Figure 2. Correlation between the results of next-generation sequencing and real-time PCR.

(a) DNA libraries were prepared from sera spiked with different loads of human herpesvirus 6 (HHV-6), and sequencing reads were mapped to the reference genome. Gray and very light gray colors in the viral genome alignments represent average and maximal coverage in aggregated 1 kbp region. The number of HHV-6 reads is indicated in the upper right of each coverage plot. Total sequencing reads of sera spiked with 1000, 100, and 10 copies/ml HHV-6 are 15514298, 14904684, and 16868138 reads, respectively. (b) The number of HHV-6 reads detected by next-generation sequencing in sera was compared with the HHV-6 viral load that was measured with real-time PCR. Open circles indicate sera from patients with HHV-6 infection, and closed circles indicate sera spiked with HHV-6, as shown in Fig. 2a. The number of HHV-6 reads per sample is shown per 5,000,000 total reads. Correlations were determined using regression analysis. Dotted line, detection limit of real-time PCR.