A Systems Biology Approach to Malaria Immunity

This is a phase I study that will assess the acquisition of immunity to Pf malaria over the course of 5 sequential Controlled Human Malaria Infections (CHMI) over 2-4 years, in 10 healthy adult participants. 10 subjects will initially be challenged with 5 uninfected mosquitoes (mock), followed by 5 challenges with 5 mosquitoes infected with drug sensitive, P. falciparum parasites (strain NF54) 2, 8, 14-20, 20-32, and 32-36 months later. For the final four infective CMHIs six additional immunologic malaria-naïve subjects will be enrolled and challenged as infectivity controls. If dropouts occur within the original 10 person cohort, and two or more CHMI remain, back-up replacement volunteers will be recruited to undergo successive CHMI with the core group. All volunteers (repeat CHMI subjects and infectivity controls) will be evaluated as part of an inpatient stay (or outpatient daily follow-up) to diagnose Pf malaria infection and treat with Coartem(R) (artemether/lumefantrine) or Malarone(R) (Atovaquone/proguanil). Daily observation will occur from Study Days 9-19 or until three-day directly observed therapy for P. falciparum infection is complete and two negative smears separated by a time interval \>12 hours have been documented. A third negative smear \>12 hours after the previous two daily smears will be documented to affirm malaria cure. Infectivity Controls enrolled as part of CHMI #5 will be treated based on concomitant us qPCR results. The repeat CHMI subjects will have additional outpatient visits days 1, 3, 5, and 7 after the challenge to obtain blood samples to monitor the development of immunity. The study is expected to last for 48 months and will include approximately 34 healthy male and female volunteers (10 active study volunteers and 18 naïve controls to confirm Pf infectivity during the 2nd -5th CHMI challenges) ages 18 to 50 years, inclusive, from the greater Baltimore community. The primary objective of this study is to determine whether protective immunity against parasite infection develops following repeat CHMI. The secondary objectives are to: 1) determine whether clinical signs and symptoms of malaria decrease in intensity and duration following repeat CHMI, 2) track the production of antibodies that react with P. falciparum sporozoites and blood stage parasites.