The final Tm range for each primer set was adjusted after testing of this clinical panel. Based on the results from the testing of clinical samples and according to NSA performed during the design, two primer sets targeting the S gene region of HBV (NP11/97 and NP11/97-mod) have two different Tm ranges depending on the HBV genotype ( Figure 2 -wells G1 and G3). The lower Tm range (74.5-75.5uC) was detected for genotype A and the higher Tm range (76.8-77.4uC) -for genotypes B, C, and D. The difference in Tm ranges occurred due to single nucleotide polymorphism (SNP) in the amplicon sequence leading to a difference in the G/C nucleotide content of the products. Table 4 summarizes the results from testing the 17 virus-positive clinical samples using the developed array. At least two different specific primer sets could detect a target virus in all cases, with one exception: one HIV-1 positive sample (#4) with ,4 viral genome copies per PCR reaction was amplified with only one primer set (NP175/174). HIV-1 positive clinical samples (#1-#3) with 51-80 viral genome copies/ml of plasma or 2-3 copies/PCR reaction were detected with at least two primer sets. All six HCV-positive samples (#7 to #12) with 16-2,570 viral genome copies/ml of plasma tested positive with both HCV-specific primer sets. Three HBV-positive samples (#15, #16, #17) at 21-66 copies/PCR tested positive by the three HBV-specific primer sets and two HBV-positive samples (#13, #14) with 6-10 copies/PCR tested positive with two out of three HBV-specific primer sets. It is important to note that none of the primer sets showed any crossreactivity with other viruses in the panel of clinical samples tested.