van Vliet Vera J E, Roscow Olivia, Kim Kihun, Mark Brian L, Kikkert Marjolein, Tait-Burkard Christine
Molecular Virology Laboratory, Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, 2333 ZA Leiden, The Netherlands.
The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK.
Int J Mol Sci. 2025 May 29;26(11):5254. doi: 10.3390/ijms26115254.
Infectious bronchitis virus (IBV) is a coronavirus first isolated in the 1930s infecting chickens. IBV causes great economic losses to the global poultry industry, as it affects egg production and causes mortality by leaving the host susceptible to secondary bacterial infections. Even though vaccines are available, they are poorly cross-protective against new variants of the virus, which are always on the cusp of emerging. Effective antiviral therapies, or possibly the production of transgenic animals immune to IBV infection, are therefore sorely needed. As the papain-like protease (PLpro) of IBV has deubiquitinating activity besides its crucial ability to cleave the viral polyprotein, we have applied a novel strategy of selecting ubiquitin variants (UbVs) from a phage-displayed library that have high affinity to this viral protease. These UbVs were found to inhibit the deubiquitinating activity of PLpro and consequently obstruct the virus's ability to evade the innate immune response in the host cell. By obstructing the proteolytic activity of PLpro, these UbVs were seemingly able to inhibit viral infection as assessed using immunofluorescence microscopy. Whilst virus infection was detected in around 5% of UbV-expressing cells, the virus was present in around 30-40% of GFP (control)-expressing cells. This suggests that the expression of UbVs indeed seems to inhibit IBV infection, making UbVs a potentially potent and innovative antiviral strategy in the quest for control of IBV infections.
传染性支气管炎病毒（IBV）是一种在20世纪30年代首次分离出的冠状病毒，可感染鸡。IBV给全球家禽业造成了巨大经济损失，因为它会影响产蛋量，并使宿主易受继发性细菌感染从而导致死亡。尽管有疫苗可用，但它们对该病毒的新变种交叉保护作用较差，而新变种总是处于出现的边缘。因此，迫切需要有效的抗病毒疗法，或者可能需要培育对IBV感染具有免疫力的转基因动物。由于IBV的木瓜样蛋白酶（PLpro）除了具有切割病毒多聚蛋白的关键能力外，还具有去泛素化活性，我们应用了一种从噬菌体展示文库中筛选对这种病毒蛋白酶具有高亲和力的泛素变体（UbV）的新策略。发现这些UbV可抑制PLpro的去泛素化活性，从而阻碍病毒在宿主细胞中逃避先天免疫反应的能力。通过阻碍PLpro的蛋白水解活性，这些UbV似乎能够抑制病毒感染，这是通过免疫荧光显微镜评估得出的。虽然在约5%表达UbV的细胞中检测到了病毒感染，但在约30%-40%表达绿色荧光蛋白（对照）的细胞中发现了病毒。这表明UbV的表达确实似乎能抑制IBV感染，使UbV成为控制IBV感染的一种潜在有效且创新的抗病毒策略。
