Table 1.

Groups of ducks used to evaluate the effect of immunosuppression on persistence of Newcastle disease virus under different treatments.

Antibody grouping of ducks	Group code of ducks	Number of ducks	Treatments
			Dexamethasone	vNDV	Vaccination
Low antibody level	1a	13	+	+	+
	1b	3	+	−	+
	1c	13	−	+	+
	1d	3	−	−	+
Medium antibody level	2a	13	+	+	+
	2b	3	+	−	+
	2c	13	−	+	+
	2d	3	−	−	+
Nonimmunized	3a	12	+	+	−
	3b	3	+	−	−
	3c	12	−	+	−
	3d	3	−	−	−

+: respective treatment administered; −: no treatment; vNDV: velogenic Newcastle disease virus; Groups tabulated as “a”: immunosuppressed and challenged with vNDV disease virus; Groups tabulated as “b”: immunosuppressed but not challenged; Groups tabulated as “c”: not immunosuppressed but challenged with vNDV; Groups tabulated as “d” are controls for group c: not immunosuppressed nor challenged; Group 3: comprises unvaccinated controls for the 4 test groups.