Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, 858 Madison Avenue, Memphis, TN, 38103, USA.
Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin, Madison, WI, 53705-2222, USA.
Antiviral Res. 2019 Jul;167:25-34. doi: 10.1016/j.antiviral.2019.04.004. Epub 2019 Apr 7.
Currently, there are no licensed human vaccines or antivirals for treatment of or prevention from infection with encephalitic alphaviruses. Because epidemics are sporadic and unpredictable, and endemic disease is common but rarely diagnosed, it is difficult to identify all populations requiring vaccination; thus, an effective post-exposure treatment method is needed to interrupt ongoing outbreaks. To address this public health need, we have continued development of ML336 to deliver a molecule with prophylactic and therapeutic potential that could be relevant for use in natural epidemics or deliberate release scenario for Venezuelan equine encephalitis virus (VEEV). We report findings from in vitro assessments of four analogs of ML336, and in vivo screening of three of these new derivatives, BDGR-4, BDGR-69 and BDGR-70. The optimal dosing for maximal protection was observed at 12.5 mg/kg/day, twice daily for 8 days. BDGR-4 was tested further for prophylactic and therapeutic efficacy in mice challenged with VEEV Trinidad Donkey (TrD). Mice challenged with VEEV TrD showed 100% and 90% protection from lethal disease when treated at 24 and 48 h post-infection, respectively. We also measured 90% protection for BDGR-4 in mice challenged with Eastern equine encephalitis virus. In additional assessments of BDGR-4 in mice alone, we observed no appreciable toxicity as evaluated by clinical chemistry indicators up to a dose of 25 mg/kg/day over 4 days. In these same mice, we observed no induction of interferon. Lastly, the resistance of VEEV to BDGR-4 was evaluated by next-generation sequencing which revealed specific mutations in nsP4, the viral polymerase.
目前，尚无针对脑炎病毒感染的治疗或预防的许可人类疫苗或抗病毒药物。由于流行是零星且不可预测的，并且地方性疾病很常见但很少被诊断出来，因此很难确定需要接种疫苗的所有人群；因此，需要一种有效的暴露后治疗方法来中断正在进行的爆发。为了满足这一公共卫生需求，我们继续开发 ML336，以提供具有预防和治疗潜力的分子，该分子可能与委内瑞拉马脑炎病毒（VEEV）的自然流行或故意释放情况有关。我们报告了对 ML336 的四种类似物的体外评估结果，以及对其中三种新衍生物 BDGR-4、BDGR-69 和 BDGR-70 的体内筛选结果。观察到最大保护作用的最佳剂量为每天 12.5mg/kg，每天两次，共 8 天。BDGR-4 进一步在接受 VEEV 特立尼达驴（TrD）挑战的小鼠中进行了预防和治疗功效的测试。在感染后 24 和 48 小时分别治疗时，接受 VEEV TrD 挑战的小鼠分别有 100%和 90%的几率免受致命疾病的侵害。我们还测量了 BDGR-4 在接受东部马脑炎病毒挑战的小鼠中的 90%保护率。在对单独使用 BDGR-4 的小鼠的进一步评估中，我们在 4 天内观察到高达 25mg/kg/天的剂量，通过临床化学指标没有观察到明显的毒性。在相同的小鼠中，我们没有观察到干扰素的诱导。最后，通过下一代测序评估了 VEEV 对 BDGR-4 的抗性，结果显示病毒聚合酶 nsP4 发生了特定突变。
