Toxoplasma

Question 1

Lifecycle

Answer 1

We ingest fecal cysts or tissue cysts
Cysts release bradyzoites
Bradyzoites differentiate into tachyzoites

Question 2

Tachyzoites

Answer 2

Invade host cells
Rapidly divide
Differentiate into bradyzoites which form cysts
Secrete micronemes then rhoptries then dense granules

Question 3

Surface AntiGens (SAGs)

Answer 3

Adhesin
Many SAGs to bind many tissue types

Question 4

Tachyzoite secretion order

Answer 4

Micronemes
Rhoptries
Dense granules

Question 5

MICtroneme proteins (MIC) - Apical Membrane Antigen 1 (AMA1)

Answer 5

Required for invasion
AMA1 is essential so you have to knockdown

Question 6

RhOptery “Neck” proteins (RONs) (esp. RON2)

Answer 6

Secreted into host cell
Receptor for AMA1
Pulls parasite in

Question 7

AMA1-RON2 complex

Answer 7

Coimmunoprecipitate
RON2 and other RONs assemble and pull AMA1 to pull parasite in

Question 8

The moving junction

Answer 8

Filters out host plasma membrane proteins
Prevents activation of the immune system

Question 9

Immune response

Answer 9

Acute phase =
Tachyzoites replicate, lyse cells, spread
Th1 to IFNgamma to activate macrophages
Chronic phase=
Happens when you lose Th1 to IFNgamma
Bradyzoites form tissue cysts

Need a little bit of IL10 or you get cytokine storm and death

Question 10

ROP16 kinase

Answer 10

T1 = high virulence by inhibiting proinflammatory response
T2 = low virulence

Question 11

PAMPs and PRRs

Answer 11

GPIs of SAGs - TLR2/4

Question 12

Why is IL10 required?

Answer 12

So you don’t get cytokine storm and death