EBV infection of human neutrophils. Neutrophils were incubated with EBV for 5 to 15 minutes to allow binding to the cell surface. Virus-bound cells were then cultured at 37°C for varying time periods. (A) Virus was in contact with the cell membrane (original magnification [OM] × 76,000); (inset) at higher magnification, characteristic EBV virion in contact with cell membrane, showing its electron dense core representing viral DNA (OM × 90,000). (B) Fusion of viral and cellular membranes was found (OM × 80,000). (C and D) Internalization and presence of viral capsids were observed within the cytoplasm and the nucleus of neutrophils (OM × 39,000). N, nucleus. These results are represenative of six other experiments. Approximately one third of the cells were found to be infected by EBV.