From the Spanish Red Cross Transfusion Center, and the National Research Council, Autonomous University of Madrid, Madrid, Spain.
BACKGROUND: This study evaluated the efficacy of photochemical treatment (PCT) with amotosalen and ultraviolet A (UVA) light to inactivate Trypanosoma cruzi in contaminated platelet (PLT) components. STUDY DESIGN AND METHODS: Fifteen pools of buffy-coat PLTs (BC-PLTs) were inoculated with approximately 5 x 10(3) to 5 x 10(5) per mL of viable T. cruzi of the G, Tulahuen (T), or Y strains. Samples from BC-PLTs were assayed for infectivity before and after PCT with 150 micromol per L amotosalen and 3 J per cm(2) UVA light. Infectivity was determined with three different methods: 1) in vitro culture to detect viable epimastigotes, 2) [(3)H]thymidine incorporation in culture, and 3) in vivo inoculation into interferon-gamma receptor (IFN-gammaR)-deficient mice. RESULTS: The in vitro assay yielded viable parasite titers of 3.9 x 10(5), 2.8 x 10(4), and 5.6 x 10(3) per mL (corresponding to 5.6, 4.4, and 3.8 logs/mL) for the Y, T, and G strains, respectively. PCT was able to inactivate all three strains of T. cruzi to below the limit of detection (10 parasites/mL) in the sensitive in vivo assay. Because 10-mL samples, each concentrated into a 1-mL sample for inoculation, were tested in the in vivo assay, log reductions achieved were greater than 5.6, greater than 4.4, and greater than 3.8 for the Y, T, and G strains of T. cruzi, respectively. CONCLUSIONS: The pathogen reduction system with amotosalen HCl and UVA demonstrated robust efficacy for inactivation of high doses of three different strains of T. cruzi and offers the potential to make the PLT supply safer.