The tolerance of the probe against sm was tested using targets (70 nt) with every third nt harboring an sm (referring to the reading frame of the matrix 2 protein of the H3N2 Influenza A) in regions of different length. The 33%9F, 33%12F and 33%15F targets have a region containing 18, 16, or 14 sm between two flanking regions of 9, 12, or 15 perfectly matching nt, respectively. The 33%9nt, 33%12nt and 33%15nt targets have a region of 20, 19 or 18 sm in combination with one region of 9, 12 and 15 perfectly matching nt at the 5 0 end ( Figure 3D , nt sequences in Supplementary  Table 2A and B) . As demonstrated in Figure 3A and B (and confirmed in Figure 3C ), the targets 33%9nt and 33%9F failed to hybridize with the InflA probe, while the 33%15F target hybridized at both hybridization temperatures (60% of the total MFI, 3517 MFI, at 45 C; 39% of the total MFI, 1934 MFI, at 55 C). The 33%12F target with its two 12 nt flanking regions only hybridized at 45 C (45% of the total MFI, 2635 MFI). The 33%15nt, with one contiguous region of 15 perfectly matching nt also hybridized only at 45 C (23% of the total MFI, 1352 MFI; MFI result taken from Figure 3A and B). Thus, for a 70-mer probe to hybridize with a target containing a relatively long stretch of sm, it must have (i) one uninterrupted perfectly matching region of at least 15 nt at 45 C, and longer than 15 nt at 55 C, or (ii) two uninterrupted matching regions of at least 12 nt at 45 C or 15 nt at 55 C.