A recombinant auxotrophic vaccinal BCG Pasteur strain complemented to leucine amino acid expressing a Schistossoma mansoni Sm14 protein, i. e. rBCG Pasteur [Delta]leuD/p[Delta]K410-hsp60*-Sm14, said vaccinal strain being obtained according to the following steps: (a) amplification by PCR of a fragment containing an Sm14 expression cassette containing a modified hsp60* promoter, using - a pAU5-Sm14 vector as template, said vector having a modified hsp60 sequence which has a deletion of four base pairs immediately upstream of the promoter region in combination with the loss of the first base pair of the hsp60 promoter sequence and is designated therefor as hsp60*, and - primers PSm14F, i.e. TAT ATA TAT ATA TAG GCG CCA CCA CAA CGA CGC GC - SEQ ID NO:3 and PSm14R, i. e. CGC GGG CGC CTT AGG ATG ATC GTT TAT A - SEQ ID NO:4; (b) digestion with a NAR1 enzyme of an amplicon of 816 bp, i. e. hsp60*-Sm14, obtained by the PCR amplification of step (a), providing a hsp60*-Sm14 amplicon; (c) cloning of the hsp60*-Sm14 amplicon obtained in step (b) in a pUP410 vector digested with the Nar1 enzyme, giving rise to a pUP410-hsp60*-Sm14 construct; (d) evaluating an ability of the construct pUP410-hsp60*-Sm14 to express the Sm14 protein in Mycobacterium vaccae; (e) removing the kanamycin resistance gene from the pUP410-hsp60*-Sm14 construct by digestion with an endonuclease restriction HindIII; and (f) re-circularization of the digested pUP410-hsp60*-Sm14 construct without the kanamycin resistance gene using T4 ligase to produce the digested pUP410-hsp60*-Sm14 construct, which is used to transform a BCG Pasteur auxotrophic strain, i. e. BCG [Delta]leuD, to produce a recombinant auxotrophic BCG Pasteur strain complemented to leucine amino acid expressing a Schistossoma mansoni Sm14 protein, i. e. BCG Pasteur [Delta]leuD/p[Delta]K410-hsp60*-Sm14. (a) amplification by PCR of a fragment containing an Sm14 expression cassette containing a modified hsp60* promoter, using - a pAU5-Sm14 vector as template, said vector having a modified hsp60 sequence which has a deletion of four base pairs immediately upstream of the promoter region in combination with the loss of the first base pair of the hsp60 promoter sequence and is designated therefor as hsp60*, and - primers PSm14F, i.e. TAT ATA TAT ATA TAG GCG CCA CCA CAA CGA CGC GC - SEQ ID NO:3 and PSm14R, i. e. CGC GGG CGC CTT AGG ATG ATC GTT TAT A - SEQ ID NO:4; - a pAU5-Sm14 vector as template, said vector having a modified hsp60 sequence which has a deletion of four base pairs immediately upstream of the promoter region in combination with the loss of the first base pair of the hsp60 promoter sequence and is designated therefor as hsp60*, and - primers PSm14F, i.e. TAT ATA TAT ATA TAG GCG CCA CCA CAA CGA CGC GC - SEQ ID NO:3 and PSm14R, i. e. CGC GGG CGC CTT AGG ATG ATC GTT TAT A - SEQ ID NO:4; (b) digestion with a NAR1 enzyme of an amplicon of 816 bp, i. e. hsp60*-Sm14, obtained by the PCR amplification of step (a), providing a hsp60*-Sm14 amplicon; (c) cloning of the hsp60*-Sm14 amplicon obtained in step (b) in a pUP410 vector digested with the Nar1 enzyme, giving rise to a pUP410-hsp60*-Sm14 construct; (d) evaluating an ability of the construct pUP410-hsp60*-Sm14 to express the Sm14 protein in Mycobacterium vaccae; (e) removing the kanamycin resistance gene from the pUP410-hsp60*-Sm14 construct by digestion with an endonuclease restriction HindIII; and (f) re-circularization of the digested pUP410-hsp60*-Sm14 construct without the kanamycin resistance gene using T4 ligase to produce the digested pUP410-hsp60*-Sm14 construct, which is used to transform a BCG Pasteur auxotrophic strain, i. e. BCG [Delta]leuD, to produce a recombinant auxotrophic BCG Pasteur strain complemented to leucine amino acid expressing a Schistossoma mansoni Sm14 protein, i. e. BCG Pasteur [Delta]leuD/p[Delta]K410-hsp60*-Sm14.