Predicting Blomia tropicalis allergens using a multiomics approach

The domestic mite Blomia tropicalis is a major source of allergens in tropical and subtropical regions. Despite its great medical importance, the allergome of this mite is not sufficiently studied. Only 14 allergen groups have been identified in B. tropicalis so far, even though early radioimmunoelectrophoresis techniques (27 uncharacterized allergen complexes) and comparative data based on 40 allergen groups officially recognized by WHO/IUIS in domestic astigmatid mites, suggest that a large set of additional allergens may be present. Here, we use a multiomics approach to assess the allergome of B. tropicalis using genomic, transcriptomic sequence data, and a highly sensitive protein abundance quantification. Out of 14 known allergen groups, we confirmed 13 (one WHO/IUIS allergen, Blo t 19, was found to be a contaminant originated from a nematode) and identified 16 potentially novel allergens using sequence similarity. These data indicate that B. tropicalis shares 27 known/deduced allergen groups with pyroglyphid house dust mites (genus Dermatophagoides). Among them, five allergen-encoding genes were highly expressed at the transcript level: Blo t 1, Blo t 5, Blo t 21 (known), Blo t 15, and Blo t 18 (predicted). However, at the protein level, a different set of most abundant allergens was found: Blo t 2, 10, 11, 20 and 21 (mite bodies) or Blo t 3, 4, 6 and predicted Blo t 13, 14 and 36 (mite feces). We show the use of an integrated omics method to identify and predict an array of mite allergens and advanced, label-free proteomics to determine allergen protein abundance. Our research identifies a large set of novel putative allergens and shows that expression levels of allergen-encoding genes may not be strictly correlated with the actual allergenic protein abundance in the mite bodies.