Abstract / Summary
Protein kinase CK2 (CK2), a ubiquitously expressed serine/threonine kinase, has emerged as a key host factor exploited by several viruses, including Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here, we investigate the role of CK2 subunits in SARS-CoV-2 replication and evaluate the antiviral potential and broad-spectrum anti-coronavirus activity of two CK2 inhibitors: the previously described ATP-competitive inhibitor CX-4945 and a newly developed, highly selective bivalent inhibitor, AB668. The siRNA-mediated knockdown of CK2 subunits significantly reduced SARS-CoV-2 replication, highlighting its essential role in the viral lifecycle. Co-immunoprecipitation assays revealed that the SARS-CoV-2 nucleoprotein interacts with CK2. Furthermore, bio-layer interferometry assays demonstrated that the nucleoprotein specifically binds to the tetrameric CK2 holoenzyme (CK2α2β2) but not to individual CK2α or CK2β subunits. Pharmacological inhibition of CK2 with AB668 exhibited potent antiviral activity, significantly reducing viral replication by targeting a pre-replicative or RNA-replicative step of the viral life cycle. Importantly, AB668 displayed broad-spectrum antiviral activity, effectively inhibiting both HCoV-OC43 (β-CoV) and HCoV-229E (α-CoV). In summary, our findings establish CK2 as a critical host factor for SARS-CoV-2 replication and identify AB668 as a promising candidate for broad-spectrum antiviral therapy. With its high selectivity, minimized off-target effects, and efficacy against multiple coronaviruses, AB668 represents a valuable chemobiological and therapeutic tool.