Abstract: New pertussis toxin (PT) mutants are described being immunologically active and having reduced or no toxicity, characterized in that at least one of the amino acid residues Glu129, Asp11, Trp26, Arg9, Phe50, Asp1, Arg13, Tyr130, Gly86, Ile88, Tyr89, Tyr8, Gly44, Thr53 and Gly80 of subunit S1 amino acid sequence is deleted and substituted by a different amino acid residue selected in the group of natural amino acids; Bordetella strains capable of providing and secreting said PT mutants and means and methods for obtaining them are also described. The Bordetella strains and the PT mutants produced by them are particularly suitable for the preparation of effective cellular and acellular antipertussis vaccines.

Abstract: New analogues of thymopentin (TP5) and of its tetrapeptide fragment (TP5.sup.1-4) containing two non-contiguous retro-inverted bonds in the peptide chain are described which are of the general formula (I) ##STR1## where R is hydrogen or an acyl radical, and R.sup.1 is an --OR.sup.2 group or an ##STR2## group where R.sup.2 is a hydrogen atom or a hydrocarbon radical, and R.sup.3 is a hydrogen atom or a hydroxyl group, and the corresponding pharmaceutically acceptable salts of acid or basic addition, possess immunomodulating activity.

Abstract: The specification relates to a synthetic peptide converted into a salt comprising one or more amine groups and capable of potentiating in vivo the primary and secondary antibody response to thymo-dependent and thymo-independent antigens having low immunogenicity.Injectable preparations comprising a solution of the peptide in a pharmacologically acceptable solvent are particularly useful as adjuvants in therapy.

Abstract: New analogues of thymopentin (TP5) and of its tetrapeptide fragment (TP5.sup.1-4) containing two non-contiguous retro-inverted bonds in the peptide chain are described.The new compounds, of general formula (I) ##STR1## where R is hydrogen or an acyl radical, andR.sup.1 is an --OR.sup.2 group or an ##STR2## group where R.sup.2 is a hydrogen atom or a hydrocarbon radical, and R.sup.3 is a hydrogen atom or a hydroxyl group,and the corresponding pharmaceutically acceptable salts of acid or basic addition, possess immunomodulating activity.

Abstract: The invention is concerned with the use of a compound analogous to tuftsin, having the formula (I) ##STR1## or of a pharmaceutically acceptable base-addition or acid-additon salt thereof, as an adjuvant in order to potentiate, in a living organism, the antibody response against either natural or synthetic antigens, as well as with the novel compositions for vaccines which comprise one or more of said antigens together with an adjuvating amount of the compound of formula (I) or of one of its addition salts.