Comparison of the Susceptibility of Naive and Pre-immune Volunteers to Infectious Challenge With Viable Plasmodium Vivax Sporozoites.
试验速览
- 阶段
- 1 期
- 状态
- 已完成
- 发起方
- 入组人数
- 16
- 试验地点
- 1
- 主要终点
- Pre-patent period onset
研究概览
简要总结
This study is a randomized clinical trial designed to compare the susceptibility of naive and pre-immune volunteers to infectious challenge with viable Plasmodium vivax sporozoites. The term preimmune hereafter denoted only previous experience with infection by this parasite and not a definite state of immunity to malaria infection. The study hypothesis is that pre-immune volunteers present a delayed onset of malaria clinical and parasitological manifestations when compared to naive individuals. The development of this study will establish a protocol for evaluating the effectiveness of vaccine candidates against P. vivax in subsequent Phases IIa and IIb clinical trials.
详细描述
This study is a prospective controlled, blinded clinical trial, designed to establish the differences on infectivity of an infectious challenge with P. vivax sporozoites between human volunteers with and without history of malaria.
Study subjects
This study will require the involvement of two types of volunteers:
-
Parasite donors: 5-15 P. vivax-infected patients who will serve as parasites donors for experimental infection of mosquitoes, who will be enrolled in the endemic area.
-
Volunteers for infectious challenge Two other groups of volunteers will be exposed to mosquitoes infected with P. vivax sporozoites. A group of 7 people without previous exposure to malaria (naive) and another 12 people with a history of previous malaria infection (pre-immune).
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Basic Science
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 45 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Age 15 to 60 years.
- •Hemoglobin levels > 9g/dL.
- •Presence of Current P. vivax infection.
- •Absence of other Plasmodium species determined by thick blood smear and PCR.
- •Blood parasite count of 0.1% or more.
- •Absence of other acute or chronic diseases.
- •Being able to sign an informed consent form.
- •Healthy 18 to 45 years old man or non-pregnant women.
- •To have the capacity to sign an informed consent in a free and voluntary way.
- •To have an acceptable understanding of the clinical trial through the approval of a questionnaire regarding the information given in the consent process.
- •Obligatory use of adequate contraceptive method from beginning of recruitment and screening time up to three months after last immunization.
- •Do not have chronic or acute diseases. These conditions will be determined by clinical history, physical exam and laboratory tests.
- •To accept not traveling to malaria endemic areas during the clinical trial should
- •To have telephone at home or mobile phone that permit permanent contact for follow up
- •Being willing to participated during both steps of the clinical trial.
排除标准
- •history of blood transfusion in the last six months.
- •Pregnancy in women.
- •Have received antimalarial treatment before the diagnosis.
- •Pregnant or nursing women.
- •History of moderate or severe insect, or food allergies.
- •G-6PD deficiency or any Hb genetic defect.
- •Symptoms, signs or data from laboratory test that suggests any systemic disorder like renal, hepatic, cardiovascular, pulmonary, psychiatric disorders or other illnesses that could interfere with results of clinical trial or could compromise the health of the volunteer.
- •To have antibodies against hepatitis C, VIH, or hepatitis B superficial antigen and/or hepatitis B core antibodies.
- •To have any abnormality in the parameters assessed by blood laboratory tests
- •Presence or history of an auto-immune disease.
- •History of surgical removal of the spleen (splenectomy).
- •Use of medical treatment known to alter the immune system before 3 months to recruitment.
研究组 & 干预措施
Naive volunteers
Volunteers without previous exposure to malaria, and negative antibody titers (<1:20) against native protein of P. vivax.
干预措施: P. vivax infected mosquito bites (Biological)
Pre-immune volunteers
Volunteers with previous exposure to malaria, and positive antibody titers against native protein of P. vivax
干预措施: P. vivax infected mosquito bites (Biological)
结局指标
主要结局
Pre-patent period onset
时间窗: Two months after the challenge
begining at day 7 after mosquito bites exposure, both groups of volunteers will be evaluated with dayly Thick blood smear to compare the malaria onset between the pre-immune and naive groups.
次要结局
- Immune response(Two months after the malaria challenge)
研究者
Socrates Herrera Valencia
Director
Malaria Vaccine and Drug Development Center