Parasite vaccines Flashcards
What is a DNA vaccine?
injection with genetically engineered DNA so cells directly produce an antigen, producing a protective immunological response
What is a viral vector vaccine?
Live viruses to carry DNA into human cells. The DNA contained in the virus encodes antigens that, once expressed in the infected human cells, elicit an immune response.
What is a prime boost vaccine?
Immunization with the same immunogen during the prime and booster doses or a regimen of priming the immune system with an immunogen and then boosting with a different immunogen
What are transmission blocking vaccines?
Vaccines that target the sexual stage of the parasite to block the transmission.
Describe irradiated sporozoite vaccines for malaria. What is the immunological aim of these vaccines?
Why do heat killed sporoziotes not work?
Multiple doses of irradiated sporozoites. They must be capable of invading and infecting cells and undergoing a few rounds of normal replication, after this they die and some immunity is conferred.
The aim is to produce T cells (both CD8+ and CD4+) to produce IFN gamma which inhibits the development of the liver stages.
Heat killed- cannot invade hepatocytes and undergo initial development which is the stage thought to confer immunity.
How can we genetically alter malaria and how can this have immunogenic effects?
Can genetically alter malaria parasites e.g. to have DNA strand breaks which cause the genetic arrest of [arasites and in mice, this has been shown to elicit sterile immunity.y
What is the RTS,S vaccine made of? What was seen in the phase III trials?
Circum sporoziote protein repeats PLUS hepatitis B surface antigen. (Plus an adjuvant).
Phase III saw an increased risk of meningitis and cerebral malaria in children BUT not in infants (infants may not have a well enough developed immune system.
Which is another protein which may make a better vaccine than CSP and when is it expressed (malaria)?
TRAP (thrombospondin adhesive protein) expressed as soon as the parasite touches the hepatocyte.
What is the potential malaria blood-stage vaccine?
A vaccine neutralising GPI which is thought to induce the pathways leading to pathology by malaria. Doesn’t necessarily BLOCK infection but should reduce blood parasitemia by producing lots of antibodies.
What is RH5 (malaria)?
A malarial invasion ligand secreted fro apical organelles during the invasion. antibodies against it block invasion.
It is not a target of naturally acquired immunity in endemic areas but level do show a protective correlation.
