D3.396 - A new B-cell epitope profiling of glutathione S-transferase allergens supports mite-specific cross-reactivity within different species

Glutathione S-transferases (GST) are clinically relevant allergens from helminths, mites, and cockroaches and have been implicated in IgE cross-reactivity in tropical countries. Although GST-allergenicity is well recognized, the specific B-cell epitopes that may explain cross-species IgE reactivity remain poorly defined. This study aimed to identify and compare B-cell epitopes in GSTs from Ascaris lumbricoides (Asc l 13), Blattella germanica (Bla g 5), Periplaneta americana (Per a 5), Blomia tropicalis (Blo t 8), Dermatophagoides pteronyssinus (Der p 8), Dermatophagoides farinae (Der f 8), and Tyrophagus putrescentiae (Tyr p 8), and to evaluate their sequence identity as a proxy for potential cross-reactivity.

GST amino acid sequences were retrieved from UniProt. Linear and conformational B-cell epitopes were predicted with a combination of sequence and structure-based computational tools (AlgPred 2.0, IgPred, BepiPred 3.0, ABCpred, BCPREDS, BcePred, DiscoTope 3.0). Next, we identified consensus B epitopes predicted by most computational tools. Identity percentages were calculated across species for each predicted epitope to assess conservation patterns among GSTs, and these results were validated using the Consurf tool.

GST allergens showed low to moderate similarity between helminths (Asc l 13) and cockroaches (Per a 5 = 19.4%; Bla g 5 = 36.3%), in contrast to high conservation among mite GSTs (43–76%). Thirty-five consensus B-cell epitopes were selected through in silico analysis. Overall, B-epitope identity among helminth and cockroach species was low to moderate (20–40%), whereas mite GSTs epitopes showed higher identity, as validated by Consurf. The peptide 169SLIPDFLS176 from Asc l 13 shows 50-62.5% identity between GST from cockroaches and mites. We identified B-epitopes mite-specific, such as 55LDFPNCPYYIDGNV68 from Der f 8, which shows 57.1% identity with Blo t 8, 78.5% with Der p 8, and 92.8% with Tyr p 8. 4PILGYWDIRGYAQP17 from Der p 8 exhibits 57-81% identity with mite GSTs. The B-epitope 150GTSITYVDFWLYEY163 from Tyr p 8 shares 64-71% identity with mite GSTs.

GST allergens exhibit heterogeneous B-cell epitopes, with high conservation among GST from mites, supporting and validating intra-mite cross-reactivity and targeted IgE studies, and the design of new CRD (component-resolved diagnosis) and future multi-epitope personalized immunotherapy.