Intracellular and Membrane Immunofluorescence Investigations on Cells Infected With Herpesvirus saimiri

Summary Herpesvirus saimiri (HVS)-induced intracellular and cell membrane antigens were demonstrated in infected owl monkey cells by indirect immunofluorescence methods. Sera from HVS-infected owl monkeys were the source of antibody. The fluorescent reagent was a fluorescein isothiocyanate (FITC)-conjugated caprine antihuman γ-globulin. The effectiveness of the procedure was evaluated on owl-monkey lymphoid cells infected with HVS. Intracellular antigens were detected in infected cells after in vitro cultivation but not in uninfected cells or fresh biopsy material from HVS-infected monkeys. These antigens were demonstrated with post-HVS infection sera from 6 owl monkeys but not with sera taken before or within 5 days after HVS infection. HVS-associated membrane antigens were shown in cells productively infected with the virus. The appearance of these antigens coincided with cytopathogenic changes associated with the viral infection. This was particularly evident in an infected owl-monkey kidney culture where only the rounded cells, not the adherent monolayer, contained both intracellular and membrane antigens. Similar observations were obtained when vero cells, cocultivated with a non-virus-producing marmoset lymphoid cell line, showed cytopathology characteristic of HVS infection. These results demonstrate that membrane antigens are expressed in cells infected with HVS and suggest that their synthesis is a late event in the replicative cycle of this virus.