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Viral infection is a risk factor for TB disease in infants

ABSTRACT: 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.

ORGANISM(S): Homo sapiens

PROVIDER: GSE98550 | GEO | 2018/12/05

REPOSITORIES: GEO

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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 PBMC collected pre or 28 days post vaccinated, stimulated with either Ag85A peptides (20 samples) or media alone (60).

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)

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Viral infection is a risk factor for TB disease in infants

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