327620.fig.002
Figure 2: Sensitivity analyses of the two-tube assay based on the automatic electrophoresis. Lanes 1 to 5 contain PCR products of pre-mixed viral targets in tube 1 of 2  ×  106 to 200 copies. Lanes 7 to 11 contain PCR products of pre-mixed viral targets in tube 2 of 2  ×  105 to 20 copies. Lanes 6 and 12 are the negative controls of tube 1 and tube 2, respectively. Lane MM, molecular marker. The detection sensitivity in tube 1 with 9 pre-mixed viral targets was 2000 copies per reaction and 200 copies per reaction in tube 2 with 8 pre-mixed templates. Only the amplicons of sH1N1 and CoV 229E were absent with dilutions of 200 copies of pre-mixed viral targets in tube 1 (Lanes 5), and only the amplicons of CoV NL63, HMPV, and RSVB were absent with dilutions of 20 copies of pre-mixed templates in tube 2 (Lanes 11). The primer dimers which were inevitable in the multiplex PCR are increasingly apparent with the dilution of template.