Performance evaluation of the Maxwell 16 System for extraction of influenza virus RNA from diverse samples

This study evaluated the performance of the Maxwell 16 System (Promega) for extraction of influenza virus (flu-v) RNA from diverse samples compared to a classical manual method (QIAamp Kit, QIAGEN). Following extraction by the two methods, all samples were analyzed by Real-time RT-PCR. Results revealed that the use of the standard Maxwell 16 protocol (Maxwell 16-S) resulted in good linearity and precision across a wide concentration range and higher sensitivity of detection from flu-v stock suspensions than the manual method. Compared with the latter method, Maxwell 16-S extracted RNA more efficiently (higher RNA yield and/or fewer PCR inhibitors) from throat swabs and bronchoalveolar lavage fluids, while both methods performed comparably on fecal samples from human and poultry in terms of overall threshold cycle values and detection rates although the Maxwell 16-S co-purified more inhibitors from fecal samples. The capacity of this system to remove inhibitors from fecal matrix was improved by using a modified Maxwell 16 protocol with a reduced sample input, which eliminated all false-negatives produced by the Maxwell 16-S. These findings suggest that the Maxwell 16 System is suitable for RNA extraction from multiple-source samples for diagnosis of influenza and viral load determination and that a proper reduction in starting sample volume may improve the detection of flu-v from complex matrices such as feces. Additionally, this system allows flexible sample throughput and labor-saving sample processing with little or no risk of cross-contamination.