Antiviral innate immune function of Chinese sturgeon (Acipenser sinensis) IFNe2

Chinese sturgeon (Acipenser sinensis) is a critically endangered fish species found in the Yangtze River of China, for which there is scarce immunological research. Type Ⅰ interferons (IFNs) are widely recognized as pivotal cytokines in the host's antiviral immune response. Therefore, the present study aimed to investigate the immune function of interferon e2 in A. sinensis (rAsIFNe2). The recombinant A. sinensis interferon e2 protein (rAsIFNe2) was expressed through prokaryotic expression, and its effects on antiviral-related genes and its antiviral activity were analyzed. Real-time quantitative PCR (RT-qPCR) results showed that rAsIFNe2 significantly activated the expression of interferon-stimulated genes (ISGs) in A. sinensis fin cells, such as Mx, Viperin, PKR, and ADAR4 with 460.95-fold and 669.01-fold changes at 24 h, a 42.76-fold change at 6 h, and 6.72 fold change at 12 h of incubation, respectively. Furthermore, rAsIFNe2 also helped host cells establish an antiviral state by activating the expression of IRF1, IRF2, IRF3, IRF7, IFNe1, IFNe2 and IFNe3 genes with increases by 11.56, 3.08, 9.72 and 1 083.07 times at 6 h, a 2.15-fold change at 3 h, a 119.15-fold change at 12 h, and a-6.88 fold change at 3 h of incubation, respectively. In the spring viremia of carp virus (SVCV)-infected carp epithelial cells (EPC) model, rAsIFNe2 induced the expression of Mx, PKR, and Viperin in EPC cells with 13.29-fold and 14.36-fold changes at 6 h, and a 19.25-fold change at 24 h of infection. The SVCV virus G, N, and P genes in EPC cells were significantly downregulated by rAsIFNe2 with 388.50, 259.74 and 979.91-fold changes after 24 h, thereby reducing the lesions. These results indicate that AsIFNe2 plays a role in the host's antiviral innate immune response, providing a theoretical basis for understanding the interferon immune system of A. sinensis and treating viral diseases.