Abstract: The invention concerns peptides derived from helimomicine by substitution of one or several amnio acids, characterised in that the peptides correspond to formula (I) : X1, X2, X3, X4, X5, X6, C7, X8, X9, X10, X11, X12, X13, X14, X15, X16, X17, C18, X19, X20, X21, C22, X23, X 24, X25, X26, X27, X28, X29, X30, X31, X32, X33, X34, X35, X36, X37, X38, X39, C40, X41, C42, X43, X44 wherein X1, X17, X21, X43 are amino acids; X16, X44 are small polar amino acids; X19 is a large polar amino acid; X36 is a small or lightly hydophobic amino acid; X38 is a lightly hydrophobic or small amino acid; the substitutions being such that: at least one of X1, X17, X21, X43 is a basic or polar, advantageously large polar amino acid, and/or at least one of the amnio acids X16, X44 is a basic amino acid or a large polar amino acid, and/or X19 is a basic amino acid, and/or at least one of the amino acids X36, X38 is a strongly hydrophobic amino acid.

Abstract: The subject of the present invention is a DNA fragment which encodes a protein capable of being recognised by an antiserum against the transferrin receptor of the strain IM2394 or IM2169 of N. meningitidis as well as a process for producing the said protein by a recombinant route. By way of example, such a DNA fragment encodes the tbp1 subunit of the strain IM2394 or IM2169 or the tbp2 subunit of the strain IM2394 or IM2169.

Abstract: The subject of the present invention is a DNA fragment which encodes a protein capable of being recognised by an antiserum against the transferrin receptor of the strain IM2394 or IM2169 of N. meningitidis as well as a process for producing the said protein by a recombinant route. By way of example, such a DNA fragment encodes the tbp1 subunit of the strain IM2394 or IM2169 or the tbp2 subunit of the strain IM2394 or IM2169.