Evaluation of a Subunit H5 Vaccine and an Inactivated H5N2 Avian Influenza Marker Vaccine in Ducks Challenged with Vietnamese H5N1 Highly Pathogenic Avian Influenza Virus

Table 2

Efficacy of H5 vaccines in ducks challenged with avian influenza virus [A/VN/1203/04 (H5N1)].

Vaccine group1	Challenge dose; (EID50)	Morbidity2	Mortality2 (Mean time to death)	HI serology3		Virus isolation-oropharyngeal4		Virus isolation-cloacal4
				Prechallenge; No.>HI 10 (GMT>HI 10)	Postchallenge; No.>HI 10 (GMT>HI 10)	Day 2	Day 4	Day 2	Day 4
Control	10^5.3	2/7^2	5/7 (4.8 days)	0	1 (2560)	7/7 (3.21)	5/5 (3.42)	1/7 (0.04)	0/5
TLL H5; High-dose adjuvant	10^5.3	0/8	0/8	6 (16)	8 (160)	0/8	0/8	0/8	0/8
Inactivated; H5N2 vaccine.	10^5.3	0/7	1/7 (day 7)	7 (119)	6 (160)	0/7	0/7	0/7	0/7
Inactivated; H5N2 with TT	10^5.3	0/7	1/7 (day 8)	7 (49)	6 (422)	0/7	0/7	0/7	0/7

1 The TLL vaccine was given in 3 doses 1, 4 and 5 weeks of age, the other vaccines were given at 1 and 4 weeks of age and challenge was at 9 weeks of age with 10^5.3 EID₅₀ of the H5N1 virus.
2 Number affected/total challenged. Morbidity refers to neurological signs of head tilt, ataxia, and weakness.
3 Haemagglutination inhibition (HI) test results using A/VN/1203/04 (H5N1) antigen showing the number of ducks positive with HI titre>10 and the geometric mean titre (GMT) for the positive ducks is shown in parenthesis.
4 Number shedding virus/number alive at each time point. Values in parenthesis are mean viral titres expressed in log₁₀ TCID₅₀/mL.