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MIIM30014 Virology > Pathogenesis (11,12,13) > Flashcards

Pathogenesis (11,12,13) Flashcards

1
Q

What is FALSE about viral pathogenesis?

a. Many enveloped viruses are stable to low pH and proteases
b. Most viral infections aren’t established to cause illness
c. Many viral particles are sensitive to heat, drying and UV
d. Viruses can still replicate and be transmitted in the absence of symptoms

A

a. Many enveloped viruses are stable to low pH and proteases

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2
Q

What largely determines the course of a viral infection?

a. Specific viral tropism (receptor specificity)
b. The entry route of the virus
c. The immune response of the host
d. The ability for the virus to be passed congenitally

A

c. The immune response of the host

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3
Q

How might a virus enter a host via the skin?

a. Through the bite of an infected animal, like HIV
b. By injection, like rabies
c. By mechanical trauma, like HPV
d. By a mosquito bite, like poxvirus

A

c. By mechanical trauma, like HPV

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4
Q

What is FALSE about entry via the respiratory tract?

a. Defences in healthy people include the muco-cillary escalator, sinus filtering and immune cells
b. Immune responses are largely mediated by IgE
c. Droplets that are larger than 10um often lodge in the nose when inhaled
d. Barriers include alveolar macrophages and a temperature gradient

A

b. Immune responses are largely mediated by IgE

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5
Q

Which virus is unlikely to replicate in the lower respiratory tract?

a. Influenza virus
b. Adenovirus
c. Parainfluenzavirus
d. Rhinovirus

A

d. Rhinovirus

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6
Q

What is a feature of viruses that enter by the alimentary route?

a. Acid stable and resistant to bile salts
b. Envelope for protection in low pH environments
c. Must be able to invade mucosal layer
d. Must not interact with proteolytic enzymes

A

a. Acid stable and resistant to bile salts

d. proteolytic enzymes actually sometimes required

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7
Q

Which virus enters via the alimentary route despite having an envelope?

a. Influenza
b. Coronavirus
c. Rhinovirus
d. Hepatitis A

A

b. Coronavirus

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8
Q

Which virus is MOST likely to invade deep tissue?

a. Herpes Simplex Virus
b. Influenza Virus
c. Papillomavirus
d. Rhinovirus

A

a. Herpes Simplex Virus

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9
Q

What leads to secondary viremia?

a. When the virus in present in the blood
b. When the virus multiplies in secondary lymphoid tissue
c. When passive viremia switches to active viremia
d. When viruses become associated with cells of the immune system

A

b. When the virus multiplies in secondary lymphoid tissue

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10
Q

What does NOT happen at the capillary endothelial cells?

a. Some viruses replicate in the endothelial cells and release progeny into tissue
b. Some viruses cross to tissue using monocytes and lymphocytes
c. Some viruses cross the cells via transcytosis
d. Some viruses activate proteases that degrade tight junctions between the cells, aiding passage

A

d. Some viruses activate proteases that degrade tight junctions between the cells, aiding passage

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11
Q

What can happen during neural spread of viruses?

a. They can only travel within the CNS
b. The uncoated nucleocapsid can passively travel along axons or dendrites
c. Viruses are at risk of CTL attack due to MHC I expression
d. Herpes simplex virus cannot travel back to the epithelium after entering the CNS

A

b. The uncoated nucleocapsid can passively travel along axons or dendrites

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12
Q

How does Rabies virus spread?

a. The virus replicates at the infection site before entering the CNS from the bloodstream
b. It enters peripheral axons by invading the myelin sheath
c. It replicates in myocytes before traveling to the spinal cord through peripheral nerves
d. It has unidirectional movement that allows it to reach the salivary gland

A

c. It replicates in myocytes before traveling to the spinal cord through peripheral nerves
d. Not unidirecitonal movement

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13
Q

What is involved in the infection and spread of Herpes Virus, VZV?

a. VZV utilises viremia before using neural spread to stay latent in the dorsal root ganglia
b. The virus enters the host following an animal bite and replicates in the muscle before utilising neural spread
c. VZV can undergo secondary viremia or spread neuronally and can’t utilise both processes during the same infection
d. Infection is first established in the lower respiratory tract before the viral replicates in the spleen

A

a. VZV utilises viremia before using neural spread to stay latent in the dorsal root ganglia

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14
Q

What is NOT involved in the shedding and transmission of viruses?

a. Viruses of the respiratory tract are most often spread by aerosols
b. HIV can be spread in semen and milk
c. Viruses are often excreted into the faeces from intestinal epithelial cells or the liver
d. CMV is most likely to be spread by mosquito or in cervical secretions

A

d. CMV is most likely to be spread by mosquito or in cervical secretions

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15
Q

• Virulence refers to the “capacity” to produce disease.

A

T

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16
Q

• Most symptoms of a viral infection are due to our own immune system.

A

T

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17
Q

• Symptoms of Norovirus infection last for four days and the virus is only shed during this period.

A

F

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18
Q

• The most common route of viral entry is via the skin.

A

F (RT)

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19
Q

• Droplets that are 5-10um in size usually lodge in the airways when inhaled.

A

T

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20
Q

• HIV cannot enter the alimentary tract through epithelial cells unless there is a breach in the surface, such as in the rectal route.

A

T

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21
Q

• Measles and dengue can spread in CD4+ T lymphocytes to demonstrate cell-associated viremia.

A

F (monocytes)

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22
Q

• Some viruses can be spread vertically from host to progeny by crossing the placenta or via the birth canal during labour.

A

T

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23
Q

• Viruses that cause acute respiratory disease are spread at a high titre for long periods.

A

F (

24
Q

• Enveloped Hepatitis B particles can be shed in the faeces and are extremely infectious.

A

F

25
Q

• Both VZV and Measles can be spread by rash lesions.

A

F (only VZV)

26
Q

What is not a consideration for viral tropism?

a. Receptors must be expressed ubiquitously
b. Accessibility
c. Permissivity
d. Local factors as preventatives

A

a. Receptors must be expressed ubiquitously

27
Q

Why is influenza confined to the respiratory tract?

a. NA is cleaved next to a fusion peptide to become infectious
b. When the endosome reaches pH 9, the fusion peptide changes conformation
c. HA is cleaved by tryptase Clara which is unique to the respiratory tract
d. Furin cleaves HA so it cannot exit the respiratory tract

A

c. HA is cleaved by tryptase Clara which is unique to the respiratory tract

28
Q

Why is H5N1 so virulent?

a. HA cleavage is dependent on the action of tryptase clara
b. There is an insertion of acidic AA residues at the HA cleavage site
c. HA can be cleaved by Furin which is expressed ubuqutiously
d. It doesn’t have a requirement for NA cleavage during virion release

A

c. HA can be cleaved by Furin which is expressed ubuqutiously

29
Q

How can papillomavirus replicate in the skin?

a. By initially transcribing early genes in the mature, apical layer
b. By first transcribing structural genes to establish infection of the skin
c. By utilising cellular tRNAs in the basal layer that translate structural proteins
d. By starting replication in basal germinal cells which have proteins that block transcription of late structural genes

A

d. By starting replication in basal germinal cells which have proteins that block transcription of late structural genes

30
Q

What is an accurate example of a cytocidal virus?

a. During cytoplasmic replication, Pox virus encodes a DNase to act on host DNA
b. Adenovirus encodes protease 2A which cleaves eIF4g to shutdown host translation
c. Rotavirus inhibits transport of cellular mRNA to the cytoplasm
d. Influenza virus encodes tryptase clara which cleaves cellular glycoproteins

A

a. During cytoplasmic replication, Pox virus encodes a DNase to act on host DNA

31
Q

What is FALSE about cytopathic effects of viral proteins?

a. Formation of syncytia is common during measles infection
b. Flavivirus and Rotavirus produce cytoplasmic inclusions
c. Accumulated viral proteins are rarely cytotoxic and aid in diagnosis by microscopy
d. Adenovirus can cause nuclear inclusions

A

c. Accumulated viral proteins are rarely cytotoxic and aid in diagnosis by microscopy

32
Q

What is true about T-cell mediated pathology?

a. Hepatitis B leads to CD4+ mediated responses which leads to a viral rash
b. HCV mediates a CD8+ response that leads to hepatocyte lysis and liver damage
c. Measles can lead to a type IV hypersensitivity reaction and rash due to CD4+ responses
d. CD4+ mediated response of cytokine that recruit eosinophils can clear hepatitis B infection

A

c. Measles can lead to a type IV hypersensitivity reaction and rash due to CD4+ responses

33
Q

Which correctly describes a virus that causes immunosuppression?

a. HIV replicates in CD4+ cells which leads to their demise
b. Norovirus has a non-productive replicative stage that occurs in T cells and macrophages
c. Measles can replicate in dendritic cells and macrophages
d. Rotavirus produces granzymes that lyse CD4+ T cells

A

a. HIV replicates in CD4+ cells which leads to their demise

34
Q

• Poliovirus and Rhinovirus are both enteroviruses which are activated by low pH.

A

F (only polio activated)

35
Q

• Host cells can be damaged by lysis due to the release of non-enveloped viruses and replication cycle of enveloped viruses.

A

T

36
Q

• LCMV has a non-lytic persistence in growth hormone producing cells in pituitary gland and specifically reduce the transcription of growth hormone mRNA.

A

T

37
Q

• Some viruses encode oncogenes whose expression leads to transformation and reduced cell proliferation.

A

F

38
Q

• Antibody dependent enhancement is when cross reactive antibodies neutralise the virus to such high degrees that tissue is damaged.

A

F

39
Q

• HCV affects lymphocytes which impacts antibody production and the formation/deposition of immune complexes with rheumatoid factors leading to tissue damage.

A

T

40
Q

• A CCR5 mutation was selected for during the Black Death and the mutation is associated with HIV resistance.

A

T

41
Q

What would not be used to quantify virulence?

a. Measurement of the reduction of CD4+ T cells following poliovirus infection
b. Mean time to death
c. Mean time to symptoms appear
d. Measurement of weight loss

A

a. Measurement of the reduction of CD4+ T cells following poliovirus infection

42
Q

Which is not a class of viral virulence genes?

a. Gene products that alter the ability to replicate
b. Gene products that modify host defence mechanism
c. Genes that prevent spread in host
d. Toxic viral proteins

A

c. Genes that prevent spread in host

43
Q

What is FALSE about viral gene products that alter a viruses ability to replicate?

a. Mutants can arise that exhibit reduced replication in the host AND cell culture
b. Wildtype viruses only replicate in the host and not cell culture
c. Mutants can arise that exhibit reduced replication in the host but not cell culture
d. An ideal vaccine would be based on a mutant that only replicates in cell culture

A

b. Wildtype viruses only replicate in the host and not cell culture

44
Q

Which statement about viral gene products that modify host defence mechanisms is FALSE?

a. Virokine and Viroreceptors can interfere with host intrinsic defences
b. The genes affect replication and not virulence
c. Most virokine and virorecpetors are encoded for by DNA viruses
d. Viroreceptors are homologs of host receptors

A

b. The genes affect replication and not virulence

45
Q

What is NOT a feature of NSP4?

a. It is produced by Rotavirus and acts as an enterotoxin by increasing calcium in enterocytes
b. It is a non-structural glycoprotein that aids in the formation of the viral envelope
c. It acts as a chaperone during virion assembly
d. It is produced by poliovirus to disassemble the golgi complex

A

d. It is produced by poliovirus to disassemble the golgi complex

46
Q

What is involved in genome recombination?

a. Mixed RNA segments are packaged during assembly to generate diversity
b. Host DdDp switches between two viral genome templates in the same cell
c. A chimeric viral genome is produced from two different viral strains
d. It cannot occur in viruses that produce sub-genomic RNAs

A

c. A chimeric viral genome is produced from two different viral strains

47
Q

Which is a correctly described protein essential in poliovirus virulence?

a. 3AB is cleaved to release 3A and 3B (VpG)
b. 2BC impairs the function of GTPases that regulate COP transfer
c. 3A recruits COPII to facilitate formation of the replication complex
d. 2ABC is a NTPase

A

a. 3AB is cleaved to release 3A and 3B (VpG)

48
Q

Which virus is associated with disassembly of the golgi?

a. Rotavirus
b. Poxvirus
c. Poliovirus
d. Norovirus

A

c. Poliovirus

49
Q

What is involved in the pathogenesis of poliovirus?

a. It manipulates the host secretory pathway to upregulate MHCII
b. It hijacks the host secretory pathway to aid virion production
c. It causes the Golgi to disassemble and prevents cytokine secretion
d. It causes the Golgi to over-produce viral encoded glycosylated proteins

A

c. It causes the Golgi to disassemble and prevents cytokine secretion

50
Q

What is FALSE about ebola pathogenesis?

a. Secreted glycoproteins act as decoys to sequester host antibodies and avoid neutralisation
b. VP35 prevents IRF3 activation to block IFN production
c. VP24 prevents STAT1 entering the nucleus to down regulate IFN production
d. Transcriptional editing results in the production of 10 different glycoproteins

A

d. Transcriptional editing results in the production of 10 different glycoproteins

51
Q

• Poliovirus type 1 won’t infect mouse CNS but poliovirus type 2 is neuro-virulent.

A

T

52
Q

• Dengue virus is the most neurovirulent Flavivirus.

A

F (Japanese encephalitis virus)

53
Q

• Viral virulence can be compared between different viruses if the same assay is used.

A

F

54
Q

• A virus may be neurovirulent if injected to the CNS and not neuroinvasive if injected into the skin.

A

T

55
Q

• A single nucleotide change in the 5’ NCR of poliovirus can reduce neurovirulence.

A

T

56
Q

• RNA polymerase efficiently corrects errors during replication.

A

F

57
Q

• COPII mediates retrograde movement.

A

F

MIIM30014 Virology (23 decks)

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