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Flashcards in Viro exam 1 Deck (59):

Edward Jenner is credited with creating immunization against?

a. Smallpox
b. Rabies
c. Polio
d. Yellow fever

a. Smallpox


True or False

Electron microscopy is one type of physical virus quantification test?



The gastrointestinal tract has several defense mechanisms to combat viral infection. Which one of the following defense mechanisms is not found in the GI tract?

a. Defensins
b. IgA antibodies
c. Macrophages
d. Mucociliary blanket

d. Mucociliary blanket (found in the respiratory tract)


True or False

Rhinoviruses are viruses of the respiratory tract and cause common cold. Rhinoviruses primarily infect the nasopharynx, and not the alveoli. This is because the nasal passages maintain a higher temperature compared to the alveoli.

False- the other way around. nasal passages have a lower temp facilitating rhinovirus replication, whilst the high temp of the alveoli is not conducive for rhinovirus replication


Which one of the following proteins of enveloped viruses regulates the internal environment of a virus by controlling the influx and eflux of ions?

a. Fusion protein
b. Hemagglutinin
c. Matrix protein
d. Channel protein

d. Channel protein


True or False?

If you discover a new virus in 2017, then the Baltimore classification system would be followed to classify the virus?

False-ICTV system is the standard now


Virulence depends only on the virus?

False-also depends on host factors and environment


Rabies has never been reported before in St. Kitts. Suddenly, a few cases of rabies are reported from St. Kitts, especially among dogs that accompanied incoming RUSVM students from the USA. In this context rabies would be a _______ disease in St. Kitts?

a. Enzootic
b. Panzootic
c. Exotic
d. Epizootic

c. Exotic


True or False?

Hospital acquired viral infection are also known as Nosocomial transmission?



True or False?

Rapid changes in the structure of a viral antigen of a virus over time due to mutations is also known as Antigenic Multiplicity?

False- this is known as plasticity


What is the smallest virus? Biggest?

smallest-porcine circovirus
largest- Poxvirus


What is the shape of the Ebolavirus?

a. Bullet shaped
b. Rod shaped
c. Brick shaped
d. Filament shaped

d. Filament shaped


True or False

The ability of some viruses to alter their shape or size is known as pleomorphism?



Which common morphology method uses computer graphics to create an electron density map to recreate a virus structure?

a. X-ray crystallographic method
b. Cryo-electron microscopy
c. Electron microscopy
d. Nuclear magnetic resonance

a. X-ray crystallographic method


What are the four common methods to determine virus morphology?

1. Electron microscopy
2. Cryo-electron microscopy
3. X-ray crystallographic method
4. Nuclear magnetic resonance


What is the protein shell of a virus that envelopes the viral nucleic acid or genome?

a. Capsomere
b. Envelope
c. Capsid
d. Nucleosome

c. Capsid


Which of the following is not a function of the viral capsid?

a. Uncoating of the genome in the host cell
b. Determines the antigenicity of a virus
c. Interacting with the host cell membranes to form an envelope
d. Increasing the size of the virus

d. Increasing the size of the virus


Which of the following is not a component of a virus?

a. Nucleic acid
b. Capsid
c. Envelope
d. Capsule

d. Capsule


True or False

The viral matrix protein is located between the viral nucleic acid and the capsid?



Which one of the following is not a mechanism of genetic diversity in viruses?

a. Reassortment
b. Point mutations
c. Recombination
d. Conjugation

d. Conjugation


True or False?

Non structural proteins are seen in extracellular virions



What is an incomplete virion?

A virion without nucleic acid.


True or False?

A defective virion contains non-viral genome within the capsid, such as host nucleic acid instead of viral nucleic acid.

False, this is the definition of a Pseudovirion.

A defective virion is a virus that cannot replicate because it lacks a full complement/copy of viral genes.


An incomplete virion is composed of ____?

a. Only nucleic acid
b. Only lipid envelope
c. Only capsid
d. Lipid envelope and nucleic acid, no capsid

c. Only capsid


True or False?

Viruses have the ability to multiply by division?

False- They cannot multiply outside of the host cell. Outside of the host cell the are dormant particles.


What is the best culture system for isolation and propagation of viruses and is also used in producing viral vaccines?

Primary cell culture


Which cell line can be used to produce vaccines?

a. Finite cell lines
b. Continuous cell lines
c. Host cell lines

a. Finite cell lines


True or False?

Continuous cell lines are derived directly from cancer cells?



True or False?

Phenol red indicator changes color of the medium to red when it senses a drop in the pH?

False- Phenol red indicator changes the color to either orange or yellow when it senses a change (fall) in pH


True or False?

A blood ring in an egg shows that the embryo is starting to grow and that the egg is fertile?

False- a blood ring shows early embryonic death


What are the four routes of egg inoculation?

1. Yolk sac inoculation
2. Allantoic cavity inoculation
3. Amniotic cavity inoculation
4. Chorioallantoic membrane inoculation (CAM)


Which of the following is not a physical assay for the quantification of viruses?

a. Electron microscopy
c. Pock assay
d. qPCR

c. Pock assay-biological assay


True or False?

All viruses can exit the host by budding?

False- naked viruses cannot exit the host by budding as they lack an envelope


True or False?

Pathogenesis refers to the ability of a Virus to cause disease in a host?

False. Pathogenicity refers to the ability of a virus to cause disease in a host.

Pathogenesis is the manner/mechanism of development of a disease.


What is the term used to describe the degree of pathogenicity of an infecting virus?



Which is not a defense mechanism that the skin has to fight off viruses entering the host?

a. Dense layer of keratin
b. Dryness
c. High pH
d. Bacterial Flora
e. a, b, d
f. All of the above

c. The skin has a low pH to help keep out viruses


True or False

In a disseminated infection the infection spreads beyond the primary site of infection?



Which type of release of viruses facilitates virus dispersal?

a. Apical
b. Basolateral

a. Apical

Basolateral release provides access to underlying tissues facilitating systemic spread.


What is viremia?

The presence of a virus in the blood.


True or False

Mosquito bites can transmit some some viruses directly to the blood. This is a case of active viremia?

False. This is a case of Passive Viremia. Active viremia requires initial replication of virus in the host.


What is a neurovirulent virus?

a. Viruses that enter the CNS after infection of a peripheral site
b. Viruses that cause disease of nervous tissue, manifested by neurological symptoms and often death
c. Viruses that can infect neural cells. Infection may occur by neural or hematogenous spread

b. Viruses that cause disease of nervous tissue, manifested by neurological symptoms and often death


What is tropism?

The specificity/affinity of a virus for a specific host tissue.


True or False?

Pantropic viruses can replicate in more than one host tissue/organ?



In cell fusion how many cells are fused together by the plasma membrane to produce a larger cell that is prone to premature cell death?

a. 1
b. 2
c. 3
d. 4

d. 4 (4 or more are fused)


What type of inclusion bodies are seen in herpesvirus infection?

a. Negri bodies
b. Owl's eye inclusion bodies
c. Adenovirus inclusion bodies
d. Pigeon's eye inclusion bodies

b. Owl's eye inclusion bodies


In tissue culture, visible morphological changes/damages to monolayer cells resulting from virus infection is also known as ______?

a. Teratogenic effect
b. Cytopathic effect
c. Lethal effect
d. Somatopathic effect

b. Cytopathic effect


What are the two apoptotic pathways?

1. The intrinsic (mitochondrial) pathway
2. The extrinsic (death receptor) pathway


True or False?

Cytotoxic T lymphocytes can also initiate apoptosis of a virus infected target cell?



What are two important tumor suppressor genes?

a. Rb
b. Rs
c. p53
d. p52
e. a and c
f. b and d

e. a and c


What does Rb block?

a. EF2
b. E2F
c. 2EF
d. FE2

b. E2F (E2F facilitates cell division)


In which type of cells does cancer form if infected with a virus?

a. Permissive cells
b. Non-permissive cells

b. Non-permissive cells


True or False?

Replication of oncogenic DNA viruses in a permissive host cell usually causes host-cell transformation and cancer?

False. Replication in permissive cells the replication is able to take place and usually ends in cell lysis.

Replication in non-permissive cells causes host-cell transformation and cancer.


Which one of the following is not a host response to a viral infection?

a. Passive
b. Initial
c. Innate
d. Adaptive

b. Initial


True or False?

Interferons are virus specific, i.e. for each virus there will be a specific interferon?



True or False?

Adaptive immunity only includes cellular response?

False. Adaptive immunity includes cellular and humoral response.


What do neutralizing antibodies bind to prevent virus attachment and entry into the host cell?

capsid or envelope


True or False?

Adaptive immunity is virus specific?



True or False?

Rapid changes in the structure of a viral antigen of a virus over time due to mutations is also known as antigenic multiplicity?


Rapid changes in the structure of a viral antigen of a virus over time due to mutations is known as antigenic plasticity.


What is the mortality rate?

a. The number of deaths among the clinically ill animals.
b. The percentage of animals in a population that develop clinical signs attributable to a particular virus over a defined period of time.
c. The number of animals in a population that die from a particular disease over a specified period of time.

c. The number of animals in a population that die from a particular disease over a specified period of time.