gp96-peptide vaccination of mice against intracellular bacteria

Abstract

This work demonstrates that gp96 preparations isolated from cells infected with intracellular bacteria induce cytotoxic T-lymphocyte responses and confer protection. Our findings extend previous reports on the immunogenicity of gp96-associated peptides to antigens derived from intracellular bacteria. Immunization with gp96 may therefore represent a promising vaccination strategy against bacterial pathogens.

FIG. 1

gp96 isolated from organs of L monocytogenes-infected mice prime CD8⁺ CTL. Ten days after s.c. immunization of C57BL/6 mice with 30 μg of gp96 from Listeria-infected organs (closed symbols) or noninfected organs (open symbols), the spleens were removed and splenocytes were stimulated as described before. On day 12, cultures were tested for CTL activity on RMA cells alone (triangles) or RMA cells pulsed with HKL antigens (diamonds) in a standard ⁵¹Cr release assay.

FIG. 2

Protection against listerial infection by gp96 from infected mice. C57BL/6 mice were treated with PBS alone (group 1) or immunized s.c. with gp96 (30 μg) from organs of noninfected C57BL/6 mice (group 2) or gp96 (30 μg) from organs of L. monocytogenes-infected C57BL6 mice (group 3). Ten days after immunization, mice were infected i.v. with L. monocytogenes organisms. On day 5, the numbers of CFU in spleens and livers were determined. Underlined numbers indicate differences (log 10) between the average numbers of CFU observed for experimental groups and those observed for PBS-treated controls. The individual numbers of CFU are illustrated by the closed diamonds, and the bars illustrate the mean number of CFU per group. The experiment, with 5 animals per group, has been repeated with comparable results. ∗, significant protection (P < 0.001, Mann-Whitney test).

FIG. 3

gp96 complexes isolated from organs of M. tuberculosis-infected mice induce protective immunity against tuberculosis in mice. C57BL/6 mice were immunized s.c. with gp96 (30 μg) from organs of noninfected C57BL/6 mice (group 1) or from organs of M. tuberculosis-infected mice (group 2). Mice were infected 10 days after immunization with M. tuberculosis strain H37Rv. The numbers of CFU in spleens and livers of 5 animals per group were determined on day 28 after infection. Numbers indicate differences (log 10) between the average numbers of CFU of experimental groups and that of the PBS-treated control. The experiment was repeated with comparable results. ∗, significant protection (P < 0.001, Mann-Whitney test).