Mastitis, a disease that affects dairy herds worldwide and causes huge economic losses to the Brazilian dairy sector has the Staphylococcus aureus bacteria as one of the major etiologic agents. S. aureus is an infectious pathogen, which can be isolated from clinical infections, but is most often associated with chronic and subclinical mastitis, with an augmentation of the somatic cell count (SCC) in milk. This pathogen has several virulence factors, which are important in the bacterium-host relationship and in the pathogenesis of the disease. Due to the important role that S. aureus surface components have in the establishment and colonization of the bovine mammary glands, these virulence factors have been the subject of studies related to immune protection. This project aims to characterize surface components of S. aureus isolated from bovine mastitis in or from the South, Southeast, Midwest, Northeast and North regions of Brazil, and to assess the immunogenic potential of a nanocarrier developed from biopolymers extracted from these bacteria, conjugated or not with the D domain of fibronectin binding protein (FnBPA), involved in the pathogenesis of staphylococcal mastitis. The use of nanotechnology expands the possibilities to be explored in the presentation of antigens to the immune system and in the response modulation. Joining the project are seven research centers of Embrapa (respectively, Embrapa Agrosilvopastoral, Embrapa Coastal Tablelands, Embrapa Dairy Cattle, Embrapa Instrumentation, Embrapa Rondônia, Embrapa Southeast Livestock and Embrapa Temperate Agriculture), the Federal University of Juiz de Fora, the Federal University of Lavras, the Université Paris Diderot (Paris 7), and the National Institute of Agricultural Technology of Argentina (INTA Rafaela). The partner institutions provide bacteria to be used in control tests, hyperimmune sera, evaluation of the immune response and expertise in the extraction and nanoencapsulation of bacterial polysaccharides. It is expected at the end of the project progress in knowledge of the main factors of virulence of S. aureus involved in bovine mastitis in Brazil, of their immunogenic potential, and the opening of new frontiers in terms of adjuvants and nanostructured immunomodulators, thus contributing to the reduction in somatic cell count and in the use of antibiotics in dairy herds.