Molecular and immunologic characterization of new isoforms of the Hevea brasiliensis latex allergen hev b 7: evidence of no cross-reactivity between hev b 7 isoforms and potato patatin and proteins from avocado and banana.
BACKGROUND
Hev b 7 is a Hevea brasiliensis latex allergen with sequence identities of 39% to 42% to patatins recently identified as potato allergens. The complementary DNAs encoding 2 different Hev b 7 isoforms were previously reported.


OBJECTIVE
The aim of this study was to determine the sequence variation of Hev b 7 and to compare the IgE reactivity of individual isoforms in vitro and in vivo. A further objective was to evaluate possible cross-reactivities between Hev b 7 and patatins and proteins from banana and avocado.


METHODS
An H brasiliensis lambda ZAP complementary DNA (cDNA) library was screened with use of a Hev b 7 cDNA probe. Four Hev b 7 isoforms were produced in recombinant form and their IgE-binding capacities were compared. IgE immunoblot inhibitions and ELISA inhibition assays were used to investigate the possible cross-reactivity between Hev b 7 and recombinant potato patatin and proteins from avocado and banana.


RESULTS
Two new isoforms, S2 and D2, were identified by sequencing 32 cDNA clones with full-length coding regions. All 4 recombinant isoforms displayed esterase activity and identical IgE-binding capacities. The new isoforms S2 and D2 were evaluated in skin prick tests and provoked responses equivalent to natural Hev b 7. No cross-reactivity was observed between Hev b 7 isoforms and potato patatin and proteins from avocado and banana.


CONCLUSIONS
All 4 recombinant Hev b 7 isoforms have equivalent IgE-binding capacity and therefore represent suitable reagents for the development of in vitro and in vivo diagnostic tests. Hev b 7, patatins, and their homologs appear not to contribute to cross-reactivity in the latex-fruit syndrome.
Sowka
S
S
Department of General and Experimental Pathology, University of Vienna, Vienna, Austria.
Hafner
C
C
Radauer
C
C
Focke
M
M
Brehler
R
R
Astwood
J D
JD
Arif
S A
SA
Kanani
A
A
Sussman
G L
GL
Scheiner
O
O
Beezhold
D H
DH
Breiteneder
H
H
D000328:Adult; D000485:Allergens / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D001483:Base Sequence; D002265:Carboxylic Ester Hydrolases; D003429:Cross Reactions / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D004950:Esterases / Q000378:metabolism; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000378:metabolism; D019770:Lauraceae; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000276:immunology; D011110:Polymorphism, Genetic; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry* / Q000276:immunology* / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000276:immunology / Q000302:isolation & purification; D019862:Zingiberales
D000485:Allergens; D052179:Antigens, Plant; D010940:Plant Proteins; D020033:Protein Isoforms; D011994:Recombinant Proteins; C113002:allergen Hev b 7; C043222:patatin protein, Solanum tuberosum; D007073:Immunoglobulin E; D004950:Esterases; D002265:Carboxylic Ester Hydrolases