A recent study by Portevin et al. found that infection with modern strains (according to the occurrence of the TbD1 genomic deletion) induced a significantly weaker immune response compared to ancient strains, as measured by levels of TNF-α, IFN-γ, IL-6, IL-10, IL12p40/p70, IL-15, MCP-1, MIP-1α, MIP-1β, VEGF, CXCL9 and Rantes [11]. This evidence concerns the gene IL6 and infection.