Induced Blood-Stage Plasmodium Vivax Infection With HMPBS02-Pv Challenge Agent in Healthy Malaria-Naive Adults to Produce a Plasmodium Vivax Parasite Cell Bank for Future Studies

This is a single-center, open-label study using induced blood-stage malaria (IBSM) to produce a human malaria parasite (HMP) bank for use in future studies. This study will be conducted in up to two participants. Participants will be inoculated intravenously (IV) with human malaria parasite blood stage P. vivax (HMPBS02-Pv) parasite-infected erythrocytes (day 0) and then monitored closely via outpatient clinic visits, phone visits, and while inpatient at the NIH Clinical Center (CC) for symptoms and signs of malaria to characterize the safety, tolerability, and infectivity in healthy malaria-naive participants inoculated with P. vivax. Blood sampling will be done periodically to measure parasitemia via quantitative polymerase chain reaction (qPCR) targeting the P. vivax 18S rRNA gene.

The threshold for the commencement of collection of blood for production of the HMP bank and subsequent antimalarial rescue treatment with artemether/lumefantrine will occur when the Malaria Clinical Score is >6 (admission within 24 hours of notification), or parasitemia is >20,000 parasites/mL, or at the investigator s discretion. When this threshold is reached, the participant will be admitted to the NIH CC for further safety assessments before undergoing the blood collection procedure.

After blood collection, the first dose of artemether/lumefantrine will be administered and the participant will remain inpatient for 48-72 hours to monitor for safety and tolerability of rescue therapy, and to ensure adequate clinical and parasitological response to treatment. In the unlikely and unprecedented event that artemether/lumefantrine fails to clear parasitemia, participants will be treated with chloroquine. If oral administration of either artemether/lumefantrine or chloroquine is not possible (e.g., the participant is vomiting), the participant will receive IV treatment with artesunate. After discharge, participants will be followed on an outpatient basis for monitoring of safety and parasite clearance. Follow-up for safety assessments will be performed on day 28 plus or minus 3, day 56 plus or minus 7 (phone call only), and day 90 plus or minus 7 (End of Study).

Participants may also be evaluated for the presence of sexual parasite stages (gametocytes) and other parasite lifecycle stages in the blood during the study using quantitative reverse transcriptase PCR (qRT-PCR).

Objectives: Primary Objective: The collection of blood from healthy participants experimentally infected with P. vivax isolate HMPBS02-Pv for the production of a P. vivax blood-stage parasite bank for use in future studies.