2b. Spiking and rt-PCR assays. A 200ml volume of each 8,950 clinical specimens was spiked (according to the procedure described above) before extraction which was performed onto the MagNA Pure LC instrument (Roche) using the High Pure Viral Nucleic Acid Kit (DNA extraction) or the MagNA Pure LC RNA isolation High Performance kit (RNA extraction) according to manufacturer's recommendations. CSF, amniotic fluids, biopsy tissues, effusions and aqueous humor were processed for DNA+RNA extraction using the BioRobot EZ1 with the Virus Mini Kit v2.0 (both from Qiagen). Reverse transcription was performed for RNA viruses using the TaqMan Reverse Transcription Reagents kit (Roche) and random hexanucleotides as per manufacturer's instructions. For each specimen: (i) rt-PCR reactions were carried out according to medical prescription (Table 1) , and (ii) distinct rt-PCR reactions for detection of T4 or MS2 were performed under a 15 mL reaction format (7,5 mL of mastermix, 3 pmol of each primer and 1,2 pmol of probe) and a standard cycling protocol (50uC for 2 min, 95uC for 10 min and 45 cycles 95uC for 15 sec, 60uC for 1 min). 2c. Interpretation of results. For each series of T4 and MS2 rt-PCR, the mean Ct value and the standard deviation within the series were calculated. Each individual reaction was subsequently analysed as follows: