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 1

Efficacy of TLL H5 vaccine 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	10^4.3	1/6^2	5/6 (6 days)	0	1 (320)	4/6 (2.27)	6/6 (3.66)	0/6	0/5
TLL H5 High-dose	10^4.3	0/5	1/5 (day 7)	0	4 (452)	1/5 (0.42)	3/5 (1.87)	0/5	0/5
TLL H5 Low-dose adjuvant	10^4.3	0/6	0/6	0	5 (184)	0/6	0/6	0/6	0/6
TLL H5 High-dose adjuvant	10^4.3	0/5	0/5	2 (14)	3 (508)	0/5	0/5	0/5	0/5

1The TLL vaccine was given as 2 doses at 3 weeks interval with challenge 4 weeks later. Challenge was with 10^4.3 EID₅₀ of the H5N1 virus.
2Number affected/total challenged. Morbidity refers to neurological signs of head tilt, ataxia and weakness.
3Haemagglutination 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.
4Number shedding virus/number alive at each time point. Values in parenthesis are mean viral titres expressed in log₁₀ TCID₅₀/mL.