Cross-reaction of recombinant termite (Coptotermes formosanus) tropomyosin with IgE from cockroach and shrimp allergic individuals

Authors: VARGAS, AURORA - Louisiana State University; MAHAJAN, AVANIKA - University Of New Mexico; TILLE, KATHERINE - Malcolm Grow Medical Clinics And Surgical Center; RANS, TONY - Allergy/immunology Research Center Of North Texas; CHAMPOUX, E - Allergy/immunology Research Center Of North Texas; Grimm, Casey; COTTONE, CARRIE - New Orleans Mosquito, Termite & Rodent Control Board; RIEGEL, CLAUDIA - New Orleans Mosquito, Termite & Rodent Control Board; CHIAL, HEIDI - Biomed Bridge; WILSON, BRIDGET - University Of New Mexico; Mattison, Chris

Submitted to: Annals of Allergy, Asthma & Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2017
Publication Date: 3/5/2018
Citation: Vargas, A.M., Mahajan, A., Tille, K., Rans, T.S., Champoux, E., Grimm, C.C., Cottone, C.B., Riegel, C., Chial, H., Wilson, B., Mattison, C.P. 2018. Cross-reaction of recombinant termite (Coptotermes formosanus) tropomyosin with IgE from cockroach and shrimp allergic individuals. Annals of Allergy, Asthma & Immunology. 120(3):335-337.

Interpretive Summary: The incidence of allergic diseases, including asthma and food allergies, seems to be increasing and poses substantial health, emotional, and economic burdens. Cockroaches are considered a major class of airborne allergens contributing to allergic disease in urban areas world-wide. Tropomyosin is a a muscle protein and is a major allergen in cockroaches, house dust mites, and shellfish such as shrimp. Tropomyosin is recognized by immunoglobulin-E (IgE) antibodies in allergic patients. Cockroaches and termites are closely related evolutionarily within the order Blattodea and share some behavioral similarities. Termites are a significant pest and typically live within and around urban centers, especially in the Southern United States. Due to the evolutionary similarity, recombinant termite tropomyosin was expressed and purified to determine if it is recognized by IgE from allergic patients. The recombinant termite tropomyosin was recognized by IgE from cockroach and shrimp allergic patients. This is the first study to demonstrate directly that a recombinant termite tropomyosin cross-reacts with IgE from both cockroach and shrimp allergic patients. These results suggest that termite tropomyosin may pose a threat to those with cockroach or shellfish allergies due to cross-reactivity, and may contribute as a sensitizing agent in geographic areas infested with termites.

Technical Abstract: Arthropod tropomyosins are considered pan-allergens and they are commonly cross-reactive. The Formosan subterranean termite Coptotermes formosanus (C. formosanus) is closely related to cockroaches in the order Blattodea and is a common household pest in tropical and subtropical parts of the world. C. formosanus tropomyosin is 98-99% identical to cockroach tropomyosin and is 83-84% identical to shellfish tropomyosin. Recombinant C. formosanus tropomyosin was expressed in E. coli purified as a histidine-repeat fusion protein using affinity chromatography. Circular dichroism of the purified protein demonstrated a characteristic a-helical structure similar to that observed for recombinant shrimp tropomysin (Pen a 1). In vitro digestion of the purified protein using porcine pepsin or porcine trypsin resulted in an 11-12 kDa protein fragment that remained intact for at least one hour under these conditions tested. A commercial anti-tropomyosin antibody previously used to characterize heat-induced changes to IgE-reactive tropomyosins from crustaceans and mollusks recognized the recombinant termite tropomyosin. Two protein bands, at approximately 36 kDa and 35 kDa, from the soluble whole body termite extract were recognized by the same antibody. IgE binding to the recombinant termite tropomyosin from five of 16 allergic donor samples was clearly detected. The recombinant termite tropomyosin caused a dose-dependent increase in degranulation response comparable to that seen with recombinant Pen a 1 when tested with serum IgE from a shrimp allergic donor. This is the first study to demonstrate directly that a recombinant termite tropomyosin cross-reacts with IgE from both cockroach and shrimp allergic patients. These results suggest that termite tropomyosin may pose a threat to those with cockroach or shellfish allergies due to cross-reactivity, and may contribute as a sensitizing agent in geographic areas infested with termites.