Viral infection is a risk factor for TB disease in infants

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. PBMC collected pre or 28 days post vaccinated with MVA85A or Candin Placebo, stimulated with either BCG or media alone.