Molecular cloning of Per a 1 and definition of the cross-reactive Group 1 cockroach allergens

Background: Sensitization to allergens produced by German and American cock roaches is strongly associated with the cause of asthma, Most of the cockro ach allergens identified to date have been species specific. Objective: The aim of this study was to identify and sequence cross-reactiv e cockroach allergens. Methods: A Periplaneta americana cDNA library was screened with IgE antibod y from patients in the United States who were allergic to cockroach and who were sensitized to Blattella germanica. Results: A cDNA clone was isolated that contained an 870-bp sequence with a 695-bp open reading frame, encoding a 231 amino acid protein, molecular we ight 26.2 kd, Plaque immunoassays using anti-Bla gl and anti-Per a 1 mAbs a nd a panel of human IgE antibodies showed that the protein expressed by the se clones was Per a 1. Sequence homology searches showed that Per a 1 was h omologous to 5 previously reported, but unidentified, sequences from B germ anica and P americana. These sequences encoded proteins with multiple molec ular sizes containing approximately 100 amino acid repeats. The Per a 1 seq uence also showed 31% identity to a mosquito precursor protein, ANG12, whic h may be involved in digestion. The Per a 1 cDNA was expressed in Pichia pa storis to produce purified recombinant allergen (yield, 14 mg/L). Conclusion: The results define the molecular structure and antigenic relati onships between a new family of cross-reactive "Group 1" allergens produced by both P americana and B germanica. These recombinant allergens and speci fic mAbs will provide toots to improve the diagnosis and treatment of aller gic diseases caused by cockroaches.