Typhoid fever is an important enteric pathogen causing Salmonella typhi, is still extremely common in developing countries of the world. Therefore, this study was an attempt to develop an experimental vaccine against typhoid fever through determination of the immunogenic properties of Vi antigen when loaded on chitosan and tetanus toxoid in laboratory animals. Recorded results showed that the antibody titers were significantly elevated: in (T1) Vi Ag + chitosan groups(620.8±364.8) increased significantly than other groups; (T2) Vi Ag group (448±117.73), (T3) Vi + Tetanus toxoid group (537.6±142.53) and (T4 ) Vi Ag+ Ch. +TT group (121.6±38.4) at (P≤ 0.05). The gene expression of CD25 and CD29 was done by RT-qPCR . The results of relative gene expression in CD25 gene showed that in T4 group (5.1936±2.17) was increased significantly than other groups, which were; T1 (2.5604±0.64), T2 (3.7032±0.54) and T3 (4.4739±1) at (P≤ 0.05). The results of relative gene expression in CD29 gene showed that T3group recorded significantly increment (162.3256±89.52) than other groups, which were; T1 (33.8276±16.6), T2 (59.6817±26.65), and T4 (37.9605±3.09) at (P≤ 0.05). This findings were supported by the increment of total white blood cells in immunized animals and was clearly determined in lymph nodes of spleen & thymus which increased in size and numbers which active germinal centers.
Keywords: CD25 marker, CD29 marker ., Chitosan nanoparticles, Tetanus Toxoid, Vi antigen
