Efficacy, Safety and Immunogenicity Study of GlaxoSmithKline(GSK) Biologicals' Candidate Malaria Vaccine 257049 in the Sporozoite Challenge Model in Healthy Malaria-naïve Adults

Inclusion Criteria

Inclusion criteria for enrolment to the primary phase:

• Subjects who, in the opinion of the investigator, can and will comply with the requirements of the protocol.
• A male or non-pregnant female 18 to 50 years of age at the time of first vaccination.
• Written informed consent obtained from the subject before screening procedures.
• Free of obvious health problems as established by medical history and clinical examination before entering into the study.
• Available to participate for the duration of the study (approximately 15 months per vaccinated subject in the delayed fractional dose group, approximately 10 months per vaccinated subject in the 0, 1, 2-month schedule and approximately 7 months per subject in the infectivity control group).
• Female subjects of non-childbearing potential may be enrolled in the study.
• Non-childbearing potential is defined as pre-menarche, current tubal ligation, hysterectomy, ovariectomy or post-menopause.
• Female subjects of childbearing potential may be enrolled in the study, if the subject:
• has practiced adequate FDA-approved contraception for 30 days prior to vaccination, and
• has a negative pregnancy test on the day of vaccination, and
• has agreed to continue adequate FDA-approved contraception during the entire treatment period and for 2 months after completion of the vaccination series and/or malaria challenge.

Inclusion criteria for enrolment to the booster phase:

• Subjects who, in the opinion of the investigator, can and will comply with the requirements of the protocol.
• Written informed consent obtained from the subject before screening procedures.
• Subjects vaccinated in the primary phase of the study (not applicable to new infectivity controls), having undergone sporozoite challenge during the primary phase of the study.
• Available to participate for the duration of the booster phase of the study (approximately 3 months).
• Female subjects of non-childbearing potential may be enrolled in the study.
• Non-childbearing potential is defined as pre-menarche, current tubal ligation, hysterectomy, ovariectomy or post-menopause.
• Female subjects of childbearing potential may be enrolled in the booster phase of the study, if the subject:
• has practiced adequate FDA-approved contraception for 30 days prior to day of booster vaccination, and
• has a negative pregnancy test on the day of booster vaccination, and
• has agreed to continue adequate FDA-approved contraception during the entire treatment period and for 2 months after completion of the booster vaccination and/or malaria rechallenge.

Exclusion Criteria

For enrolment to the primary & booster phase:

• Any confirmed or suspected immunosuppressive or immunodeficient condition, including immunodeficiency virus (HIV) infection.
• Acute disease and/or fever at the time of enrolment to booster phase.
• Acute disease is defined as the presence of a moderate or severe illness with or without fever. Subjects with a minor illness without fever may be enrolled at the discretion of the investigator.
• Fever is defined as temperature ≥ 38.0°C (100.4°F) on oral, axillary or tympanic setting. The preferred route for recording temperature in this study will be oral.
• Acute or chronic, clinically significant pulmonary, cardiovascular, hepatic or renal functional abnormality, as determined by physical examination or laboratory screening tests.
• Evidence of increased cardiovascular disease risk, "moderate" or "high", according to the National health and nutrition examination survey I (NHANES I) criteria.

Note: NHANES I criteria will be applied for all subjects including subjects aged 18-35 years old.

• An abnormal baseline screening electrocardiogram (EKG), defined as one showing pathologic Q waves and significant ST-T wave changes; left ventricular hypertrophy; any non-sinus rhythm excluding isolated premature atrial contractions; right or left bundle branch block; or advanced A-V heart block.
• Fem