It is our goal to develop and test a series of genetically engineered malaria vaccines and understand the molecular basis for immunogenicity of selected epitopes of Plasmodium falciparum. These studies intend to lead to the formulation of an effective vaccine for human use. The work proposed is based on antigenized antibodies (AgAbs) as a new tools to conformationally constrain oligopeptides suspected to mediate protective immunity and on AgAbs genes for direct immunization purposes. AgAbs genes are engineered to encode in antigenic determinants from P. falciparum parasite in the hypervariable loops of variable region. There are five objectives to this application: Modeling and testing of the dominant B-cell epitope of P. falciparum sporozoite antigen to analyze a series of site-directed mutants of the (NANP)3 epitope using human sera from protected and nonprotected individuals and murine monoclonal antibodies against NANP)n. The scope is to seek the best correlation between primary structure, immunological expression, recognition by the various serological probes and protection either in vitro or in vivo. Development and testing antigenized antibodies expressing a TRAP epitope involved in invasion of hepatocytes using the amino acid sequence WSPCSVTCG considered to confer sulfo- galactosyl-cerebroside (sulfatide) binding properties to CS protein which is considered to be involved in the invasion of hepatocytes by sporozoites. Development of a protective vaccine against the sporozoite and blood stages of P. falciparum infection for the simultaneous elicitation of immunity against sporozoite are blood-stage antigens of the parasite. This will be engineered and tested until satisfactory and reproducible results in vivo are obtained. Studies will be designed at establishing their relative immunogenicity at the B and T cell level, independently. The ability of AgAbs to confer protection will be tested in Aotus monkeys, a strain susceptible to P. falciparum infection. Adjuvanticity studies to test a variety of immunization procedures aimed at enhancing antibody responses such as AgAbs/cytokines chimeras or AgAbs/dendritic cells. Gene immunization to explore the possibility to directly immunize with plasmid DNA of the genomic gene for antigenized antibody encoding for specific P. falciparum epitopes. This new approach may, according to recently publish data, facilitate immunization procedure and yield not only a humoral antibody but also cell-mediated responses of the cytotoxic type. These two effects will be obtained by incorporating either B- or T-cell epitopes in the antibody gene. The overall approach is new characterizes itself over conventional synthetic vaccines for: a) molecular specificity, b) stability and three- dimensionality, and c) concrete possibility to test immunogenicity and protection of various parasite's antigens. The new method constitutes a powerful, simple and inexpensive way to develop effective malaria vaccines.
