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Immunology > Malaria > Flashcards

Malaria Flashcards

1
Q

what is the pathology of malaria

A

recurrent fever, parasites in peripheral blood smears, enlarged spleen, TNF induction, glomerulonephritis, cerebral malaria

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2
Q

which antigen confers resistance to P.virax malaria

A

Duffy antigen

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3
Q

what confers resistance to Plasmodium falciparum

A

unfavourable conditions eg sickle cell anaemia, glucose-6-phosphate dehydrogenase deficiency and ovalocytis

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4
Q

how is the infection acquired

A

through mosquito vectors derived through the bite and into the blood

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5
Q

what does the parasite first enter as

A

sporozoite

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6
Q

what cells do sporozoites infect

A

liver cells

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7
Q

for how long do sporozoites replicate in liver cells

A

10-16 days

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8
Q

when are sporozoites released

A

after differentiation

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9
Q

what is the new form of sporozoite which is released from liver cells

A

merozoite

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10
Q

what cells do merozoites infect

A

red blood cells

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11
Q

what form has the highest pathogenicity

A

merozoites

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12
Q

why does host develop cyclic fevers when merozoites infect RBCs

A

due to RBC bursting peridically so merozoit can infect more cells

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13
Q

how does the parasite replicate in liver cells and RBCs

A

asexually

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14
Q

how soon do symptoms appear after being bitten

A

10-15 days

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15
Q

which species of malaria parasite causes the most deaths

A

p. falciparum

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16
Q

what is the liver phase called

A

the exoerythrocytic phase

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17
Q

what is the RBC phase called

A

erythrocitic phase

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18
Q

how does the parasite escape undetected from liver cells

A

by wrapping itself in cell membrane of infected liver cell

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19
Q

what do some of the merozoites a sexually divide into

A

schizonts

20
Q

what do merozoites which do not divide asexually into schizonts do

A

differentiate into sexual forms called gametocytes

21
Q

what form is taken up by the mosquito when it feeds on blood

A

gametocytes

22
Q

what is produced when the male gametocyte undergoes rapid nuclear division

A

8 flagellated daughter cells called microgametes

23
Q

where do gametocytes mature

A

in the mosquito gut

24
Q

what is produced when female and male gametocytes fuse

A

ookinete

25
Q

after the ookinete develops to form a oocyst what happens

A

the oocyst ruptures, releasing 100s of sporozoites into mosquito body which migrate to salivary glads

26
Q

how does a lack of the duffy antigen confer resistance to p. vivax

A

the duffy antigen is the receptor used by p. vivax merozoites to enter RBC

27
Q

what are the reasons for lack of adaptive immuniy to malaria

A

antigenic diversiy between species, strains and stages
‘hiding’ in RBCs
little T cell memory
misdirection or supression of immune response

28
Q

what is the immune response to sporozoites in the pre erythrocytic stage (stage 1)

A

sporozoites are in blood so vulnerable to sera antibodies which prevent invasion and motility and all of anti-sera reacts to circumsporoite protein

29
Q

what is the repeat found in the highly antigeneic repeat sequence of the circumsporoite protein

A

NANP or NVDP

30
Q

what is thought to be th reason for variation in the repeats of the repeat region in csp

A

decoy antigen

31
Q

what is the immune response to pre-erythrocytic stage in the liver (stage 2)

A

parasite Ags expressed on hepatocyte surface causing specific CD8+ response as well as induction of IL-1 IL-6 IFNg and TNF and ntrogen oxide

32
Q

what is the immune response to erythrocytic stages

A

initially TH1 response, releaseing cytokines incl IFNg to induce cell mediated response
later TH2 induce Ab dependant response

33
Q

what is the immune respose to the merozoites stage 1 of erythrocytic stage (extracellular stage)

A

elicits antibody responce blocking invasion into RBCs

antibodies respond to antigens on surface eg MSP-1 and Ags released by organelles

34
Q

which protein aside from CSP has highly variable regions which potentially serve as a decoy

A

MSP-1

35
Q

what is the immune response to trophozoites, stage 2 of erythrocytic pathway (in RBCs)

A

infected cells express proteins on RBC surface eg PfEMP-1 so Ig response to these block cytoadherance

36
Q

what are the 2 ways fevers are induced in malaria

A

contents of burst RBC may be phagocytosed activating release of cytokines IL-1 and TNF.
GPI anchored proteins on parasite surface activate macrophage release of cytokines

37
Q

how does periodic fever benefit the person suffering from malaria

A

inhibits parasite growth however aids parasite synchronisation and survival so fever switches off when levels fall below threshold as safeguard mechanism causing it to be periodic

38
Q

how might TNF regulate parasite growth

A

negative feedback mechanism

39
Q

what is the effect of IFNg on TNF

A

TNF is potentiated

40
Q

what percentage of infections lead to cerebral malaria

A

1%

41
Q

what is the clinical patholog of cerebral malaria

A

coma

42
Q

what causes coma in cerebral malaria

A

accumulation of parasitised RBCs in capillaries of the brain, blocking normal blood flow

43
Q

which receptor is found to be upregulated in cerebral malaria

A

TNFR

44
Q

at what level does antigen diversity occur

A

population level

45
Q

at what level does antigen variation occur

A

individual level

Immunology (11 decks)

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