Molecular mechanism of enhancing the immune effect of the Newcastle disease virus vaccine in broilers fed with Bacillus cereus PAS38.

The aim of this study was to explore the molecular mechanism of enhancing the immune effect of the Newcastle disease virus (NDV) vaccine in broilers fed with Bacillus cereus PAS38. The results showed that the NDV antibody titer of broilers in the treatment group supplemented with B. cereus PAS38 was higher than that of the control group, and the difference was significant at 28 days of age (P < 0.05). The spleen, thymus and bursa of fabricius of 42-day-old broilers were quickly collected to construct a differentially expressed gene library of suppression subtractive hybridization (SSH). A total of 31 immune-related differentially expressed genes were screened from three immune organs, of which 15 were up-regulated and 16 were down-regulated. After silencing the up-regulated genes MIF, CD74, DOCK2 and KLHL6, the expression levels of cytokines (Akirin2, NF-κB, IL-2, IL-4, IL-6, IFN-γ and TNF-α) in lymphocytes were reduced to varying degrees. B. cereus PAS38 might be involved in the proliferation, differentiation, activation, migration of B lymphocytes and vaccine antigen presentation by up-regulating the expression of MIF, CD74, DOCK2, KLHL6 and other genes. Moreover, it also stimulated plasma cells to produce immunoglobulins and specific antibodies, thereby improving the humoral immune function of broilers and enhancing the immune effect of the NDV vaccine.