Photoinactivation of cell-free human immunodeficiency virus by hematoporphyrin monomethyl ether

Human immunodeficiency virus (HIV) particles that remain in the blood of patients are frequently ignored as targets for AIDS treatment. We therefore investigated the use of photodynamic therapy (PDT) with hematoporphyrin monomethyl ether (HMME) as a means of inactivating cell-free HIV in vitro. Virus particles including HIV-1IIIB, resistant HIV-1 variants, HIV-1 clinical variants, and HIV-2 variants were incubated with HMME for 40 min, followed by irradiation with a 630-nm semiconductor laser at an energy density of 0.3 J/cm2. The antiviral effects were evaluated by counting syncytium formation or measuring p24 antigen expression levels in supernatants by enzyme-linked immunosorbent assay. The relationships between photoinactivation and HMME concentrations, energy density, power density and antioxidants (NaN3 and d-mannitol) were also assessed using the above methods. All the tested virus particles were completely responsive to HMME-PDT. HMME concentration and energy density were positively correlated with photoinactivation of HIV, while power density was negatively correlated. Both sodium azide and d-mannitol weakened the inhibitory effect of PDT on virus-induced membrane fusion, with d-mannitol having a stronger effect. HMME-PDT can inactivate HIV particles, and may therefore represent a promising treatment for AIDS patients.