The present application provides a modified Brucella strain, its use as a medicament, and its use as a medicament for the treatment and!or prevention ofbmcellosis. The Brucella strain has been modífied through an inactivation ofthe wzm gene. Further, the present application provides a pharmaceutical composition which comprises the modífied Brucella strain, its use as a medicament, and its use as a medicament for the treatment and!or prevention ofbmcellosis. The present application also provides a kit which comprises the modífied Brucella strain and a pharmaceutically acceptable carrier or diluent and its use for the treatment and!or prevention of bmcellosisPeer reviewedConsejo Superior de Investigaciones Científicas (España), Universidad Pública de NavarraA1 Solicitud de patente con informe sobre el estado de la técnic