New antigen from intracellular pathogens, useful in vaccines against bacterial and viral infections, comprises sequences from extracellular domains of type III membrane proteins, also derived antibodies

Antigen (Ag) derived from an intracellular pathogenic microorganism (A) comprises at least one peptide fragment (F) consisting of the concatenation of the sequences of at least two adjacent extracellular domains (ECD) in the native structure of a type III membrane protein (PIII), having an even number of transmembrane domains, from (A). Independent claims are also included for the following: (1) antibody (Ab) directed against the specified PIII, produced by immunization with Ag; (2) reagent or kit for diagnosing a latent or chronic infection by (A) that contains Ab; (3) isolated nucleic acid (I) that encodes Ag; (4) probes and/or primers containing 10-30 nucleotides corresponding to the junction between sequences encoding a transmembrane domain (TMD) and an ECD of the specified PIII; (5) recombinant eukaryotic or prokaryotic vector that includes (I) as an insert; and (6) eukaryotic or prokaryotic cells modified by the vector of (5). Antigène dérivé d'un microorganisme intracellulaire pathogène, caractérisé en ce qu'il comprend au moins un fragment peptidique essentiellement constitué par la concaténation des séquences d'au moins deux domaines extracellulaires adjacents dans la structure native d'une protéine membranaire de type III à 2n domaines transmembranaires dudit microorganisme intracellulaire pathogène, anticorps conformationnels dérives, et leurs applications.