In Vitro Antiviral Activity of NanB Bacterial Sialidase Against Avian Influenza H9N2 Virus in MDCK cells.

Abstract The Avian influenza virus is an infectious agent that may cause global health problem issues in poultry and potentially zoonotic. In 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 MDCK cells. NanB sialidase was purified from P. multocida for testing its toxicity and its ability to hydrolyze its sialic acid receptors on MDCK cells. H9N2 challenge virus was propagated in MDCK cells until cytopathic effects (CPE) appeared. Antiviral activity of NanB sialidase was conducted using MDCK cells, and then observed based on cell morphology, viral copy number, and expression of apoptosis-mediating genes. NanB sialidase effectively hydrolyzes Neu5Acα(2-6)Gal sialic acid at the dose of 129 mU/ml, while at 258 mU/ml it cause toxicity on MDCK cells. Antiviral activity of sialidase is evident based on the significantly decrease in viral copy number at all doses administrated. 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.