A conserved antigen induces respiratory Th17-mediated broad serotype protection against pneumococcal superinfection.

Several vaccines targeting bacterial pathogens show reduced efficacy upon concurrent viral infection, indicating that a new vaccinology approach is required. To identify antigens for the human pathogen Streptococcus pneumoniae that are effective following influenza infection, we performed CRISPRi-seq in a murine model of superinfection and identified the conserved lafB gene as crucial for virulence. We show that LafB is a membrane-associated, intracellular protein that catalyzes the formation of galactosyl-glucosyl-diacylglycerol, a glycolipid important for cell wall homeostasis. Respiratory vaccination with recombinant LafB, in contrast to subcutaneous vaccination, was highly protective against S. pneumoniae serotypes 2, 15A, and 24F in a murine model. In contrast to standard capsule-based vaccines, protection did not require LafB-specific antibodies but was dependent on airway CD4⁺ T helper 17 cells. Healthy human individuals can elicit LafB-specific immune responses, indicating LafB antigenicity in humans. Collectively, these findings present a universal pneumococcal vaccine antigen that remains effective following influenza infection. [Display omitted] • CRISPRi-seq in pneumococcal superinfection identified lafB as crucial for virulence • LafB catalyzes the formation of a glycolipid important for cell wall homeostasis • Intranasal vaccination with LafB protects against pneumococcal non-vaccine serotypes • Nasal vaccine-induced protection depends on lung Th17 lymphocytes with TRM features Liu et al. identify lafB as crucial for Streptococcus pneumoniae replication in vivo using CRISPRi-seq. Intranasal vaccination with flagellin-adjuvanted LafB induces lung Th7 lymphocytes that protect against superinfections with various pneumococcal serotypes in mice. Healthy individuals can elicit LafB-specific immune responses, suggesting that LafB is a universal, capsule-independent pneumococcal antigen. [ABSTRACT FROM AUTHOR]