Propolis Silver Nanoparticles as an Adjuvant in Immunization of Rats with Citrobactor Freundii Antigens

This study aimed to examine the impact of Citrobacter freundii killed whole cell sonicated antigen (KWCSAg) alone and in combination with propolis nanoparticles on humoral immunoglobulin (IgG) and cellular immune responses of rats. The ELISA interleukin 4 (IL4) and IgG, delayed-type hypersensitivity (DTH) skin test, and phagocytosis activity tests were used in this study. In total, 45 rats were divided into five groups of 9 rats. The first group received a 1,000 μg\ml dose of KWCSAg-CF. The second group received an injection of 1,000 μg/ml of KWCSAg-CF antigen and 30 mg/ml of propolis AgNPs. The third group received an injection of 1,000 μg/ml of KWCSAg-CF antigen along with 10 mg/ml of propolis AgNPs. The fourth group was subjected to 30 mg/ml of propolis AgNPs. One ml of phosphate-buffered saline (pH 7.2) was injected into the fifth group (the negative control group). The rats received booster injections of the same antigens after 14 days. Blood was obtained from them to detect immunoglobulin and interleukin 4 (IL-4) on days 21, 28, 32, 46, 50, and 60 following the injection. The second group showed the most significant rise in IL-4 and IgG concentration, followed by the third group, the first group, and the fourth group, compared to the negative control group (fifth group). In all immunized groups, the DTH test results demonstrated an increase in the means of induration with significant differences (P<0.05) of the concentrated antigen after 24 and 48 h, and subsequently a decrease after 72 h, compared to the negative control group. At 48 h after the concentrated antigen was indurated, the second group displayed the most significant increase in diameter.