The article explores the role of the papain-like protease (PLpro) in SARS-CoV-2 infection and its impact on the host's innate immune response. PLpro is a crucial enzyme in coronaviruses, essential for processing viral polyproteins to form a functional replicase complex and enabling viral spread. It also plays a role in cleaving host proteins, helping the virus evade immune responses. The study compares SARS-CoV-2 PLpro (SCoV2-PLpro) with SARS-CoV PLpro (SCoV-PLpro), revealing differences in their substrate preferences. While both share 83% sequence identity, SCoV2-PLpro preferentially cleaves the ubiquitin-like protein ISG15, whereas SCoV-PLpro targets ubiquitin chains. Structural analysis shows that SCoV2-PLpro has a high affinity for ISG15, contributing to the cleavage of ISG15 from interferon-responsive factor 3 (IRF3), thereby suppressing type I interferon responses. Inhibition of SCoV2-PLpro with GRL-0617 reduces viral replication and maintains antiviral immunity. The study highlights the potential of targeting SCoV2-PLpro as a therapeutic strategy against SARS-CoV-2. Additionally, the research demonstrates that SCoV2-PLpro interacts with different host proteins compared to SCoV-PLpro, influencing pathways such as IFN and NF-κB. The findings suggest that PLpro plays a dual role in viral spread and immune modulation, and that inhibiting PLpro could be a promising approach for treating SARS-CoV-2 infections. The study also identifies GRL-0617 as a potential inhibitor of SCoV2-PLpro, which can block viral replication and enhance antiviral immune responses. Overall, the research underscores the importance of PLpro in SARS-CoV-2 pathogenesis and provides insights into its potential as a therapeutic target.The article explores the role of the papain-like protease (PLpro) in SARS-CoV-2 infection and its impact on the host's innate immune response. PLpro is a crucial enzyme in coronaviruses, essential for processing viral polyproteins to form a functional replicase complex and enabling viral spread. It also plays a role in cleaving host proteins, helping the virus evade immune responses. The study compares SARS-CoV-2 PLpro (SCoV2-PLpro) with SARS-CoV PLpro (SCoV-PLpro), revealing differences in their substrate preferences. While both share 83% sequence identity, SCoV2-PLpro preferentially cleaves the ubiquitin-like protein ISG15, whereas SCoV-PLpro targets ubiquitin chains. Structural analysis shows that SCoV2-PLpro has a high affinity for ISG15, contributing to the cleavage of ISG15 from interferon-responsive factor 3 (IRF3), thereby suppressing type I interferon responses. Inhibition of SCoV2-PLpro with GRL-0617 reduces viral replication and maintains antiviral immunity. The study highlights the potential of targeting SCoV2-PLpro as a therapeutic strategy against SARS-CoV-2. Additionally, the research demonstrates that SCoV2-PLpro interacts with different host proteins compared to SCoV-PLpro, influencing pathways such as IFN and NF-κB. The findings suggest that PLpro plays a dual role in viral spread and immune modulation, and that inhibiting PLpro could be a promising approach for treating SARS-CoV-2 infections. The study also identifies GRL-0617 as a potential inhibitor of SCoV2-PLpro, which can block viral replication and enhance antiviral immune responses. Overall, the research underscores the importance of PLpro in SARS-CoV-2 pathogenesis and provides insights into its potential as a therapeutic target.