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Animal Body 2 > Virology > Flashcards

Virology Flashcards

1
Q

Name 3 routes of pathogen entry

A

Respiratory tract, skin, urogenital tract (also conjunctiva and mouth)

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2
Q

What are 3 barriers of the GI tract against viral infection

A

pH 2, proteases and mucus (also bile salts)

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3
Q

Name 3 viruses that infect GI epithelial cells after bypassing host defense mechanisms

A

Rotavirus, parvovirus and adenovirus

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4
Q

What are 3 barriers of the respiratory tract against viral infection

A

Mucous, ciliated epithelia and secreted IgA

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5
Q

What happens to airborne droplets smaller than 5um

A

They remain airborne for long periods

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6
Q

What happens to airborne droplets larger than 5um

A

They are subject to gravity and get caught in nasal turbinates

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7
Q

Define viremia

A

The presence of virus in the blood after they bypass the lymphatics

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8
Q

Name 2 cell types virions can encounter in the blood

A

Cells of the reticuloendothelial system and vascular endothelial cells

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9
Q

Describe 3 outcomes of virions interacting with reticuloendothelial cells

A
  1. Virus is phagocytosed and presented to the immune system
  2. Virus resists phagocytosis and there is prolonged viremia
  3. Virus replicates after being phagocytosed and causes an increased secondary viremia
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10
Q

At what point/where can viral particles infect vascular endothelial cells

A

If they are localized in the endothelial cells of capillaries and venules at the point where the vascular endothelial barrier is the thinnest

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11
Q

What is intra-axonal spread

A

When a virus enters sensory and motor neurons and travels through them to the CNS

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12
Q

What is a virus, and what makes it different from a bacteria?

A

A small obligate intracellular parasite
The largest viral genome is smaller than the smallest bacterial genome

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13
Q

Capsid + genome =

A

Nucleocapsid

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14
Q

Influenza: genome, enveloped/non-enveloped

A

-ssRNA segmented genome
Enveloped

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15
Q

Rinderpest: genome, enveloped/non-enveloped

A

-ssRNA non-segmented genome
Enveloped

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16
Q

Coronavirus: genome, enveloped/non-enveloped

A

+ssRNA non-segmented genome
Enveloped

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17
Q

What is the smallest virus known to infect birds/mammals and what are its features

A

Porcine circovirus
ssDNA genome (3 genes), non-enveloped

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18
Q

What are anti-receptors on the virus particle called?

A

Virus attachment protein

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19
Q

Define an attachment factor

A

It doesn’t cause a conformational change in an anti-receptor

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20
Q

Speaking broadly, which types of viruses use endocytosis for cell entry

A

All non-enveloped and some enveloped (flu)

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21
Q

Nucleic acid is always read…

A

3’ to 5’

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22
Q

Nucleic acid is always synthesized…

A

5’ to 3’

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23
Q

What are the 7 classes of viruses

A

dsDNA, ssDNA, dsRNA, +ssRNA, -ssRNA, retroviridae, reversiviruses

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24
Q

What causes virus-induced cell lysis

A

Viroporins

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25
Q

What are the 3 things required for virus budding

A
  1. One or more viral membrane proteins
  2. One or more viral matrix proteins
  3. The viral genome
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26
Q

What do viruses use to help with membrane fission

A

The cell ESCRT pathway

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27
Q

List 5 viral spread mechanisms

A
  1. Exit then re-entry
  2. Fusion of PM of infected and uninfected cells
  3. Virus surfing (stays bound to cell membrane)
  4. Induced migration of infected cell
  5. Actin “comet” formation
28
Q

Define cytopathic effect

A

Any cell abnormality induced by virus infection

29
Q

How do viruses cause CPE?

A

Shutdown host protein synthesis (cap snatching in influenza virus), apoptosis, permeability changes

30
Q

Define inclusion body

A

Non-membrane bound organelle comprised of virus components

31
Q

Define syncytium

A

Cell surface fusion of multiple cells to an infected cell

32
Q

How do you detect viral genome for DNA viruses vs RNA viruses

A

PCR for DNA
RT-PCR for RNA

33
Q

How do you quantify virus infectivity

A

Assay CPE from titrated samples

34
Q

Which cell types/effectors are seen most immediately after infection with a virus

A

IFN a/b (type I IFN) and NK cells

35
Q

What are 2 type I IFNs

A

Alpha and beta

36
Q

What is a type II IFN

A

Gamma

37
Q

Are IFNs virus specific?

A

No

38
Q

What is the role of IFNs

A

They react with uninfected cells to make them resistant to infection from other viruses

39
Q

What are the main producers of IFN alpha

A

Macrophages

40
Q

What are the main producers of IFN beta

A

Fibroblasts

41
Q

Which viral genome is best at inducing IFNs

A

RNA viruses

42
Q

What do macrophages produce to prevent viral infection

A

IFN-alpha, TNF-alpha and IL-12

43
Q

What do NK cells majorly produce

A

IFN-gamma (also TNF-alpha)

44
Q

Which cells do NK cells recognize

A

Those which have down regulated MHCI expression and those which have IgG attached

45
Q

List 3 ways antibodies can neutralize virus infectivity

A
  1. Block attachment to a receptor
  2. block virus fusion and entry
  3. block uncoating of virus
46
Q

How does the innate immune response contribute to immune-mediated viral disease

A

IFN/inflammatory response can cause minor symptoms
Cytokine storm

47
Q

How does the cell-mediated immune response contribute to immune-mediated viral disease

A

Cell-mediated immunity contributes to cellular infiltrates and oedema, and in cases where this does not stop once the pathogen is cleared it will cause issues

48
Q

What are poxvirus virulence genes mainly linked to

A

To subverting host defenses - not necessarily essential for replication

49
Q

Which Sialic acid linkage does avian influenza target?

A

alpha 2,3

50
Q

Name 3 genetic basis’s for host resistance to viral infection

A
  1. host range variation
  2. variation in innate genes
  3. variation in host genes needed for replication
51
Q

What host gene is involved in resistance to influenza

A

Mx gene

52
Q

What is different about low and high pathogenic influenza

A

High pathogenic strains are able to have HA cleaved by ubiquitous proteases, whereas low pathogenic HA can only be cleaved by a few

53
Q

Where are Ag/Ab complexes likely to localize in cases where they are present in excess

A

Kidney glomeruli, brain, spleen, lymph nodes

54
Q

Virus persistence in the population is ___ from persistence in the host

A

Independent

55
Q

R0 is defined as….

A

The average number of new cases arising from one infection in a totally susceptible population

56
Q

Which influenza species majorly affects animals and humans

A

Influenza A

57
Q

Explain the basis of antigenic drift in influenza

A

The viral RdRp is very error prone which means there can be a lot of small mutations, this creates sequence variations in HA and NA and makes a strain you were previously infected with pathogenic again

58
Q

Describe the influenza genome and how it contributes to antigenic drift/shift

A

It is a -ssRNA genome that requires and RdRp (antigenic drift) and is segmented (antigenic shift)

59
Q

How is measles virus persistent

A

It relies on new susceptible hosts

60
Q

How does EIAV persist

A

Antigenic variation within the initial infecting population creates new populations to which the host does not have an immune response to

61
Q

List 3 forms of immune evasion

A
  1. antigenic variation
  2. hiding (immune privileged site, latency)
  3. immunosuppression
62
Q

What is an immune privileged site

A

Regions in the body that are naturally less subject to immune responses than other areas

63
Q

What are the two disease syndromes cause by BVDV

A

BVD and mucosal disease

64
Q

When does a calf need to be infected with BVDV for persistent infection to develop

A

Between 80-125 days in utero

65
Q

When can mucosal disease develop in BVDV

A

When the non-cytopathic type mutates to cytopathic or the animal is exposed to cytopathic biotype in persistently infected animals

66
Q

What are some stimuli known to reactivate herpesvirus

A

U.V light, immunosuppression or general stress to the body

Animal Body 2 (6 decks)

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