Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom.
Royal Belfast Hospital for Sick Children, Belfast Health & Social Care Trust, Belfast, United Kingdom.
Antimicrob Agents Chemother. 2020 Jan 27;64(2). doi: 10.1128/AAC.02034-19.
Respiratory syncytial virus (RSV) causes severe lower respiratory tract infections in young infants. There are no RSV-specific treatments available. Ablynx has been developing an anti-RSV F-specific nanobody, ALX-0171. To characterize the therapeutic potential of ALX-0171, we exploited our well-differentiated primary pediatric bronchial epithelial cell (WD-PBEC)/RSV infection model, which replicates several hallmarks of RSV disease Using 2 clinical isolates (BT2a and Memphis 37), we compared the therapeutic potential of ALX-0171 with that of palivizumab, which is currently prescribed for RSV prophylaxis in high-risk infants. ALX-0171 treatment (900 nM) at 24 h postinfection reduced apically released RSV titers to near or below the limit of detection within 24 h for both strains. Progressively lower doses resulted in concomitantly diminished RSV neutralization. ALX-0171 was approximately 3-fold more potent in this therapeutic RSV/WD-PBEC model than palivizumab (mean 50% inhibitory concentration [IC] = 346.9 to 363.6 nM and 1,048 to 1,090 nM for ALX-0171 and palivizumab, respectively), irrespective of the clinical isolate. The number of viral genomic copies (GC) was determined by quantitative reverse transcription-PCR (RT-qPCR), and the therapeutic effect of ALX-0171 treatment at 300 and 900 nM was found to be considerably lower and the number of GCs reduced only moderately (0.62 to 1.28 log copies/ml). Similar findings were evident for palivizumab. Therefore, ALX-0171 was very potent at neutralizing RSV released from apical surfaces but had only a limited impact on virus replication. The data indicate a clear disparity between viable virus neutralization and GC viral load, the latter of which does not discriminate between viable and neutralized RSV. This report validates the RSV/WD-PBEC model for the preclinical evaluation of RSV antivirals.
呼吸道合胞病毒（RSV）可导致婴幼儿严重的下呼吸道感染。目前尚无针对 RSV 的特效治疗方法。Ablynx 公司一直在开发一种针对 RSV F 蛋白的特异性纳米抗体，ALX-0171。为了评估 ALX-0171 的治疗潜力，我们利用分化良好的原代小儿支气管上皮细胞（WD-PBEC）/RSV 感染模型，该模型复制了 RSV 疾病的多个特征。使用 2 株临床分离株（BT2a 和 Memphis 37），我们比较了 ALX-0171 与目前用于高危婴儿 RSV 预防的 palivizumab 的治疗潜力。感染后 24 小时给予 ALX-0171（900 nM）治疗可使两种病毒株的 RSV 病毒滴度在 24 小时内降低至接近或低于检测下限。剂量逐渐降低会导致 RSV 中和作用相应减弱。与 palivizumab 相比，ALX-0171 在这种治疗性 RSV/WD-PBEC 模型中效力提高了约 3 倍（ALX-0171 的平均 50%抑制浓度 [IC] 为 346.9 至 363.6 nM，palivizumab 为 1048 至 1090 nM），与临床分离株无关。通过定量逆转录 PCR（RT-qPCR）确定病毒基因组拷贝数（GC），结果表明，ALX-0171 治疗 300 和 900 nM 的治疗效果要低得多，GC 数仅适度减少（0.62 至 1.28 log 拷贝/ml）。palivizumab 也有类似的发现。因此，ALX-0171 对从顶端表面释放的 RSV 具有很强的中和作用，但对病毒复制的影响有限。数据表明，活病毒中和与 GC 病毒载量之间存在明显差异，后者不能区分活病毒和中和的 RSV。本报告验证了 RSV/WD-PBEC 模型在 RSV 抗病毒药物的临床前评估中的应用。
