Type I interferons are a subset of cytokines playing central roles in host antiviral defense, and their effects depend on the interaction with the heterodimeric receptor complex. Surprisingly, two pairs of the receptor subunits, CRFB1 and CRFB5, and CRFB2 and CRFB5, have been identified in fish, but the studies about preferential receptor usage of different fish IFN subtypes are rather limited. In this study, the three receptor chains of type I IFNs named as On-CRFB1, On-CRFB2 and On-CRFB5 were identified in Nile tilapia, Oreochromis niloticus. These three genes were constitutively expressed in all tissues examined, with the highest expression level observed in muscle and liver, and were rapidly induced in liver following the stimulation of poly(I:C). Interestingly, it is possible that all three subtypes of tilapia IFNs are able to signal through two pairs of the receptor subunits, On-CRFB1 and On-CRFB5, and On-CRFB2 and On-CRFB5. More importantly, tilapia group I IFNs (On-IFNd and On-IFNh) preferentially signal through a receptor complex composed of On-CRFB1 and On-CRFB5, and group II IFNs (On-IFNc) preferentially signal through a receptor complex comprised of On-CRFB2 and On-CRFB5. The present study thus provides new insights into the receptor usage of group I and group II IFNs in fish.

I型干扰素是细胞因子在宿主抗病毒防御中发挥核心作用的子集，其作用取决于与异二聚体受体复合物的相互作用。令人惊讶的是，已经在鱼类中鉴定出两对受体亚基CRFB1和CRFB5以及CRFB2和CRFB5，但是关于不同鱼类IFN亚型的优先受体使用的研究相当有限。在这项研究中，在尼罗罗非鱼，尼罗罗非鱼（Oreochromis niloticus）中鉴定了三个I型干扰素受体链，分别称为On-CRFB1，On-CRFB2和On-CRFB5。。这三个基因在所有检查的组织中组成性表达，在肌肉和肝脏中观察到最高的表达水平，并且在刺激poly（I：C）后迅速在肝脏中诱导。有趣的是，罗非鱼IFN的所有三个亚型都可能通过两对受体亚基On-CRFB1和On-CRFB5以及On-CRFB2和On-CRFB5发出信号。更重要的是，罗非鱼的I类干扰素（On-IFNd和On-IFNh）优先通过由On-CRFB1和On-CRFB5组成的受体复合物发出信号，而II类干扰素（On-IFNc）则优先通过由On-CRFB5组成的受体复合物发出信号。 -CRFB2和On-CRFB5。因此，本研究为鱼类中I组和II组IFN的受体使用提供了新见解。