Characterization of glycoprotein C of HSZP strain of herpes simplex virus 1

Sequences of UL44 genes of strains HSZP, KOS and 17 of herpes simplex virus 1 (HSV-1) were determined and the amino acid sequences of corresponding gl ycoproteins (gC) were deduced. In comparison with the 17 strain, the HSZP s train showed specific changes in 3 nucleotides and in 2 amino acids (aa 139 and 147, both from Arg to Trp) in the antigenic locus LII. The change at a a 147 was situated within the GAG-binding epitope. In a similar comparison, KOS strain had changes in 3 nucleotides and 3 amino acids (aa 3, 14, and 3 00). The UL44 genes of HSZP and KOS strains were expressed in insect Sf-21 cells by means of the baculovirus (Bac-to-Bac(TM)) expression system. As sh own by immunoblot analysis, both the recombinant baculoviruses (B1-HSZP and B6-KOS) expressed a glycosylated gC, the M-r of which (116 K) was lower th an that of gC synthesized in Vero cells (129 K) infected with strains HSZP or KOS. In addition, smaller gC-specific proteins (of apparent M-r of 50-58 K and 98 K) corresponding to a non-glycosylated precursor polypeptide and/ or incomplete forms of the partially glycosylated gC were found. When Balb/ c mice were immunized with Sf-21 cells expressing gC, the recombinant gC-HS ZP represented a more efficient immunogen possibly due to its stronger expr ession in these cells. The corresponding gC-HSZP antiserum reacted in enzym e-linked immunosorbent assay (ELISA) equally well with HSZP and KOS virion antigens and neutralized HSZP strain at a low titer. Both gC-HSZP and gC-KO S antisera detected the homologous as well as the heterologous gC antigens in Vero cells regardless whether infected with strains HSZP, KOS or 17, rev ealing the presence of gC from 6 to 16 hrs post infection (p.i.) in the cyt oplasm, on the nuclear membrane and at the cell surface.