Control volunteers (n = 6) were recruited to undergo malaria challenge without vaccination to confirm the infective efficacy of the sporozoite challenge. Vaccine follow-up visits for groups 1–7 were on days 2, 7 and 28 following each vaccination with additional visits on day 90 (groups 1–5) and day 150 after first vaccination (groups 6 and 7). In addition, all challengees were seen regularly

during the three weeks following challenge (see sporozoite challenge below) and then 35 and 150 days Torin 1 chemical structure following challenge. Blood was collected regularly for safety assessments and immunogenicity. FP9-PP and MVA-PP were manufactured according to Good Manufacturing Practice (GMP) regulations by Impfstoffwerk Dessau-Tornau (IDT, Roßlau, Germany). The polyprotein vaccine insert (‘L3SEPTL’) has been fully described

before [4]. It contains six pre-erythrocytic malaria antigens linked together in a single protein (from N to C terminus): liver stage antigen 3 (LSA3) [12], sporozoite threonine and asparagine FK228 order rich protein (STARP) [13], exported protein-1 (Exp1) [14], Pfs16 [15], thrombospondin-related adhesion protein (TRAP) [16] and liver stage antigen-1 (LSA1) [17]. All except possibly Pfs16 are pre-erythrocytic antigens; LSA3, Exp1 and STARP are also expressed by blood-stage parasites and Pfs16 is also a sexual-stage antigen [4]. Vaccines were stored at the trial site at −80 °C and thawed shortly before administration. Each dose was given intradermally into the skin overlying the deltoid muscle of the upper arm. Doses

were divided equally between both arms. Vaccine sites were temporarily covered with an absorbent dressing which was removed when the vaccine sites were reassessed approximately 30 min later. Volunteers were asked to complete study diary cards for the first seven days after vaccination, beginning with the evening of the vaccination day. These recorded local reactions (pain, redness, swelling, itching, warmth and scaling) and systemic symptoms (oral temperature, feverishness, myalgia, arthralgia, nausea or vomiting, lethargy, headache and malaise). Temperature was measured with an oral digital thermometer (Servoprax GmbH) supplied by the investigators and redness and swelling were recorded as maximal diameters (ensuring else the measurement passed through the puncture site). On each clinic attendance the investigators independently collected the same measurements. Adverse events (AEs) were recorded at each clinic visit in response to direct questioning, self-reporting on volunteer diary cards and examination of the vaccine site at each attendance by the investigators. Severity scales used for grading are shown in Online Table A. AEs were judged as either unrelated or possibly, probably or definitely related to vaccination by the investigator, taking into account the symptoms and time since vaccination. All AEs were followed until resolution where possible.