EXPRESSION OF MEMBRANE-BOUND AND SECRETED FORMS OF EQUINE HERPESVIRUS-1 GLYCOPROTEIN-D BY RECOMBINANT BACULOVIRUS

Analyses of the synthesis and processing of recombinant full-length gl ycoprotein D of equine herpesvirus type 1 (EHV-1; gD392) or recombinan t truncated go (gD352) expressed in baculovirus-infected Sf9 cells rev ealed the following: (1) go polypeptides encoded by both recombinant b aculoviruses react with go-specific antibodies including peptide-speci fic antiserum that neutralizes EHV-1 in a plaque reduction assay, (2) both the full-length recombinant gD392 and the truncated gD352 are exp ressed predominantly as go species that contain high mannose-type olig osaccharides (55 kDa and 52 kDa, respectively), (3) both the full-leng th recombinant gD392 and the truncated gD352 are also expressed in les ser amounts as go species that contain complex-type oligosaccharides ( 58 kDa and 55 kDa, respectively) as well as the unglycosylated forms o f go (43 kDa and 37 kDa, respectively), (4) flow cytometric analyses o f cells expressing gD392 revealed that go first appears on the cell su rface at 24 h post infection; by 60 h, 95% of the cells express high l evels of cell surface go, (5) cells expressing gD352, in contrast to c ells expressing gD392, secrete go into the extracellular medium. This initial demonstration that immunoreactive EHV-1 glycoprotein D can be produced as a secreted polypeptide in the baculovirus system should pr ovide reagents to assess the potential use of go as a subunit vaccine in an animal model.