Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of Microbiology and Immunology

In this work we investigated the effect of selected polyanionic compounds on filovirus glycoprotein (GP) - mediated cell entry. Using lentiviral pseudoparticles bearing the GPs of Marburg virus (MARV) and Zaire Ebolavirus (ZEBOV), we found out that all the tested polyanionic compounds had an inhibitory effect on filovirus GP-mediated cell entry. The cytotoxic profile of our tested compounds was investigated and found to be satisfactory. DS 5000 was selected for further testing. Its half maximal inhibitory concentration (IC ) on MARV and ZEBOV 50 viral pseudoparticles cell entry was 4.46æg/ml and 0.8æg/ml, respectively. These concentrations are obviously much lower than the concentrations which can exert an anticoagulant activity. We also found a significant inhibitory effect of DS 5000 on other viral pseudoparticles which belong to filoviruses and also to other virus families. The inhibitory effect of DS 5000 on MARV and ZEBOV viral pseudoparticles cell entry was also confirmed in a variety of cell lines. Other experiments were performed for more understanding of the mechanism by which DS 5000 inhibit the filoviral cell entry. These include: (1) testing the effect of DS 5000 on MARV and ZEBOV attachment to EAhy cells by measuring the concentration of p24 antigen using ELISA. This test revealed significant inhibition of MARV pseudoparticles cell attachment at DS 5000 concentrations of 5 and 50 æg/ml, whereas insignificant inhibition of cell attachment was observed with ZEBOV viral pseudoparticles at DS 5000 concentrations of 50 æg/ml, (2) virus binding assays using amicon tubes. This revealed significant inhibition of ZEBOV and MARV pseudoparticles cell entry, when the pseudoparticles were incubated with DS 5000 50æg/ml for 1 hour before centrifugation in amicon tubes and (3) testing the effect of DS 5000 pre-treatment of EAhy cells on the viral pseudoparticles cell entry. This test revealed no significant effect of the cell pre- treatment on the pseudoparticles cell entry. Our findings suggest that DS 5000 acts most probably on the viral glycoproteins preventing virus interaction with the cell surface receptors

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