Sublancin is a glycosylated
antimicrobial peptide produced by Bacillus subtilis 168 possessing antibacterial and immunomodulatory activities. This study was aimed at investigating the effects of
sublancin on immune functions and serum antibody titer in specific pathogen-free (SPF) broiler chickens vaccinated with
Newcastle disease (ND)
vaccine. For this purpose, 3 experiments were performed. Experiment 1: SPF broiler chicks (14 days old) were randomly allotted to 1 of 7 groups including a blank control (BC),
vaccine control (VC), and 5 (3-7) vaccinated and
sublancin supplemented at 5, 15, 30, 45, and 60 mg activity/L of water, respectively. Vaccinated groups (2-7) were vaccinated with ND
vaccine by intranasal and intraocular routes at the 14th day. On 7, 14, 21, and 28 days post vaccination (dpv), the blood samples were collected for the determination of serum hemagglutination inhibition (HI) antibody titer. Experiment 2: SPF broiler chicks were divided into 1 of 3 groups, i.e., blank control (BC),
vaccine control (VC), and
sublancin treatment (ST). On 7, 14, and 21 dpv, the blood samples were collected for measuring HI antibody titer by micromethod. Experiment 3: the design of this experiment was the same as that of experiment 2. On 7 and 21 dpv, pinocytosis of peritoneal macrophages, B lymphocyte proliferation assay, measurement of CD4+ and CD8+ T cells, and serum
cytokine quantitation were carried out. It was noted that
sublancin promoted B lymphocyte proliferation, increased the proportion of CD8+ T lymphocyte subpopulations, and enhanced the antibody titer in broiler chickens. In addition, it was also observed that
sublancin has the potential to induce the secretion of IFN-γ,
IL-10, and
IL-4. In conclusion, these findings suggested that
sublancin could promote both humoral and cellular immune responses and has the potential to be a promising
vaccine adjuvant.