566

Low molecular weight dextran sulfate prevents human cytomegalovirus entry into porcine cells and is effective against clinical isolates

Anne-Laure Millard¹, Aline M. Taveira¹, Robert Rieben², Jörg D. Seebach³, Nicolas J. Mueller¹

¹Division of Infectious Diseases, University Hospital Zürich, Zürich; ²Department of Clinical Research, University of Bern, Bern; ³Department of Immunology and Allergology, University Hospital and Medical Faculty of Geneva, Geneva, Switzerland

Low molecular weight dextran sulfate (DXS) acts as an endothelial cell (EC) protectant and prevents human complement- and NK cell-mediated cytotoxicity in vitro. In combination with cyclosporin A, DXS induces long-term graft survival in a xenotransplantation model in vivo and is very effective in protecting vasculature and tissue from ischemia/reperfusion injury. Human cytomegalovirus (HCMV) infection following organ transplantation can initiate endothelial cell activation and vascular injury that may facilitate graft rejection. In this study, we further characterized DXS in order to define its influence on HCMV infection.

Human and porcine EC were treated with DXS and antiviral activity was quantified by measurements of virus titre and viral growth kinetics.

Dose response experiments performed in human EC indicated that pre-treatment 250 ng/ml DXS reduced HCMV infectivity by 75% and 2.5 µg/ml completely prevented the formation of infectious particles. Immunofluorescence as well as Western blot analysis demonstrated that viral replication was already blocked at the immediate early phase resulting in absence of pp65 nuclear accumulation and in limited expression of the immediate early proteins IE1/IE2. In addition, DXS had an inhibitory effect on a clinical isolate, as assessed by the reduction of HCMV DNA copy numbers in the cells and in the supernatants of infected cultures. Entry assays pointed out that pre-treatment of human EC with DXS led to a complete block of entry. Moreover, DXS also abrogated HCMV entry and replication into porcine EC. Finally, in vitro analyses indicated that DXS may exert its antiviral activity through direct binding to the virions.

If a similar effect can be reproduced in vivo, DXS, in combination with conventional immunosuppressive protocols, may represent a promising agent to reduce the risk of HCMV reactivation following allo- and xenotransplantation.