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.