The cereolysin AB genes from Bacillus cereus VKM-B164 have been expressed in Bacillus anthracis strains: virulent H-7 (PXO1, PXO2), vaccine STI-1 (PXO1), 221 (without its own plasmids). Expression was achieved by cloning the genes in a high copy number plasmid pE194. This construct was integrated with host genomes in amplified form. Gold hamsters were vaccinated with parental and recombinant B. anthracis STI-1 and 221 strains and challenged with virulent ones subcutaneously. Gold hamsters vaccinated with 221 strains showed, absence of protection. STI-1 immunisation protected against the H-7 strain, but did not protect against the recombinant strain. STI-1 recombinant strain protected gold hamsters against the H-7 as well as the recombinant H-7 strains. The results describe the modulation of immunopathogenic properties of B. anthracis due to expression of cereolysin AB genes.