Project description:B6 mice were immunized with either 2000 cfu of ova expressing Listeria monocytogenes (LM-ova) or 100ug whle ovalbumin adjuvanted with 50ug polyIC + 50ug anti-CD40 (FGK45). 7 days later, tetramer staining CD8+ T cells from the spleen were flow sorted to purity (~98%), the RNA isolated, reverse transcribed and the resulting cDNA analyzed by gene array MoGene-1_0-st-v1 gene expression determined in naïve (CD44lo) and day 7 post Listeria chalelneg or combined adjuvant vaccine immunization (internally referred to as "synergy").
Project description:Protection from pathogens relies on both humoral (antibody-mediated) and cellular (T cell-mediated) responses. While infections robustly elicit both of these types of immunity, currently approved vaccine adjuvants largely fail to induce significant T cell responses. However, recent work by our lab and others suggests that the mechanisms governing vaccine-elicited T cells (Tvac) may be substantially different than those governing infection-elicited T cells (Tinf). We have recently demonstrated that optimal subunit vaccine-elicited T cell responses rely on different cytokine signals (IL-27 and 15) and metabolic function (oxidative phosphorylation vs. aerobic glycolysis) leading to phenotypically and functionally different outcomes (memory vs. effector). Our goal was to investigate the transcriptional programming that promotes Tvac formation. Using a single-cell RNA-seq approach, we compared Tvac and Tinf at day 7 post-immunization or infectious challenge to determine the heterogenity of CD8 T cell responses at this peak timepoint.
Project description:CD4 T cells promote innate and adaptive immune responses, but how vaccine-elicited CD4 T cells contribute to immune protection remains unclear. Here we evaluated whether induction of virus-specific CD4 T cells by vaccination would protect mice against infection with chronic lymphocytic choriomeningitis virus (LCMV). Immunization with vaccines that selectively induced CD4 T cell responses resulted in catastrophic inflammation and mortality following challenge with a persistent form of LCMV. Immunopathology required antigen-specific CD4 T cells and was associated with a cytokine storm, generalized inflammation, and multi-organ system failure. Virus-specific CD8 T cells or antibodies abrogated the pathology. These data demonstrate that vaccine-elicited CD4 T cells in the absence of effective antiviral immune responses can trigger lethal immunopathology. Splenic GP66-specific CD4 T cells from mice immunized with either a LMwt vaccine (sham) or LMgp61 vaccine (CD4 vaccine) were purified by FACS on day 8 post-infection with LCMV clone 13
Project description:Listeria monocytogenes is a foodborne intracellular bacterial pathogen leading to human listeriosis. Despite a high mortality rate and increasing antibiotic resistance no clinically approved vaccine against Listeria is available. To identify antigens for this bacterial pathogen that can be encoded in mRNA vaccine formulations, we screened for Listeria epitopes presented on the surface of infected human cell lines by mass spectrometry-based immunopeptidomics. In between more than 15,000 human self-peptides, we detected 68 Listeria epitopes from 42 different bacterial proteins, including several known antigens. Peptide epitopes presented on different cell lines were often derived from the same bacterial surface proteins, classifying these antigens as potential vaccine candidates. Encoding these highly presented antigens in lipid nanoparticle mRNA vaccine formulations resulted in high levels of protection in vaccination challenge experiments in mice. Our results pave the way for the development of a clinical mRNA vaccine against Listeria and demonstrate the power of immunopeptidomics for next-generation bacterial vaccine development.
Project description:CD4 T cells promote innate and adaptive immune responses, but how vaccine-elicited CD4 T cells contribute to immune protection remains unclear. Here we evaluated whether induction of virus-specific CD4 T cells by vaccination would protect mice against infection with chronic lymphocytic choriomeningitis virus (LCMV). Immunization with vaccines that selectively induced CD4 T cell responses resulted in catastrophic inflammation and mortality following challenge with a persistent form of LCMV. Immunopathology required antigen-specific CD4 T cells and was associated with a cytokine storm, generalized inflammation, and multi-organ system failure. Virus-specific CD8 T cells or antibodies abrogated the pathology. These data demonstrate that vaccine-elicited CD4 T cells in the absence of effective antiviral immune responses can trigger lethal immunopathology.
Project description:Successful development of HIV-vaccination strategies will also depend on the ability to use novel approaches to analyse and integrate immunogenicity data generated in vaccine trials. The ANRS VAC 18 trial evaluated the immunogenicity of HIV-LIPO-5 vaccine (5 HIV peptides coupled to a palmytoil tail) administered at W0, 4, 12 and 24 in healthy volunteers. 62-69% of vaccinees developed HIV-specific ELISpot responses by W26. Here we present extensive immunogenicity assessments in a subset of vaccinees using ELISpot, lymphoproliferation, intracellular cytokine staining (ICS), cytokine multiplex and transcriptomic analyses. Peripheral blood mononuclear cells from volunteers collected before and following vaccinations were stimulated with HIV LIPO 5 vaccine, Gag peptides contained or not in the vaccine as controls. Different time points and stimulation conditions were compared, using false discovery rate to control for test multiplicity. 74% and 30% of vaccinees had cultured ELISpot and lymphoproliferation responses at W14, respectively. Ex-vivo ICS showed mainly single IL-2 producing cells. Secretion of IFN-γ, TNF-α, IL-5, and IL-13 increased significantly in response to Gag stimulation after culture at W14 compared to W0. An induction of metallothionein genes was consistently detected after HIV-LIPO-5 stimulation at W0 and W14 related to the adjuvant effect of the lipid tail. After vaccination (W14), significant probes increased substantially (>1200 probes) including IFN-γ, CXCL9, IL2RA, TNFAIP6, CCL3L1 and IL-6 W14 (fold change > 100%). In conclusion, HIV LIPO-5 vaccination elicited memory precursor responses with a Th1 and Th2 profile. The signature profile before vaccination provides information about the adjuvant effect of the lipid tail. Consistently with cytokine responses, vaccination is associated with a modulation in gene expression. This combined approach allowed to identify new signatures of HIV vaccine response and indicates that HIV-LIPO-5 could be further developed as a prime component of heterologous prime boost strategies. PBMC mRNA of 12 healthy volunteers, stimulate in four different conditions (HIV-LIPO-5, Gag+, Gag-, NS) during 6 and 24 hours before and after vaccination (week 0 and week 14)