Susceptibility of rabbits to Treponema pallidum after infection with Mycobacterium bovis

Immunization of guinea pigs with recombinant TmpB antigen induces protection against challenge infection with Treponema pallidum Nichols

Treponema pallidum-susceptible guinea pigs of strain C4D were immunized with recombinant T. pallidum antigens TmpA, TmpB, TmpC, and TmpA plus TmpB plus TmpC; with Escherichia coli membranes; or with adjuvant alone. Animals in groups of five received six immunizing injections, each of 100 micrograms of antigen incorporated in RIBI adjuvant. After the sixth immunization, all experimental and nonimmunized controls were intradermally challenged with 3 x 10(6) T. pallidum Nichols freshly extracted from infected rabbit testes. Although high titers of antitreponemal antibodies in the fluorescent-treponemal-antibody test or an enzyme-linked immunosorbent assay were evoked in all animals immunized with recombinant antigens, only guinea pigs receiving TmpB antigen demonstrated protection expressed by the development of significantly (P less than 0.01) smaller, atypical lesions of significantly (P less than 0.01) shorter duration and devoid of or containing fewer T. pallidum organisms than lesions in the remaining immunized and control animals.

Latex bead technique for detection of the plaque-forming cell response to teratocarcinoma tumor antigens

A latex bead technique modified for measuring the plaque-forming cell (PFC) response to teratocarcinoma tumor antigens in syngeneic animals is described. With this method one can detect both the primary (IgM) and the secondary (IgG) immune response to tumor antigens. Optimal detection of the PFC response depends on the proper ratio of sheep red blood cells to latex beads and the dose of tumor cell antigen used for immunization. The presence of fetal calf serum interfered with immunization of animals and the coating of the latex beads with the tumor cell antigens. The plaques obtained in response to immunization with teratocarcinoma cell antigens varied in size, probably reflecting the complex immune response to more than one class of antigens on tumor cells.