Studied by 175 people
includes questions from all tests (that could be converted). Only half questions from ch 2 because there were missing questions on the key
Which organisms can be infected by viruses?
All of them
True or False: Viruses are small enough to pass through a 0.2 micron filter
True
Do all viruses have envelopes?
No
What was a major advancement in virology that allowed us to examine the lifecycle of viruses?
Development of viral tissue culture
How far back in time did viruses originate
4 billion years ago
Viruses that are enveloped obtain this structure from which part or parts of the host cell?
Plasma Membrane
What proteinaceous structure connects the capsid to the envelope
Matrix
Highest to lowest order of the rank system
Realm, Order, Family, Genus, Species
Baltimore Classification System is based off of what viral component
Viral nucleic acid within the virion
What enzyme must all RNA viruses bring into the infected cell with them for the life cycle?
RNA-dependent RNA pol
In the Hershey-Chase Blender Experiments the S35-labled protein of the bacteriophage was found where in the progeny phages?
Not found
Strain
Genetically stable virus that differs from the parent strain phenotypically
Variant
Virus that contains mutations from the parental strain
Baltimore class that uses a reverse transcriptase
Class 6
Baltimore class that can immediately be translated by ribosomes
Class 4
Viral tropism
Types of cells that a virus can infect
Viral tropism is controlled by
Cell surface receptors
What percentage of the human genome consists of defunct endogenous retroviruses
10
What are some ways viruses resolve the competition between host mRNA and viral mRNA for translational machinery
degrading host mRNAs, contain elements in viral mRNA to increase affinity to ribosome, cleave and obtain host cell mRNA caps
What amendment did Fredricks and Relman make to Koch's and River's criteria for linking a virus to a particular disease
Detection of viral nucleic acids in diseased organs but not in unaffected organs
In a standard clinical virology laboratory setting, which techniques are routinely performed for rapid identification
elisa and pcr
Most antivirals are designed to impair which component of a virus
viral enzymes
What do cells do natural killer cells recognize
cells that show reduced expression of mhc I on their surface
What two major cell types can eliminate viral cells through apoptosis
Natural killer and CD8+ T-cells
Innate immunity
general non-specific defense against pathogens
secondary immune response
immunological memory
phagocytosis
uptake and killing of microbes
What do pathogen recognition receptors do
identify viral pathogens
What do Toll-like receptors do
they are sensors capable of detecting characteristics unique to a virus
Dendritic cells
Express high levels of mhc i and ii molecules and function as scouts to identify pathogens at the body's surfaces and mucosal sites
How do viruses evade host defense
mutate outer surface proteins, latency, inactivate cytokine signaling, inactivate immune cells
Major function of MHC II
presents peptides derived from engulfed viruses
What happens when ds-RNA-activated protein kinase (cellular altruism) is activated in a virally infected cell
Viral RNA degradation and host RNA degradation
Virally infected cell will present foreign antigens on where?
MHC I
Virally infected cells are recognized by which cell type?
CD8
If you were performing a Viral Detection ELISA, what would be coated on your 96-well dish
Antibody specific for viral pathogen
How are live-attenuated viruses produced
a virus is immediately repeatedly cultured in nonhuman cultured cells or animals
What results would indicate the highest viral levels in a RT-PCR
Ct of 10
Prevalence
total number of casesI
Incidence
new cases
Toll-like receptors recognize viral
RNA or DNA
What proteins are secreted following the activation of TLRs
cytokines
Three corners of the epidemiological triangle
host, agent, environment
longitudinal study
study that examines individuals over time
Once ingested polioviruses initially invade which two tissues
peyers patchers or tonsils
what percentage of cases are asymptomatic in polio
95%
Where does the polio lifecycle occur
the cytoplasm
What would happen in the rna genome of poliovirus was transfected or delivered directly in to mouse cells
Rna genome would be translated by host ribosomes into a polyprotein
IRES stands for
Internal Ribosomal entry site
What does the IRES do
Permits translation of poliovirus RNA without the need for a 5' 7-methyl G cap
What attributes of the IRES facilitates and enhances its function
Contains extensive regions of secondary stem-loop structures binding to translation factors
A poliovirus with a mutated VPg would be unable to
initiate replication
The poliovirus 2A protein has numerous functions that includes a role in
polyprotein processing and inhibiting host cell transcription
What poliovirus polypeptide is structural
VP4
What poliovirus polypeptide is a polymerase
3D
In poliovirus the cloverleaf structure at the 5' end is critical for binding what factors to initiate replication
VPg and 3D
Why is the Sabin vaccine no longer used in the US
potential risk of contracting paralytic polio
What receptor on the cellular surface is bound by the H glycoprotein of the influenza virus
sialic acid
Why do influenza viruses not need to code for or contain a protease
mRNA molecules are produced that code for a single protein
Influenza A host range
humans, pigs, horses, birds, and marine mammals
Which influenza is responsible for pandemics
A
Who is the sole host of the influenza B virus
humans
Where does uncoating and membrane fusion of influenza take place
inside endosomes
Which influenza viral protein is involved in viral shedding
Neuraminadase
Which influenza protein functions as an ion channel
M2
T or F; Antibodies against hemagglutinin function would reduce virion release from infected host cells
False
Hallmark clinical characteristic of rabies
hydrophobia
Standard and immediate post-exposure treatment of a recent bite wound from an animal with rabies virus can include the following
immunoglobulin treatment and vaccine administration
Rabies virus replicates within the ______ following transport from the ______
Cell body; axon
How does rabies virus escape detection from the immune system
RVP antagonizes IFN responses
A rabies virus with a nonfunctional L protein would primarily be unable to
Cap or polyadenylate viral mRNA
which of the following is a known receptor for rabies virus entry
nAch receptor
Where is the nAch receptor located in the neuromuscular junction
postsynaptic junction
Which animal propagates the most human rabies related deaths in Asia
dogs
Which animal propagates the most human rabies related deaths in the US
bats
Poxvirus genome
linear dsDNA, ITRs at the end of the genome, encodes at least 200 genes. dumbbell shaped core with nucleic acid, virion contains lateral bodies with various enzymes
Where does the poxvirus replication occur
cytoplasm, dependent on viral pol
MV poxvirus
2 membranes
EV poxvirus
1 membrane
Poxvirus genomes code for which enzymes
dna dependent rna pol VETF capping enzymes methylating enzymes
poxvirus gene is regulated by
viral promoter regions
Early mRNAs of poxvirus code for
viroreceptors and virokines
late mRNAs of poxvirus code for
early transcription factors and structural proteins
poxvirus immune evasion
inhibit complement, inhibit cytokines, inhibit chemokines, and block cytokine receptors
why do pustules and vesicles appear in poxvirus
virus invades the capillary epithelium of the dermal layer of the skin
Where is the distribution of pustules and vesicles in poxvirus
arms and face
why was variola a good candidate for global eradication
narrow host range, genetically stable, surveillance of the disease was easy, disease is acute and self-limiting
Dryvax vaccine
originally derived from horsepox, cultured on the skin of calves and freeze dried
TPOXX
blocks action of wrapping protein
HHV2
genital herpes
HHV1
Mouth cold soresH
HHV4
EBV
HHV5
CMV
herpesvirus lytic infection is in which cells
epithelial
herpes latent infection in which cells
neuronal
Herpesvirus establishes latency by:
LAT expression, microRNA species limit HSV early gene expression, virus persists as an episome
HSV-2 establishes latency where
sacral ganglia
HHV3 establishes latency where
spinal nerves
reactivation of herpesvirus is associated with
physical and emotional stress, UV exposure, pregnancy
Receptor for herpes
heparan sulfate
Note
Flashcard