The invention relates to an immunogenic composition which comprises, firstly, a carrier and, secondly, as antigenic structure, conjugates comprising all or part of the amino acid sequences of at least one peptide derived from an extracellular loop of the P-170 protein, each peptide being combined with several molecules of fatty acid containing a carbon chain of between C12 and C24 so as to allow, under suitable administration conditions, the induction of anti-P-170 antibodies.