College of Veterinary Medicine, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China.
Int J Mol Sci. 2023 May 12;24(10):8637. doi: 10.3390/ijms24108637.
Bovine viral diarrhea virus (BVDV) is a highly contagious viral disease which causes economic losses to the cattle industry. Ethyl gallate (EG) is a phenolic acid derivative which has various potentials to modulate the host response to pathogens, such as via antioxidant activity, antibacterial activity, inhibition of the production of cell adhesion factors, and so on. This study aimed to evaluate if EG influences BVDV infection in Madin-Darby Bovine Kidney (MDBK) cells, and to understand the antiviral mechanism. Data indicated that EG effectively inhibited BVDV infection by co-treatment and post-treatment in MDBK cells with noncytotoxic doses. In addition, EG suppressed BVDV infection at an early stage of the viral life cycle by blocking entry and replication steps but not viral attachment and release. Moreover, EG strongly inhibited BVDV infection by promoting interferon-induced transmembrane protein 3 (IFITM3) expression, which localized to the cytoplasm. The protein level of cathepsin B was significantly reduced by BVDV infection, whereas with treatment with EG, it was significantly enhanced. The fluorescence intensities of acridine orange (AO) staining were significantly decreased in BVDV-infected cells but increased in EG-treated cells. Finally, Western blot and immunofluorescence analyses demonstrated that EG treatment significantly enhanced the protein levels of autophagy markers LC3 and p62. Chloroquine (CQ) significantly increased IFITM3 expression, and Rapamycin significantly decreased it. Thus, EG may regulate IFITM3 expression through autophagy. Our results showed that EG could have a solid antiviral activity on BVDV replication in MDBK cells via increased IFITM3 expression, lysosomal acidification, protease activity, and regulated autophagy. EG might have value for further development as an antiviral agent.
牛病毒性腹泻病毒（BVDV）是一种高度传染性的病毒病，会给牛养殖业造成经济损失。没食子酸乙酯（EG）是一种酚酸衍生物，具有多种调节宿主对病原体反应的潜力，如通过抗氧化活性、抗菌活性、抑制细胞黏附因子的产生等。本研究旨在评估 EG 是否会影响 MDBK 细胞中的 BVDV 感染，并了解其抗病毒机制。数据表明，EG 以非细胞毒性剂量通过共处理和后处理有效地抑制了 MDBK 细胞中的 BVDV 感染。此外，EG 通过阻断进入和复制步骤而不是病毒附着和释放来抑制病毒生命周期的早期阶段的 BVDV 感染。此外，EG 通过促进干扰素诱导跨膜蛋白 3（IFITM3）的表达强烈抑制 BVDV 感染，IFITM3 定位于细胞质。BVDV 感染显著降低了组织蛋白酶 B 的蛋白水平，而用 EG 处理则显著增强了其水平。吖啶橙（AO）染色的荧光强度在 BVDV 感染的细胞中显著降低，但在 EG 处理的细胞中增加。最后，Western blot 和免疫荧光分析表明，EG 处理显著增强了自噬标志物 LC3 和 p62 的蛋白水平。氯喹（CQ）显著增加 IFITM3 的表达，雷帕霉素则显著降低其表达。因此，EG 可能通过自噬调节 IFITM3 的表达。我们的结果表明，EG 可通过增加 IFITM3 的表达、溶酶体酸化、蛋白酶活性和调节自噬来调节 BVDV 在 MDBK 细胞中的复制，具有良好的抗病毒活性。EG 可能具有作为抗病毒药物进一步开发的价值。
