A soluble host signal drives rapid, brain-predominant capsular thickening in Streptococcus pneumoniae via a putative sodium-dependent transporter (SPD_0642) and capsular prepromoter sequence
This study reveals that *Streptococcus pneumoniae* rapidly and specifically thickens its capsular layer in response to a soluble host signal, particularly within brain tissue, through a mechanism involving the SPD_0642 transporter and a specific promoter element, thereby enhancing virulence and modulating the host immune response.