Parasites

Question 1

Give four examples of Apicomlexa parasites.

Answer 1

Plasmodium, Toxoplasma, Cryptosporidiosis and Eimeria.

Question 2

Give two examples of Kinetoplastida parasites.

Answer 2

Trypanosoma, Leishmania.

Question 3

Which organism has the smallest eukaryotic genome?

Answer 3

Microsporidia (fungi)

Question 4

Give three examples of Trypanosomatid parasites

Answer 4

African Trypanosoma, American Trypanosoma and Leishmania

Question 5

How do Trypanosomes evade host immune defences?

Answer 5

Antigenic variation

Question 6

How does malaria evade host immune defences?

Answer 6

Polymorphisms in dominant surface antigens between organisms.

Question 7

How do amoeba avoid host cell defences?

Answer 7

Degrade complement at the surfaces

Question 8

How do leishmania and toxoplasma evade host defenses?

Answer 8

Inactivate intracellular enzymes or reactive oxygen species and nitrogen metabolites.

Question 9

Is chloroquine used to treat malaria?

Answer 9

No, resistant since the 60s

Question 10

Via which cells does malaria enter the liver?

Answer 10

Kupffer cells

Question 11

What form of malaria is in the liver?

Answer 11

Schizont

Question 12

How is malaria released from the liver?

Answer 12

In merosomes packed with merozoites to hide malaria just prior to invasion of RBCs.

Question 13

In what form does malaria enter the liver?

Answer 13

Sporozite

Question 14

Which form of malaria cells are activated in the mosquito as blood cools?

Answer 14

Gametocytes. The trophozoites are digested.

Question 15

What is the mode of action of profilactive antimalarials?

Answer 15

Prevent release of merozoites from the liver.

Question 16

What is the mode of action of curative antimalarials?

Answer 16

Interference with sexual reproduction.

Question 17

How can transmission of malaria be blocked potentially?

Answer 17

By blocking sexual reproduction in the mosquito.

Question 18

List the 5 steps of merozoite entry into erythrocytes.

Answer 18

Attachement 
Re-orientation
Forming tight junction
Inwards motion using actinomyosin motor
Completion of parasitophorous vacuole

Question 19

Describe the proteins the merozoite uses to attach to RBCs.

Answer 19

PFEMP1 encoded by the Var family of genes. Only one type is expressed on each parasite, which allows immune evasion.

Question 20

Describe the steps taken by malaria for formation of a schizont from a zygote.

Answer 20

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.

Question 21

How may rounds of symbiosis gave rise to apicomplexa?

Answer 21

2

Question 22

How many membranes does apicomplexa have?

Answer 22

4, from 2 rounds of symbiosis

Question 23

What is the function of the microneme and rhoptry of plasmodium?

Answer 23

Secrete granules to invade RBCs

Question 24

What is the apicomplast?

Answer 24

Unpigmented chloroplast remnant

Question 25

Does cryptosporidium (an apicomplexan parasite) have an apicoplast?

Answer 25

No

Question 26

What does cryptosporidium cause?

Answer 26

Water borne diarrhoea

Question 27

Does the cryptosporidium have an insect vector?

Answer 27

No

Question 28

What drug is used to treat cryptosporidiosis?

Answer 28

Nitazoxanide

Question 29

What is the arthropod vector of Theileria?

Answer 29

Ticks

Question 30

Which cells does theileria infect?

Answer 30

Leukocyte

Question 31

How does theileria evade host immune responses?

Answer 31

Prevents apoptosis of the host cell by interferering with NF-kB signalling.

Question 32

How does theileria ensures it even distribution between the two daughter cells of its host cell during host cell mitosis?

Answer 32

Uses host cell mitotic spindle