Table 1. Evaluation of pathogenicity according to FAdV-4 passage number and host age in SPF chickens
| Age (d) | Group | Virus titer (TCID50/dose) | Mortality | Gross lesions | Histological lesion score | Virus detection rate | Mean bodyweight gain (g) at days post challenge (DPC) |
| HN | HP | Liver | Heart | Liver | CT | 3 | 5 | 10 | 14 |
| 1 | LH | 6.31 × 107 | 20/20* | 2/20 | 13/20 | 1.4 ± 0.37a | 1.7 ± 0.86 | 17/20 | 12/20 | – | – | – | – |
| YS4 | 6.31 × 108 | 20/20 | 0/20 | 17/20 | 1.5 ± 0.76 | 1.8 ± 1.01 | 18/20 | 13/20 | – | – | – | – |
| YS9 | 4.73 × 108 | 20/20 | 1/20 | 13/20 | 1.5 ± 0.76 | 1.3 ± 0.85d | 19/20 | 18/20 | – | – | – | – |
| Control | – | 0/20 | 0/20 | 0/20 | 0.0 ± 0.00 | 0.0 ± 0.00 | 0/20 | 0/20 | – | – | – | – |
| 14 | LH | 6.31 × 107 | 0/20 | 0/20 | 3/20 | 0.1 ± 0.31abc | 0.0 ± 0.00 | 0/20 | 1/20 | 42.7 | 14.6 | 73.6 | 48.7 |
| YS4 | 6.31 × 108 | 4/20 | 4/20 | 4/20 | 1.7 ± 1.27b | 0.0 ± 0.00 | 9/20 | 13/20 | 8.3 | 16.6 | 49.5 | 74.0 |
| YS9 | 4.73 × 108 | 1/20 | 1/20 | 1/20 | 1.2 ± 0.88c | 0.2 ± 0.41d | 6/20 | 7/20 | 23.3 | 11.7 | 60.1 | 47.7 |
| Control | – | 0/20 | 0/20 | 0/20 | 0.0 ± 0.00 | 0.0 ± 0.00 | 0/20 | 0/20 | 33.0 | 19.5 | 61.3 | 31.6 |
Dead chicken number / tested chicken number.
The statistically different values (p<0.05) were observed between groups.
FAdV-4, fowl adenovirus serotype-4; SPF, specific-pathogen-free; LH, liver homogenate; YS4, virus passaged 4 times in yolk sac of SPF chicken embryonated egg; YS9, virus passaged 9 times in yolk sac of SPF chicken embryonated egg; HN, hepatic necrosis; HP, hydrppericardium; CT, cecal tonsil.