BLOC1S3 and infection: To determine whether apoptosis triggered by Rp would facilitate infection and replication of rickettsiae in tick cells, we tested for different infection rates and quantities of Rp by treating infected AAE2 cells with Z-VAD-FMK [carbobenzoxy-valyl-alanyl-aspartyl-(O-methyl)-fluoromethylketone; a pan-caspase inhibitor], sabutoclax (a pan-Bcl-2 inhibitor), or DMSO (dimethyl sulfoxide; a solvent control) (Fig. 3).