Evidence has been presented that herpes simplex virus (HSV) immunoglobulin (IgG) Fc receptors are composed of a complex of two glycoproteins, gE and gl. In previous studies, cells infected with HSV-1 mutants lacking either gE or gl bound lower levels of soluble IgG than cells infected with wild-type viruses suggesting that both gE and gl were required for IgG binding. We have reevaluated the Fc receptor activity of these mutants using a more sensitive assay involving IgG-coated erythrocytes and have found that cells infected with a gE- mutant HSV-1 did not bind IgG-coated erythrocytes whereas cells infected with a gl- mutant retained some Fc binding activity. To further study HSV-induced Fc receptors recombinant adenovirus vectors expressing gE or gl were constructed. Cells expressing gE alone bound both soluble IgG and IgG-coated red cells, although the binding was consistently lower than that observed with HSV-infected cells or cells expressing both gE and gl. Cells expressing only gl were unable to bind either soluble IgG or IgG-coated erythrocytes. These results support the conclusion that both gE and gl are required for full Fc receptor activity, although gE alone can bind IgG to a lesser extent.
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