Abstract：
The avian influenza virus is an infectious agent that may cause global health problems in poultry and is potentially zoonotic. In the recent decades, bacterial-derived sialidases have been extensively studied for their ability to inhibit avian influenza virus infections. In this study, the antiviral activity of NanB sialidase from Pasteurella multocida was investigated through in vitro analysis using Madin-Darby canine kidney (MDCK) cells. NanB sialidase was purified from P. multocida to test its toxicity and its ability to hydrolyse its sialic acid receptors on MDCK cells. The H9N2 challenge virus was propagated in MDCK cells until cytopathic effects appeared. Antiviral activity of NanB sialidase was tested using MDCK cells, and then observed based on cell morphology, viral copy number, and expression of apoptosis-mediating genes. NanB sialidase effectively hydrolysed Neu5Acα(2,6)-Gal sialic acid at a dose of 129 mU/ml, while at 258 mU/ml, it caused toxicity to MDCK cells. Antiviral activity of sialidase was evident based on the significant decrease in viral copy number at all doses administered. The increase of p53 and caspase-3 expression was observed in infected cells without sialidase. Our study demonstrates the ability of NanB sialidase to inhibit H9N2 virus replication based on observations of sialic acid hydrolysis, reduction in viral copy number, and expression of apoptosis-related genes. The future application of sialidase may be considered as an antiviral strategy against avian influenza H9N2 virus infections. RESEARCH HIGHLIGHTSNanB sialidase effectively hydrolyses Neu5Acα(2,6)-Gal at a dose of 129 mU/ml.NanB sialidase from Pasteurella multocida can inhibit the entry of H9N2 virus into cells.NanB sialidase of Pasteurella multocida prevents infection-induced cell apoptosis.NanB sialidase reduces the H9N2 viral copy number in MDCK cells.
摘要：
禽流感病毒是一种传染性病原体，可能导致家禽和潜在的人畜共患的全球健康问题。近几十年来,已经广泛研究了细菌来源的唾液酸酶抑制禽流感病毒感染的能力。在这项研究中，使用MDCK细胞通过体外分析研究了来自多杀性巴氏杆菌的NanB唾液酸酶的抗病毒活性。从多杀性疟原虫中纯化NanB唾液酸酶以测试其毒性和其水解MDCK细胞上的唾液酸受体的能力。H9N2攻击病毒在MDCK细胞中繁殖,直到出现细胞病变效应(CPE)。使用MDCK细胞进行NanB唾液酸酶的抗病毒活性，然后根据细胞形态观察，病毒拷贝数，和凋亡介导基因的表达。NanB唾液酸酶以129mU/ml的剂量有效水解Neu5Aca(2-6)Gal唾液酸，而在258mU/ml时，它对MDCK细胞产生毒性。基于在所有施用剂量下病毒拷贝数的显著降低,唾液酸酶的抗病毒活性是明显的。在没有唾液酸酶的感染细胞中观察到p53和caspase-3表达的增加。我们的研究表明，根据唾液酸水解的观察，NanB唾液酸酶抑制H9N2病毒复制的能力，减少病毒拷贝数，和凋亡相关基因的表达。唾液酸酶的未来应用可能被认为是针对禽流感H9N2病毒感染的抗病毒策略。
