Wijayalath Wathsala, Majji Sai, Villasante Eileen F, Brumeanu Teodor D, Richie Thomas L, Casares Sofia
US Military Malaria Vaccine Program, Naval Medical Research Center/Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA.
Malar J. 2014 Sep 30;13:386. doi: 10.1186/1475-2875-13-386.
Malaria is a deadly infectious disease affecting millions of people in tropical and sub-tropical countries. Among the five species of Plasmodium parasites that infect humans, Plasmodium falciparum accounts for the highest morbidity and mortality associated with malaria. Since humans are the only natural hosts for P. falciparum, the lack of convenient animal models has hindered the understanding of disease pathogenesis and prompted the need of testing anti-malarial drugs and vaccines directly in human trials. Humanized mice hosting human cells represent new pre-clinical models for infectious diseases that affect only humans. In this study, the ability of human-immune-system humanized HLA-DR4.RagKO.IL2RγcKO.NOD (DRAG) mice to sustain infection with P. falciparum was explored.
Four week-old DRAG mice were infused with HLA-matched human haematopoietic stem cells (HSC) and examined for reconstitution of human liver cells and erythrocytes. Upon challenge with infectious P. falciparum sporozoites (NF54 strain) humanized DRAG mice were examined for liver stage infection, blood stage infection, and transmission to Anopheles stephensi mosquitoes.
Humanized DRAG mice reconstituted human hepatocytes, Kupffer cells, liver endothelial cells, and erythrocytes. Upon intravenous challenge with P. falciparum sporozoites, DRAG mice sustained liver to blood stage infection (average 3-5 parasites/microlitre blood) and allowed transmission to An. stephensi mosquitoes. Infected DRAG mice elicited antibody and cellular responses to the blood stage parasites and self-cured the infection by day 45 post-challenge.
DRAG mice represent the first human-immune-system humanized mouse model that sustains the complex vertebrate life cycle of P. falciparum without the need of exogenous injection of human hepatocytes/erythrocytes or P. falciparum parasite adaptation. The ability of DRAG mice to elicit specific human immune responses to P. falciparum parasites may help deciphering immune correlates of protection and to identify protective malaria antigens.
疟疾是一种致命的传染病，影响着热带和亚热带国家的数百万人。在感染人类的五种疟原虫中，恶性疟原虫导致的疟疾发病率和死亡率最高。由于人类是恶性疟原虫唯一的自然宿主，缺乏便捷的动物模型阻碍了对疾病发病机制的理解，并促使需要直接在人体试验中测试抗疟药物和疫苗。携带人类细胞的人源化小鼠代表了针对仅影响人类的传染病的新型临床前模型。在本研究中，探索了人免疫系统人源化HLA-DR4.RagKO.IL2RγcKO.NOD（DRAG）小鼠维持恶性疟原虫感染的能力。
给4周龄的DRAG小鼠输注HLA匹配的人类造血干细胞（HSC），并检查人类肝细胞和红细胞的重建情况。在用感染性恶性疟原虫子孢子（NF54株）攻击后，检查人源化DRAG小鼠的肝期感染、血期感染以及向斯氏按蚊的传播情况。
人源化DRAG小鼠重建了人类肝细胞、库普弗细胞、肝内皮细胞和红细胞。在用恶性疟原虫子孢子进行静脉攻击后，DRAG小鼠维持了从肝期到血期的感染（平均每微升血液中有3 - 5个寄生虫），并允许向斯氏按蚊传播。受感染的DRAG小鼠引发了针对血期寄生虫的抗体和细胞反应，并在攻击后第45天自愈了感染。
DRAG小鼠代表了首个无需外源注射人类肝细胞/红细胞或适应恶性疟原虫寄生虫就能维持恶性疟原虫复杂脊椎动物生命周期的人免疫系统人源化小鼠模型。DRAG小鼠对恶性疟原虫寄生虫引发特异性人类免疫反应的能力可能有助于解读保护的免疫相关性并识别保护性疟疾抗原。
