Avian Interferon-Inducible Transmembrane Protein Family Effectively Restricts Avian Tembusu Virus Infection

Chen, Shilong; Wang, Long; Chen, Jieying; Zhang, Lanlan; Wang, Song; Goraya, Mohsan U.; Chi, Xiaojuan; Na, Yang; Shao, Wenhan; Yang, Zhou; Zeng, Xiancheng; Chen, Shaoying; Chen, Ji-Long

In particular, IFN-α and IFN-β were greatly upregulated by 152-and 1,415-fold at 24 hpi, respectively (Figures 2A,B) . The expression of IFN-λ was modestly upregulated by 8.5-fold at 24 hpi ( Figure 2C) . The expression of duck IFITM1, 2, and 3 were gradually induced and reached their maximum value at 72 hpi. Strikingly, expression of duck IFITM1 was markedly increased by over 100-folds at 72 hpi (Figures 2D-F) . These observations were further confirmed by RT-PCR analysis (Supplementary Figure 1) . Moreover, we examined the mRNA expression profile of IFNs and IFITMs in kidney and bursa of fabricius tissues. We found that in kidneys, the mRNA levels of IFNs and IFITMs were modestly upregulated until 48 hpi and then declined (Supplementary Figure 2) . IFNs and IFITMs expressions in bursa Frontiers in Microbiology | www.frontiersin.org FIGURE 2 | Expression of IFNs and IFITM family is strongly upregulated in duck in response to ATMUV infection. Twenty five 7-day-old healthy mule ducklings were challenged by intramuscular injection with 4.0 × 10 5 ELD 50 of ATMUV in a volume of 0.4 mL per duckling. Three randomly selected ducklings were sacrificed at 0, 12, 24, 48, and 72 hpi, respectively. Their spleen tissues were collected for examination of IFN-α (A), IFN-β (B), IFN-λ (C), and IFITM1, 2, 3 (D-F) mRNA expression using qRT-PCR. The mRNA levels were normalized to the endogenous β-actin level and the expression at 0 hpi was set to 1.0. Expression at 12-72 hpi was compared to its expression at 0 hpi. Each sample was analyzed in triplicate and the results are depicted as means ± SD (n = 3). Statistical significance was determined by one tail Student's t-test analysis. *P < 0.05, **P < 0.01. of fabricius were slightly increased with the highest levels at 12 hpi and then declined (Supplementary Figure 3) . Taken together, these data indicate that ATMUV infection can trigger innate immune response in ducklings, including upregulation of IFNs and IFITMs.