Targeting of drug loaded immunoliposomes to herpes simplex virus infected corneal cells: an effective means of inhibiting virus replication in vitro.

The goal of our studies was to develop liposomes containing antiviral drugs and targeted with antiviral antibody (immunoliposomes) that would be effective at inhibiting replication of herpes simplex virus (HSV) in vitro. To achieve this, a monoclonal antibody to glycoprotein D of HSV was derivatized with palmitic acid and was incorporated into the lamellae of dehydration-rehydration vesicles. The gD containing immunoliposomes were shown to bind specifically to HSV-infected rabbit corneal cells in vitro, whereas control immunoliposomes prepared with a monoclonal antibody of the same class as the anti-gD failed to preferentially bind to virus-infected cells. The gD immunoliposome binding was inhibitable by pretreatment with rabbit anti-HSV serum but not by aggregated normal serum. Thus liposome binding was judged to represent an antigen-antibody reaction not binding to Fc receptors expressed by cells infected with HSV. Immunoliposomes loaded with iododeoxyuridine (IUDR) leaked drug rapidly at 37 degrees C, whereas acyclovir (ACV)-loaded liposomes still contained 48% of drug after 24 hr at 37 degrees C. The ACV-liposomes retained 44% of drug after 14 days at 4 degrees C. The ability of immunoliposomes to inhibit virus replication was compared with that of untargeted and empty liposomes by means of virus yield assays in vitro, Immunoliposomes loaded with either IUDR or ACV inhibited virus replication, although ACV-containing immunoliposomes were the most efficacious. The implications of our in vitro results for the development of immunoliposomes suitable for the treatment of ocular herpes infection are briefly discussed.