Passive immunization involves utilizing polyclonal or monoclonal antibodies as a form of immunotherapy. Antibodies can mediate their effects through several mechanisms, including opsonization and C-mediated lysis, but in particular antibody-dependent cell-mediated cytolysis (ADCC) and neutralization. Antibody immunotherapy has been demonstrated to be efficacious for the treatment and prevention of infection or disease caused by viruses other than herpes simplex virus (HSV) (Abzug et al., 1995; Reed et al., 1988; Feltes et al., 2003; Saez-Llorens et al., 1998; Subramanian et al., 1998; The IMpact-RSV Study Group, 1998). While intriguing data exist in animal models suggesting that such a therapeutic intervention may also be of benefit in the management of HSV infections, to date no controlled studies have demonstrated the benefit of such an approach in humans. This chapter explores the potential of such an approach in people, as well as the limitations in current knowledge.

Immune responses following HSV infection

Host resistance to HSV infections includes non-specific mechanisms such as interferons, neutrophils, complement, macrophages, and natural killer cells, as well as specific mechanisms including humoral (antibody) immunity, T-cell-mediated immunity (such as cytotoxic T-cells and T-helper activity), and cytokine release. The relative importance of these various mechanisms is different for initial vs. recurrent HSV disease. Animal studies suggest that activated macrophages, interferons, and, to a lesser extent, natural killer cells are important in limiting initial HSV infection, whereas humoral immunity and cell-mediated immunity are important in controlling both initial and recurrent infections.