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[Display omitted] • Per a 13 was firstly identified as a novel family of allergen in American cockroach. • The full-length cDNA encoding Per a 13 was firstly isolated. Both nPer a 13 and rPer a 13 were purified and characterized. • Among the patients, 49.3 % were reacted to Per a 13. Patients with allergic rhinitis were more sensitized. Cockroaches are an important source of indoor allergens. Environmental exposure to cockroach allergens is closely associated with the development of immunoglobulin E (IgE)-mediated allergic diseases. However, the allergenic components in the American cockroaches are not fully studied yet. In order to develop novel diagnostic and therapeutic strategies for cockroach allergy, it is necessary to comprehensively investigate this undescribed allergen in the American cockroach. The full-length cDNA of the potential allergen was isolated from the cDNA library of the American cockroach by PCR cloning. Both the recombinant and natural protein molecules were purified and characterized. The allergenicity was further analyzed by enzyme linked immunosorbent assay, immunoblot, and basophil activation test using sera from cockroach allergic patients. A novel allergen belonging to glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was firstly identified in the American cockroach and named as Per a 13. The cDNA of this allergen is 1255 base pairs in length and contains an open reading frame of 999 base pairs, encoding 332 amino acids. The purified Per a 13 was fully characterized and assessed to react with IgEs from 49.3 % of cockroach allergic patients, and patients with allergic rhinitis were more sensitized to it. Moreover, the allergenicity was further confirmed by immunoblot and basophil activation test. We firstly identified GAPDH (Per a 13) in the American cockroach, which is a novel type of inhalant allergen derived from animal species. These findings could be useful in developing novel diagnostic and therapeutic strategies for cockroach allergy. [ABSTRACT FROM AUTHOR]

The Humulus japonicus pollen is one of the most common allergenic pollens in China. However, little is unveiled regarding the allergenic components in Humulus japonicus pollen. Our study aimed to purify and identify the pathogenesis-related 1 (PR-1) protein from Humulus japonicus pollen, and to characterize the molecular and immunochemical properties of this novel allergen. The natural PR-1 protein (named as Hum j PR-1) was purified from Humulus japonicus pollen extracts with a combined strategy of chromatography, and identified by mass spectrometry. The coding sequence of Hum j PR-1 was confirmed by cDNA cloning. The recombinant Hum j PR-1 was expressed and purified from Escherichia coli. The allergenicity was assessed by immunoblot, enzyme-linked immunosorbent assay (ELISA), inhibition ELISA, and basophil activation test using Humulus japonicus allergic patients' whole blood. The physicochemical properties and 3-dimensional structure of it were comprehensively characterized by in silico methods. The allergenicity analysis revealed that 76.6 % (23/30) of the Humulus japonicus pollen allergic patients displayed specific IgE recognition of the natural Hum j PR-1. The cDNA sequence of Hum j PR-1 had a 516-bp open reading frame encoding 171 amino acids. Physicochemical analysis indicated that Hum j PR-1 was a stable and relatively thermostable protein. Hum j PR-1 shared a similar 3-dimensional folding pattern with other homologous allergens, which was a unique αβα sandwich structure containing 4 α-helices and 6 antiparallel β-sheets, encompassing 4 conserved CAP domain. The natural PR-1 was firstly purified and characterized as a major allergenic allergen in Humulus japonicus pollen. These findings would contribute to developing diagnostic and therapeutic strategies for Humulus japonicus pollinosis. • The natural Hum j PR-1 was firstly purified and characterized as a major allergenic allergen in H. japonicus pollen. • Hum j PR-1 showed high sensitization rate of 76.6 % (23/30) in Humulus japonicus pollen-allergic patients. • Hum j PR-1 had a unique αβα sandwich structure with 4 conserved CAP domain. [ABSTRACT FROM AUTHOR]