final exam - virology (copy)

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 cases

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 (Remember, +ssRNA)

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

=Mature virion; 2 membranes

EV poxvirus

Extracellular virion; 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

vaccinia virus 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 sores

HHV4

EBV

HHV5

CMV

herpesvirus lytic infection is in which cells

epithelial

herpes latent infection in which cells

neuronal

Herpesvirus establishes latency by:

LAT exon 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