Project description:Background: Tuberculosis (TB) remains a global health problem, with vaccination likely to be a necessary part of a successful control strategy. Results of the first Phase 2b efficacy trial of a candidate vaccine, MVA85A, evaluated in BCG-vaccinated infants were published last year. Although no improvement in efficacy above BCG alone was seen, cryopreserved samples from this trial provide an opportunity to study the immune response to vaccination in this population. Methods: We investigated blood samples taken before vaccination (baseline) and one and 28 days post-vaccination with MVA85A or placebo (Candin). The IFN-γ ELISpot assay was performed at baseline and on day 28 to quantify the adaptive response to Ag85A peptides. Gene expression analysis was performed at all three timepoints to identify early gene signatures predictive of the magnitude of the subsequent adaptive T cell response using the significance analysis of microarrays (SAM) statistical package and gene set enrichment analysis. Results: One day post-MVA85A, there is an induction of inflammatory pathways compared to placebo samples. Modules associated with myeloid cells and inflammation pre- and one day post-MVA85A correlate with a higher IFN-γ ELISpot response post-vaccination. By contrast, previous work done in UK adults shows early inflammation in this population is not associated with a strong T cell response but that induction of regulatory pathways inversely correlates with the magnitude of the T cell response. This may be indicative of important mechanistic differences in how T cell responses develop in these two populations following vaccination with MVA85A. Conclusion: The results suggest the capacity of MVA85A to induce a strong innate response is key to the initiation of an adaptive immune response in South African infants but induction of regulatory pathways may be more important in UK adults. Understanding differences in immune response to vaccination between populations is likely to be an important aspect of developing successful vaccines and vaccination strategies. Trial registration: ClinicalTrials.gov number NCT00953927 Whole blood collected 1 day post-vaccination with MVA85A or Candin placebo (82 samples)

Project description:Background: Tuberculosis (TB) remains a global health problem, with vaccination likely to be a necessary part of a successful control strategy. Results of the first Phase 2b efficacy trial of a candidate vaccine, MVA85A, evaluated in BCG-vaccinated infants were published last year. Although no improvement in efficacy above BCG alone was seen, cryopreserved samples from this trial provide an opportunity to study the immune response to vaccination in this population. Methods: We investigated blood samples taken before vaccination (baseline) and one and 28 days post-vaccination with MVA85A or placebo (Candin). The IFN-γ ELISpot assay was performed at baseline and on day 28 to quantify the adaptive response to Ag85A peptides. Gene expression analysis was performed at all three timepoints to identify early gene signatures predictive of the magnitude of the subsequent adaptive T cell response using the significance analysis of microarrays (SAM) statistical package and gene set enrichment analysis. Results: One day post-MVA85A, there is an induction of inflammatory pathways compared to placebo samples. Modules associated with myeloid cells and inflammation pre- and one day post-MVA85A correlate with a higher IFN-γ ELISpot response post-vaccination. By contrast, previous work done in UK adults shows early inflammation in this population is not associated with a strong T cell response but that induction of regulatory pathways inversely correlates with the magnitude of the T cell response. This may be indicative of important mechanistic differences in how T cell responses develop in these two populations following vaccination with MVA85A. Conclusion: The results suggest the capacity of MVA85A to induce a strong innate response is key to the initiation of an adaptive immune response in South African infants but induction of regulatory pathways may be more important in UK adults. Understanding differences in immune response to vaccination between populations is likely to be an important aspect of developing successful vaccines and vaccination strategies. Trial registration: ClinicalTrials.gov number NCT00953927

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-Î³, TNF-Î±, 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-Î³, 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)

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Immune response to MVA85A or placebo in BCG-vaccinated South African infants at days 0 and 28 post-vaccination

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