Efficient strategy for constructing duck enteritis virus-based live attenuated vaccine against homologous and heterologous H5N1 avian influenza virus and duck enteritis virus infection

Table 2 Protective efficacy of C-KCE-HA against H5N1 lethal virus XN/07 challenge in ducks

Challenge virus	Challenge time pv	Vaccine	Virus isolation from the swabs (shedding/total log ₁₀ EID ₅₀ /mL)						No. surviving/total
			Day 3 pc		Day 5 pc		Day 7 pc
			Oropharyngeal	Cloacal	Oropharyngeal	Cloacal	Oropharyngeal	Cloacal
XN/07	1 week	C-KCE-HA	0/7	0/7	0/7	0/7	0/7	0/7	7/7
		C-KCE	7/7(3.1 ± 0.6)	5/7(2.4 ± 0.5)	—	—	—	—	0/7
		PBS	7/7(4.2 ± 0.5)	6/7(3.8 ± 0.4)	—	—	—	—	0/7
	3 weeks	C-KCE-HA	0/7	0/7	0/7	0/7	0/7	0/7	7/7
		C-KCE	7/7(2.7 ± 0.6)	6/7(2.4 ± 0.6)	—	—	—	—	0/7
		PBS	7/7(4.3 ± 0.7)	7/7(4.3 ± 0.7)	—	—	—	—	0/7
	12 weeks	C-KCE-HA	0/7	0/7	0/7	0/7	0/7	0/7	7/7
		C-KCE	7/7(2.7 ± 0.7)	7/7(2.6 ± 1.1)	—	—	—	—	0/7
		PBS	7/7(2.1 ± 0.9)	4/7(1.8 ± 1.2)	—	—	—	—	0/7
	36 weeks	C-KCE-HA	0/7	0/7	0/7	0/7	0/7	0/7	7/7
		C-KCE	7/7(3.1 ± 0.3)	6/7(2.1 ± 0.5)	—	—	—	—	0/7
		PBS	7/7(2.7 ± 0.7)	7/7(1.8 ± 0.6)	—	—	—	—	0/7

One-month-old SPF ducks were used in these studies. Groups of seven ducks were inoculated subcutaneously with 10⁵ PFU of C-KCE-HA, 10⁵ PFU of C-KCE or with PBS as a control. They then were challenged intramuscularly with 100-fold DLD₅₀ homologous (XN/07) AIVs at 1 week, 3 weeks, 12 weeks or 24 weeks post-vaccination (pv). Oropharyngeal and cloacal swabs were collected on days 3, 5, and 7 post-challenge (pc) and titrated in SPF eggs. All of the ducks in C-KCE and PBS groups died within 5 days. The horizontal line indicates that the animals had died by that time point.

ISSN: 1297-9716