Elimination of both cell-free and cell-associated HIV infectivity in plasma by a filtration/methylene blue photoinactivation system

BACKGROUND: Methylene blue phototreatment effectively inactivates cell-free viruses in plasma while maintaining coagulation activities. However, this treatment is considered to be less effective for cell-associated virus inactivation. This report describes a new virus elimination system designed to eliminate cell-associated viruses with a cell-removal filter followed by methylene blue photoinactivation of cell-free viruses in plasma. STUDY DESIGN AND METHODS: Fresh plasma was inoculated with HIV or HIV-infected Molt4 cells (Molt4(IIIB)). The plasma was transferred to a bag containing methylene blue by passing it through a cell-removal filter and was irradiated with white fluorescent light. HIV infectivity was detected by indirect fluorescence assay. In parallel studies, coagulation activities in identically treated plasma were measured during 1 year of storage at -80 degrees C. RESULTS: Initial cell-free HIV titer of 10(6.2) TCID(50) per 0.1 mL dropped to 10(-0. 3) and <10(-0.5) TCID(50) per 0.1 mL after 10 or 20 J per cm(2) radiation, respectively. Cellular components were not detectable in plasma after filtration. The cell-free state of the plasma was ascertained from the observation that the DNase-resistant beta-globin gene, as a marker of intact WBCs, was not detected in the filtrates by PCR. The infectivity of Molt4(IIIB) was reduced to below the detection limit after filtration and radiation, and proviral HIV DNA was not detected in the filtrates by PCR. Coagulation activities including factor VIII in the treated plasma were maintained at more than 76 percent compared with the percentage in untreated plasma after 1 year of storage. CONCLUSION: The filtration/methylene blue photoinactivation system eliminated both cell-free and cell-associated HIV infectivities from plasma while maintaining coagulation activities for 1 year at -80 degrees C storage.