Parasites Flashcards
Give four examples of Apicomlexa parasites.
Plasmodium, Toxoplasma, Cryptosporidiosis and Eimeria.
Give two examples of Kinetoplastida parasites.
Trypanosoma, Leishmania.
Which organism has the smallest eukaryotic genome?
Microsporidia (fungi)
Give three examples of Trypanosomatid parasites
African Trypanosoma, American Trypanosoma and Leishmania
How do Trypanosomes evade host immune defences?
Antigenic variation
How does malaria evade host immune defences?
Polymorphisms in dominant surface antigens between organisms.
How do amoeba avoid host cell defences?
Degrade complement at the surfaces
How do leishmania and toxoplasma evade host defenses?
Inactivate intracellular enzymes or reactive oxygen species and nitrogen metabolites.
Is chloroquine used to treat malaria?
No, resistant since the 60s
Via which cells does malaria enter the liver?
Kupffer cells
What form of malaria is in the liver?
Schizont
How is malaria released from the liver?
In merosomes packed with merozoites to hide malaria just prior to invasion of RBCs.
In what form does malaria enter the liver?
Sporozite
Which form of malaria cells are activated in the mosquito as blood cools?
Gametocytes. The trophozoites are digested.
What is the mode of action of profilactive antimalarials?
Prevent release of merozoites from the liver.
What is the mode of action of curative antimalarials?
Interference with sexual reproduction.
How can transmission of malaria be blocked potentially?
By blocking sexual reproduction in the mosquito.
List the 5 steps of merozoite entry into erythrocytes.
Attachement Re-orientation Forming tight junction Inwards motion using actinomyosin motor Completion of parasitophorous vacuole
Describe the proteins the merozoite uses to attach to RBCs.
PFEMP1 encoded by the Var family of genes. Only one type is expressed on each parasite, which allows immune evasion.
Describe the steps taken by malaria for formation of a schizont from a zygote.
Zygote become a mobile ookinete, which releases chitinase to break the peritrophic membrane (chitin covering gut epithelium). It forms a cyst where sexual reproduction occurs to form motile sporozytes.
How may rounds of symbiosis gave rise to apicomplexa?
2
How many membranes does apicomplexa have?
4, from 2 rounds of symbiosis
What is the function of the microneme and rhoptry of plasmodium?
Secrete granules to invade RBCs
What is the apicomplast?
Unpigmented chloroplast remnant
Does cryptosporidium (an apicomplexan parasite) have an apicoplast?
No
What does cryptosporidium cause?
Water borne diarrhoea
Does the cryptosporidium have an insect vector?
No
What drug is used to treat cryptosporidiosis?
Nitazoxanide
What is the arthropod vector of Theileria?
Ticks
Which cells does theileria infect?
Leukocyte
How does theileria evade host immune responses?
Prevents apoptosis of the host cell by interferering with NF-kB signalling.
How does theileria ensures it even distribution between the two daughter cells of its host cell during host cell mitosis?
Uses host cell mitotic spindle
