Replication of herpes simplex virus type 1 (HSV-1) involves a step in which a parental capsid docks onto a host nuclear pore complex (NPC). For this reason, the virus entry machinery is an excellent target for antiviral therapeutics. This initial attachment then triggers a cascade of molecular interactions involving multiple viral and host cell proteins and receptors, leading to penetration of the viral nucleocapsid and tegument proteins into the cytoplasm. Vero cells were preloaded with antibodies specific for proteins of interest and infected with HSV-1 containing a green fluorescent protein-labeled capsid, and capsids bound to the nuclear surface were quantified by fluorescence microscopy. When CD4+ T cells numbers decline below a critical level (400/μl of blood) cell-mediated immunity is compromised and the body becomes progressively more susceptible to opportunistic infections (3). This observation showed that the gIII- mutant was strictly defective in adsorption but fully competent to produce productive infections once induced to attach. Similarly, ISIS 5652 was able to inhibit entry of preattached virions into cells at 37°C, but the mutant did not exhibit resistance in this assay.
The keystone of this work is that for the first time, we describe the ability of KSHV-infected B cells to preferentially use cellular (alphaV) or viral (gB) receptors to specifically bind cells, depending upon the stage of the cell cycle and infection.