Project description:Analysis of PBMC from 10 week old infants vaccinated with BCG at birth. During follow-up 26 infants developed tuberculosis (TB) (non-protected by BCG) and 20 infants did not develop TB despite documented exposure (protected by BCG). PBMC were stimulated with media only or reconstituted BCG for 4 and 12 hours. Results provide insight into the mechanisms behind the failure of BCG to protect against disease.
Project description:Prenatal exposures such as infections and immunisation may influence infant responses. We had an opportunity to undertake an analysis of responses in infants within the context of a study investigating the effects of maternal mycobacterial exposures and infection on bacille Calmette-Guerin (BCG) vaccine-induced responses in Ugandan infants. Gene expression profiles for pathways associated with maternal LTBI and with maternal BCG scar were examined using samples collected at one (n=42) and six (n=51) weeks after BCG immunisation using microarray. Interferon and inflammation response pathways were up-regulated in infants of mothers with LTBI at six weeks, and in infants of mothers with a BCG scar at one and six weeks after BCG immunisation. Maternal BCG scar had a stronger association with infant responses than maternal LTBI, with an increased proinflammatory immune profile.
Project description:The objective of this study was to compare recall responses to vaccine antigens at 3 months and 9 months of age in infants who were vaccinated at birth or at 1 month. PBMC were obtained at 9 months of age from infants who were vaccinated at birth (n=25) or 1 month (n=25). The PBMC were cultured in the presence or absence of CRM197 antigen for 72 hours. At the termination of the cultures, total RNA was extracted from the PBMC. The RNA was pooled into groups of n=5 subjects per group, following by labeling and hybridization to Affymetrix microarrays.
Project description:Bacille Calmette Guerin (BCG) is the most widely administered vaccine in the world yet its mechanism of action remains unclear. In this study, we have used samples from a human mycobacterial challenge study in which previously BCG-vaccinated or BCG-naïve UK adults were challenged intradermally with a standard dose of BCG vaccine. BCG remaining at the site of vaccination was quantified by polymerase chain reaction from a skin biopsy sample taken two weeks post-challenge and was used as a measure of BCG growth and functional anti-mycobacterial immunity. Using gene expression microarrays and flow cytometric analysis of intracellular cytokine production, we show that the magnitude of the immune response is greater in previously vaccinated volunteers and that this correlates with reduced mycobacterial growth but increased scarring at the vaccination site. In particular the IFNγ and IL-17 pathways are strongly induced in previously vaccinated volunteers and correlate with reduced mycobacterial growth in this population. This study supports the use of BCG challenge as a tool for evaluating vaccine efficacy and identifying mechanisms of anti-mycobacterial immunity
Project description:Cattle were vaccinated at week 0 with the live attenuated M. bovis BCG SSI vaccine strain; some animals remain as non-vaccinated controls. After eight weeks animals were challenged intranodally with 108 BCG Tokyo cfu. Lymph nodes were harvested at week 11 and bacterial load in lymph nodes evaluated. Some BCG vaccinates had bacterial loads similar to those found in non-vaccinated animals (not-protected) and some animals had lower bacterial loads (protected) than non-vaccinated animals. Immune responses to mycobacteria were monitored in vitro by stimulation of whole blood with medium, purified protein derivative from M. bovis (PPD-B) or live BCG Tokyo longitudinally. Blood samples from 6 BCG-protected, 6 BCG-not-protected and 6 not-vaccinated. Challenged cattle stimulated with mycobacterial antigens or not were used to prepare RNA for RNAseq analysis at weeks 0 (vaccination), 8 (challenge), 9, 10 and 11. The outcome of this project would help not only in the selection of vaccine candidates but would also inform on the formulation of novel vaccines/vaccination strategies.
Project description:Bacillus Calmette–Guérin (BCG) vaccination immediately after birth provides overall protection against immune disorders in healthy infants. However, for vulnerable infants such as preterm or low birth weights, delayed BCG vaccination is usually recommended. The mechanism underlying this clinical application remains obscure. Here we reported that BCG vaccination abrogated the transitory appearance of immunosuppressive myeloid cells in neonatal mice, that is myeloid-derived suppressor cells (MDSCs) represented as the important immunoprotection against inflammatory diseases in early life. A combination of single-cell transcriptome, metabolite profiling, and functional analysis revealed that the upregulation of mTOR/HIF1a signaling and the enhanced glycolysis explained the underlying mechanism. Consequently, BCG vaccination significantly exacerbated the severity of necrotizing enterocolitis (NEC), a common clinical emergency primarily affecting preterm or low birth weight infants. Adoptive transfer of MDSCs or pharmalogical inhibition of glycolysis or mTOR signaling efficiently relieved the severity of NEC upon BCG vaccination. These observations suggest that BCG may diminish the protective mechanism of myeloid cells and enhances the susceptibility of NEC in vulnerable neonates.
Project description:The objective of this study was to compare recall responses to vaccine antigens at 3 months and 9 months of age in infants who were vaccinated at birth or at 1 month.
Project description:The reason for the largely variable protective effect against TB of the vaccine Bacille Calmette-Guerin (BCG) is not understood. In this study, we investigated whether epigenetic mechanisms are involved in the response of immune cells to the BCG vaccine. We isolated peripheral blood mononuclear cells (PBMCs) from BCG-vaccinated subjects and performed global DNA methylation analysis in combination with functional assays representative of innate immunity against Mycobacterium tuberculosis infection. Enhanced containment of replication was observed in monocyte-derived macrophages from a sub-group of BCG-vaccinated individuals (identified as ‘responders’). A stable and robust differential DNA methylation pattern in response to BCG could be observed in PBMCs isolated from the responders but not from the non-responders. Gene ontology analysis revealed that promoters with altered DNA methylation pattern were strongly enriched among genes belonging to immune pathways in responders, however no enrichments could be observed in the non-responders. Our findings suggest that BCG-induced epigenetic reprogramming of immune cell function can enhance anti-mycobacterial immunity. Understanding why BCG induces this responses in responders but not in nnon-responders could provide clues to improvement of TB vaccine efficacy.
Project description:The immune response against tuberculosis relies, at least in part, on CD4+ T cells. Protective vaccines require the induction of antigen-specific CD4+ T cells via mycobacterial peptides presented by MHC class-II in infected macrophages. We have purified MHC class-I and MHC-II peptides and analysed them by mass spectrometry. We have successfully identified 97 mycobacterial peptides presented by MHC-II and 54 presented by MHC-I, from 76 and 41 antigens, respectively. The sequences of selected peptides were confirmed by spectral match validation and immunogenicity evaluated by IFN-gamma ELISpot against peripheral blood mononuclear cells from volunteers vaccinated with BCG, M.tb latently infected subjects or patients with tuberculosis disease. Three antigens were expressed in viral vectors, and evaluated as vaccine candidates alone or in combination in a murine aerosol M.tb challenge model. When delivered in combination, the three candidate vaccines conferred significant protection in the lungs and spleen compared with BCG alone, demonstrating proof-of-concept for this unbiased approach to identifying novel candidate antigens.
Project description:Immune activation is associated with increased risk of tuberculosis (TB) disease in infants. We performed a prospective case–control analysis to identify the drivers of immune activation in infants and found cytomegalovirus (CMV) stimulated IFN-γ-expressing cells to be associated with CD8+ T cell activation (Spearman’s rho r = 0.241, p <0.0001). Among 49 infants who developed incident TB disease and 129 matched controls who remained healthy we found that CMV and Epstein–Barr virus (EBV) specific IFN-γ responses were associated with increased risk of developing TB (Fisher’s Exact Test, p=0.049, OR 2.14, 95% CI 1.03-4.47), and associated with a shorter time to TB diagnosis (Log Rank Mantel-Cox p=0.012). T cell activation and CMV are associated with lower mycobacterial antigen-specific immune responses following immunization with Bacille Calmette-Guerin (BCG) and MVA85A, suggesting that increased susceptibility to TB in infants with virus infection may, in part, be due to poor responsiveness to vaccination. Understanding of the causes and impact of T cell activation could transform strategies used to protect against TB disease.