Increased survival time in mice vaccinated with a branched lysine multiple antigenic peptide containing B- and T-cell epitopes from T. gondii antigens.

To develop a multiple antigenic peptide (MAP) vaccine against toxoplasmosis, tri-epitope MAP constructs were made in dimeric fashion. The constructs included one B-cell and two T-cell epitopes derived from Toxoplasma gondii antigens (SAG1, GRA4 and GRA1) situated in tandem through the GGG spacer sequence, with the latter positioned adjacent to a polylysine core. Immunization of BALB/c and Kunming mice with the MAP construct in Freund's adjuvant induced not only humoral immunes response but cellular responses. These responses were accompanied by significant levels of splenocyte proliferation and interferon gamma (IFN-γ) in vitro. After lethal challenge, vaccinated mice had increased survival time in comparison to unvaccinated controls. Our data demonstrate that a MAP construct could trigger strong humoral and cellular responses against T. gondii, and that this MAP is a vaccine candidate worth further development.