TABLE 1.
Competitive viral replication in immunosuppressed cotton ratsa
| Group | n (no. alive at endpoint) | Virus | Time to harvest | % of PZ-resistant virus (no. with no virus detected in lungs) |
|---|---|---|---|---|
| A | 7 (5) | A2 | 4 wk | 0 ± 0 |
| B | 7 (5) | MP4 | 4 wk | 106 ± 13 (1) |
| C | 7 (6) | A2/MP4 (1:1) | 4 days | 85 ± 11 (1) |
| D | 12 (8) | A2/MP4 (1:1) | 4 wk | 93 ± 8 (0) |
a
Cyclophosphamide was given to induce immunosuppression as described in Materials and Methods. Infections were performed intranasally with viruses or virus mixtures (A2 and MP4). Deaths occurred in each group, likely due to immunosuppression or complications of anesthesia. Lungs were taken at the times shown, differential plaque assay were performed to determine the amounts of each virus present, and the proportion of antibody-resistant virus was calculated.