A viral inactivation technique developed by Cryopharm Corp. hasproven effective in targeting and breaking up the nucleic acid in viruses_ without destroying platelets in the blood _ in in vitro tests. In apaper published in the June 1994 issue of Proceedings of the NationalAcademy of Sciences, the company said the studies showed thepromise of the technology as a way of sterilizing blood productswithout compromising the quality of the blood component beingtreated.The trials targeted a model bacteriophage. However, the technologycan also be used to attack HIV, cytomegalovirus and other viruses,according to Roger Hackett, director of corporate development for thePasadena, Calif. company. Hackett said the technology could also beused for therapeutic, as well as diagnostic applications, such as in thetransfusion of platelets and red blood cells made from whole blood orplasma. "This is a breakthrough for therapeutic cellular bloodtransfusion."The technology could be applied to all blood components _ platelets,red blood cells, white blood cells and plasma, he said.Cryopharm's approach incorporates a non-toxic viral sensitizer, CP-38,a halogenated derivative of psoralen, that targets light energy ontoviruses. When platelets are irradiated with ultraviolet A radiation in thepresence of these sensitizers, a chemical reaction is initiated whichbreaks apart all viral nucleic acids, and prevents the virus fromreplication. Since blood components do not contain genomic nucleicacid, they are not affected by the reaction."The sensitizer upon photoactivation can inactivate a modelbacteriophage deliberately inoculated into platelet concentrates withacceptable recovery of platelet properties as measured by severalassays including a hypotonic shock response assay. Furthermore, theseresults can be obtained in pure plasma under normal oxygen tensionsand without the introduction of quenchers," the researchers reported.They said the chemical structure of the sensitizer could be varied toincrease viral killing capacity while diminishing collateral damage tocellular and protein constituents.Hackett noted that the technique could be used on viruses with a lipidenvelope, such as HIV, as well as on those without, such as hepatitis Aor parvovirus."By appropriate chemical design of the reagent, we can cause it to havea much higher affinity for nucleic acid at the core of the virus so thatspurious binding to cell membranes or protein is significantly reduced,"Hackett said. n
-- Philippa Maister
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