Yields of Viral and Circulating Cell-Free Nucleic Acids Using the QIAamp® Circulating Nucleic Acid Kit

Fragmented DNA and RNA circulate as cell-free nucleic acids in plasma, serum, urine and other body fluids. Access to these molecules for analysis may allow for detection of certain disease states based on a blood sample. In this study the extraction efficiency of a large volume nucleic acid extraction kit for circulating and viral nucleic acids was assayed with different downstream qPCR assays. For circulating DNA in plasma the yield was 7- to 9-fold higher with the large volume kit compared to the QIAamp DNA Blood Mini protocol with improved recovery of short DNA fragments. The microRNA extraction protocol of the large volume kit was found to deliver significantly increased microRNA yields (Delta Ct from 3 to 4) compared to the kit's standard protocol. For viral nucleic acids, 95% detection rates were: HBV DNA 0.25 IU/ml and HIV-1 RNA 14.2 IU/ml. The results demonstrate that the QIAamp Circulating Nucleic Acid Kit can serve as a sample preparation solution for processing up to 5 ml cell-free body fluid, it allows for small elution volumes, and can extract and concentrate circulating nucleic acids, including microRNA, and viral nucleic acids up to 250 fold.