Virus-Specific, Labile, Nonvirion Antigen in Herpesvirus-Infected Cells

Abstract

The search for a specific, serologically identifiable nonvirion antigen (i.e., not a structural component of the virus) in cells infected with herpes simplex virus (HSV) was undertaken as an approach to the problem of the possible role of this virus in certain types of human cancer.Synthesis of structural components of HSV could not be prevented by a variety of inhibitors of DNA synthesis or by incubation at certain high or low temperatures, and it was, therefore, necessary to devise methods for the detection of nonvirion antigen in the presence of virion antigens. This was achieved by means of specially prepared and absorbed antisera only after the unusual lability and sedimentability of the nonvirion component became apparent. The special sera were derived from guinea pigs hyperimmunized with uncentrifuged extracts of guinea pig kidney culture cells freshly prepared three hours after infection with 20 to 30 plaque-forming units (PFU) of HSV per cell. It was possible to remove the neutralizing (N) antibodies for live virus and the complement-fixing (CF) antibodies for the sedimentable and soluble virion antigens, without loss of CF antibodies for nonvirion antigen, by absorption of these sera with uncentrifuged, HSV infected cell extracts that had been stored at +4 degrees or -66 degrees C, or both, for a sufficiently long time to permit the disappearance of the labile, nonvirion components. Human, rabbit, and guinea pig sera obtained after infection or after "ordinary" hyperimmunization had no CF antibodies for the labile, nonvirion antigen after comparable absorption. The nonvirion antigen detected in this manner is specific not only for HSV but also for the type (or strain?) of HSV, since infection of guinea pig kidney culture cells with vaccinia virus or type 2 (genital) HSV yielded no antigen detectable with the absorbed serum prepared against the type 1 HSV strain; the type 2 HSV produced large amounts of type 1 HSV virion antigen under these conditions, and the vaccinia virus large amounts of antigen reactive with ordinary rabbit antivaccinial serum. The nonvirion antigen was formed at maximum concentration early (3 hr) after high multiplicity HSV infection in guinea pig cells but late in the infectious process (12-24 hr) in rabbit or HEp 2 cells. The supernatant fluid had only 50 per cent of the activity after centrifugation at 1500 g for ten minutes and none after a further centrifugation at 33,360 g for one hour. Storage at +4 degrees C for eight to nine days led to complete loss of activity of the nonvirion antigen but no loss of activity of the various sedimentable and soluble virion antigens. At -66 degrees C or lower temperatures 50 per cent of the activity was lost in seven days and further loss occurred at different rates in extracts of guinea pig, rabbit and HEp 2 cells.