- Recombinant birch pollen allergens (rBet v 1 and rBet v 2) contain most of the IgE epitopes present in birch, alder, hornbeam, hazel, and oak pollen: a quantitative IgE inhibition study with sera from different populations. Niederberger, V., Pauli, G., Grönlund, H., Fröschl, R., Rumpold, H., Kraft, D., Valenta, R., Spitzauer, S. J. Allergy Clin. Immunol. (1998)