Benjamin S. Weeks, Periasamy Sundaresan, Thandavarayan Nagashunmugam, Eugene Kang, Harvey M. Friedman

Herpes simplex virus-1 (HSV-1) glycoprotein E (gE) is a multifunctional protein capable of both binding the Fc portion of IgG and mediating cell-to-cell spread of HSV-1. Here we report that the domain on gE involved in IgG binding is distinct from the domain involved in mediating cell-to-cell spread. To do this we have used five mutants of the HSV-1 strain NS: NS-gE(null), a gE deletion virus; rNS-gE(null), a gE rescued virus; NS-gE339, a gE mutant virus with a four amino acid insert at position 339; rNS-gE339, a gE rescue of NS-gE339; and NS-gE406, a gE mutant virus with the same four amino acids inserted at position 406. Using IgG coated sheep red blood cells in rosetting assays, we show that the NS-gE339 does not bind IgG, yet retains the ability to mediate normal cell-to-cell spread. These results demonstrate that the gE domain involved in IgG binding differs from the domain involved in cell-to-cell spread.