MALARIAL VACCINES

IMMUNE RESPONSE TO MALARIAL PARASITE NAI(Non-adaptive immunity)-protection against the clinical disease

IMMUNE RESPONSE TO MALARIAL PARASITE

IMMUNE RESPONSE TO MALARIAL PARASITE PfMEP1-expressed on infected erythrocytic surface and mediates binding of parasite to receptors(CD36, chondoitin sulfate A(CSA)

AGS WHICH ARE FAVORABLE CANDIDATES FOR VACCINES Accesibilty Induce protective response (memory) Lack/limited antigenic diversity Eg:PfEMP1, Circumsporozoite Ag Combine antigens from different stages Combine several Antigens from a single stage-Eg-MSP1

AGS WHICH ARE FAVORABLE CANDIDATES FOR VACCINES Type of immune response-TH/TC or B-cell response

FACTORS AFFECTING VACCINES Parasite factors Host factors Geographic and social factors drug resistance increase in multiplication rate antigenic polymorphism immunity cytokines genetics( sickle cell trait, MHC locus) age ( no celebral malaria in infants) pregnancy assess to treatment political stability cultural and economic factors trasmission intensity

VACCINE STRATEGIES Anti-infection vaccines- Irradiated sporozoites-usually used for malaria naïve travellers Drawbacks not practical as delivered via a mosquito bite protection for a short period no protection against erythrocytic parasites

MUTANT Hb TAKES THE STING OUT OF MALARIAL INFECTION Thalassemia HbC Modification of Glucose-6-phosphate dehydrogenase Ovalocytosis Duffy Ag–protects against P.vivax infection

VACCINE STRATEGIES Anti- morbidity/mortality vaccines Designed against erythrocytic parasites Drawbacks low immunity induced for a short time

VACCINE STRATEGIES Transmission blocking vaccines Gametocyte –containing blood that is used as the infection source for the mosquito is mixed with serum from animals immunized with human antibodies

TYPES OF VACCINES IN TRIAL Synthetic peptide vaccine Recombinant vector vaccine Recombinant antigen vaccine-RTS,S vaccine DNA vaccine- use of gene gun

MUTANT Hb TAKES THE STING OUT OF MALARIAL INFECTION Sickle cell anaemia seen mainly in Africa,India, Mediterranaean, Middle East 1 in every 13 American blacks are carriers Mutant Hb-S instead of Hb-A Rupture of infected RBC’s and polymerisation of Hb makes it diffucult for the parasite to digest