Table 4. Virological parameters measured in animals subjected to four separate challenge experiments (Exp.1, 2, 3 and 4)*.
| Parameters | Group I (n = 10) | Group II (n = 10) | Group III (n = 10) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Exp. 1 | Exp. 2 | Exp.3 | Exp.4 | Exp. 1 | Exp. 2 | Exp.3 | Exp.4 | Exp. 1 | Exp. 2 | Exp.3 | Exp.4 | |
| Total no. shedder birds (%) | 8 (80%)a | 4 (40%)b | 4 (40%) b | 2 (20%)c | 5 (50%) d | 8 (80%) a | 8 (80%) a | 2 (20%) c | 10 (100%) e | 10 (100%) e | 10 (100%) e | 10 (100%) e |
| Shedder birds that died | 2 | 2 | 2 | 1 | 5 | 3 | 2 | 1 | 10 | 10 | 10 | 10 |
| Shedder birds that recovered | 6 | 2 | 2 | 1 | 0 | 5 | 6 | 1 | 0 | 0 | 0 | 0 |
| Total no. sick birds but did not shed virus | 2 | 6 | 6 | 8 | 5 | 2 | 2 | 8 | 0 | 0 | 0 | 0 |
| Mean virus load/ shedder birds | ||||||||||||
| Third dpc | 4.1±1.2 | 2.7±0.4 | 3.6±0.3 | 3.1±0.1 | 3.3±0.2 | 3.6±1.2 | 3.9±1.3 | 3 | 3.9±1 | 3.5±0.3 | 4.4±0.4 | 3±0.5 |
| Sixth dpc | 3.2±0.4 | 3.2±0.1 | 4.1±0.7 | 2.0±0.1 | 3.5±1.1 | 3.2±0.3 | 3.1±1 | 2.4±0.6 | 3.6±0.6 | 3.6±0.5 | 4.1±0.8 | 3.5±0.3 |
| Ninth dpc | 0 | 0 | 4.2 | 0 | 3.3±0.3 | 4.5±0.3 | 4.5±0.2 | 3.7 | **NA | NA | 3.8±1.2 | 4±0.5 |
| Fourteenth dpc | 0 | 0 | 2.5 | 0 | 0 | 0 | 0 | 3.9 | NA | NA | 5±0.7 | 4.8±0.8 |
| Mean virus load/shedder birds that died | 3.9 ±0.5 | 3.5 | 3.4±1.2 | 3.4 | 3.6±0.5 | 4.5±0.2 | 4.5±0.2 | 3.9 | 4.7±0.7 | 5.1±0.5 | 5.4±0.6 | 4.7±0.7 |
Different superscripts in a row denote the presence of statistically significant (p ≤0.05) differences
*Experiment 1, 2, 3 and 4 were carried out on birds of 21, 28, 35 and 42 days of age. In both cases, Group 1 (vaccinated with rHVT-H5 vaccine at 1 day old), Group II (vaccinated with inactivated KV-H5 vaccine at 8 days old), Group III (unvaccinated control). All birds were challenged with HPAI H5N1 virus (A/Chicken/Egypt/128S/2012 (H5N1)) (GeneBank Accession No. JQ858485) via the oculo-nasal route with 100 ul (50_ul in eye, 50_ul in nose) of inoculum containing 106 EID50 per duck.
** NA = not applicable as all birds died before 10 dpc.