LacR and TrxB are key virulence factors involved in pneumococcal meningitis as identified by a genome-wide...

Pneumococcal meningitis is the most common form of bacterial meningitis, with high case fatality rates. Bacterial genetics influence disease severity, but the underlying mechanisms remain poorly understood. Here, we evaluated top variants from a genome-wide association study (GWAS) linking Streptococcus pneumoniae genetic variation to disease outcome. Fifteen S. pneumoniae knockout mutants were tested for virulence in a zebrafish embryo meningitis model; six showed reduced virulence compared to wild-type, but four were excluded following competitive index and growth assays. Loss of SPV_1044 (lacR) and SPV_1393 (trxB) resulted in lower bacterial loads, impaired neuroinvasion and a reduced inflammatory response. Furthermore, deletion of lacR, encoding a regulator of galactose metabolism, led to delayed growth in galactose and human cerebrospinal fluid. Deletion of trxB, encoding thioredoxin reductase, increased susceptibility to oxidative stress. This proof-of-concept study, combining pathogen GWAS with in vivo validation, identifies two pneumococcal virulence genes linked to disease severity.