title: Reduction of PCR-amplifiable DNA by ethylene oxide treatment of forensic consumables.
abstract: A reliable method to provide molecular biology products free of contaminating DNA is of forensic interest. Ethylene oxide (EO) treatment has been demonstrated as an effective method in published studies. This study aimed to address some additional experiments that are closer to forensic practice. In the first part of this study, different consumables such as cotton swabs, latex gloves and micro test tubes were spiked with saliva, blood and skin cells to mimic a real-life contamination scenario. EO treatment was performed for a period of 3, 5, 7, and 10h, respectively. For comparison, gamma and electron beam treatment was applied. In the second part of this study, a cell culture line (K562) was used to apply defined cell counts on cotton swabs followed by EO treatment for 3 and 5h. After extraction of samples, the DNA content was quantified using a real-time PCR based system. STR analysis was performed using a latest generation STR kit to meet current sensitivity limits. A good correlation of real-time PCR results and STR results was observed. This work confirmed the findings of earlier studies showing that chemical EO treatment is much more successful in reducing the amount of PCR-amplifiable DNA than ionising radiation. Furthermore, the efficacy of EO treatment is affected by the nature of the samples. DNA in saliva was more susceptible to damage by EO gas than DNA in blood. Our results show, that accessibility of the sample to EO gas has a strong influence on the method's efficiency. While treatment of samples on cotton swabs packed into gas-permeable bags was very successful, samples inside a closed micro test tube were resistant to the same treatment conditions. Our work with defined K562 cell numbers and multi-copy quantitative PCR could show that a 5h EO treatment results in a 10(5) fold reduction of PCR-amplifiable DNA. Corresponding STR-PCR results also show only sporadic allele calls in the Mini-loci range, providing a reliable interpretation of forensic analysis. Finally, we do recommend an EO treatment of forensic consumables and a multi-copy quantitative PCR approach to establish reliable treatment conditions.
authors.affiliation: Federal Criminal Police Office, 65173 Wiesbaden, Germany. Electronic address: Katharina.Neureuther@bka.bund.de.
authors.forename: Katharina
authors.initials: K
authors.lastname: Neureuther
authors.affiliation: Federal Criminal Police Office, 65173 Wiesbaden, Germany.
authors.forename: Edyta
authors.initials: E
authors.lastname: Rohmann
authors.affiliation: Federal Criminal Police Office, 65173 Wiesbaden, Germany.
authors.forename: Manuela
authors.initials: M
authors.lastname: Hilken
authors.affiliation: Federal Criminal Police Office, 65173 Wiesbaden, Germany.
authors.forename: Marie-Luise
authors.initials: ML
authors.lastname: Sonntag
authors.affiliation: Federal Criminal Police Office, 65173 Wiesbaden, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Herdt
authors.affiliation: Federal Criminal Police Office, 65173 Wiesbaden, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Koennecke
authors.affiliation: Hannover Medical University, Dept. of Clinical Immunology & Rheumatology, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Jacobs
authors.affiliation: Sterigenics Germany GmbH, Kasteler Str. 45, 65203 Wiesbaden, Germany.
authors.forename: Michalina
authors.initials: M
authors.lastname: Adamski
authors.affiliation: Sterigenics Germany GmbH, Kasteler Str. 45, 65203 Wiesbaden, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Reisbacher
authors.affiliation: Sterigenics Germany GmbH, Kasteler Str. 45, 65203 Wiesbaden, Germany.
authors.forename: Knut
authors.initials: K
authors.lastname: Alfs
authors.affiliation: Sterigenics NV, Vaartdijk 3, Box 302, B-3018 Leuven, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Strain
authors.affiliation: Federal Criminal Police Office, 65173 Wiesbaden, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Bastisch
mesh_terms: D004247:DNA / Q000235:genetics*; D005027:Ethylene Oxide / Q000737:chemistry*; D053803:Forensic Genetics; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D004247:DNA; D005027:Ethylene Oxide
keywords: Consumables; Contamination; Ethylene oxide; Forensic standard; Quantification