Quantification of UVC-induced DNA damages in Escherichia coli by UVC treatment of platelet concentrates

THERAFLEX UV-Platelets system (Macopharma), a novel PI technology for platelet concentrates (PC), works by UVC illumination of PC. According to the literature the inactivation of pathogens is based on the UVC-induced damage of nucleic acids. The absorption of UVC light produces two predominant types of DNA damage: Cyclobutane pyrimidine dimers (CPD) and pyrimidine (6-4) pyrimidone photoproducts (6-4PP).

Aim of the current study was to quantify the amounts of UVC-induced photoproducts in the DNA of Escherichia coli (E. coli) introduced by pathogen inactivation treatment of bacterially contaminated PCs using the THERAFLEX UV-Platelets system. Plasma-reduced PCs in additive solution SSP+ (Macopharma) were inoculated with E. coli (PEI-B-P-19) to a final concentration of approx. 10⁶ colony forming units (CFU)/mL. PCs (n=3, 350 mL) were UVC-treated on the MacoTronic UV illumination device (Macopharma) and samples were taken for determination of the bacterial concentration and for quantification of the amounts of photoproducts by ELISA (OxiSelect UV-induced DNA Damage ELISA Kit, Cell Biolabs).

The results are shown in Table 1. E. coli was inactivated by UVC treatment down to the detection limit resulting in a reduction factor of ≥ 6.1 log steps. UVC-induced damage in the DNA of E. coli was monitored by the quantification of CPD and 6-4PP photoproducts. The amount of CPD and 6-4PP increased dose dependently to a final CPD concentration of 32.9 ± 7.4 ng/µg DNA and 6-4PP concentration of 8.2 ± 2.7 ng/µg DNA at 100% UVC dose, respectively.

The results of this study suggest that the mode of action of the THERAFLEX UV-Platelets system is based on dose-dependent, UVC-mediated alterations in nucleic acids including CPD and 6-4PP photoproducts.

UG received grants from the Research Foundation of the German Red Cross Blood Services (Deutsche Forschungsgemeinschaft der Blutspendedienste des Deutschen Roten Kreuzes) and Macopharma for the development of the UVC-based PI technology for platelets