Abstract: Process for preparing a derivative of the fragment B of diphtheria toxin, which comprises treating an aqueous solution of the diphtheria toxin with an aliphatic mono- or di-aldehyde having a chain length of 1 to 6 carbon atoms at an aldehyde concentration of 0.0015 M to 0.035 M, at 1.degree. to 20.degree. C, for 5 minutes to 50 hours, reacting the toxin, before or after the treatment with aldehyde, in the presence of a compound splitting off di-sulfide bridges, with a proteolytic enzyme, recovering the derivative of fragment B from the solution obtained in the presence of a denaturing agent by protein-chemical isolation processes and separating it from the denaturing agent.

Abstract: The present invention provides a protective antigen from Bordetella pertussis, a process for its preparation by extraction of the pathogens and furthermore products, especially pertussis vaccines, which contain this antigen.

Abstract: The present invention relates to derivatives of tetanus toxin, a process for their preparation by treating an aqueous solution of tetanus toxin with an aliphatic mono- or dialdehyde, reacting the toxin, before or after the aldehyde treatment, with a denaturing agent in the presence of a compound reducing disulfide bridges obtaining the derivative of the light chain in the presence of the denaturing agent by way of protein-chemical isolation processes and suitably separating it from the denaturing agent, and compositions containing said derivatives.

Abstract: An atoxic, immunogenic product obtained by treating tetanus toxin with a proteinase, a process for its manufacture and a tetanus vaccine containing as the essential ingredient said atoxic immunogenic product.