Tsetse- trypanasome interactions Flashcards
What are the features of a tsetse fly?
Obligate blood feeders, both males and females blood feed. Develop larva and give birth to live young, have milk glands resembling mammals.
What helps trypanosome survival in the blood?
Antigenic variation - pleomorphic so only slender forms undergo antigenic variation, not stumpy forms.
Outline the life cycle of T. brucei in tsetse flies
Trypomastigote enters midgut with blood meal and differentiates to procyclic trypomastigotes to cross the peritrophic matrix barrier. Epimastigotes colonize the proventriculus organ in anterior midgut.
Epimastigotes differentaite into metacyclic trypomastigotes in the salivary glands and are transmitted during next blood feed.
What challenges are the parasites faced with?
Tsetse are very resistant to tryp infection. Challenges include midgut survival, crossing peritrophic matrix, migration to salivary gland and transmission.
How does age influence tsetse vectorial capacity?
The younger flies are more susceptible to tryp infection. Percentage of parasite after first blood meal is much higher than later blood meals.
What are the factors that challenge or help the parasite in the midgut?
Sialic acid its taken up by the tryp and helps with parasite survival.
ROS and blood complement have a negative effect on parasite survival
EP protein protects the midgut from parasite establishment through molecular mimicry.
Hydrolases in midgut
Symbionts - wigglesworthia has a negative effect on parasite establishment by priming the immune system to make tsetse more resistant
Sodalis has a positive effect - balance impact from wigglesworthia.
What does wigglesworthia produce that is needed by both tsetse and tryp?
Proline and folic acid. Resulting in competition for resources and nutritional starvation.
What part of the midgut do trypanosomes establish infection in?
They breach the PM and establish infection in ectoperitrophic space so they can stick and not be excreted during regular blood meals.
How is saliva affected by trypanosome infection?
Down-regulates many saliva proteins to alter the composition and feeding behaviour.
Few are up-regulated including serpins involved in preventing blooding clotting at bite site.
