This study is a human challenge study to assess the minimum infective mosquito bite dose in a controlled human malaria Infection (via P. vivax sporozites) in healthy volunteers. The results will inform the development of a P. vivax mosquito-delivered CHMI trial platform, supporting safer and more accurate vaccine efficacy assessments. Conducting the trial in individuals genetically and immunologically similar to the target population will also enhance the relevance of findings to real-world endemic settings.
This study is funded by the UK Wellcome Trust. The grant reference number are Oxford/MORU: 212336/Z/18/Z and 212336/Z/18/A, and Mahidol University: 212336/A/18/Z and 212336/A/18/A.
Healthy adult aged 20 to 55 years with weight more than 50 kg.
No recent malaria infection.
Red blood cells positive for the Duffy antigen/chemokine receptor (DARC).
CYP2D6 alleles consistent with normal metaboliser status.
None
Sequential
Mosquito bite (1 or 2 or 3)
Other interventionSuccessful feeding of 1, 2, or 3 Plasmodium vivax-infected mosquitoes
The minimum number of infected mosquito bites.
The minimum number of infected mosquito bites needed to reliably result in a P.vivax infection in all 8 participants at a given bite dose group, as defined by two consecutive positive qPCR results or presence of parasitemia on malaria blood film
Prepatent period across different groups.
Measurement of the prepatent period (time from challenge to first qPCR-positive result) in participants across different mosquito bite groups.
Humoral immune responses
Characterisation of humoral immune responses (antibody titress) to Plasmodium vivax infection, stratified by the number of mosquito bites received.
Humoral immune responses
Characterisation of humoral immune responses (Cytokine response) to Plasmodium vivax infection, stratified by the number of mosquito bites received.
Cellular immune responses
Characterisation of cellular immune responses (T-cell profiles) to Plasmodium vivax infection, stratified by the number of mosquito bites received.
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University of Oxford
Lead sponsor
Mahidol University
Collaborator
