Interferon-Stimulated Gene 15 Knockout in Mice Impairs IFNα-Mediated Antiviral Activity

Type I interferon (IFN) plays an important role in the host defense against viral infection by inducing expression of interferon-stimulated genes (ISGs). In a previous study, we found that porcine interferon-stimulated gene 15 (ISG15) exhibited antiviral activity against PRV in vitro. To further investigate the antiviral function of ISG15 in vivo, we utilized ISG15 knockout (ISG15(-/-)) mice in this study. Here, we demonstrate that ISG15(-/-) mice were highly susceptible to PRV infection in vivo, as evidenced by a considerably reduced survival rate, enhanced viral replication and severe pathological lesions. However, we observed no significant difference between female and male infected WT and ISG15(-/-) mice. Moreover, ISG15(-/-) mice displayed attenuated antiviral protection as a result of considerably reduced expression of IFN beta and relevant ISGs during PRV replication. Furthermore, excessive production of proinflammatory cytokines may be closely related to encephalitis and pneumonia. In further studies, we found that the enhanced sensitivity to PRV infection in ISG15(-/-) mice might be caused by reduced phosphorylation of STAT1 and STAT2, thereby inhibiting type I IFN-mediated antiviral activity. Based on these findings, we conclude that ISG15 is essential for host type I IFN-mediated antiviral response.

Automated summary

ISG15 plays a crucial role in the host antiviral response, as demonstrated by its knockout leading to increased susceptibility to PRV infection and loss of antiviral protection. ISG15 deficiency results in reduced expression of IFN beta and relevant ISGs, and excessive production of proinflammatory cytokines may contribute to pathological damage.