To establish an amplification protocol suitable for both DNA and RNA viruses, we used the described Phi29-amplification method WTA [2] that has included a ligation step prior to the amplification step, thereby generating larger templates for Phi29. The WTA performed on a HCV + serum sample (RNA virus) resulted in a ,200,000-fold increase in signal (Figure 2A and Table 1 ), as compared to only 3-fold without ligation (data not shown). The WTA RT-reaction and ligation step did not have any adverse effects when performed on a DNA-virus such as JCV from a CSF sample ( Figure 2B and Table 1 ), enabling us to run both viral DNA and RNA through the same amplification protocol prior to microarray hybridization. The WTA was used on 12 different DNA or RNA viruses found in 7 different types of clinical samples (Table 1 and Figure 2 ). The fold increase in PCR signal comparing before and after WTA, ranged from 330 to 564610 6 . The highest fold increase was detected for the circular viruses JCV, BKV and HPV (Table 1 and Figure 2B ). Such circular genomes have previously been shown to be efficiently amplified by Phi29 polymerase, through rolling circle amplification (RCA) [29, 30] . The lowest increase in signal was seen for Rota A found in faeces (Table 1 ) due to large quantities present already before amplification (Ct = 12), which resulted in a Ct-value of 7 after Table 1 ). The fold increase in PCR signal for gDNA (b-actin) was analysed in samples representing all 7 types of clinical samples, and showed no or low levels of b-actin amplification (Table S2) . WTA-amplified samples were purified and typical yield after 8 hours of WTA was ,25 mg (data not shown) showing good size distribution ( Figure 2C ).