FIG 1.

Binding analysis of 87 human sera to HSV-1 and -2. A threshold OD₄₅₀ of 0.5 was set to stratify binding activity of 87 human sera against HSV-1 HF and HSV-2 MS purified virions coated on an ELISA plate. In detail, a panel of 5 sera (A to E) from healthy uninfected subjects was tested for HSV-1 and -2 binding activity. The cutoff corresponding to an OD₄₅₀ of 0.5 was set at 2.5 times the higher OD signal registered for the negatives in order to minimize the binding contribution of possible antibody cross-reactivity. Serum E represents the nonneutralizing (non-NT) control for the experiments. Blue boxes indicate positive sera, and white boxes indicate negative ones. Moreover, sera were stratified into six categories: sera able to bind only HSV-1 (light red) or only HSV-2 (light green), sera that bind both viruses equally (gray), sera that preferentially bind HSV-1 over HSV-2 (red) and vice versa (green), and negative sera (black). Positive and negative control sera were added as well.