Clinical Evaluation of an Automated Nucleic Acid Isolation System

摘要

Nucleic acid isolation is among the most technically demanding and labor-intensive procedures performed in molecular diagnostic laboratories. Although considerable progress has been made in automating the amplification and detection steps of nucleic acid amplification assays, sample preparation is still performed manually in many laboratories. Various automated systems have been developed to streamline these procedures, ranging from versatile robotic stations to systems dedicated to specific amplification platforms or formats. The MagNA Pure LC system (Roche Applied Science, Indianapolis, IN) uses robotics, precision pipettors, and magnetic glass particles to purify DNA, RNA, mRNA, or total nucleic acid from various sample types. The samples are dissolved and simultaneously stabilized by incubation with a buffer containing denaturing agents and proteinase K. Nucleic acids are bound to the surface of the magnetic glass particles, and several washing steps remove the unbound substances. The purified nucleic acids are then eluted in a low-salt buffer, with elution volumes ranging from 50 to 100 μL. The instrument can process up to 32 samples in 1.5 h; it can also automate PCR set-up and transfer the purified nucleic acids directly into a wide variety of reaction vessels, including LightCycler capillary tubes (Roche Applied Science), 96-well microplates, standard PCR tubes, and COBAS AMPLICOR amplification rings (Roche Diagnostics). We developed and verified MagNA Pure LC (software Ver. 2.1) protocols for use with a quantitative test for cytomegalovirus (CMV) DNA (COBAS AMPLICOR MONITOR CMV Test) (1) and a qualitative test for hepatitis C virus (HCV) RNA (AMPLICOR HCV Test version 2.0) (2). The MagNA Pure LC total nucleic acid reagent set was used to recover CMV DNA and HCV RNA from EDTA plasma. The starting sample volume in each case was 200 μL. The total nucleic acid isolation reagent set and instrument were used as recommended by the manufacturer with the following …