Parasite Vaccines & Molecular Diagnostics Flashcards
3 main classifications of parasites
protozoa - microscopic one-celled organisms
helminths - nematodes, trematodes, cestodes
ectoparasites - ticks, fleas, lice, mites
heirloom parasties
inerited form primary ancestors
souvenir parasites
acquired through contact w animals (migration and agriculture; trravel)
neglected tropical diseases helminth
taeniasis/cysticerosis
Guinea worm disease
Echinococcosis
foodborne trematodiases
lymphatic filariasis
soil-transmitted helminthiases
schistosomiasis
onchocerciasis
prozoan neglected tropical diseases
Chagas
Leishmaniasis
human adrican trypanosoiasis
extoparasitic neglected tropical diseases
scabies
other exctoparasites
NTDs
- not a lot of funding
- neglected tropical diseases
- largely preventrable and treatable through efficient delivery of drug treatment, clean drinking water, eradication of vectors, etc.
vaccine against malaria
RTSS/AS01
- >/= 5 months
- Plasmodium falciparum
- Abs against circumsporozoite
- protection short-lived; waning immunity
- transmission unchanged; does not target gametocytes (sexual stage) so children will still carry infection to innfect mosquitoes = does not change population transmission
GVAP
global vaccine action plan
- prevent mmillionso f deats by 2-2- through more equitale access to existing vaccines for people in all communities
- WHO; enjoy lives free from vaccinep reventable diseases
types of vaccines
inactivated : killed version; Hep A, Rabies, flu
live-attenuated: weakened version; MMR
mRNA vaccinesL proteins triggering immune response; COVID-19
subunit, recombinantr, polysaccharide and conjugate vaccines: pieces; S. pneumoniae, Hep B, HPV
toxoid vaccines: toxin iteself; Dip, tetanus
Viral vector vaccines: modified virus to eliver protection; ebola; COVID-19
parasite vaccines
no other effective vaccine against human parasitic infections
- parasites = diverse strategies for immune evasion
- must elicit a response that outperforms naturally acquired immunity
what does RTS,S/AS01 target?
pre-erythrocytic, blood, and mosquito stages of parasite
Leishmania sp vaccine
prophylactic
therapeutic
- currently in development target different species, proteins, strains, etc.
hookworm vaccines
phase 1 clinical trials
- 3 different vaccines
- target larval or adult stage
Schistosoma vaccines
target different proteins or lifecycle stage
serology
antigen detection, Ab detection, hemagglutination, immunofluorescence, etc.
molecular-based approaches to diagnose parasitic infections that are faster and more accurate
real time PCR, loop-mediated isothermial amplification
sequencing
proteomics
why is microscopy still so common today for looking at parasitic infections?
- cost-effective, variety of samples
- ISSUES: time-consuming, labour intensive, staff with specific expertise
when to use serology based assays
when direct exam microscopy not possible (chronic phase of infection = no longer presenting symptoms)
similar TAT to microscopy
more sensitive and specific
highest yield:
- microscopy inconclusive
- low parasitemia/asympt
- low egg production/sporadic nature
- monitoring of parasite clearance
end point PCR
low throughput analysis of 1 target in a single-closed tube
- Leishmania PCR
ENDPOINT PCR BENEFITS
- SIGNIFICANT COST SAVINGS
- MODERATE TATS
- MODERATE LABOUR INTENSITY
- INCREASED SENSITIVITY
real time PCR
- high throughput analysis of 1+ targets in a single closed tube reaction
- allows for quantification of original template NAs through various fluorescent chemistry
- ex: Malaria PCR confirmation
benefits of real time PCR
- significant cost savings
- rapid TAT
- can witness in real time; no need for elctorphoelectrophoresisresis
- less labour intensive
- increased sensitivity
Sanger sequenecing
- rapid high throughput sequencing of gnomes to be carried out in single instrument
- low per nucleotide sequencing cost
- limited use = research
> limited databases
> genome size - potential for novel strain typing, molecular epidemiology and antimicrobial resistance
