Hev b 6.02 (
hevein), identified as a major
allergen from
natural rubber latex (NRL), is involved in the
latex-fruit syndrome and also acts as a pathogenesis defense-related
protein. Its 3D structure has been solved at high resolution, and its linear
epitopes have already been reported. However, information about conformational
epitopes is still controversial, even though it is relevant for an accurate diagnosis and treatment, as well as for the study of
allergen-antibody molecular interactions. We sought to analyze the
B-cell epitopes of Hev b 6.02 at a molecular and structural level, using specific recombinant
antibodies. We obtained a murine
monoclonal antibody (mAb 6E7) and three human single chain fragments (scFvs A6, H8, and G7) anti-Hev b 6.02 that were able to compete for
hevein binding with serum IgEs from
latex allergic patients. In vitro assays showed that the mAb 6E7 and scFv H8 recognized the area of Hev b 6.02 where the aromatic residues are exposed; while the scFv G7 defined the amino and carboxy-terminal regions that lie close to each other, as a different
epitope. The structural modeling of the Hev b 6.02-scFv H8 and Hev b 6.02-scFv G7 complexes revealed the putative regions of two conformational
epitopes. In one of these, the aromatic residues, as well as polar side chains are important for the interaction, suggesting that they are part of a dominant conformational
epitope also presented on the Hev b 6.02-IgE interactions.
Antibodies recognizing this important
allergen have potential to be used to diagnose and ultimately treat
latex allergy.