TABLE 1.
Establishment of detection limit of HCV qualitative RNA assay (TMA) applied to DBSa
| HCV RNA serum concn (in IU/ml) | Estimated input (in IU) of HCV RNAb | No. positive/no. tested | % Positive results |
|---|---|---|---|
| 604,000 | 33,250 | 8/8 | 100 |
| 120,800 | 6,640 | 8/8 | 100 |
| 24,160 | 1,328 | 8/8 | 100 |
| 4,830 | 265 | 6/7 | 85.7 |
| 960 | 53 | 6/8 | 75 |
| 190 | 10.6 | 0/8 | 0 |
| 38 | 2.1 | 0/8 | 0 |
| 0 | 0 | 0/8 | 0 |
a
Uncoagulated blood from a viremic patient (viral burden, 604,000 IU/ml) was diluted with fresh blood from an HCV-seronegative individual. Eight five-fold serial blood dilutions were spotted to form multiple replicate DBS that were extracted and assayed as described in the text.
b
Estimated HCV RNA input in the DBS was determined by adjusting values for viremia in serum for the volume of blood spotted and for the relative hematocrit value.