Caveolin 1 is a conserved host factor mediating Bacillus cereus hemolysin BL toxin cytolytic toxicity

Abstract

Hemolysin BL (HBL) is a tripartite α‑pore‑forming toxin and a major Bacillus cereus virulence factor. Although LITAF and its homolog CDIP1 were previously identified as host receptors that promote HBL‑induced cytolysis, mice lacking both proteins remain only partially protected, indicating the existence of additional determinants of susceptibility. Using genome‑wide CRISPR knockout screens in Litaf−/−/Cdip1−/− mouse embryonic fibroblasts and human HT1080 cells, we identify caveolin‑1 (CAV1), a caveola‑associated membrane protein, as a third conserved host factor required for HBL cytolytic activity. Confocal imaging and co‑immunoprecipitation analyses show that CAV1 colocalizes with HBL and physically associates with the toxin at the plasma membrane. Notably, mice lacking all three factors (Litaf/Cdip1/Cav1 triple knockouts) are completely resistant to HBL toxin challenge, establishing CAV1 as an additional host factor mediating HBL toxin cytotoxicity. These findings define a tripartite host factor system required for HBL toxin activity and position CAV1 as an additional host determinant to B. cereus virulence. Author summary: Hemolysin BL (HBL), a tripartite pore‑forming toxin produced by Bacillus cereus, relies on host receptors to trigger cytolysis. Although HBL toxin receptors LITAF and CDIP1 promote susceptibility to HBL, their loss provides only partial protection in mice, suggesting additional host determinants. Genome‑wide CRISPR screens in LITAF/CDIP1‑deficient mouse and human cells identify caveolin‑1 (CAV1) as a conserved, additional host factor required for HBL toxin‑mediated cytotoxicity. CAV1 physically associates with HBL at the plasma membrane, and mice lacking all three receptors/factors (LITAF, CDIP1, and CAV1) are completely resistant to HBL challenge. These findings define a tripartite receptor/factor system essential for HBL toxicity and reveal CAV1 as a key host determinant of B. cereus virulence. Bacillus cereus hemolysin BL (HBL) uses the host receptors LITAF and CDIP1 for cytotoxicity, but the loss of both only protects the host partly. This study shows that Caveolin 1 completes a three-factor host system whose combined loss confers full resistance to HBL.

Original publication: PLOS Biology (2026-08-21). Source. Source DOI: 10.1371/journal.pbio.3003957.