Week 10 Flashcards
1
Q
Megatrypanosomes
A
- way bigger than typical trypanosomes
- Stercorarian, but live in the bloodstream
- cruzi-like in the insect, brucei-like in the mammal
- Infect a range of mammals
- Only cause disease in otherwise stressed animals (immunocompromised)
- Only 1/ml of blood
- Life-long infection
- genetically look more like T.cruzi
2
Q
What we know about the genome of megatrypanosomes
A
- don’t know much
- live free in the blood, but DON’T have antigenic variation
- have all the genes necessary for
quorum sensing
(function differently than others, more sensitive to density bc. it only likes to have about 1 per ml of blood)
3
Q
Cell surface of megatrypanosomes
A
- Found one large gene family shared with leishmania
- Found a smaller set shared with T. cruzi.
- Four unique large gene families
- glycosylation sites present
- highly expressed
4
Q
Survival strategy of megatrypanosomes
A
- Stealth – too few parasites to bother with
- Cell surface that is variable, sticky and dense (similar to T. cruzi)
- allows for protection against complement and related things
5
Q
T. theileri compared to T. brucei
A
- Same host
- same environment
- same individuals even sometimes
- very different trade-offs
T. brucei - grows to high densities
- causes huge infection
- higher efficiency in transmission but less chances
T. theileri - few organisms
- lower efficiency transmission but more chances
6
Q
Phylum Apicomplexa
A
- most successful and have greatest impact
- not motile (except as gametes)
- All endoparasites of animals
- Many have a spore/cyst stage
- defining feature is the apical complex
7
Q
Apical complex
A
- helps enter host cell
- Present in stages that enter host cells
composed of: - Dense rings at the anterior of the cell
- conoid
- secretory vesicles that act in entry (rhoptries and micronemes), pre-formed and full of all proteins and molecules needed to infect host cell
8
Q
Cell features of Apicomplexa
A
- Dense granules: secretory vesicles for intracellular stage (not associated with apical complex)
- apicoplast: non-photosynthetic plastid (kind of like a chloroplast)
- it has 4 membranes (secondary endosymbiont)
- essential organelle that makes biological building blocks for the parasite
9
Q
Toxoplasma gondii
A
- only member of its own genus
- Infects any warm-blooded animal
- Invades any nucleated cell
- really likes cats
10
Q
Life cycle of t. gondii
A
- ideal cycle is the sexual cycle that occurs in the feline intestine
- it poops out zygotes that turn into cysts
- they live in the environment until ingested
-either taken back into a feline or enters asexual cycle (in mammals/birds) - stays in this host until it gets back into a feline
- if it does not, it is a dead end
11
Q
Infection of T.gondii in humans
A
- healthy people generally no symptoms
Common infection routes: - Undercooked meat
- Contact with cat feces
12
Q
Congenital toxoplasmosis
A
- Occurs when a woman becomes newly (1st time) infected while pregnant
- About 1/3 of fetuses will become infected
- can cause spontaneous abortion, still birth, premature birth, or overt disease at birth
13
Q
Toxoplasmic encephalitis
A
- disease is serious in the immunocompromised
- loss of immune control leads to
recrudescence of latent infections in the eyes and brain - Lesions in the brain causing lethargy, apathy, incoordination, dementia, and convulsions
- acute cases can be treated
14
Q
paratenic host
A
- intermediate host that isn’t required for the life cycle but it still happens
- Substitute intermediate host, not required
15
Q
Mind control and t. gondii
A
- believed that it could be altering paratenic host behaviour to favour consumption by a feline
- rodent literature indicates that T.
gondii infection reduces felid aversion
