The purpose of the study is to compare, in healthy HSV seronegative and HSV seropositive subjects, the humoral and cellular immune response of herpes simplex candidate vaccines containing gD from two different cell lines and using gD-Alum as control.

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

Inclusion Criteria:

• Between 18 and 45 years of age
• Written informed consent
• Female volunteers must be using contraception and should avoid becoming pregnant for the duration of the vaccination course
• Serology: Groups 1, 3, 4 and 5: HSV-1 AND HSV-2 seronegative (by gD2 ELISA); Group 2: HSV seropositive by gD2 ELISA before entry

Exclusion Criteria:

• Any previous vaccination against Herpes simplex.
• Any previous administration of MPL.
• Pregnancy or lactation.
• Patient is immuno-compromised or is receiving immuno-modifying therapy of any kind.
• Clinical signs of acute or febrile illness at the time of entry into the study.
• Any administration of immunoglobulins during the vaccination course or within one month of vaccination.
• Any vaccination within one week of study vaccination.
• Previous known hypersensitivity to vaccination or to any component of the vaccine.
• Simultaneous participation in any other clinical trial with an investigational drug or vaccine. Subjects currently in a follow-up period of a vaccine study can be included.
• Recent history of alcoholism or drug abuse (within the past 6 months).
• Life-threatening or serious cardiac (NYHA grades III-IV), gastrointestinal, hepatic, renal, hematological or immunological disorder which, in the opinion of the investigator, would preclude entry into the study.