Mark G. Stevens

Role of immune responses to a GroEL heat shock protein in preventing brucellosis in mice vaccinated with Brucella abortus strain RB51.

Resistance to infection with virulent Brucella abortus strain 2308 and antibody and lymphocyte proliferative responses to a recombinant 60 kDa B. abortus GroEL heat shock protein were measured in mice vaccinated with attenuated B. abortus strain RB51. Mice at 12-20 weeks after vaccination with 5 x 10(8) colony forming units (CFU) of strain RB51 had increased resistance to infection with strain 2308 and increased antibody and lymphocyte proliferative responses to GroEL following challenge infection with 2308. However, these mice at 12-20 weeks after vaccination did not have greater resistance to infection than mice vaccinated with 5 x 10(6) CFU of strain RB51, which had no increased antibody or lymphocyte proliferative response to GroEL. These results indicate that mice vaccinated with strain RB51 can have antibody and cell-mediated immune responses to GroEL during infection with virulent strain 2308, although neither response appeared to have an essential role in vaccine-induced immunity to brucellosis.

Comparative effects of bovine cytokines on cattle and bison peripheral blood mononuclear cell proliferation

Proliferation of peripheral blood mononuclear cells (PBMC) from cattle and bison was measured following stimulation of PBMC with bovine cytokines. Bovine interleukin 1 beta (BoIL-1 beta), interleukin 2 (BoIL-2) or granulocyte-macrophage colony-stimulating factor (BoGM-CSF) at 0.1-100 U/ml were incubated for 48 h with PBMC alone or with PBMC and various mitogens. These included concanavalin A (Con A), phytohemagglutinin (PHA), pokeweed mitogen (PWM) or Escherichia coli 055:B5 lipopolysaccharide (LPS) at 10-0.1 micrograms/ml. BoIL-2 alone, but not BoIL-1 beta and BoGM-CSF alone, induced proliferation of cattle and bison PBMC in the absence of mitogens. In addition, BoIL-1 beta and BoIL-2, but not BoGM-CSF, enhanced proliferation of cattle and bison PBMC induced by mitogens. These results indicate that BoIL-1 beta and BoIL-2 stimulate cattle and bison PBMC proliferation in a similar manner, whereas BoGM-CSF does not appear capable of stimulating either cattle or bison PBMC proliferation.

Research articleEffect of Brucella abortus transfer factor in preventing murine brucellosis

Mice vaccinated with a protein extract of attenuated Brucella abortus strain 19 had increased resistance to infection with virulent B. abortus strain 2308 and had increased antibody responses to strain 2308. However, resistance to infection and antibody responses were not increased when nonvaccinated recipient mice were given transfer factor preparations that were obtained from either vaccinated donor mice or strain 2308-infected donor mice. Vaccination of mice with the strain 19 extract plus treatment with each transfer factor preparation also did not further increase resistance to infection or antibody responses when compared with mice that received the vaccine alone. These results suggest that transfer factor from mice that have either vaccine-induced protective immunity to B. abortus or active B. abortus infections does not enhance antibody responses and resistance to infection with B. abortus.