Abstract: For further studying the allergenic activity, we expressed the hyaluronidase from Rhynchium brunneum using the baculovirus expression system.Two full-length sequences encoding hyaluronidase and antigen 5 (GenBank accession no. EU624135 and EU624136) were cloned by RT-PCR and RACE from R.. brunneum venom. The two allergen genes were designated as Rhy b 2 and Rhy b 5 according to the allergen nomenclature system. Sequence analysis showed the two genes share high similarity with allergens from other wasps, suggesting that the cross\|reactivity could happen tested with these allergens. The hyaluronidase from R. brunneum venom was found to lack the B-cell epitope, which was elucidated to be formed by 9 conserved amino acids in the hyaluronidase from Apis mellifera venom. Furthermore, the two important arginines among the 9 amino acids were also absent. Comparison of antigen 5 from R. brunneum with that from Vespula vulgaris showed that their C-terminals (containing T-cell epitope) were almost the same, but their N.terminals (containing B-cell epitope) were definitely different. Thus, the conformation dependent on B-cell epitope in this allergen could be also absent. We so speculated that the two allergens could be natural hypoallergen and have potential application value in allergen-specific immune therapy.

Key words: Rhynchium brunneum, hyaluronidase, antigen 5, gene cloning, expression, allergen-specific immune therapy