Development and Evaluation of the Biological Adjuvant Bivalent Vaccine for Preventing Newcastle Disease and Infectious Bursal Disease

Table 5

Protection efficacy against IBDV (BC6/85 strain) challenge of each group in chickens.

Group	BF/BW ratio^a	Histopathological BF lesion score^b						Protection^c	IBDV in BF^d
		0	1	2	3	4	5
rClone30-VP2L-chGM-CSF	1.693 ± 0.347	6	1	0	0	0	0	7/7 (100%)	0
rClone30-VP2L	1.491 ± 0.363	3	2	1	1	0	0	5/7 (71%)	2
IBDV-B87 vaccine	2.853 ± 1.269	2	2	1	1	1	0	4/7 (57%)	3
rClone30-chGM-CSF	1.063 ± 0.286	0	0	0	3	4	0	0/7 (0%)	7
rClone30	0.974 ± 0.0.278	0	0	0	1	5	1	0/7 (0%)	7
Negative control	0.894 ± 0.237	7	0	0	0	0	0	7/7 (100%)	0
Challenge control	1.745 ± 0.379	0	0	0	0	5	2	0/7 (0%)	7

(a) BF/BW ratios was calculated by bursal weight × 1000 then divided by body weight and presented as the mean ± standard deviation from each group. (b) Histological bursal lesion scores were given to each chicken based on the increasing severity of bursal atrophy (0: no lesion, 1: slight change, 2: scattered or partial bursal damage, 3: 50% or less follicle damage, 4: 51–75% follicle damage, and 5: 76–100% bursal damage). (c) Protection was defined by the number of chickens with histopathological bursal lesion score 0 and 1/the number of chickens in the group. (d) Detected by real-time PCR. Number of chickens positive for IBDV in BF tissue at 96 h postchallenge.