Table 1.
Results of the pathogenicity study using four IBV strains.
| Groupa | Dose, median embryo infectious doses (log 10)b | Morbidity (%) | Mortality (%) | Virus recoveryc |
Antibody (%)d |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 4e | 8 | 12 | 16 | 20 | 4e | 8 | 12 | 16 | 20 | ||||
| CK/CH/LHLJ/04Vf | 4.8 | 100 | 40 | + | + | + | − | − | 0/9(0) | 6/7(86) | 6/6(100) | 6/6(100) | 6/6(100) |
| CK/CH/LDL/04II | 4.7 | 100 | 30 | + | + | + | − | − | 0/9(0) | 7/7(100) | 7/7(100) | 7/7(100) | 7/7(100) |
| CK/CH/LXJ/02I | 4.8 | 100 | 20 | + | + | − | − | − | 3/10(30) | 8/8(100) | 8/8(100) | 8/8(100) | 8/8(100) |
| CK/CH/LSHH/03I | 4.8 | 100 | 20 | + | − | − | − | − | 0/10(0) | 8/8(100) | 8/8(100) | 8/8(100) | 8/8(100) |
| Control | – | 0 | 0 | − | − | − | − | − | 0/10(0) | 0/10(0) | 0/10(0) | 0/10(0) | 0/10(0) |
a
Ten chicks per group.
b
Dose per chick, 100 μL.
c
Two procedures were used for virus recovery after challenge. First, lesions in embryos that had been inoculated with pooled samples (tracheal swabs) were observed. Second, RT-PCR using oligonucleotide primers N(+) and N(−) on RNA recovered from allantoic fluid of the same eggs was conducted. The results from the two procedures were identical.
d
Number seroconverted/number inoculated.
e
Days after challenge.
f
CK/CH/LHLJ/04V passage 3 (P3) was used for the virulence study.