Metagenome of healthy blood human donors
1 mL of plasma was filtered through 0.45 micrometre filter and was used to extract nucleic acids with the QIAAMP Ultra Sens Virus Kit (Qiagen). RNA was cleaned with TRIzol LS reagent (Invitrogen), extracted with the QIAamp Viral RNA Mini kit and amplified using the QuantiTect Whole Transcriptome kit (Qiagen). RNA amplification products were used for library preparation using Nextera XT DNA library preparation kit (Illumina).