For the detection of HHV-6, a real-time PCR assay with fluorescent probes complementary to the sequence lying within the amplified product was used. The tests were run on a LightCycler 2.0 instrument (Roche) with the commercial quantitative MutaREAL ® HHV-6 kit (ALPCO). All samples were examined according to the manufacturer's instructions. Every tested sample was amplified with an internal control (positive control of the DNA extraction and amplification process). Each amplification reaction also included, besides the tested samples, positive HHV-6-specific controls and a negative control of the DNA extraction and amplification process.