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.