Sequence polymorphisms of major German cockroach allergens Bla g 1, Bla g 2, Bla g 4, and Bla g 5.
BACKGROUND
The allergenicity of allergens could be influenced by amino acid substitutions in B- or T-cell epitope regions. The German cockroach is known to produce potent allergens inducing strong IgE-mediated allergic reactions. This study was performed to investigate sequence variations in major allergens of the German cockroach.


METHODS
Reverse transcriptase PCR was used to amplify the cDNA sequences encoding major allergens of the German cockroach (Bla g 1, Bla g 2, Bla g 4, and Bla g 5).


RESULTS
The deduced amino acid sequences revealed 38 Bla g 1 variants with 1-7 amino acid substitutions (98.6-99.8% identity), 28 Bla g 2 variants with 1-3 substitutions (99.1-99.7%), 27 Bla g 4 variants with 0-32 substitutions (82.4-100%), and 8 Bla g 5 variants with 1-2 substitutions (99.0-99.5%), respectively. Bla g 1 and Bla g 2 showed sporadic amino acid substitutions despite the divergence in their sequences. Bla g 4 exhibited frequent variations, with clusters of substitutions in residues 29-38, 52-80, and 132-155. Sequence variations in Bla g 4 imply the presence of multiple isoforms and isoallergens, which may in turn have various effects on the IgE-binding capacity and T-cell responsiveness. Only 8 variants were found in Bla g 5, with infrequent amino acid changes of one or two residues.


CONCLUSIONS
Analyses of T-cell and IgE-binding epitope regions would clarify the effect of sequence polymorphisms on allergenicity, which in turn will aid in the design of allergen formulations for diagnosis and immunotherapy for cockroach allergies.
Jeong
Kyoung Yong
KY
Department of Parasitology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul, Korea.
Lee
Haeseok
H
Shin
Kwang Hyun
KH
Yi
Myung-hee
MH
Jeong
Kyoung-jin
KJ
Hong
Chein-Soo
CS
Yong
Tai-Soon
TS
D000485:Allergens / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D003058:Cockroaches / Q000235:genetics* / Q000276:immunology; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D019476:Insect Proteins / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D000485:Allergens; D018076:DNA, Complementary; D019476:Insect Proteins