Feeding with 4,4′-diaponeurosporene-producing Bacillus subtilis enhances the lactogenic immunity of sow

Abstract The delivery of specific antibodies produced by oral administration of the porcine epidemic diarrhea virus (PEDV) vaccine by sow to newborn piglets via colostrum is an effective strategy to prevent porcine epidemic diarrhea (PED). However, there is a lag in the development of the corresponding vaccine due to the rapid mutation rate of PEDV, which could significantly increase the difficulty of PED prevention and control in pig farms. Hence, congenital lactogenic immunity was assessed by feeding 4,4′-diaponeurosporene-producing Bacillus subtilis (B.S-Dia) to sow on the 80th day of gestation in order to protect newborn piglets from PEDV infection. Firstly, we found that the quantities of T lymphocytes and monocytes in the blood and colostrum of sow after oral administration of B.S-Dia were significantly increased as observed by flow cytometry, whereas the proliferative activity of T lymphocytes in colostrum was also markedly increased. Furthermore, enzyme-linked immunosorbent assay (ELISA) results revealed that levels of TGF (Transforming growth factor) -β, Interleukin (IL) -6, lysozyme and lactoferrin were significantly increased. Finally, it was found in the piglets’ challenge protection test that offspring pigs of which sow was exposed to oral administration of B.S-Dia during pregnancy did not develop diarrhea symptoms and intestinal pathological changes 48 h after infection with PEDV, and the load of PEDV in the jejunum and ileum was significantly reduced, but offspring pigs of which was exposed to oral administration of PBS during pregnancy developed pronounced diarrhea symptoms and extensive PEDV colonization was noted both in the jejunum and ileum. In summary, oral administration of B.S-Dia by sow substantially increased congenital lactogenic immunity, thereby preventing newborn piglets from being infected with PEDV.