The Induction of HIV Gag-Specific CD8+ T Cells in the Spleen and Gut-Associated Lymphoid Tissue by Parenteral or Mucosal Immunization with RecombinantListeria monocytogenesHIV Gag

Abstract

The induction of mucosal immunity is crucial in controlling viral replication during HIV infection. In this study we compare the ability of a recombinant Listeria monocytogenes that expresses and secretes the HIV Ag Gag to induce CD8+ T cells against this Ag in the spleen, mesenteric lymph nodes, and Peyer’s patches and the ability to provide effector Gag-specific CD8+ T cells to the lamina propria after i.v., oral, or rectal administration of the vaccine. The levels of Ag-specific CD8+-activated T cells were measured ex vivo using intracellular cytokine staining for IFN-γ and H-2Kd Gag peptide tetramer staining. We found that all routes of immunization induced Gag-specific CD8+ T cells in the spleen. After secondary infection, we observed substantial increases in splenic levels of CD8+ T cells, and levels of Gag-specific cells were similar to those against listeriolysin O, the immunodominant Ag of L. monocytogenes. Both primary and secondary oral immunization resulted in abundant Gag-specific CD8+-activated T cells in the lamina propria that constituted ∼35% of the CD8 compartment. However, significant levels of Gag and listeriolysin O-specific CD8+ T cells were observed in mucosal lymphoid tissue only after two immunizations, perhaps because they had already entered the lamina propria compartment after a single immunization. In the context of HIV, a mucosally administered vaccine seems best calculated to prompt an immune response that is capable of preventing infection. The data presented in this report demonstrate that mucosally administered Listeria can prompt such a response and that booster doses can maintain this response.

Multimeric Soluble CD40 Ligand and GITR Ligand as Adjuvants for Human Immunodeficiency Virus DNA Vaccines

“…While a head-to-head comparison of a pSP-D-CD40L-adjuvanted vaccine with other vaccines has not yet been performed, it is instructive to compare these results with those of other studies in BALB/c mice that employed exactly the same CD8 ϩ T-cell target cell (AMQMLKETI peptide-pulsed P815 cells) for either CTL assays or as a stimulator in IFN-␥ ELISPOT assays. By these measures, the results in this report equaled or exceeded those reported for chimpanzee adenovirus 68-based or vaccinia virusbased Gag vaccines (22), a flavivirus Kunjin Gag vaccine (32), or Gag delivered intraperitoneally using live Listeria monocytogenes as a vector (68). Stronger CD8 ϩ T-cell responses using these assays were reported for a vesicular stomatitis virus vector (30) ϩ T-cell responses to a modest degree (25), but the experiments herein failed to detect any significant effects of multimeric soluble CD40L on CD4 ϩ T-cell-proliferative responses and cytokine production.…”

Oral Immunization with RecombinantListeria monocytogenesControls Virus Load after Vaginal Challenge with Feline Immunodeficiency Virus

“…We observed a loss of both CD4 ϩ and CD8 ϩ T cells in sham-and LM-wt-immunized cats, while LMgag/pND14-Lc-env-immunized cats maintained IEL subpopulations at FIV-naïve control levels. Oral immunization of mice with HIV-Gag recombinant L. monocytogenes has resulted in Gag-specific responses in about 35% of lamina propria CD8 ϩ T cells (58). Induction of such a robust T-cell response in combination with sIgA may prevent the establishment of viral reservoirs and depletion of CD4 ϩ T cells in the intestine.…”

“…Several studies using the mouse model have demonstrated the potential of L. monocytogenes as an HIV vaccine vector (24, 30, 43-45, 58, 62, 64). It has been shown that recombinant L. monocytogenes can induce a strong CTL response and long-lived memory response to HIV Gag and that oral administration with recombinant L. monocytogenes stimulates a strong intestinal mucosal cellular immune response (24,45,58,62,64). Given the potential of L. monocytogenes as a biologic vaccine vector against HIV, recombinant L. monocytogenes needs to be investigated in a challenge system.…”

Pseudovirion Particle Production by Live Poxvirus Human Immunodeficiency Virus Vaccine Vector Enhances Humoral and Cellular Immune Responses

“…Intracellular-cytokine staining assays were performed essentially as previously described (37). Single-cell splenocyte suspensions were cultured for 6 h in R10 medium supplemented with 5% recombinant interleukin 2 (IL-2) (Hemagen Diagnostic, Inc.) and 5 g per ml of anti-CD28 antibody (no.…”