Hypericin as an inactivator of infectious viruses in blood components

Background: Hypericin is a potent virucidal agent with activity against a broad range of enveloped viruses and retroviruses.The effective virucidal activity emanates from a combination of photodynamic and lipophilic properties. Hypericin binds cell membranes (and, by inference, virus membranes) and crosslinks virus capsid proteins. This action results in a loss of infectivity and an inability to retrieve the reverse transcriptase enzymatic activity from the virion. Study Design and Methods: Since hypericin is devoid of adverse action in most blood components and blood analyses, it is investigated as an additive with potential to inactivate infective viruses in blood components intended for transfusion. Results: Complete inactivation of 10 6 tissue culture-infective doses of human immunodeficiency virus was obtained in whole blood and in diluted packed red cells after illumination with fluorescent light for 1 hour. Loss of viral infectivity to cultured CEM cells has been monitored by use of a detection assay for human immunodeficiency virus p55 in enzyme-linked immunosorbent assay and cytopathic assays. In physiologic media, hypericin interacts with albumin and lipoproteins, retaining the virucidal activity in bound form. The molecule is negatively charged and forms organic and inorganic monobasic salts (ion pairs) in physiologic pH. Various ion pairs differ in virucidal efficacy. Conclusion: The apparent transfusibility of hypericin, taken together with the efficacy of the virucidal activity, the broad range of enveloped viruses affected, and the absence of adverse effects on stored red cells, may render hypericin useful for inactivation of infectious viruses in red cells