Abstract: Provided herein includes a method for characterizing a target cell-free nucleic acid (cfNA) molecule present in a biological sample such as a urine sample. It comprises isolating total cfNAs from the biological sample without prior preprocessing such as centrifugation to remove cell debris, and characterizing the target cfNA molecule based on the isolated total cfNAs. When the target cfNA is a low molecular weight (LMW) molecule, the method additionally comprises a fractionation step to obtain LMW nucleic acids from the total cfNAs before characterization. The method can detect significantly more copies of the target cfNA molecule compared with existing methods which typically discard the cell debris from the biological sample. Another method is also provided, which substantially recovers cfNAs from the usually discarded cell debris, thus also capable of detecting significantly more copies of the target cfNA molecule.

Abstract: A method and a kit for identifying HBV-host junction sequences (HBV-JSs) from a biological sample are provided. The method includes: preparing a DNA sample (e.g. DNA library) and performing at least one round of enrichment. Each round of enrichment includes a sub-step of capturing HBV DNA sequence-containing DNA molecules from the DNA sample by means of an HBV probe set, which includes a plurality of elaborately designed HBV primers configured to selectively and respectively target different regions of an HBV genome, and each HBV primer is labelled with an immobilization portion such as biotin moiety so as to allow immobilization onto a solid support such as magnetic beads. The method and kit can be used for non-invasively detecting HBV-JSs using a urine sample and other body fluids. The information of the HBV-JSs can be further utilized in the screening, diagnosis, prognosis and management of HBV-associated HCC.