chromosme
replicate in nucleus and have dna genome
parvovirus structure and genome
ssDNA, nonenveloped icosahedral
distinct characteristics of parvovirus
dependent on host cell cycle, must become ds before transcription
parvovirus genetics
2 ORFs, 6 rna species
structure and genome of papilliomavirus
naked icosahedral, curcular ds dna
where is uncoating of papylomovirus
nucleus
what is unique about polyomavirus transcritption
there are early promoters and late promoters
what is an early promoter in transcritpion
proteins for replication, regulatory proteins, proteins that alter host cell
how does late mrna synthesis work
uses same primary transcript with alternative splicing
roles of large t antigen
dna replication, increased transcription of late genes, decreaased transcription of early genes, cell transformation
where is assembly of polyomavirus
nucleus
how is polyomavirus relesased
lysis
where does nuclear dna viruses translate mrna
cytoplasm
structure and genome of adenovirus
non enveloped icosahedral, dsDNA. not associated with histones
how does adenovirus get in cell
endocytosis
where does dna get released after uncoating
nucleus
immediate early and early proteins of adenovirus
transcription, dna synthesis, interfere with host anti viral defense
where does adenovirus assemble
nucelus
how is adenovirus different from papillomavirus
encodes its own dna polymerase
herpes structure
enveloped icosahedral, dsDNA
how does herpes pentrate the cell
fusion, partial uncoating in cytoplasm, fully encoded in nucleus
where does herpes replicate
nucleus by viral dndp
