Aim: To clarify in-vivo early dynamic changes of antigen-presenting cells (APCs) infected with recombinant attenuated Salmonella typhimurium.
Methods: BALB/c mice were orally infected with recombinant attenuated Salmonella typhimurium expressing green fluorescent protein (GFP) X4550 (pYAGFP). Peritoneal macrophages were taken out 3 days after infection, cultured for 24 hours, and observed under the fluorescent microscope. Moreover, BALB/c mice were also infected intravenously with X4550 (pYAGFP) and low density cells (LDCs) were isolated and prepared from mouse spleen and liver 3,6 and 12 hours after infection. Infection rates of macrophages and dendritic cells (DCs) were analyzed by flow cytometry.
Results: About 50% peritoneal macrophages were X4550 (pYAGFP) positive. Infection rates of macrophages in spleen and liver were about 20%-40%. As for the DCs, the infection rates in spleen and liver were about 4%-10% and 10%-20%, respectively.
Conclusion: Recombinant attenuated Salmonella can be captured by APCs in-vivo in early infection, which provides a precondition for inducing effective immune responses.