Molecular cloning and characterization of tropomyosin, a major allergen of Chironomus kiiensis, a dominant species of nonbiting midges in Korea.
Chironomids are widely and abundantly distributed in the vicinity of standing waters. Larvae of Chironomus and some other genera are known to contain hemoglobins, which have been described as a major allergen, and the adults that have no hemoglobins also have been reported to contain allergens. In this study, we tried to establish the role of chironomid allergy and characterize the allergen of Chironomus kiiensis adults. Skin tests using C. kiiensis adult extracts were performed on patients with allergic symptoms. A cDNA library of C. kiiensis adults was screened with C. kiiensis immune mouse sera to identify allergens, and results were confirmed using skin test-positive human sera. Recombinant allergen was expressed in Escherichia coli and purified by affinity chromatography using nickel-nitrilotriacetic acid agarose to investigate its allergenic properties. Out of 275 allergic patients 14.2% showed a positive reaction to C. kiiensis adult crude extracts in the skin test. The tropomyosin was cloned by immunoscreening and expressed in Escherichia coli. C. kiiensis tropomyosin has a high homology at the amino acid level with tropomyosins which were previously known to be allergens in various arthropods (Periplaneta americana, 86.3%; Panulirus stimpson, 78.9%; Dermatophagoides pteronyssinus, 76.5%). Specific immunoglobulin E antibodies reacting to recombinant tropomyosin were detected in 17 (81%) of 21 patients whose skin test results were positive. Cross-reactivity against house dust mites and other insects was noticed with mouse anti-recombinant tropomyosin immune serum. C. kiiensis adults were shown to be an important source of inhalant allergens in Korea. Molecular cloning of C. kiiensis tropomyosin was performed and IgE reactivity was demonstrated using skin test-positive human sera. Recombinant tropomyosin will be useful for further studies or clinical applications.
Jeong
Kyoung Yong
KY
Department of Parasitology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul. South Korea.
Yum
Hye-Yung
HY
Lee
In-Yong
IY
Ree
Han-Il
HI
Hong
Chein-Soo
CS
Kim
Dong Soo
DS
Yong
Tai-Soon
TS
D000485:Allergens / Q000235:genetics / Q000276:immunology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002683:Chironomidae / Q000276:immunology*; D003001:Cloning, Molecular; D015723:Gene Library; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000097:blood; D007723:Korea; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D014335:Tropomyosin / Q000235:genetics* / Q000276:immunology*
D000485:Allergens; D011994:Recombinant Proteins; D014335:Tropomyosin; D007073:Immunoglobulin E