Parasites/Malaria Flashcards
What are the 2 classes of parasites?
is there a comparison between gene number & complexity?
what organelles do parasites contain?
why are secretory organelles needed?
what is the plastid? how can this be used to prevent malaria?
what do some parasites not have? so how are proteins made?
unicellular eukaryotes = microparasites
multicellular eukaryotes = macroparasites
no
mitochondria, ribosomes, genome etc, secretory organelles & plastid
parasite can replicate & evade immune system & secrete proteins into host
no longer photosynthetic- encodes bacterial proteins & ribosomes
antibiotics (derived from endosymbiotic event)
mitochondria- have mitosome
no genome
no ribosomes
proteins made in cytoplasm & translocated into mitosome
What is the plastid in malaria?
how many membranes?
where did it evolve from?
apicoplastid
4
- primary endosymbiosis of eukaryotic cell engulfing cyano & become red algae
- red algae engulfed by euakryotic cell
what is the Cyrptospordium life cycle?
why is diarrhoea better for the parasite?
what is better than parasite drugs?
ingested in food- enters cells of small intestine & releases oocysts which released into faeces back into environment
aids transition into environment
controlling the vector- e.g mosquito nets
what is the 5 step malaria life cycle?
where do symptoms take place in cycle?
how can you diagnose malaria by microscopy? why is it unideal?
what is a better way to diagnose it?
- parasite/sporozoite migrate into liver & replicate (no symptoms)
- burst into blood & replicate in red blood cells- bursts out
- can re-invade RBCs or differentiate into gametocytes
- gametocytes are taken up by mosquito when bites again
- in mosquito, male & female gametocytes differentiate to form zygotes (on fusion) = sporozoites- ready for infection
when burst into blood from liver = erythrocytic stage
take blood smear/sample & stain with Giemsa- expensive, trained user
rapid diagnostic test- HRP2 which is taken at erythrocytic stage
how do HRP2 rapid diagnostic tests diagnose malaria?
what are the steps for using it?
how does it work?
how does the control work?
HRP2 is a protein made by parasite & exported into red blood cells & when they burst they enter blood
put buffer in hole, blood in square
- blood & buffer mix- buffer contains detergent which breaks open RBC and parasites to release more HRP2
- anti gold HRP2 antibodies immobilised on strip & HRP2 bind to them
- strip turns pink as the complexes accumulate
control antibodies are also immobilised & recognise the anti-HRP2 antibody (gold) but without HRP2 so control strip turns pink too
What is antigenic variation in parasites?
why can trypanosoma brucei evade the immune system’s antibody response?
what are these controlled by?
how can the expression site switch VSG expression?
how can you switch expression site with array conversion?
telomeric VSG conversion?
segmental VSG conversion?
one parasite express new coat so when immune system kicks in & produces antibodies against old antigens- new one will survive- cycle
VSG densely packed on surface so igG antibodies cant access plasma membrane - keep varying the VSGs
blood stream expression sites- many on different chromosomes but only 1 expressed at one time
switch off w histone modifications & switch on with histone modifications
copy silent VSG DNA into active blood stream expression site (DNA repair pathway)
with DNA repair pathway take end of telomere/chromosome & copy into expression site
take fragments different VSG & assembly into 1 complete VSG gene & copy into blood stream expression site (DNA repair pathway)
What different lifecycle of malaria could you focus on for the vaccine?
What is the RTS,S vaccine based on?
how does the vaccine work?
Sporozoites, liver stage, RBC stage (HRP2)
based on CS protein on surface of sporozoites
made of fragment R3 which codes for CS & is fused to hepatitis B protein- produce virus like particle but without parasitic DNA & immune system stimulated with adjuvant lipid A & saponin
Making the malaria vaccine in a mouse model for pre-erythrocytic stage (liver)—–
what is the 1st step?
what do you do after to check?
what do you do after?
how could you find out if you knockout the gene if you can still generate sporozoites?
what are the cons of using this as a means of vaccination?
find gene essential for parasite to grow in the liver = UIS3
knockout gene & check if parasite makes it to liver & no further
subject mice with UIS3- parasites (gene knocked out) if are protected against infection & compare with wildtype parasites
allow mosquitos feed on mice infected with UIS3- parasites & convert this stage parasite to sporozoites in salivary gland & stain liver- parasites make it to liver & still form sporozoites but don’t replicate in liver
making lots of sporozoites = expensive
liver parasites = cold storage & expensive & unideal
What is the merozoite stage?
what interaction is needed for merozoites to interact with RBCs?
how can you use this to make a vaccine?
blood stage after liver
RH5 proteins on merozoites & Basigin cell receptor on RBC
use RH5 as a vaccine to produce anti-RH5 antibodies to physically block the interaction
What information can be used to make transmission blocking vaccines?
what protein is present on these?
how can you make a vaccine?
what is SMFA?
how does it work?
Gametocytes which cause transmission as fuse into sporozoites
PFS48/45
make anti-PFS48/45 antibodies- so when taken up by mosquito & in midgut- they will bind onto gametocytes so they can’t fuse & form sporozoites
standard membrane feeding assay- test for transmission blocking
allow mosquitos to feed on blood of gametocytes- measure the uptake
then add antibodies into serum & see if block development of parasites
