The data implicate that mHSA, or a well defined structure thereof, might be applicable as a drug against viral infection, and that the inoculation of mHSA into infected individuals might overcome adaptive immune tolerance. As was shown in animals, the active immunization of rats with Freund's adjuvant together with a high dose of chlorinated autoantigen induced an immune response against the HOCl-modified protein [27] . Induction of autoantibody might be a risk factor in the direct application of HOCl-modified proteins into body fluids but seems to be no major problem when applied as a topical microbicide. On the other hand, serum albumin is an important carrier for drugs and enzymes. In particular the transport of the enzyme MPO across the endothelial barrier depends on a specific interaction between HSA and MPO [28] . The HSA-binding epitope on MPO was identified as a short linear region (aa 425-454), causing high-affinity binding to HSA. The very close proximity of HSA and MPO implicates that HSA might be highly susceptible for MPO-dependent modifications. This also suggests that MPO-modified serum albumin is a common self antigen and therefore might be tolerated by the immune system.