Structural and immunogenic evaluation of silk proteins from Bombyx mori using advanced bioinformatics and deep...

Silk from Bombyx mori is a premier biomaterial. Yet, comprehensive structural and immunoinformatic characterization of its protein components-fibroin subunits (FibH, FibL, P25) and five sericin isoforms-remains incomplete, hindering rational design of biocompatible medical devices. We integrated AlphaFold3 structural prediction with multi-algorithm immunoinformatic profiling (VaxiJen, NetMHCpan, BepiPred, AllerTOP, ToxinPred) to establish structure-immunogenicity relationships across the silk proteome. Structural modeling revealed that FibL and P25 adopt well-defined architectures (pTM = 0.85), whereas FibH exhibited low confidence (ipTM/pTM = 0.28), reflecting its intrinsically disordered pre-assembly state. Sericins displayed predominantly disordered conformations that undergo partial ordering upon complexing with FibL-P25-Cu²⁺, supporting a disorder-to-order templating mechanism for fiber assembly. Immunoinformatic analysis revealed striking antigenic heterogeneity: P25 emerged as uniquely hypoimmunogenic, with subthreshold antigenicity (VaxiJen: 0.395), a single strong MHC-I binder for a single HLA allele, and minimal MHC-II reactivity. Conversely, FibL and FibH showed the highest potential for inducing CD8+ and CD4+ cell responses among the fibroin subunits, respectively. Ser-4 and Ser-1 exhibited a broad MHC coverage, presenting ≥ 10 strong binders in 81% and 30% of MHC-I alleles, respectively, as well as ≥ 4 high-priority peptides across all 27 and 6 tested MHC-II alleles, respectively. Allergenicity prediction classified FibH, FibL, Ser-2, and Ser-5 as probable allergens. All proteins were non-toxic. These findings challenge the paradigm that sericins exclusively drive silk immunogenicity, revealing instead an HLA-dependent risk profile dominated by FibL, FibH, Ser-4, and Ser-1. This computational framework provides a rational foundation for engineering hypoimmunogenic silk variants through P25 enrichment, epitope deletion, or HLA-matched biomaterial selection.