effective delivery of dna vaccines using a salmonella vector in a mouse model

Dna vaccines can effectively induce cellular immune responses by producing endogenous antigens, which is particularly important in dealing with intracellular pathogens. they are also a good choice for rapid, large-scale screening to determine the immunogenicity of new antigens because of being stable and easy to produce. in addition, the dna immunization process is relatively simple. however, naked dna molecules do not efficiently enter the cells, resulting in low gene expression. therefore, researchers have focused on designing strategies to increase the cellular uptake of dna vaccines, such as using bacterial or viral carriers. the aim of this study was to find the best conditions for successful delivery of dna vaccines using salmonella vectors in mouse models. an attenuated strain of salmonella typhimurium sl7207 (∆aroa, ∆hisg) harboring a mammalian expression plasmid containing a green fluorescent protein encoding sequence was used for oral administration in six balb/c mice (female, 4 weeks old). three different doses of salmonella (108, 109 and 1010) were used, and plasmid delivery to splenic monocytes was monitored by fluorescent microscopy 24 and 48 hours after administration. the majority of splenic monocytes showed green fluorescence 24 hours following administration, and after 48 hours almost all of them were green fluorescent. based on the results, the dose of 109 seemed to be the better condition and showed the best results.