Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA.
Biodefense Therapeutics, JPdM-BDTx, 110 Thomas Johnson Dr., Frederick, MD, USA.
Malar J. 2019 Feb 15;18(1):38. doi: 10.1186/s12936-019-2661-x.
Rodent malaria models are extensively used to predict treatment outcomes in human infections. There is a constant need to improve and refine these models by innovating ways to apply new scientific findings and cutting edge technologies. In addition, and in accordance with the three R's of animal use in research, in vivo studies should be constantly refined to avoid unnecessary pain and distress to the experimental animals by using preemptive euthanasia as soon as the main scientific study objective has been accomplished.
The new methodology described in this manuscript uses the whole-body bioluminescence signal emitted by transgenic, luciferase-expressing Plasmodium berghei parasites to assess the parasite load predicted parasitaemia (PLPP) in drug and control treated female ICR-CD1 mice infected with 1 × 10 luciferase-expressing P. berghei (ANKA strain) infected erythrocytes. This methodology can replace other time-consuming and expensive methods that are routinely used to measure parasitaemia in infected animals, such as Giemsa-stained thin blood smears and flow cytometry.
There is a good correlation between whole-body bioluminescence signal and parasitaemia measured using Giemsa-stained thin blood smears and flow cytometry respectively in donor and study mice in the modified Thompson test. The algebraic formulas which represent these correlations can be successfully used to assess PLPP in donor and study mice. In addition, the new methodology can pinpoint sick animals 2-8 days before they would have been otherwise diagnosed based on behavioural or any other signs of malaria disease.
The new method for predicting parasitaemia in the modified Thompson test is simple, precise, objective, and minimizes false positive results that can lead to the premature removal of animals from study. Furthermore, from the animal welfare perspective of replace, reduce, and refine, this new method facilitates early removal of sick animals from study as soon as the study objective has been achieved, in many cases well before the clinical signs of disease are present.
啮齿动物疟疾模型被广泛用于预测人类感染的治疗效果。为了改进和完善这些模型，需要不断创新方法，应用新的科学发现和前沿技术。此外，根据动物在研究中的三个 R 原则，活体研究应不断改进，一旦主要的科学研究目标已经完成，就通过预先实施安乐死来避免实验动物遭受不必要的痛苦和伤害。
本文描述的新方法学利用表达荧光素酶的转基因伯氏疟原虫发出的全身生物发光信号，评估用药物处理和对照处理的雌性 ICR-CD1 小鼠感染 1×10 个表达荧光素酶的伯氏疟原虫（ANKA 株）感染性红细胞后的寄生虫载量预测疟疾发病率（PLPP）。这种方法可以替代其他耗时且昂贵的方法，用于测量感染动物的疟疾发病率，例如吉姆萨染色薄血涂片和流式细胞术。
在改良的汤普森试验中，供体和研究小鼠的全身生物发光信号与吉姆萨染色薄血涂片和流式细胞术测量的疟原虫血症之间存在良好的相关性。代表这些相关性的代数公式可以成功地用于评估供体和研究小鼠的 PLPP。此外，新方法可以在动物因疟疾疾病的行为或任何其他迹象而被诊断之前，提前 2-8 天发现患病动物。
改良的汤普森试验中预测疟疾发病率的新方法简单、精确、客观，并且最大限度地减少了可能导致动物过早从研究中移除的假阳性结果。此外，从动物福利的替代、减少和优化的角度来看，这种新方法可以促进一旦研究目标已经实现，就尽早将患病动物从研究中移除，在许多情况下，在疾病的临床症状出现之前就可以做到。
