Biotin-dependent metabolism controls germinal center fate and vaccine-induced antibody diversification

Nutrient availability shapes antibody responses, yet its role in metabolic checkpoints governing germinal center (GC) B-cell differentiation remains incompletely defined. Using heterozygous (HZ) Slc5a6 M60K mice modeling human loss-of-function mutations in the multivitamin transporter SLC5A6, we found that deficient biotin imports impaired mitochondrial metabolism and restricted preGC-to-dark zone progression after vaccination. Single-cell transcriptomics and RNA velocity revealed disrupted GC trajectories, while B-cell receptor repertoire analysis showed impaired class-switch recombination, somatic hypermutation, and vaccine-induced clonal diversity. Spatial multiplexed imaging showed reduced GL7-high GC-associated B-cell regions. Flow cytometric analyses revealed reduced frequencies of RBD-specific B cells and RBD-specific GL7⁺CD95⁺ GC B cells in HZ mice, with higher frequencies after biotin supplementation. Pseudovirus assays demonstrated impaired neutralization of Wuhan-Hu-1 and Omicron BA.2. Dietary biotin supplementation restored GC-associated differentiation, antibody diversification, and vaccine-induced humoral responses. These findings identify biotin-dependent mitochondrial metabolism as an important checkpoint linking micronutrient availability to GC B-cell differentiation and vaccine responsiveness.