hIFNAR1/R2-EC Mouse

Interferons (IFNs) are a multigene family of cytokines that play critical roles in antiviral defense and regulation of tumor immunity ^[1]. Human IFNs are classified into type I, II, and III based on receptor-binding specificity. Among them, type I IFNs comprise nearly 20 subtypes, whose signaling relies on a heterodimeric receptor composed of IFNAR1 and IFNAR2 subunits. Ligand binding triggers the JAK-STAT signaling pathway, inducing the expression of interferon-stimulated genes (ISGs) and thereby executing antiviral and immunomodulatory functions ^[2-3]. IFN-α2, an early discovered and well‑characterized type I IFN subtype, has been approved for clinical use against chronic hepatitis B virus (HBV) infection and certain tumors since the 1990s. However, its clinical application is limited by low response rates and severe side effects ^[4-5]. Furthermore, the interaction between human IFN and IFNAR is species‑specific, rendering wild-type mice largely unresponsive to human type I IFN — a major obstacle for dissecting the functions of human IFN subtypes and developing novel interferon‑based therapeutics ^[6].

The hIFNAR1/R2-EC mouse model harbors chimeric receptors (IFNAR-hEC) consisting of the humanized IFNAR extracellular domain and murine transmembrane and intracellular domains, while preserving the regulatory elements and signal peptide regions of the murine Ifnar1/2 loci. Using gene editing, the region from aa.27 in exon 2 to partial intron 2 of the mouse Ifnar1 was replaced with the IFNAR1 chimera CDS, and the region from aa.22 in exon 3 to partial intron 3 of the mouse Ifnar2 was replaced with the IFNAR2 chimera CDS. This immunocompetent mouse model responds robustly to human type I IFNs. It enables characterization of the differential activation of the JAK-STAT pathway by human IFN-α2, α14, and other subtypes, and supports in vivo validation of the long‑term antiviral efficacy of clinically used pegylated human IFN‑α2 in HBV replication models. It therefore provides a powerful platform for investigating the antiviral and immunomodulatory mechanisms of human type I IFN subtypes and for preclinical evaluation of interferon‑based drugs ^[7].