This is a clinical trial in which healthy volunteers will be administered one or two experimental malaria vaccines. ChAd Pfs-IMX313 will either be administered alone or with MVA Pfs25-IMX313 in a prime-boost regime.

All vaccines will be administered intramuscularly.

Group 1 will receive one dose of ChAd63 Pfs25-IMX313 at 5x10^9 vp.

Group 2A will receive one dose of ChAd63 Pfs-IMX313 at 5x10^10 vp.

Group 2B will receive one dose of ChAd63 Pfs-IMX313 at 5x10^10 vp and one dose of MVA Pfs25-IMX313 at 1x10^8 pfu eight weeks later.

Group 2C will receive one dose of ChAd63 Pfs25-IMX313 at 5x10^10 vp and one dose of MVA Pfs25-IMX313 at 2x10^8 pfu eight weeks later.

The study will assess the safety of the vaccinations, and the immune responses to the vaccination. Immune responses are measured by tests on blood samples.

Healthy volunteers will be recruited in Oxford and Southampton, England.

Inclusion Criteria:

The volunteer must satisfy all the following criteria to be eligible for the study:

• Healthy adults aged 18 to 50 years
• Able and willing (in the Investigator's opinion) to comply with all study requirements
• Willing to allow the investigators to discuss the volunteer's medical history with their General Practitioner
• For females only, willingness to practice continuous effective contraception (see below) during the study and a negative pregnancy test on the day(s) of screening and vaccination
• Agreement to refrain from blood donation during the course of the study
• Provide written informed consent

Exclusion Criteria:

The volunteer may not enter the study if any of the following apply:

• Participation in another research study involving receipt of an investigational product in the 30 days preceding enrolment, or planned use during the study period
• Prior receipt of an investigational malaria vaccine or any other investigational vaccine likely to impact on interpretation of the trial data.
• Administration of immunoglobulins and/or any blood products within the three months preceding the planned administration of the vaccine candidate
• Any confirmed or suspected immunosuppressive or immunodeficient state, including HIV infection; asplenia; recurrent, severe infections and chronic (more than 14 days) immunosuppressant medication within the past 6 months (inhaled and topical steroids are allowed)
• History of allergic disease or reactions likely to be exacerbated by any component of the vaccine, e.g. egg products.
• Any history of anaphylaxis in relation to vaccination
• Pregnancy, lactation or willingness/intention to become pregnant during the study
• History of cancer (except basal cell carcinoma of the skin and cervical carcinoma in situ)
• History of serious psychiatric condition likely to affect participation in the study
• Any other serious chronic illness requiring hospital specialist supervision
• Suspected or known current alcohol abuse as defined by an alcohol intake of greater than 42 units every week
• Suspected or known injecting drug abuse in the 5 years preceding enrolment
• Seropositive for hepatitis B surface antigen (HBsAg)
• Seropositive for hepatitis C virus (antibodies to HCV)