Binding between the LAV gp120 and our inhibitor was observed in a SPR assay with gp120 covalently linked to a biosensor chip. Binding to gp120 was only monitored with HOCl-modified serum albumin and non-modified serum albumin showed no binding activity. As shown before [16] , mHSA binding is also specific to the West Nile virus domain III and does bind to similar domains of Yellow Fever and Dengue-2 virus, respectively. Since mHSA also binds to WNV envelope, we suggest that the binding of HOCl-modified serum albumin to HIV-1 or WNV envelope is neither a highly epitope specific event nor does it mirror a fundamental, yet undiscovered, molecular step of the WNV or HIV-1 entry process. Such non-specific binding events are common in many other pathogen-host interactions. For example malaria parasites use negatively charged chondroitin-sulfate-proteoglycan (CSPG) structures to attach to the membrane surface of their host cells [19] . For HIV-1, heparan-sulfate-proteoglycan (HSPG) is such an attachment factor [20] and heparan sulphates as well as other polyanions are efficient inhibitors of HIV-1 infection [21, 22] . Our current hypothesis is that pathogens which coat their core particle with the membrane of the host cell need a simple mechanism to attach to cells possessing an identical membrane structure. This membrane-membrane contact must be mediated by the external envelope glycoprotein complex present in the viral membrane and might be a first non-specific binding event to initiate the next step, binding to specific receptors.