Evaluation of Cell Lysis Techniques for Direct Amplification of Sexual Assault Samples

Sexual assault is one of the most common crimes committed today with a delay in sample processing, resulting in the “rape kit backlog”. The traditional method to extract DNA from these samples containing both male and female DNA is a differential extraction; taking hours to process. This study examined a variety of different cell lysis techniques to develop a method which can consistently generate high-quality profiles at a fast rate and with low volumes when compared to the currently used method in our laboratory. Six lysis methods, in addition to the currently used forensicGEM™ Sperm kit, were performed on semen swabs from ten donors. Quantification using Investigator® Quantiplex HYres revealed all lysis methods performed comparably to the control method (p\u3e0.06). Samples were amplified using the Promega™ PowerPlex® Fusion 5C System with a target DNA template input of 0.25ng where three alternative methods were found to produce similar results to that of the control: Casework Direct, alkaline lysis, and NP-40 lysis buffer due to their increase in peak heights and their interlocus balance being similar to the control (CV=0.38) or lower. Similar results were reported when STR amplification was repeated with samples metering a specific volume to simulate sample processing on a microfluidic device. However, HGH cell lysis was also found to perform comparably to the control when this approach was performed. Overall, the data provided positive preliminary results for the use of alternative lysis techniques both for traditional in-tube assays, as well as the chip-based approach for a microfluidic device