Abstract
Cells infected with herpes simplex virus type 1 (HSV-1) express a cell surface receptor able to bind the Fc portion of immunoglobulin G (IgG). Of the four human IgG subclasses, the HSV-1 Fc receptor, like staphylococcal protein A, binds to all except IgG3. In this paper, we describe the binding of a number of animal IgG and IgG subclass molecules to HSV-1-infected cells and compare this binding to that of protein A. Although only few representatives from each animal order were tested, we found that IgG from Carnivora and Rodentia did not bind or bound only slightly to the HSV-1 receptor, whereas IgG from Primates, Lagomorpha, and Artiodactyla bound well. This pattern was clearly different from the species spectrum of IgG binding of protein A. Differences between the two receptors were also found when animal IgG subclasses were tested. The pronounced differences in affinity for the HSV-1 Fc receptor between immunoglobulins from, for example, mouse and rabbit may influence the interpretation of animal studies with this virus.