A study on the reactogenicity, safety, immune response, and efficacy of a targeted immunotherapy against HSV in healthy participants aged 18-40 years or in participants aged 18-60 years with recurrent genital herpes

Participants, who, in the opinion of the investigator, can and will comply with the requirements of the Protocol.

• Written informed consent obtained from the participant prior to performance of any study-specific procedure.
• Women of non-childbearing potential can be enrolled in the study.
• Women of childbearing potential can be enrolled in the study, if the participant: -Has practiced highly effective contraception for one month prior to study intervention administration, and, -Has a negative pregnancy test result at the Screening visit and on the day of each study intervention administration, and, -For PART I: Has agreed to continue highly effective contraception until the end of the study. -For PART II: Has agreed to continue highly effective contraception until 3 months after last study intervention administration.
• Seronegative for human immunodeficiency virus (HIV), as determined by laboratory screening tests. Participants documented to be seropositive to HIV will not be eligible for study participation.
• Only for PART I: Healthy participants as established by medical history and physical examination, at the discretion of the investigator, before entering into the study.
• Only for PART I: Man or woman aged 18 to 40 years, included, at the time of the first study intervention administration.
• Only for PART I: Seronegative for HSV-2 as determined by Western blot performed at the Screening visit.
• Only for PART II: Participants with recurrent genital herpes and with no significant health problems as established by medical history and physical examination, at the discretion of the investigator, before entering the study.

History of self-reported or documented recurrent lesional genital herpes frequency of at least 3 and no more than 9 reported clinical recurrences in the 12 months preceding the screening visit, or, if still on suppressive therapy within 3 months before the Screening visit, prior to initiation of suppressive therapy.

• Only for PART II: Man or woman aged 18 to 60 years, included, at the time of the first study intervention administration.
• Only for PART II: Seropositive for HSV-2 as determined by serological testingperformed at the Screening visit, or having documented laboratory-confirmed HSV 2 genital herpes (i.e., HSV-2 DNA positive by a molecular technique such as polymerase chain reaction [PCR], or HSV-2 seropositive by a type-specific serology assay such as Western Blot or other immunoassay).Only for PART II (shedding sub-cohort): Participants agreeing to collect 2 swabs per day from anogenital area for the full duration of the 5 swabbing periods planned in the study.
• Only for PART II (shedding sub-cohort) after baseline completion: Participants having collected at least 45 out of 56 anogenital swabs during the baseline period.

Medical Conditions

• Acute or chronic clinically significant pulmonary, cardiovascular, hepatic, endocrine, or renal functional abnormality, as determined by physical examination or laboratory screening tests.
• Any other clinical condition that, in the opinion of the investigator, might pose additional risk to the participant due to participation in the study or that would interfere with the efficacy and immunogenicity assessments planned in this study.
• History of any reaction or hypersensitivity likely to be exacerbated by any component of the study intervention.
• Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination.
• Hypersensitivity to latex.
• Recurrent history or uncontrolled neurological disorders or seizures.
• Haematological and/or biochemical parameters outside the normal laboratory ranges at the Screening visit, unless the laboratory abnormalities are considered not clinically significant by the investigator.
• Body mass index =<18 kg/m^2 or >=35 kg/m^2.
• Past or current Guillain-Barré syndrome.
• History of any form of ocular HSV infection, HSV-related erythema multiforme, or HSV-related neurological complications. Prior/Concomitant Therapy
• Use of any investigational or non-registered product other than the study intervention during the period beginning as of the Screening visit, or planned use during the study period.
• Planned administration/administration of a vaccine not foreseen by the Protocol in the period starting 15 days before each dose and ending 15 days after each dose of study intervention administration.
• Administration or planned administration of long-acting immune-modifying drugs at any time during the study period.
• Administration of immunoglobulins and/or any blood products or plasma derivatives during the period starting 3 months before the first dose of study intervention or planned administration during the study period.
• Chronic administration of immunosuppressants or other immune-modifying drugs during the period starting 3 months prior to the first study intervention dose. For corticosteroids, this will mean prednisone equivalent >= 20 mg/day, or equivalent. Inhaled, intra articular and topical steroids are allowed.
• Prior receipt of another vaccine containing HSV antigens.
• Only for PART II: Planned use of suppressive anti-HSV therapy from the Screening visit until the end of the study.
• Only for PART II: Planned use of tenofovir therapy, or other medication known to affect HSV shedding or genital lesions from the Screening visit until the end of the study. Only for PART II: Planned use of topical antiviral medication in the anogenital region from the Screening visit until the end of the study.
• Only for PART II: Planned use of any episodic antiviral medications during the swabbing periods (including the baseline period) (only for the shedding sub-cohort). Prior/Concurrent Clinical Study Experience
• Concurrently participating in another clinical study, at any time during the study period, in which the participant has been or will be exposed to an investigational or a non-investigational intervention. Other Exclusions
• Pregnant or lactating women.
• Woman planning to become pregnant or planning to discontinue contraceptive precautions in the period starting from the Screening visit up to 3 months post-last dose of study intervention.