In agreement with the idea that the Vi capsule reduces inflammatory responses elicited by S. Typhi, infection of THP-1-derived macrophages with noncapsulated S. Typhi (ΔtviB-vexE mutant) increased expression of the proinflammatory cytokine genes IL-6 and IL-23A compared to that in cells infected with capsulated S. Typhi (wild type) (Fig. 5B and C). This evidence concerns the gene IL23A and infection.