Total cellular DNA of the chronically infected cell cultures (for HIV-1, HIV-2; HTLV-1, HTLV-2 and VACV), viral genome cDNA copy spiked into human DNA (for HCV and WNV), and DNA isolated from human plasma of the infected individual (for HBV) were used as the positive templates in the initial testing and are listed in the last column of Table S1 . DNA or RNA panels were created by cloning of specific synthetic templates for each virus into the pGEM-T-Easy vector (Promega) by TA cloning, following by in vitro transcription to obtain RNA standards for HCV and WNV. All created plasmids are listed in Table S1 . Nucleotide numbers in Table S1 refer to the location of the partial viral genome cloned into pGEM-T-Easy vector according to the following complete genome sequences available in GenBank: HTLV-1 -L03562.2, HTLV-2 -M10060.1, HIV-1 -K02083.1, HIV-2 -J03654.1, HBV -AF462041.1, HCV -AF271632.1, VACV -AY243312.1, WNV -HQ596519.1. To establish the real-time PCR standard curve the copy number was calculated for each plasmid carrying one copy of the specific viral gene. The size of each plasmid (X b.p.) was used to determine the molecular weight in Daltons (g/mol): W (g/mol) = X b.p. (330 Da 6 2). The copy number of the target viral gene (molecules/ml) was determined from the plasmid concentration (C DNA ) and the molecular weight of each plasmid molecule: