Quantitative PCR is a useful method for evaluating vaccine induced cell mediated immune responses in frozen PBMC from children in a malaria endemic country.
In an effort to broaden the immune response induced by the RTS,S/AS02A,vaccine, we have evaluated the immunogenicity of the RTS,S antigen when combined with MSP142 and with AMA1, antigens derived from the asexual blood stage.
PfCS102 peptide was safe and highly immunogenic, allowing the design of more advanced trials to test its potential for protection. Two or three immunizations with a dose of 30 µg formulated with AS02A appeared the most appropriate choice for such studies.
Both candidate malaria vaccines were well tolerated. Anti-circumsporozoite responses were greater with RTS,S/AS01E than RTS,S/AS02D and when 3 rather than 2 doses were given. This study supports the selection of RTS,S/AS01E and a 3 dose schedule for further development in children and infants.
This review summarizes the evidence that VSAs are important targets of NAI, discusses why VSA-based vaccines might be feasible despite the extensive intra- and interclonal variation of VSAs, and how vaccines based on this type of antigens fit into the current global strategy to reduce, eliminate, and eventually eradicate the burden of malaria.