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.
