SYNTHESIS OF ALPHA-GAL EPITOPES ON INFLUENZA-VIRUS VACCINES, BY RECOMBINANT ALPHA-1,3GALACTOSYLTRANSFERASE, ENABLES THE FORMATION OF IMMUNE-COMPLEXES WITH THE NATURAL ANTI-GAL ANTIBODY

Synthesis of the carbohydrate structure Gal alpha 1-3Gal beta 1-4GlcNA c-R (termed the alpha-gal epitope) on viral glycoproteins is of intere st because of the large amounts of natural antibody (anti-Gal) produce d in humans against this epitope. The presence of alpha-gal epitopes o n inactivated virus or subviral vaccines is likely to enhance vaccine immunogenicity through in vivo complexing with anti-Gal and the subseq uent targeting of the vaccine to Fc gamma receptors on antigen present ing cells. Our previous studies have demonstrated the increased in vit ro immunogenicity of inactivated influenza virus complexed with the an ti-Gal antibody. Here we demonstrate a method for engineering the expr ession of alpha-gal epitopes on influenza virus hemagglutinin (HA) by recombinant alpha 1,3galactosyltransferase (ra1,3GT). We further demon strate the formation of immune complexes between this de novo synthesi zed epitope and anti-Gal, HA has multiple N-acetyllactosamine structur es which serve as excellent acceptors for r alpha l,3GT. The luminal p ortion of marmoset alpha 1,3GT cDNA was produced in large amounts in t he baculo virus system and isolated by affinity chromatography on nick el-Sepharose columns. ra1,3GT effectively transferred galactose from U DP-Gal to the N-acetyllactosamine residues of HA on the intact virion or to isolated HA molecules. At least 3000 alpha-gal epitopes were de novo synthesized per virion. The natural anti-Gal antibody bound to th ese epitopes in ELISA, in western blots and in solution, forming disti nct immune complexes. These data suggest that in vivo administration o f such vaccines will result in their complexing with anti-Gal, and thu s may lead to their increased immunogenicity. (C) 1997 Published by El sevier Science Ltd.