Lecture 13 - Life Cycle Of Sporozoites Flashcards
Where are sporozoites present?
They are present on mosquito salivary glands
Where to the sporozoites travel?
They travel to the liver and invade hepatocytes by binding to HS proteoglycans
What do sporozoites become?
Exocrythrocytic and multiply and burst from liver cells and go into the blood as merozoites
What happens when sporozoites enter the blood?
They mature, divide and rupture the cell and infect new erythrocytes
What are the symptoms of malaria?
The loss of RBCs as they are destroying RBCs
What type of cycle is the erythrocytes symptoms of malaria?
It is an asexual cycle
What do some merozoites differentiate into?
Gametocytes which enter the gut of the mosquito and fertilisation occurs producing a zygote
What does the zygote differentiate into?
An ookinete and crosses the midgut wall and sits extracellularly between the basal lamina and the midgut
What does the ookinete differentiate into?
Into a Oocyst and sporozoites develop inside it
Where do the sporozoites mature?
They mature and invade the hemocoel of the mosquito and then travel to the salivary glands
What happens when the sporozoites travel to the salivary glands?
The mosquito bites a new host and the cycle repeats
How do sporozoites bind when they reach the liver?
They bind via circumsprozoite protein (CSP) which is positively charged to Heparan sulphate proteoglycan on the hepatocyte cell surface
The liver heparan sulphate (HS) is ….
Highly sulphated - more than other cells
What is the interaction between CSP on HS with liver cell surface?
It is a charged:charged interaction
How do the sporozoites identify the liver HS?
Because it is highly sulphated
What are the different forms of HS?
Unsulphated form - GlcNac-1-4 iduronic acid and an over sulphated form - GlcNS6S-14IdoA2S-1-4 (which has 3 sulphates)
What of HS do the mosquitos recognise the most?
The over sulphated form