Evaluation of the antivirus activity of Enterococcus faecalis Esawy levan and its sulfated form

The screening of 15 honey isolates showed that the E. faecalis Esawy KR758759 was the most potent levansucrase producer. It recorded the highest levansucrase activity (50.55 U/mL) and the highest levan yield (37.50 g/L). The levan molecular weight was determined to be 85,658 Da. The yielded levan was classified into three forms as: crude levan (CL), dialyzed levan (DL) and sulfated levan (SL). The three levan forms were characterized by FTIR. The characterization of levan by FTIR revealed that the structure of levan was homologous to the standard levan sample. C-13 and H-1 NMR have successfully confirmed the levan structure. The antivirus activity of the three compounds was evaluated against the Newcastle disease virus (NDV). The CL recorded complete inhibition of NDV followed by DL (95%) and SL (90%). The three levan forms had an immunostimulant effect with variations degree. A mechanism was developed to suggest the role of levan as an anti-virus against NDV.