EXPRESSION AND CHARACTERIZATION OF BACULOVIRUS-EXPRESSED HERPES-SIMPLEX VIRUS TYPE-1 GLYCOPROTEIN-L

We have constructed a recombinant baculovirus expressing high levels o f the herpes simplex virus type 1 (HSV-1) glycoprotein L (gL) in Sf9 c ells. Sf9 cells infected with this recombinant virus synthesized three polypeptides of 26-27 kDa 28 kDa, and 31 kDa. The 28 and 31 kDa speci es were sensitive to tunicamycin and N-glycosidase F (PNGase F) treatm ent, suggesting that they were glycosylated. As shown by both indirect immunofluorescence and Western blot analysis, using polyclonal antibo dies to synthetic gL peptides indicated that the baculovirus expressed gL was abundant on the surface of baculovirus gL infected Sf9 cells. A small fraction of the 31 kDa polypeptide was secreted into the extra cellular medium as judged by Western blot analysis. The secreted form of gL was completely resistant to Endoglycosidase H (Endo-H), while th e membrane associated form of gL was only partially resistant to Endo- H treatment, suggesting that the secreted gL represented a subpopulati on of the membrane bound gL. Mice vaccinated with baculovirus expresse d gL produced serum antibodies that reacted with authentic HSV-1 gL. H owever, these mice produced no HSV-1 neutralizing antibody (titer <1: 10) and they were not protected from lethal intraperitoneal or lethal ocular challenge with HSV-1. Thus, when used as a vaccine in the mouse model, gL, similar to our findings with HSV-1 gH, but unlike our resu lts with the other 6 HSV-1 glycoproteins that we have expressed in thi s baculovirus system, did not provide any protection against HSV-I cha llenge.