Biolistic-mediated gene transfer using the bovine herpesvirus-1 glycoprotein D is an effective delivery system to induce neutralizing antibodies in its natural host.

A genetic vaccine consisting of the bovine herpesvirus-1 (BHV-1) glycoprotein D (gD) gene was constructed and administered to cattle using the biolistic (gene-gun) process. Results were compared to standard intramuscular injection of an inactivated whole BHV-1 commercial vaccine. Cattle genetically immunized by the gene-gun-delivered gD subunit vaccine developed high titers of IgG antibodies specific to gD demonstrating that this immunization method is a potent humoral response inducer. Further, gene-gun vaccinated cattle produced high neutralizing antibody titers to BHV-1 similar to levels induced in the commercial vaccine immunized animals. Additionally, cellular immunity was measured by an increased level of IFN-gamma mRNA detected in PBMC of cattle immunized with the gD gene or with the commercial vaccine, whereas augmented levels of IL-4 were not detected following vaccination. Because of its simplicity and effectiveness in inducing an immune response in cattle similar to a commercial vaccine, gene-gun delivery of a subunit BHV-1 gD vaccine would be a viable alternative to current immunization protocols.

The role of T cell subsets and cytokines in the regulation of intracellular bacterial infection.

Cellular immune responses are a critical part of the host's defense against intracellular bacterial infections. Immunity to Brucella abortus crucially depends on antigen-specific T cell-mediated activation of macrophages, which are the major effectors of cell-mediated killing of this organism. T lymphocytes that proliferate in response to B. abortus were characterized for phenotype and cytokine activity. Human, murine, and bovine T lymphocytes exhibited a type 1 cytokine profile, suggesting an analogous immune response in these different hosts. In vivo protection afforded by a particular cell type is dependent on the antigen presented and the mechanism of antigen presentation. Studies using MHC class I and class II knockout mice infected with B. abortus have demonstrated that protective immunity to brucellosis is especially dependent on CD8+ T cells. To target MHC class I presentation we transfected ex vivo a murine macrophage cell line with B. abortus genes and adoptively transferred them to BALB/c mice. These transgenic macrophage clones induced partial protection in mice against experimental brucellosis. Knowing the cells required for protection, vaccines can be designed to activate the protective T cell subset. Lastly, as a new strategy for priming a specific class I-restricted T cell response in vivo, we used genetic immunization by particle bombardment-mediated gene transfer.

The role of T cell subsets and cytokines in the regulation of intracellular bacterial infection

Cellular immune responses are a critical part of the host's defense against intracellular bacterial infections. Immunity to Brucella abortus crucially depends on antigen-specific T cell-mediated activation of macrophages, which are the major effectors of cell-mediated killing of this organism. T lymphocytes that proliferate in response to B. abortus were characterized for phenotype and cytokine activity. Human, murine, and bovine T lymphocytes exhibited a type 1 cytokine profile, suggesting an analogous immune response in these different hosts. In vivo protection afforded by a particular cell type is dependent on the antigen presented and the mechanism of antigen presentation. Studies using MHC class I and class II knockout mice infected with B. abortus have demonstrated that protective immunity to brucellosis is especially dependent on CD8+ T cells. To target MHC class I presentation we transfected ex vivo a murine macrophage cell line with B. abortus genes and adoptively transferred them to BALB/c mice. These transgenic macrophage clones induced partial protection in mice against experimental brucellosis. Knowing the cells required for protection, vaccines can be designed to activate the protective T cell subset. Lastly, as a new strategy for priming a specific class I-restricted T cell response in vivo, we used genetic immunization by particle bombardment-mediated gene transfer.