Termite Proteins Cross-React with Cockroach Allergens

Rationale: Allergy to cockroach is a significant problem in some urban areas.  Termites are within the order Blattodea and are evolutionarily related to cockroaches. We evaluated the ability of proteins from the Subterranean Formosan termite (Coptotermes formosanus) to cross-react with cockroach allergens.

Methods: Genomic and expressed sequence termite libraries were searched for homology to cockroach allergens using Blast 2.2.21 software.  Whole termite extracts were analyzed by mass-spectrometry and probed with anti-cockroach allergen IgG, scFv, and human IgE from cockroach allergic patients by immunoblot and ELISA. 

Results: Sequencing results indicate greater than 60% homology between predicted termite proteins and cockroach allergens including Bla g 3, Bla g 6, Bla g 7, Bla g 8, and Per a 9. Termite peptide sequences were matched to those of Bla g 7, Bla g 8, and Per a 9. Immunoblot and ELISA testing with IgG and IgE antibodies to cockroach allergens revealed cross-reaction to termite proteins.  In particular, anti-cockroach allergen antibodies were reactive to putative termite homologs of hemocyanin (Bla g 3) and tropomyosin (Bla g 7).     

Conclusions: We demonstrate that there is significant sequence homology between cockroach allergens and termite proteins, and we have identified termite orthologs for several cockroach allergens.  We show that termite proteins cross-react with antibodies to cockroach allergens, including the termite hemocyanin (Bla g 3) and tropomyosin (Bla g 7) homologs.  This research could have important consequences to the diagnostic and therapeutic allergy fields.