Table 2.
PRRSV challenge and protection study in pigs vaccinated with attenuated chimeric viruses or with parental virus
| Group | No. of pigs | Vaccination at day 0 (2 × 105 TCID50/pig) | Challenge virus at 35 days postvaccinationa | Necropsy at 14 days postchallenge (no. of pigs) |
|---|---|---|---|---|
| 1 | 9 | Parental VR2385 | VR2385 | 8b |
| 2 | 9 | Parental VR2385 | NADC20 | 9 |
| 3 | 9 | Chimera DS722 | VR2385 | 9 |
| 4 | 9 | Chimera DS722 | NADC20 | 9 |
| 5 | 9 | Chimera DS5M3 | VR2385 | 9 |
| 6 | 9 | Chimera DS5M3 | NADC20 | 9 |
| 7 | 9 | DMEM control | VR2385 | 9 |
| 8 | 9 | DMEM control | NADC20 | 9 |
a
The challenge virus dose for all viruses was 2 × 105 TCID50/pig.
b
One pig died from an unrelated cause before the challenge.