Humoral response of the mouse to Treponema pallidum

To investigate the development of the humoral immune response of mice to infection with Treponema pallidum, Balb/c and C57Bl mice were injected intradermally with 10 x 10(6) virulent organisms. Serum samples were taken from the mice at weekly intervals after infection and used in the electrophoretic transblotting technique to detect T pallidum and T phagedenis biotype Reiter antigens. The serum samples taken from infected mice at 21, 42, 84, and 126 days after infection recognised two to 15 T pallidum antigens, with a gradual but continual increase in the number of antigens recognised. The same antisera to T pallidum recognised five cross reactive T phagedenis biotype Reiter antigens. Mice injected with 10 x 10(6) heat killed T pallidum organisms failed to recognise T pallidum antigens, as shown by the blotting technique. When mice infected with T pallidum were given antibiotics, the development of the humoral response was interrupted. These experiments indicated that mice respond more slowly than rabbits to T pallidum, which may be because T pallidum is weakly immunogenic in mice.