Distinct bacterial dissemination and disease outcome in mice subcutaneously infected with Borrelia burgdorferi in the midline of the back and the footpad.

Subcutaneous inoculation of mice with Borrelia burgdorferi, the causative agent of Lyme disease, results in established infection and the development of acute arthritis and carditis, hallmarks of human disease. Because conflicting results may originate from the site of subcutaneous inoculation, we addressed the dissemination capacity of spirochetes injected in the shoulder region versus the footpad. Spirochetes inoculated in the footpad disseminated to a lesser extent to distant organs, such as the ear and the heart. This resulted in distinct degrees of joint and cardiac inflammation at the peak of the disease. The differences eventually leveled out. These results suggest that caution must be exercised in the interpretation of results obtained with routes of inoculation that do not closely represent the natural site of infection.

Delivery of the immunosuppressive antigen Salp15 to antigen-presenting cells by Salmonella enterica serovar Typhimurium aroA mutants.

A Salmonella enterica serovar Typhimurium aroA-deficient delivery system was used to target the immunosuppressive protein Salp15 to antigen-presenting cells. In vitro and in vivo infections with Salp15-containing Salmonella resulted in an impaired CD4(+)-T-cell activation, suggesting that the protein was produced by antigen-presenting cells in a physiologically active form.