Oral co-administration of bivalent protein r-BL with U-Omp19 elicits mucosal immune responses and reduces S. Typhimurium shedding in BALB/c mice

•A novel bivalent protein r-BL was produced by in-frame splicing of sseB and ompL genes of S.Typhimurium and was stably expressed in prokaryotic system.•Mucosal adjuvant U-Omp19 protected the recombinant vaccine molecule r-BL in the protease rich environment of the GI tract.•Mice immunized with r-BL+U-Omp19 demonstrated a significant rise in local mucosal immunity.•Oral immunization with r-BL+U-Omp19 effectively reduced the fecal shedding of S. Typhimurium upon oral challenge in mice model.