Parasitology Flashcards
Why are animal models especially important for the study of parasitic disease?
Parasites depend on a host -> in vitro culture is difficult/impossible
Why is it especially hard to develop good model systems for parasites?
Complex life cycles of parasites require multiple types of interaction
Why is it easier to develop model systems for protozoic parasites than for helminths?
Protozoa share a lot of characteristics with bacteria and are capable of asexual reproduction, whereas helminths require sexual reproduction in a host
Why does the sexual reproduction of helminths make them extra difficult to study?
No clonal population -> higher variation = difficult to study
Which two life cycle stages does Giardia lambia have, and where can they be found?
- Cyst -> infective stage, found in the external environment
- Trophozoite -> replicating stage, found in the intestinal gut
How does Giardia lamblia replicate?
Asexual replication by division
With how many and which cell types does Giardia lamblia interact in the intestinal gut
One cell type -> gut epithelial cells
Why is it relatively easy to culture Giardia lamblia?
Both the external & intestinal environment can be easily mimicked
High quality genome sequencing of Giardia lamblia [is/isn’t] available
High quality genomes are available
Which aspects of Giardia lamblia are often studied using model systems? (2)
- Host-pathogen interaction for different genotypes
- Transmission dynamics
How can trypanosomes be cultured?
By mimicking the various environments they require for their life cycle stages
Which life cycle stages of trypanosomes can be cultured?
- Procyclics
- Epimastigotes
- Long slender form
What is the disadvantage of culturing trypanosomes in a culture system mimicking a particular environment?
Parasites adapt to in vivo culture and often have monomorphic development -> no differentiation to further life cycle stages
How can one validate results obtained from monomorphic trypanosome cultures
By using fresh isolates to compare the results to
Genetic manipulation techniques for trypanosomes [are/aren’t] available
Genetic manipulation techniques are available
Which three types of genetic manipulation are commonly performed in trypanosomes?
- Overexpression
- RNA interference
- Knock-out
What kind of studies are often performed using trypanosome culture systems? (4)
- Antigenic variation
- RNA editing
- Kinetoplast DNA replication
- Host tissue invasion
Which two Leishmania life cycle stages can be cultured?
- Promastigotes = insect form
- Amastigotes = mammalian form
In which conditions can Leishmania amastigotes be cultured?
Mammalian cell lines
What is the disadvantage of culturing Leishmania in specific promastigote or amastigote media?
Monomorphic development
What kind of medium has to be used to culture Leishmania amastigotes, and why?
Acidic medium -> mimics conditions in phagosomes, where they usually reside
How can Leishmania host-pathogen interaction studies be performed?
Culturing them in phagocytic cell lines
Why is it impossible to culture Plasmodium spp. or develop a good animal model?
Their large number of developmental stages cannot be replicated in the lab, and animal models aren’t representative for malaria tropica
Why are animal models for malaria tropica not representative?
Organ failure due to sequestering of red blood cells does not occur
