Immunization of Human Volunteers With P. Vivax Irradiated Sporozoites
Condition: Malaria
MeSH terms: Malaria
Study type: Interventional
Phase: Phase 1/Phase 2

Summary: 
      It is possible to safely protect human volunteers immunized with P. vivax irradiated
      sporozoites from P. vivax challenge with live sporozoites.
    

Detailed description: 
      Title: Phase 1 and Phase 2a Clinical Trial: Immunization of human volunteers with P. vivax
      irr-spz. (Short name: Irrad-SPZ) Population 27 healthy adult volunteers, males and
      non-pregnant females, between 18-45 years of age, who fulfill inclusion/exclusion criteria
      (described below) as determined by clinical history and serological tests. Approximately 20
      parasitized blood-donor volunteers will be required to infected Anopheles mosquitoes which
      will be used to immunize volunteers with a total of 1000-1500 infected mosquitoes, during
      8-10 months. Afterwards challenge to prove protection.

      Number of Sites: 2 Study Duration: 2 years. Subject Duration : Step1: 1-2 hours to blood
      donors; Step 2 and 3: 2 years to immunized volunteers Objectives Primary

      • To assess the safety and protective efficacy of P. vivax irradiated sporozoite vaccination.

      Secondary

        -  To determine the immune responses and duration elicited by the P. vivax challenge in
           human Fy(+) volunteers previously immunized with irr-spz, as compared with non-immunized
           human volunteers.

        -  To determine the immune responses and duration elicited by irr-spz immunization scheme
           in human Fy(+) volunteers; comparing it with the same immunization scheme with non
           irr-spz in Fy(-) participants, and also with controls exposed to the same mosquito bite
           scheme as that of immunization but using mosquitoes without parasite infection.

        -  To study new antigens potentially useful to induce pre-erythrocytic protection against
           P. vivax malaria infection
    

Intervention name(s): Immunization with P. vivax irradiated sporozoites
Intervention type(s): Biological
Intervention description(s): Anopheles albimanus mosquitoes will be infected by artificial membrane feeding using blood from P. vivax infected donors. Once mosquitoes are positive will be irradiated at 15000 cGy and kept in boxes until use.
14 Fy(+) human volunteers in the experimental group will be immunized with 1,000-2,000 P. vivax irrad-spz bites. Seven Fy(+) volunteers in the control group will be exposed to non-infected mosquito bites. Six Fy(-) volunteers will be exposed to infective mosquito bites. For the challenge both the immunized and control groups will be exposed to 3 ± 1 infective mosquito bites. Volunteers will be closely monitored post infection and will be treated with antimalarials.
Other intervention name(s): P. vivax irradiated sporozoites vaccine
Intervention MeSH terms: Vaccines
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: GCP Good Clinical Practice; IFAT Indirect Immunofluorescence antibody test; MFA Membrane Feeding Assay; N Number (typically refers to subjects); RBC Red Blood Cells; SOP Standard Operating Procedure; TBS Thick blood smear; P. Vivax; irradiated sporozoite vaccination.