NHC Key Laboratory of Medical Virology and Viral Diseases, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100052, PR China.
Key Laboratory of Diagnosis and Treatment of Digestive System Tumors of Zhejiang Province, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo 315010, PR China.
J Gen Virol. 2021 Mar;102(3). doi: 10.1099/jgv.0.001559. Epub 2021 Feb 23.
Fibre is the viral protein that mediates the attachment and infection of adenovirus to the host cell. Fowl adenovirus 4 (FAdV-4) possesses two different fibre trimers on each penton capsomere, and roles of the separate fibres remain elusive. Here, we attempted to investigate the function of FAdV-4 fibres by using reverse genetics approaches. Adenoviral plasmids carrying fiber1 or fiber2 mutant genes were constructed and used to transfect chicken LMH cells. Fiber1-mutated recombinant virus could not be rescued. Such defective phenotype was complemented when a fiber1-bearing helper plasmid was included for co-transfection. The infection of fiber-intact FAdV-4 (FAdV4-GFP) to LMH cells could be blocked with purified fiber1 knob protein in a dose-dependent manner, while purifed fiber2 knob had no such function. On the contrary, fiber2-mutated FAdV-4, FAdV4XF2-GFP, was successfully rescued. The results of one-step growth curves showed that proliferative capacity of FAdV4XF2-GFP was 10 times lower than that of the control FAdV4-GFP. FAdV4XF2-GFP also caused fewer deaths of infected chicken embryos than FAdV4-GFP did, which resulted from poorer virus replication . These data illustrated that fiber1 mediated virus adsorption and was essential for FAdV-4, while fiber2 was dispensable although it significantly contributed to the virulence.
纤维是介导腺病毒附着和感染宿主细胞的病毒蛋白。禽腺病毒 4 型（FAdV-4）在每个五邻体衣壳上具有两种不同的纤维三聚体，而单独纤维的作用仍不清楚。在这里，我们试图通过使用反向遗传学方法来研究 FAdV-4 纤维的功能。构建了携带纤维 1 或纤维 2 突变基因的腺病毒质粒，并用于转染鸡 LMH 细胞。不能拯救纤维 1 突变的重组病毒。当包含纤维 1 的辅助质粒用于共转染时，这种缺陷表型得到了补充。纤维完整的 FAdV-4（FAdV4-GFP）感染 LMH 细胞可以被纯化的纤维 1 扣状蛋白以剂量依赖的方式阻断，而纯化的纤维 2 扣状蛋白没有这种功能。相反，纤维 2 突变的 FAdV-4，FAdV4XF2-GFP，成功地被拯救。一步生长曲线的结果表明，FAdV4XF2-GFP 的增殖能力比对照 FAdV4-GFP 低 10 倍。FAdV4XF2-GFP 引起的感染鸡胚死亡率也低于 FAdV4-GFP，这是由于病毒复制较差所致。这些数据表明纤维 1 介导病毒吸附，对 FAdV-4 至关重要，而纤维 2 虽然对毒力有重要贡献，但却是可有可无的。
