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 3

Antibody responses to tetanus toxoid antigens in ducks vaccinated with H5N2/TT marker vaccine and challenged with avian influenza virus [A/VN/1203/04 (H5N1)].

TT ELISA type	Post-vacc. 1	Post-vacc. 2	Postchallenge
	Mean(StdDev.)^3	Mean (Std Dev.)	Mean (Std Dev.)
TT C-ELISA	30.7%	62.4%	35.7%
(%inhibition)^1	(9.5%)^a	(9.2%)^b	(17.3%)^a
TT Indirect ELISA	7.7%	65.4%	67.7%
(%positive)^2	(7.4%)^c	(28.8%)^d	(31.8%)^d

1The positive-negative cut-off point for the TT C-ELISA is 30% inhibition [25].
2The positive-negative cut-off point for the TT indirect ELISA was 18.5% of mean OD of the positive control.
3Within the different TT ELISA test rows, the mean results at different times postvaccination or postchallenge with different letter superscripts (a,b or c,d,) are significantly different (𝑃<.05).