Comparative structural analysis of glycoprotein gD of herpes simplex virus types 1 and 2

We studied the synthesis and processing of the type-common glycoprotein gD in herpes simplex virus type 2 (HSV-2) and compared it structurally to glycoprotein gD of herpes simplex virus type 1 (HSV-1). We demonstrated that in HSV-2, gD undergoes posttranslational processing from a lower-molecular-weight precursor (pgD51) to a higher-molecular-weight product (gD56). Tryptic peptide analysis by cation-exchange chromatography indicated that this processing step altered neither the methionine nor the arginine tryptic peptide profile of gD of HSV-2. Comparative tryptic peptide analysis of gD of HSV-1 and HSV-2 showed that the methionine and arginine tryptic peptide profiles of these two proteins were very similar, but not identical. Some of the resolved peptides coeluted from the cation-exchange column, suggesting that some amino acid sequences of the two proteins might be very similar. However, each protein also appeared to possess several type-specific tryptic peptides. The structural similarity of these two glycoproteins correlates well with their antigenic cross-reactivity since monoprecipitin antibody to gD of HSV-1 also immunoprecipitates gD of HSV-2 and neutralizes the infectivity of both viruses to approximately the same extent.