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Animal Body 2 > Virology > Flashcards

Virology Flashcards

(66 cards)

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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
What are the 3 things required for virus budding
1. One or more viral membrane proteins 2. One or more viral matrix proteins 3. The viral genome
26
What do viruses use to help with membrane fission
The cell ESCRT pathway
27
List 5 viral spread mechanisms
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
Define cytopathic effect
Any cell abnormality induced by virus infection
29
How do viruses cause CPE?
Shutdown host protein synthesis (cap snatching in influenza virus), apoptosis, permeability changes
30
Define inclusion body
Non-membrane bound organelle comprised of virus components
31
Define syncytium
Cell surface fusion of multiple cells to an infected cell
32
How do you detect viral genome for DNA viruses vs RNA viruses
PCR for DNA RT-PCR for RNA
33
How do you quantify virus infectivity
Assay CPE from titrated samples
34
Which cell types/effectors are seen most immediately after infection with a virus
IFN a/b (type I IFN) and NK cells
35
What are 2 type I IFNs
Alpha and beta
36
What is a type II IFN
Gamma
37
Are IFNs virus specific?
No
38
What is the role of IFNs
They react with uninfected cells to make them resistant to infection from other viruses
39
What are the main producers of IFN alpha
Macrophages
40
What are the main producers of IFN beta
Fibroblasts
41
Which viral genome is best at inducing IFNs
RNA viruses
42
What do macrophages produce to prevent viral infection
IFN-alpha, TNF-alpha and IL-12
43
What do NK cells majorly produce
IFN-gamma (also TNF-alpha)
44
Which cells do NK cells recognize
Those which have down regulated MHCI expression and those which have IgG attached
45
List 3 ways antibodies can neutralize virus infectivity
1. Block attachment to a receptor 2. block virus fusion and entry 3. block uncoating of virus
46
How does the innate immune response contribute to immune-mediated viral disease
IFN/inflammatory response can cause minor symptoms Cytokine storm
47
How does the cell-mediated immune response contribute to immune-mediated viral disease
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
What are poxvirus virulence genes mainly linked to
To subverting host defenses - not necessarily essential for replication
49
Which Sialic acid linkage does avian influenza target?
alpha 2,3
50
Name 3 genetic basis's for host resistance to viral infection
1. host range variation 2. variation in innate genes 3. variation in host genes needed for replication
51
What host gene is involved in resistance to influenza
Mx gene
52
What is different about low and high pathogenic influenza
High pathogenic strains are able to have HA cleaved by ubiquitous proteases, whereas low pathogenic HA can only be cleaved by a few
53
Where are Ag/Ab complexes likely to localize in cases where they are present in excess
Kidney glomeruli, brain, spleen, lymph nodes
54
Virus persistence in the population is ___ from persistence in the host
Independent
55
R0 is defined as....
The average number of new cases arising from one infection in a totally susceptible population
56
Which influenza species majorly affects animals and humans
Influenza A
57
Explain the basis of antigenic drift in influenza
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
Describe the influenza genome and how it contributes to antigenic drift/shift
It is a -ssRNA genome that requires and RdRp (antigenic drift) and is segmented (antigenic shift)
59
How is measles virus persistent
It relies on new susceptible hosts
60
How does EIAV persist
Antigenic variation within the initial infecting population creates new populations to which the host does not have an immune response to
61
List 3 forms of immune evasion
1. antigenic variation 2. hiding (immune privileged site, latency) 3. immunosuppression
62
What is an immune privileged site
Regions in the body that are naturally less subject to immune responses than other areas
63
What are the two disease syndromes cause by BVDV
BVD and mucosal disease
64
When does a calf need to be infected with BVDV for persistent infection to develop
Between 80-125 days in utero
65
When can mucosal disease develop in BVDV
When the non-cytopathic type mutates to cytopathic or the animal is exposed to cytopathic biotype in persistently infected animals
66
What are some stimuli known to reactivate herpesvirus
U.V light, immunosuppression or general stress to the body

Animal Body 2 (6 decks)

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