Epitope specificities and antibody responses to the EG95 hydatid vaccine

Antibody isotype and epitope specificities were examined in sheep immunized with EG95, a protective recombinant vaccine against hydatid disease. All s heep immunized with EG95 as a fusion protein with glutathione S-transferase (GST) produced prominent IgG antibodies against the EG95 portion of the pr otein. Linear antibody-binding epitope specificities of EG95 were mapped us ing a series of 25 overlapping synthetic peptides. Three immunodominant reg ions were identified which generated specific IgG(1) and IgG(2) antibodies in the majority of vaccinated sheep. These regions corresponded to the EG95 -derived sequences SLKAVNPSDPLVYKRQTAKF, DIETPRAGKKESTVMTSGSA mid SALTSAIAG FVFSC. An additional immunogenic region was identified which induced almost exclusively IgG(2) antibody. This epitope was located within the sequence TETPLRKHFNLTPV. The anti-parasitic, protective effects of the EG95 vaccine correlated with the detection of specific antibody to two or more of the fo ur linear immunogenic regions. The identification of these immunogenic pept ides of EG95 may be useful in the development of a synthetic peptide vaccin e as a derivative of the EG95 recombinant.