Characterization and sequence analyses of antibody-selected antigenic variants of herpes simplex virus show a conformationally complex epitope on glycoprotein H

Abstract

Thirteen antigenic variants of herpes simplex virus which were resistant to neutralization by monoclonal antibody 52S or LP11 were isolated and characterized. The antibodies in the absence of complement potently neutralize infectivity of wild-type virus as well as inhibit the transfer of virus from infected to uninfected cells ("plaque inhibition") and decrease virus-induced cell fusion by syncytial strains. The first variant isolated arose in vivo. Of 66 type 1 isolates analyzed from typing studies of 100 clinical isolates, one was identified as resistant to neutralization by LP11 antibody. The glycoprotein H (gH) sequence was derived and compared with those of wild-type and syncytial laboratory strains SC 16, strain 17, and HFEM. The sequences were highly conserved in contrast to the diversity observed between gH sequences from herpesviruses of different subgroups. Only four coding changes were present in any of the comparisons, and only one unique coding change was observed between the laboratory strains and the clinical isolate (Asp-168 to Gly). These sequences were compared with those of antigenic variants selected by antibody in tissue culture. Twelve variants were independently selected with antibody LP11 or 52S from parent strain SC16 or HFEM. For each variant, the gH nucleotide sequence was derived and a point mutation was identified giving rise to a single amino acid substitution. The LP11-resistant viruses encoded gH sequences with amino acid substitutions at sites distributed over one-half of the gH external domain, Glu-86, Asp-168, or Arg-329, while the 52S-resistant mutant viruses had substitutions at adjacent positions Ser-536 and Ala-537. One LP11 mutant virus had a point mutation in the gH gene that was identical to that of the clinical isolate, giving rise to a substitution of Asp-168 with Gly. Both LP11 and 52S appeared to recognize distinct gH epitopes as mutant virus resistant to neutralization and immunoprecipitation with LP11 remained sensitive to 52S and the converse was shown for the 52S-resistant mutant virus. This is consistent with previous studies which showed that while the 52S epitope could be formed in the absence of other virus products, virus gene expression was required for stable presentation of the LP11 epitope, and for transport of gH to the cell surface (Gompels and Minson, J. Virol. 63:4744-4755, 1989). All mutant viruses produced numbers of infectious particles that were similar to those produced by the wild-type virus, with the exception of one variant which produced lower yields. The antibody-resistant phenotype of the LP11 mutant viruses could be partially complemented by growth or titration on wild-type gH-producing cell lines, but the mutants differed in decreased resistance to plaque inhibition or neutralization of infectivity. Taken together, these results show that gH has a conformationally complex epitope which is part of a domain which has an essential function in virus infectivity and spread. This epitope is not stable when gH is expressed in the absence of viru...

Identification and characterization of pseudorabies virus glycoprotein H

“…Antibodies against several gH-homologous herpesviral glycoproteins have been found to possess neutralizing activity (7,12,13,15,35,36). The anti-gH(PrV) peptide sera described in this report did not exhibit significant neutralizing activity either with or without addition of complement (data not shown).…”

The gH-gL Complex of Herpes Simplex Virus (HSV) Stimulates Neutralizing Antibody and Protects Mice against HSV Type 1 Challenge

“…As a second method, we used ELISA to show that the purified complex reacts with MAbs LP11, 53S, and 37S (49). Previous studies had shown that MAbs 52S, 53S, and LP11 recognize different conformation-dependent epitopes (15,18,23,46) and 37S recognizes a linear epitope (46). Thus, these two experiments indicate that gHt in the complex is antigenically correct.…”

“…Several criteria suggest that the truncated soluble complex that we are studying reflects the actual structure of the complex in the virion envelope. First, the gHt-gL complex was antigenically intact, as judged by its capacity to bind to MAbs 52S and 53S, which recognize gH conformation (49), as well as to the "gold standard" MAb LP11 (4), which recognizes conformation of the gH-gL complex (23). The baculovirus-derived truncated form of HSV-1 gH-gL (59) also bound to these antibodies.…”

Glycoprotein H of herpes simplex virus type 1 requires glycoprotein L for transport to the surfaces of insect cells

“…Homologs of gH1 have been found in members of all three subfamilies of herpesviruses (Alpha-, Beta-, and Gammaherpesvirinae) (3,18,21,23,28,29,36). gH of HSV-1 plays a role in the process of the cell-to-cell spread of virions and is required for the penetration of virions into cells (4,9,11,12,17,20). HSV-1 gH produced in mammalian expression systems is retained in the cell, most likely in the endoplasmic reticulum or cis-Golgi, and contains oligosaccharide chains that are not fully processed (7,19).…”