Protozoan Biology Flashcards
Plasmodium falciparum is vectored by which of the following insects?
-Aedes mosquitoes
-Tsetse flies
-Midges
-Anopheles mosquitoes
quiz
Anopheles mosquitoes
Which of the following parasites are members of the Apicomplexa?
-Plasmodium falciparum
-Cryptosporidium parvum
-Trypanosoma brucei
-Toxoplasma gondii
-Leishmania infantum
quiz
Plasmodium falciparum
Cryptosporidium parvum
Toxoplasma gondii
Which of the following parasites have intracellular stages?
-Toxoplasma gondii
-Plasmodium falciparum
-Human African trypanosomes
-Leishmania ssp
-Trypanosoma cruzi
quiz
-Toxoplasma gondii
-Plasmodium falciparum
-Leishmania ssp
-Trypanosoma cruzi
Toxoplasma gondii: within host cells; T. gondii can invade and infect almost any mammalian cell.
Plasmodium falciparum: within host cells; P. falciparum infects hepatocytes after sporozoite transmission and then proliferates in erythrocytes.
Human African trypanosomes: extracellularly; HATs are free-living within the blood.
Leishmania ssp: within host cells; Leishmania are taken up and reside within phagocytic cells.
Trypanosoma cruzi: within host cells; T. cruzi are taken up and reside within a range of phagocytic and non-phagocytic cells
Human African trypanosomes are vectored by which of the following insects?
-Aedes mosquitoes
-Tsetse flies
-Midges
-Anopheles mosquitoes
quiz
Tsetse flies
What kind of parasites are Plasmodium spp? What are the two most common types? How do they infect hosts?
Plasmodium spp causes malaria
- Apicomplexan parasites
- P. falciparum and P. vivax
- Infected mosquitos injects sporocytes into a human, travel to liver and infect hepatocytes where they multiply, rupture and go into bloodstream and infect blood cells and multiply further, after a couple rounds of this gametocytes form, infected mosquito takes up gametocytes, zygote forms and forms oocyst in gut wall of mosquito, oocyst bursts and travels to salivary glands, infected mosquito injects sporocytes into human
Mosquito> human (for growing)> mosquito (for sex maturation) > mosquito
only females feed on blood!
What kind of parasite is Toxoplasma gondii? How do they infect hosts?
causes toxoplasmosis
- Apicomplexan parasite
- any warm blooded animal is an intermediate host, cat is definitive host
- Cat eats infected intermediate, bradyzoites in gut and form zygote and then oocyst that is released in feces
- Intermediate host eats infected intermediate, feces, or raw meat, in gut bradyzoites and sporozites turn into tachyzoites that infect epithelial cells everywhere, tachyzoites turn into bradyzoites and form cyst in brain, liver and muscle
Cat is where sexual maturation happens
What kind of parasite is Trypanosoma brucei? How do they infect hosts?
Causes sleeping sickness
- Kinetoplasmid parasite
- Tseste flies are vectors
- Tseste fly bites mamal, extracellular so lives in blood stream and multiplies in different areas, fly bites mamal and parasite travels to fly gut and multiplies and then travels to salivary glands
- Use antigenic variation to avoid immune system and infection can take years to develop
binary fisson happens in fly and mamal
What challenges do protozoan parasites have in transmitting between different hosts and vector environments?
- Infecting hosts and specific host cells
- Undergo transmisson
- Gaining nutrients (may have to adapt to new environments)
- Avoid being killed by host
- Maintaining a balance between proliferation, forming a long-term infection and undergoing transmission
How does Plasmidium falciparum avoid immune detection?
Hides in red blood cells, they contain nutrients (ie hemoglobbin) and have no MHCs
What are the four mechanisms of VSG switching?
- Gene conversion (replace A with B)
- segmental gene conversion (replace A with bits of B,C,D)
- Telomere exchange (switch A and B)
- Transcriptional switch (transcribe bit with B instead of bit with A)
How does antigenic variation benefit Trypanosoma brucei?
- antigenic variation prolongs infection
- VSG coat on parasite surface & flagella hides invariant parasite proteins
- VSG coat switches every time immune response gets strong enough to develop antibodies against parasite
- vsg genes undergo high rates of recombination
VSG= varaint surface glycoproteins
How does Plasmodium falciporum and Trypanosoma brucei maximise transmisson whilst maintaining infection?
P. falciporum: survives in human, mates in mosquito
T. brueci: uses quorum sensing to switch coat when theres enough stumpy for transmisson
because obviously stumpy is more recognizable by the immune system and if it has VSG coat A, and then once enough stumpy is generated the slender switches its coat to B to avoid immune detection
How does antigenic variation benefit Plasmodium falciporum?
PfEMP1 protein is encoded by var genes, and var genes have high recombination rates
PfEMP1 is expressed on the surface of infected blood cells, and enables them to stick to other infected blood cells and vasostructures so they avoid the spleen which would kill them
There are three subtypes of T. brucei…
How come T. b. rhodesiense and T. b. gambiense can avoid death by host immune system and T. b. brucei cannot?
Host protein APOL1 enters parasite to kill it
Rhodesiense: can neutralize APOL1 via SRA
Gambiense: prevents APOL1 from accessing membrane via TgsGP
Brucei: doesnt have any defense against APOL1
