Malaria-mosquito interactions Flashcards
What are the stages of blood feeding behaviour?
Exploratory phase finding the host, probing, imbibing (engorged and diuresis) and withdrawal.
What is pre-diuresis?
Only in anopheles (smaller) - she sorts the plasma to remove fluid and keep blood cells = liquid comes out of anus.
Makes blood meal 1.5 x more concentrated - more space for more protein.
What does the female salivary gland have, that males do not?
Lateral lobes are not in males, and apyrase enzyme in the distal region.
What is the role of apyrase?
Blocks ADP induced platelet aggregations. So the blood does not dry up at the bite site to allow a full and efficient feed.
What is vitellogenesis?
The process of vitellogin (yolk) that is produced in the fat body and carried in the haemolymph to the ovaries to produce the egg.
In the ovaries, where is the vitellogin endocytosed?
The oolema membrane around the egg has receptors to endocytose Vg
What is the association between sporozoite or oocyst presence and persistence?
When sporozoite is present few mosquitoes gave up trying to blood feed when brushed away.
When oocyst is present, more mosquitoes give up, as at this point the parasite does not want to be transmitted.
How does sporozoite presence affect probing?
There is increase probing, because apyrase is reduced so platelets are produced and the bite site heals rapidly, therefore the mosquito transmits parasite, and has to move onto next host as doesn’t achieve full blood meal from first host.
What happens when the parasite traverses through the midgut epithelial cells?
Damage to cell, and the cell produces NOS which then forms peroxidases which results in apoptosis through protein nitration.
Rapid process so if parasite is not out of cell quick enough then it dies.
How does plasmodium reduce the mosquitoes reproductive fitness?
It reduces the Vg transcription when oocysts are present, then Vg builds up in haemolymph as Vg cannot get to the ovaries.
There is increase apoptosis and resorption of ovarian follicles.
How do PAMPs affect infection of vector?
LPS and GPI from plasmodium results in upregulation of immune gene expression and reduction in number of eggs produced.
Why might it be beneficial to the parasite to reduce mosquito reproduction?
The mosquito may live long if reproducing less so the parasite has more time to develop to sporozoite and migrate to salivary glands for transmission.
What is the role of insulin/insulin like signalling pathway in mosquitoes?
it regulates reproduction, lifespan, metabolism and pathogen resistance.
How does infection affect the insulin signalling pathways?
It changes the carbohydrate metabolism and increase glycogen levels.
