CASP9 and infection: B cells were primarily associated with apoptosis, ferroptosis, necroptosis, phagosome, and mitophagy, as reflected by the significant transcriptional up-regulation of related genes including gsdmea, bcl2l1, acsl4b, alox5a, prf1.7.1, il1b, gpx4a, gpx4b, atf3, aco1, atg13, casp3a, casp3b, apaf1, casp9, and casp8l2 (Figure 6—figure supplement 1C and D), suggesting that the B0 subset experienced severe cell death upon infection.