Introduction: objectives of herpes simplex virus vaccines seen from a historical perspective.

Herpes simplex virus (HSV) types 1 and 2 cause a variety of severe manifestations in humans. A major characteristic of HSVs is their ability to establish latent infection in sensory ganglia, where these viruses are shielded from the immune system and are impervious to the action of antiviral drugs known to date. Ideally, HSV-induced clinical syndromes should be prevented by vaccination, but two major problems arise. First, although many antiviral vaccines have successfully prevented disease, none have prevented infection. Once the virus infects cells at the portal of entry of the infection, it can establish latent infection in sensory neurons that innervate the cell. Second, while HSV disease primarily affects adults greater than 18 years of age, mass immunization in the United States is effectively carried out in the interval between nursery school and high school, and yet the vaccines must confer protection for a long time after vaccination. The central issues involved in the development of an anti-HSV vaccine include what type of vaccine should be developed, what we should expect from an HSV vaccine, and how we should monitor the effectiveness of the vaccine.