The purpose of the study is to evaluate the safety and reactogenicity of candidate gD vaccine, with or without MPL, in HSV-seropositive subjects. The immune response elicited in these subjects will also be evaluated.

At the time of conduct of this study, the sponsor GlaxoSmithKline was known by its former name SmithKline Beecham

Inclusion Criteria:

• Between 18 and 40 years of age
• Seropositive for antibodies against HSV
• Female volunteers must have been using contraceptives for at least 2 months before the entry and should avoid becoming pregnant for the duration of this study.
• Good physical condition as established by physical examination and history taking at the time of entry

Exclusion Criteria:

• Any abnormal laboratory value among the tests performed at screening.
• History of persistent hepatic, renal, cardiac or respiratory diseases
• Clinical signs of acute illness at the time of entry into the study.
• Previous history of asthma or hypersensitivity to drugs.
• Seropositive for antibodies against the human immunodeficiency virus
• Pregnancy and lactation.
• Treatment with corticosteroids or immunomodulating drugs.
• Simultaneous participation in another clinical trial.
• Administration of any other vaccine or immunoglobulins during the study period