Antigenic and Mutational Analyses of Herpes Simplex Virus

Glycoprotein B (gB), along with gD, gH, and gL, is essential for herpes simplex virus (HSV) entry. The crystal structure of the gB ectodomain revealed it to be an elongated multidomain trimer. We generated and characterized a panel of 67 monoclonal antibodies (MAbs). Eleven of the MAbs had virus-neutralizing activity. To organize gB into functional regions within these domains, we localized the epitopes recognized by the entire panel of MAbs and mapped them onto the crystal structure of gB. Most of the MAbs were directed to continuous or discontinuous epitopes, but several recognized discontinuous epitopes that showed some resistance to denaturation, and we refer to them as pseudo-continuous. Each category contained some MAbs with neutralizing activity. To map continuous epitopes, we used overlapping peptides that spanned the gB ectodomain and measured binding by enzyme-linked immunosorbent assay. To identify discontinuous and pseudocontinuous epitopes, a purified form of the ectodomain of gB, gB(730t), was cleaved by -chymotrypsin into two major fragments comprising amino acids 98 to 472 (domains I and II) and amino acids 473 to 730 (major parts of domains III, IV, and V). We also constructed a series of gB truncations to augment the other mapping strategies. Finally, we used biosenso