Immunogenicity of an alum-adsorbed synthetic multiple-antigen peptide based on B- and T-cell epitopes of the Plasmodium falciparum CS protein: possible vaccine application

Multiple-antigen peptides (MAPs), containing B- and T-cell epitopes of the Plasmodium falciparum circumsporozoite (CS) protein, have been designed to overcome the limitations of first-generation peptide vaccines caused by low epitope density, carrier toxicity and the lack of parasite-derived T-cell epitopes. The immunogenicity of a P. falciparum MAP construct (T1B4), containing four copies of the 5′ repeat cell T epitope (T1) combined with the 3′ repeat epitope (NANP)3, has been examined using different adjuvant formulations. Mice immunized intraperitoneally or subcutaneously with (T1B)4 in alum, a formulation suitable for human vaccines, developed high anti-peptide and anti-sporozoite antibody titres, comparable with those obtained with Freund's adjuvant. The MAP/alum formulation also elicited a strong anamnestic antibody response in sporozoite-primed mice, raising the possibility of using a MAP/alum vaccine to increase the low anti-sporozoite antibody levels of people living in malaria-endemic areas.