CHARACTERIZATION OF BACULOVIRUS-EXPRESSED HERPES-SIMPLEX VIRUS TYPE-1GLYCOPROTEIN-K

The DNA region encoding the complete herpes simplex virus type 1 (HSV- 1) glycoprotein K (gK) was inserted into a baculovirus transfer vector , and recombinant viruses expressing gK were isolated. Four gK-related recombinant baculovirus-expressed peptides of 29, 35, 38, and 40 kDa were detected with polyclonal antibody to gK. The 35-, 38-, and 40-kDa species were susceptible to tunicamycin treatment, suggesting that th ey were glycosylated. The 38- and 40-kDa species corresponded to parti ally glycosylated precursor gK (pgK) and mature gK, respectively. The 29-kDa peptide probably represented a cleaved, unglycosylated peptide. The 35-kDa peptide probably represented a cleaved, glycosylated pepti de that may be a precursor to pgK. Indirect immunofluorescence with po lyclonal antibody to gK peptides indicated that the recombinant baculo virus-expressed gK was abundant on the surface of the insect cells in which it was expressed. Mice vaccinated with the baculovirus-expressed gK produced very low levels (<1:10) of HSV-1 neutralizing antibody. N onetheless, these mice were partially protected from lethal challenge with HSV-1 (75% survival). This protection was significant (P = 0.02). Despite some protection against death, gK-vaccinated mice showed no p rotection against the establishment of latency. Surprisingly, gK-vacci nated mice that were challenged ocularly with a stromal disease-produc ing strain of HSV-1 had significantly higher levels of ocular disease (herpes stromal keratitis) than did mock-vaccinated mice. In summary, this is the first report to show that vaccination with HSV-1 gK can pr ovide protection against lethal HSV-1 challenge and that vaccination w ith an HSV-1 glycoprotein can significantly increase the severity of H SV-1-induced ocular disease.