Table 1.
Overview of HI titers at challenge, virus isolation data, clinical symptoms, and mortality rates
| Number of birds | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean HI titer (absolute (sd)) |
with HI titer ≥ 2^5 at challenge |
shedding virusa | with clincial symptoms |
that died | |||||||
| Exp. | Treatment |
at challenge (2log) |
at endd (2log) |
Ib | Cb | I | C | I | C | I | C |
| 1 | no vaccination challenge at d28 of age |
1.6 (1.0) | 206 (457) | 0 | 0 | 22 | 19 | 22 | 22 | 22 | 16 |
| 2 | vaccination at d1 challenge at d28 of age |
1.7 (1.3) | 166 (381) | 0 | 0 | 22 | 18 | 19 | 16 | 16 | 15 |
| 3 | vaccination at d10 challenge at d28 of age |
1.8 (0.9) | 251 (357) | 0 | 0 | 18 | 15 | 16 | 10 | 13 | 7 |
| 4 | no vaccination challenge at day 1 of age |
4.9 (1.2)c | 1.0 (0.4)f | Ndc | nd | 16 | 6 | 19 | 19 | 13 | 1 |
a total numbers in each group were 22 inoculated chickens and 22 contact-exposed chickens.
b I: inoculated chickens; C: contact-exposed chickens.
c not determined.
d only from surviving and infected birds.
e from surplus birds.
f one bird had a titer of 1024, which is omitted from this average.