Inhibiting Infectious Bronchitis Virus PLpro Using Ubiquitin Variants

International Journal of Molecular Sciences, vol. 26, pp. 5254

Abstract

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.

Authors 6

1. Vera J. E. van Vliet Aachen Molecular Virology Laboratory

   Leiden University · Roslin Institute · Leiden University Medical Center · University of Edinburgh

   Affiliation as printed

   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

2. Olivia Roscow

   University of Waterloo

   Affiliation as printed

   Department of Biology, Faculty of Science, University of Waterloo, Waterloo, ON N2L 3G1, Canada

3. Kihun Kim

   University of Manitoba

   Affiliation as printed

   Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada

4. Brian L. Mark

   University of Manitoba

   Affiliation as printed

   Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada

5. Marjolein Kikkert corresponding Aachen Molecular Virology Laboratory

   Leiden University · Leiden University Medical Center

   Affiliation as printed

   Molecular Virology Laboratory, Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical Center, 2333 ZA Leiden, The Netherlands

6. Christine Tait‐Burkard corresponding

   Roslin Institute · University of Edinburgh

   Affiliation as printed

   The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK