Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.
Antiviral Res. 2018 Apr;152:76-83. doi: 10.1016/j.antiviral.2018.02.009. Epub 2018 Feb 15.
Feline calicivirus (FCV) is a small non-enveloped virus containing a single-stranded, positive-sense RNA genome of approximately 7.7 kb. FCV is a highly infectious pathogen of cats and typically causes moderate, self-limiting acute oral and upper respiratory tract diseases or chronic oral diseases. In addition, in recent years, virulent, systemic FCV (vs-FCV) strains causing severe systemic diseases with a high mortality rate of up to 67% have been reported in cats. Although FCV vaccines are commercially available, their efficacy is limited due to antigenic diversity of FCV strains and short duration of immunity. In this study, we identified fexaramine as a potent inhibitor of FCV including vs-FCV strains in cell culture and demonstrated that fexaramine is a entry blocker for FCV by using various experiments including time-of-addition studies, generation of resistant viruses in cell culture and the reverse genetics system. A fexaramine resistant FCV mutant has a single amino acid change in the P2 domain of VP1 (the major capsid), and the importance of this mutation for conferring resistance was confirmed using the reverse genetics system. A comparative analysis of viral resistance was also performed using a peptidyl inhibitor (NPI52) targeting FCV 3C-like protease. Finally, the effects of combination treatment of fexaramine and NPI52 against FCV replication and emergence of resistant viruses were investigated in cell culture.
猫杯状病毒（FCV）是一种小的无包膜病毒，含有约 7.7kb 的单链、正链 RNA 基因组。FCV 是一种高度传染性的猫病原体，通常导致中度、自限性急性口腔和上呼吸道疾病或慢性口腔疾病。此外，近年来，报道了具有高死亡率（高达 67%）的强毒、全身性 FCV（vs-FCV）菌株引起严重全身性疾病。尽管有商品化的 FCV 疫苗，但由于 FCV 株的抗原多样性和免疫持续时间短，其效果有限。在本研究中，我们鉴定了 fexaramine 是一种在细胞培养中抑制 FCV（包括 vs-FCV 株）的有效抑制剂，并通过使用包括添加时间研究、细胞培养中产生抗性病毒和反向遗传系统在内的各种实验，证明了 fexaramine 是 FCV 的进入抑制剂。在 VP1（主要衣壳）的 P2 结构域中具有单个氨基酸变化的 fexaramine 抗性 FCV 突变体，使用反向遗传系统证实了该突变对赋予抗性的重要性。还使用针对 FCV 3C 样蛋白酶的肽抑制剂（NPI52）进行了病毒抗性的比较分析。最后，在细胞培养中研究了 fexaramine 和 NPI52 联合治疗对 FCV 复制和抗性病毒出现的影响。
