TABLE 5.

Summary of histopathological lesions in lung, trachea, spleen, intestine, and brain from chickens infected with M, F, and HN gene chimeras of NDV strains BC and GBT^a

Tissue and histopathological lesion	Control		rBC		rBC-GBT(M)		rBC-GBT(F)		rBC-GBT(HN)		rBC-GBT(F+HN)		rBC-GBT(M+F+HN)		rGBT		rGBT-BC(M)		rGBT-BC(F)		rGBT-BC(HN)		rGBT-BC(F+HN)		rGBT-BC(M+F+HN)
	S	D	S	D	S	D	S	D	S	D	S	D	S	D	S	D	S	D	S	D	S	D	S	D	S	D
Lung
Bronchial lymphoid aggregates	1	1	0	0	1	1	1	1	0	0	1	1	3	1	1	1	1	2	1	1	1	1	1	2	1	2
Parabronchitis	0	0	2	2	0	2	0	2	0	2	0	2	0	2	0	2	0	2	1	2	1	2	0	2	0	2
Epithelial hyperplasia	0	0	2	2	2	2	2	2	0	2	0	2	0	2	1–2*	2*	1	2	1	2	0	0	0	2	2*	2*
Trachea
Tracheitis	0	0	0	0	1	2	1–3	2	1	2	1–3	2	1	2	1	2	1	2	1	2	0	2	3*	2*	1	2
Mucosal attenuation	0	0	2	2	2	2	2*	2*	2–3	2	0	0	2	2	3*	2*	2*	2*	1	2	0	0	2–3	2	1–3	2
Mucosal hyperplasia	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	2	0	0	2	2	3*	2*	0	0
Necrotic/apoptotic mucosal cells	−		−		−		−		−		−		−		+		+		−		+		+		+
Spleen
Lymphoid hyperplasia	0	0	3	5	3	5	2–3	5	0	5	3	5	0	5	4	5	0	5	0	5	3	5	0	5	0	5
Intestine
Lymphohistiocytic enteritis	0	0	2–4	1–3	3	2	1–4	2–4	2–3	2	3*	2*	0	0	0	0	2*	1*	2*	2*	3*	1*	1–2*	2*	1–2*	1–2*
Mucosal hyperplasia	0	0	2–3	2	0	2	2–3	2	2–3	2	2–3	2	2	2	0	2	0	2	0	2	0	2	0	0	2	2
Brain
Meningitis	0	0	1*	1*	1–2*	2*	1	1	0	0	0	0	0	0	2	2	1*	2*	1*	2*	0	0	0	2	3*	2*
Encephalitis	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	2*	1*	3*	2*

^aThe severity (S) and distribution (D) of the histopathological lesions were scored using scales of 0 to 5. For severity, the scores indicate the following: 0, absent; 1, minimal; 2, mild; 3, moderate; 4, marked; 5, severe. For distributions, the numbers indicate the following: 0, absent; 1, focal; 2, multifocal; 3, locally extensive; 4, multifocal and coalescing; 5, diffuse. +, present; −, absent. *, the lesion was not present in all specimens.