ARS | Publication request: Epitopes from two soybean glycinin subunits antigenic in pigs

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 11, 2013
Publication Date: N/A

Interpretive Summary: Pigs fed soymeal early in life often experience a lag in growth making soy an undesirable food for young pigs. This postweaning lag in growth has in part been associated with an allergic reaction to the soybean seed storage protein glycinin. We have developed an array the represents the amino acid sequences of two subunit of this peptide. We have identified pigs that have antibodies against this protein. Using the peptide array we have identified two regions in glycinin, called epitopes,that are associated with the allergic reactions in about half of the pigs tested. Variants of allergenic portions of these subunits of glyciinin may provide the basis for breeding less allergenic soymeal.

Technical Abstract: Background: Glycinin is a seed storage protein in soybean (Glycine max) that is allergenic in pigs. Glycinin is a hexamer composed of subunits consisting of a basic and acidic portion joined by disulfide bridges. There are 5 glycinin subunits designated Gy1-Gy5. Results: Twenty seven out of 30 pigs had antibodies against glycinin in their sera. Ten of these sera had IgG against the Gy4 (A5A4B3) or Gy1 (A1aBx) subunits. Three sera stain overlapping regions between the two subunits tested, though no serum stained both A5A4B3 and A1aBx. Two sera stained a highly conserved region between A5A4B3 and A1aBx, though again neither serum stained both peptides. The basic part of A1aBx subunit was not recognized by any of the sera tested even though protein blot data indicated that the basic and acidic subunits of glycinin are nearly equally antigenic. Conclusion: Two antigenic regions of A5A4B3 and A1aBx were identified that bound antibodies in half of the sera that reacted with these two peptides. Half of the sera reacted with unique regions of A5A4B3 and A1aBx. The failure of the basic portion of A1aBx to bind pig antibodies may indicate that it is less antigenic than the basic portion of A5A4B3 and other glycinin subunits.