Progenitor Cell Assay Employing Primary Fetal Liver Cells
| Virus . | CFU-E . | CFU-E Background . | BFU-E . | BFU-E Background . |
|---|---|---|---|---|
| Uninfected | 30 ± 9 | 0 | 4 ± 2 | 0 |
| Uninfected + EPO | 172 ± 21 | 142 | 13 ± 2 | 9 |
| cEPOR | 244 ± 18 | 214 | 51 ± 6 | 47 |
| cEPORYF | 107 ± 6 | 77 | 1 ± 1 | 0 |
| cEPOR: Y1F,2-8Y | 149 ± 19 | 119 | 53 ± 4 | 49 |
| cEPORYF: 1Y | 183 ± 35 | 153 | 34 ± 4 | 30 |
| cEPORYF: 2Y | 178 ± 9 | 148 | 6 ± 1 | 2 |
| cEPORYF: 3Y | 174 ± 13 | 144 | 3 ± 2 | 0 |
| cEPORYF: 4Y | 143 ± 24 | 113 | 9 ± 1 | 5 |
| cEPORYF: 1-4Y | 179 ± 30 | 149 | ND | ND |
| cEPORYF: 5-8Y | 217 ± 42 | 187 | ND | ND |
| cEPORYF: 8Y | 172 ± 36 | 142 | 46 ± 7 | 42 |
| Virus . | CFU-E . | CFU-E Background . | BFU-E . | BFU-E Background . |
|---|---|---|---|---|
| Uninfected | 30 ± 9 | 0 | 4 ± 2 | 0 |
| Uninfected + EPO | 172 ± 21 | 142 | 13 ± 2 | 9 |
| cEPOR | 244 ± 18 | 214 | 51 ± 6 | 47 |
| cEPORYF | 107 ± 6 | 77 | 1 ± 1 | 0 |
| cEPOR: Y1F,2-8Y | 149 ± 19 | 119 | 53 ± 4 | 49 |
| cEPORYF: 1Y | 183 ± 35 | 153 | 34 ± 4 | 30 |
| cEPORYF: 2Y | 178 ± 9 | 148 | 6 ± 1 | 2 |
| cEPORYF: 3Y | 174 ± 13 | 144 | 3 ± 2 | 0 |
| cEPORYF: 4Y | 143 ± 24 | 113 | 9 ± 1 | 5 |
| cEPORYF: 1-4Y | 179 ± 30 | 149 | ND | ND |
| cEPORYF: 5-8Y | 217 ± 42 | 187 | ND | ND |
| cEPORYF: 8Y | 172 ± 36 | 142 | 46 ± 7 | 42 |
Day 13 fetal liver cells were infected with virus as described in Materials and Methods, washed, and cultured in methylcellulose at 2 × 104 cells/mL in the presence of stem cell factor but no other added growth factors. CFU-E were scored on day 2 and BFU-E were scored on day 7. For samples containing added EPO, the concentration was 2 U/mL. Results shown are means of triplicates ± standard deviation. Background was defined as the average colony count in uninfected cells without the addition of EPO.
Abbreviation: ND, not determined.