Training rhesus macaques to take daily oral antiretroviral therapy for preclinical evaluation of HIV prevention and treatment strategies

BackgroundMacaque models of simian or simian/human immunodeficiency virus (SIV or SHIV) infection are critical for the evaluation of antiretroviral (ARV)-based HIV treatment and prevention strategies. However, modelling human oral ARV administration is logistically challenging and fraught by limited adherence. Here, we developed a protocol for administering daily oral doses of ARVs to macaques with a high rate of compliance.MethodsParameters of positive reinforcement training (PRT), behavioral responses and optimal drug delivery foods were defined in 7 male rhesus macaques (Macaca mulatta). Animals were trained to sit in a specified cage location prior to receiving ARVs, emtricitabine (FTC) and tenofovir alafenamide (TAF), in a blended food mixture, which was followed immediately with a juice chaser. Consistency of daily oral adherence was evaluated in 4 trained macaques receiving clinically equivalent doses of FTC and TAF (20 and 1.5 mg/kg, respectively) in a short-term (1 month) and an extended (6 month) trial. Adherence was monitored using medication diaries and by quantifying intracellular FTC-triphosphate (FTC-TP) and tenofovir-diphosphate (TFV-DP) concentrations in peripheral mononuclear blood cells (PBMCs).ResultsTrained macaques quickly and consistently took daily oral ARVs for 1 month with an average 99.8% observed adherence. Intracellular concentrations of TFV-DP (median = 845.8 fmol/million cells [range, 620.8–1031.3]) and FTC-TP (median = 367.0 fmol/million cells [range, 289.5–413.5) in PBMCs were consistent with high adherence. Extended treatment with select subjects yielded similar observations for three months (99.5% adherence, 352/356 complete doses taken), although a sudden drop in adherence was observed after splenic biopsy surgery.ConclusionsWe demonstrate that trained macaques reliably adhere to a daily oral ARV regimen, although unexpected adherence issues are possible. Our approach, using clinical doses of oral FTC and TAF daily, further refines macaque models of HIV treatment and prevention by mimicking the human route and timing of ARV administration.

背景：感染猴免疫缺陷病毒（Simian Immunodeficiency Virus, SIV）或猴人嵌合免疫缺陷病毒（Simian/Human Immunodeficiency Virus, SHIV）的猕猴模型，是评估基于抗逆转录病毒（Antiretroviral, ARV）的HIV治疗与预防策略的核心研究工具。然而，模拟人类口服抗逆转录病毒给药的猕猴模型在实施层面颇具挑战，且普遍面临给药依从性不佳的难题。本研究开发了一种可使猕猴实现高依从性的每日口服抗逆转录病毒给药方案。
方法：本研究对7只雄性恒河猴（Macaca mulatta）的正强化训练（Positive Reinforcement Training, PRT）参数、行为反应以及最优给药载体食物进行了标准化界定。对受试猴开展训练，使其在接受混合食物递送的抗逆转录病毒药物——恩曲他滨（Emtricitabine, FTC）与替诺福韦艾拉酚胺（Tenofovir Alafenamide, TAF）前，能够固定坐在指定笼位中，给药完成后立即给予果汁作为奖励。本研究在短期（1个月）与长期（6个月）试验中，对4只经训练的猕猴的每日口服给药依从性一致性进行评估，给药剂量为临床等效剂量的FTC（20 mg/kg）与TAF（1.5 mg/kg）。依从性通过用药日志，以及对外周血单个核细胞（Peripheral Mononuclear Blood Cells, PBMCs）内恩曲他滨三磷酸（FTC-triphosphate, FTC-TP）与替诺福韦二磷酸（Tenofovir-diphosphate, TFV-DP）浓度的定量检测进行监测。
结果：经训练的猕猴可快速且稳定地完成1个月的每日口服抗逆转录病毒给药，观测到的平均依从率达99.8%。外周血单个核细胞内TFV-DP的中位浓度为845.8 fmol/百万细胞（范围：620.8~1031.3 fmol/百万细胞），FTC-TP的中位浓度为367.0 fmol/百万细胞（范围：289.5~413.5 fmol/百万细胞），该指标与高依从性的预期高度吻合。对部分受试猴开展的3个月延长给药试验得到了相似结果（依从率99.5%，完成给药352/356次），但在脾脏活检手术后，受试猴的给药依从性出现了突发性下降。
结论：本研究证实，经训练的猕猴可稳定依从每日口服抗逆转录病毒给药方案，尽管仍可能出现意外的依从性问题。本方案采用临床等效剂量的FTC与TAF每日口服给药，通过模拟人类抗逆转录病毒药物的给药途径与给药时机，进一步优化了HIV治疗与预防研究的猕猴模型。