Inactivation by phthalocyanine photosensitization of multiple forms of human immunodeficiency virus in red cell concentrates

Background: The use of phthalocyanines in conjunction with red light has been shown to inactivate model lipid-enveloped viruses in red cell concentrates. The ability of this treatment to inactivate multiple forms of human immunodeficiency virus (HIV) was evaluated in this study. Study Design and Methods: The phthalocyanines used were aluminum phthalocyanine tetrasulfonate (AlPcS(4)) and the silicon phthalocyanines HOSiPcOSi(CH3)(2)-(CH2)(3) N(CH3)(2) (Pc 4), and HOSiPcOSi(CH3)(2)(CH2)(3) N+(CH3I-(Pc 5). HIV was studied in a cell-free form, in an actively replicating form, in latently infected cells, and in blood from HIV-positive patients. Results: All three phthalocyanines inactivate greater than or equal to 10(5) infectious doses of cell-free HIV. However, only Pc 4 effectively inactivated actively replicating HIV and latently infected cells. The latter was about four times as sensitive to inactivation as was actively replicating HIV. Increasing the hematocrit of red cells during treatment decreased the rate of inactivation, especially at lower light doses. Under treatment conditions that completely inactivated the laboratory isolates of HIV, cell-associated HIV in blood from HIV-positive patients was also completely inactivated. The polymerase chain reaction signal from the gag gene of HIV was not affected on treatment of cell-free virus, but it was reduced after treatment of cell-associated HIV, particularly in some latently infected cell lines. Conclusion: Pc 4 and red light are effective in eliminating the infectivity of HIV in red cell concentrates. The usefulness of this approach for blood banking depends on future demonstration of the preservation of red cell circulatory survival and function in vivo.