This is an open label, randomized, controlled clinical trial. The primary aim of this project is to determine the safety and tolerability of NF135.C10 sporozoite immunization under chemoprophylaxis against homologous and heterologous challenge infection.
A total of 49 healthy volunteers will be allocated to receive either three immunizations with 15 NF135.C10 infected Anopheles mosquitoes (n=30), 3 immunizations with 5 NF135.C10 infected mosquitoes (n=10) or no immunizations (n=6). Immunizations in cohort A (n=20) will be performed under mefloquine prophylaxis, spaced 4 weeks apart. In cohort B, volunteers will not take mefloquine prophylaxis, instead all volunteers will be treated presumptively on day 7 after each immunization with a curative regimen of artemether/lumefantrine, regardless of parasitaemia or symptoms. Nineteen weeks after the last immunization, all volunteers plus naïve controls will be challenged either by the bites of 5 NF135.C10 (n=36) or 5 NF54 (n=13) infected mosquitoes. After challenge infection, volunteers will be followed up on an out-patient basis once daily for qPCR and safety lab measurements from day 6 until day 21 post challenge. All volunteers will be treated with a curative regimen of atovaquone/proguanil, either at the time of detection of blood stage parasitemia, or 28 days after challenge infection.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
43
Subjects will be immunized 3 times by exposure to the bites of P. falciparum NF135.C10 infected mosquitoes while taking mefloquine prophylaxis.
Subjects will receive bites from 5 Anopheles mosquitoes infected with Plasmodium falciparum NF135.C10 sporozoites.
Subjects will receive bites from 5 Anopheles mosquitoes infected with Plasmodium falciparum NF54 sporozoites.
Radboud university medical centre
Nijmegen, Gelderland, Netherlands
Frequency of Adverse Events After NF135.C10 CPS Immunization
The number of adverse events will be recorded by the trial clinicians for all participants.
Time frame: Cohort A: Inclusion until 35 days after challenge infection (35 weeks) Cohort B: Inclusion - premature end of study (22 weeks)
Magnitude of Adverse Events After NF135.C10 CPS Immunization
The severity of adverse events will be recorded (mild/moderate/severe) for each adverse event
Time frame: Cohort A: Inclusion until 35 days after challenge infection (35 weeks) Cohort B: Inclusion - premature end of study (22 weeks)
Time to Parasitemia
The effectiveness of CPS-immunization with NF135 sporozoites to protect against malaria challenge infection with homologous N135.C10 or heterologous NF54 sporozoites will be determined by the time to parasitemia in immunized versus non-immunized volunteers after the challenge infection.
Time frame: Day 1 - 28 after malaria challenge infection (28 days)
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Subjects will be immunized 3 times by exposure to the bites of P. falciparum NF135.C10 infected mosquitoes and receive presumptive treatment with artemether/lumefantrine initiated on day 7 after each immunization.
All participants will be treated with atovaquone/proguanil (1000/400 mg (= 4 tablets) 1×/day during 3 consecutive days) when they develop a malaria infection or on day 28 after malaria challenge infection.