Salmonella Serovars and Vaccination Effect on the Immune Responses of Male and Female Layers

Salmonella Enteritidis, S. Gallinarum and S. Pullorum are common serovars to infect poultry and cause diseases differently. The antibody production and cellular immune responses of male and female layers were evaluated before and after inoculation. Before inoculation, S. Gallinarum and S. Pullorum could survive and grow in 10% sera from 6-week-old layers, and S. Enteritidis and E. coli were completely eliminated. The weights of the male and female layers were increased the lowest by inoculation with S. Gallinarum, followed by S. Pullorum, and S. Enteritidis. Inoculation with S. Enteritidis, S. Gallinarum and S. Pullorum increased the antibody titer in the males depending on the serovars and maintained same higher antibody level in females. Furthermore, an increased anti-Salmonella IgG titer was associated with bactericidal ability and the level was reduced by serovars and complemente. Despite the vaccination and serovars, the male layers expressed more IgG2a than IgG1, indicating preferential activation of the Th1 pathway. The inoculation number affected the expression level of IFN-γ and IL-12 in the blood not in the secretion of the peripheral blood mononucleated cells (PBMCs) and more inoculations increased the expression of both cytokines. Inoculation increased more reactive oxygen species (ROS) production in polymorphonuclear (PMN) cells, not the PBMCs. ROS production was greater in cells from the males than from the females and greater in the cells treated with S. Enteritidis than S. Gallinarum and S. Pullorum. These three serovars and their vaccinations differed in sera killing and immune responses.