IgE Reactivity of Recombinant Pac c 3 from the Asian Needle Ant (Pachycondyla chinensis).

BACKGROUND Stings from the Asian needle ant are an important cause of anaphylaxis in East Asia. A 23-kDa protein homologous to antigen 5 is the major allergen produced by these ants. In this study, we aimed to produce a recombinant antigen 5 allergen, Pac c 3. METHODS Recombinant Pac c 3 allergen from the Asian needle ant was expressed in Pichia pastoris and purified by ammonium sulfate precipitation and Ni affinity chromatography. IgE reactivity was demonstrated by ELISA and immunoblotting. RESULTS The recombinant protein was recognized in 5 of 6 (83.3%) serum samples from patients with demonstrated anaphylaxis to ants. IgE reactivity to an antigen 5 allergen from Asian needle ant venom sac extract was specifically inhibited by the recombinant protein. It was also able to inhibit IgE binding to the vespid allergen Ves v 5 by ImmunoCAP analysis, indicating the presence of cross-reactivity. CONCLUSION A recombinant Pac c 3, cross-reactive with Ves v 5, from the Asian needle ant was successfully produced in the methylotrophic yeast P. pastoris. This protein could be useful for the development of component-resolved diagnostics.