Herpesvirus antigens on cell membranes detected by centrifugation of membrane-antibody complexes.

Herpesviruses specify new glycoproteins that bind to cell membranes and also appear in the envelope of the virion. Incubation of purified smooth membranes from infected cells with antiviral antibody results in an increase in the density of the membranes as determined by flotation in sucrose density gradients. The magnitude of this increase depends on the amount of antibody used; densities as high as 1.16 grams per cubic centimeter have been obtained (the density of the untreated membranes is 1.08 grams per cubic centimeter). Antiviral antibody does not increase the density of uninfected cell membranes nor do saline or normal rabbit serum change the densities of infected or uninfected cell mnembranes. Viral antigens-presumably the glycoproteins specified by the virus-are probably on the surface of the infected cell membranes and bind to them strongly enough to withstand the hydrodynamic forces applied to them in the sucrose gradient.