TABLE 1.
Enrichment of RCA and HDEP by successive rounds of propagation on A549 cellsa
| Round of amplifi- cation | Titer on A549 cells (HDEP infectious units/ml) | Titer on HEK-293 cells (total virus infectious units/ml) | HDEP/ Ad5.1FGF-4 ratio |
|---|---|---|---|
| 1 | 4.8 × 107 | 3.6 × 109 | 1:75 |
| 2 | 1.7 × 108 | 2.5 × 1010 | 1:147 |
| 3 | 1.6 × 106 | 4.4 × 108 | 1:275 |
| 4 | 3.3 × 109 | 4.0 × 1011 | 1:121 |
| 5 | 7.4 × 109 | 2.56 × 1012 | 1:346 |
a
The CPE-positive, secondary culture supernatant from the RCA assay was subjected to five rounds of amplification on the nonpermissive cell line A549. Infectivity was measured using a cell-based enzyme-linked immunosorbent assay on both HEK-293 and A549 cells for the five cultures, as described in Materials and Methods.