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Parasitology > T.bruci AV > Flashcards

T.bruci AV Flashcards

(49 cards)

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1
Q

What is the name of the African trypanosome?

A

T.brucei

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2
Q

What are the two forms of T.brucei?

A

T.brucei rhodesiense

T.brucei gambiense

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3
Q

Which form of T.brucei is the West African form?

A

T.brucei gambiense

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4
Q

Which form of T.brucei is the East African form?

A

T.brucei rhodesiense

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5
Q

Which form of T.brucei has an extensive reservoir in ungulates?

A

Rhodesiense

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6
Q

East African?

A

Rhodesiense

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7
Q

West African?

A

Gambiense

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8
Q

Which form of T.brucei primarily infects humans?

A

Gambiense

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9
Q

Are the East and West African forms morphologically distinguishable?

A

No

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10
Q

Lifecycle stages?

A

1) Metacyclic trypomastigotes are injected
2) Form blood stream trypomastigotes
3) Binary fission
4) Taken up by tsetse fly and become procyclic trypomastigotes in the midgut
5) Binary fission
6) Become epimastigotes as they leave the midgut, move to the salivary gland
7) Binary fission
8) Becomes metacyclic trypomastigotes

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11
Q

How many stages of infection are there?

A

Two

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12
Q

What occurs in the first stage of infection?

A

There is cyclic/relapsing fever

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13
Q

What occurs in the second stage of infection?

A

There is penetration of the blood-brain barrier, they infect the CNS

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14
Q

What are the symptoms of the second stage of infection?

A

Confusion
Loss of coordination
Interruption of sleep cycle

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15
Q

What disease does T.brucei cause?

A

Sleeping sickness

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16
Q

What is the antigenic variant present?

A

VSG

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17
Q

VSG stands for?

A

Variant Surface Glycoprotein

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18
Q

VSG is attached via a?

A

Lipid GPI anchor

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19
Q

Which form is VSG coat not present in?

A

The procylic form

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20
Q

What does the procyclic form have?

Study These Flashcards
A

A procyclin invariant coat

21
Q

VSGs all share a?

Study These Flashcards
A

Conserved tertiary structure

22
Q

VSG coat is internalised every?

23
Q

Where does endocytosis occur?

Study These Flashcards
A

Flagellar pocket

24
Q

The movement of T.brucei generates?

Study These Flashcards
A

Hydrodynamic forces

25
What do the hydrodynamic forces do?
They cause the rearward translocation of VSG
26
VSG antibody complexes move towards the flagellar pocket faster as?
The antibody acts as a sail
27
What is the flagellar pocket?
It is where the flagellum emerges It is where endocytosis takes place It is a membrane invagination
28
What is located posterior to the flagellar pocket, flagellum and basal bodies?
Kinetoplast DNA
29
VSG expression sites are located where?
At telomeres
30
What are VSG bloodstream expression sites?
Polycistronic transcriptional units
31
VSG bloodstream ES are located where?
Telomeres
32
VSG bloodstream ES encode?
VSG gene | ESAGs
33
ESAGs?
Expression Site Associated Genes
34
Expression sites are transcribed by?
RNA Pol I
35
How can VSG expression be switched?
- Expression site switch - Telomere exchange - Duplicative gene conversion - Segmental gene conversion
36
What does duplicative gene conversion require?
5' homology = 70bp repears | 3' homology= part of VSG, conserved 3' region of VSG genes
37
How many VSG genes and pseudogenes are there?
>1500
38
What produces chimaeric/mosaic VSG?
Segmental gene conversion
39
What are telomeres?
Highly recombinogenic regions of the genome
40
Where can VSG genes be located?
ES sites Telomeres Subtelomeres
41
What is always located at the telomeres?
VSG expression sites (ES)
42
Switching from one variant is not random as there is a?
Preferential hierarchy of VSG activation, switch is not a random process
43
What are the mechanisms of T.brucei immune evasion?
- Dense VSG coat - Sheltering invariant surface receptors - Invariant surface receptors in the flagellar pocket - Coat cleaning - Antigenic variation
44
Metacyclic trypomastigotes express what and why?
VSG in preparation for entry into humans
45
How many MC-ES?
~25
46
Similarities between B-ES and M-ES?
Both telomeric | Both transcribed by RNA Pol I
47
Main difference between M-ES and B-ES?
``` M-ES has ~25 ES Promoter directly upstream of VSG gene No ESAGs, only VSG is expressed Inefficient/no gene conversion due to the lack of 70bp repeats Monocistronic ```
48
B-ES is?
A polycistronic transcriptional unit
49
M-ES is?
A monocistronic transcriptional unit

Parasitology (17 decks)

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