In ovo application of a live infectious bursal disease vaccine to commercial broilers confers proper immunity

Figures & data

Table 1. Study design.

			Number of birds sampled for IBDV ELISA at days						Challenge at 22 days of age			Challenge at 36 days of age
			0	7	14	21	28	36		Number of birds			Number of birds
Group	Vaccine	Total number of birds							vvIBDV challenge virus	RT–PCR at 5 dpc	BBWR^a/BLS^b At 10 dpc	Challenge virus	RT-PCR at 5 dpc^c	BBWR/BLS at 10 dpc
Hatch	–		18
1	MB-1	33			33	33			D6948	10	20
2	MB-1	33			33	33	33	33				D6948	10	20
3	Transmune	22			22	22			D6948	10	10
4	Transmune	22			22	22	22	22				D6948	10	10
5	Mock	22		10	22	22			D6948	10	10
6	Mock	22		10	22	22	22	22				D6948	10	10

^a Bursa-bodyweight ratio × 1000.

^b Bursa lesion score.

^c Days post-challenge.

Table 2. Mortality, mean bursa-bodyweight ratios (×1000), and mean bursal lesion score after vvIBDV D6948 challenge of MB-1, Transmune or mock-vaccinated broilers by the in ovo route.

Group	Vaccine (in ovo)	D6948 challenge day	Number of birds	Mortality post-challenge	Mean BBWR^A at 10 dpc	Mean BLS^B at 10 dpc^C
1	MB-1	22	20	0%	0.66^a*	3.2^b
2	MB-1	36	20	0%	0.71^a	2.5^c
3	Transmune	22	10	0%	0.66^a	2.8^bc
4	Transmune	36	10	0%	0.69^a	4.8^a
5	Mock	22	10	20%	0.74^a	4.6^a
6	Mock	36	10	0%	0.69^a	4.5^a

^A Bursa-bodyweight ratio × 1000.

^B Bursal lesion score.

^C Days post-challenge.

*Statistical significance per challenge age X vaccine interaction (groups not sharing the same superscript letter are significantly different).

Table 3. Mean IBDV antibody response (GMT) post-vaccination.

				Geometric mean titres (GMT) of ELISA IBDV antibodies (percentage of positive sera) at days of age
Group	Vaccine (in ovo)	D6948 challenge day	Number of birds	0	7	14	22	28	36
Hatch mates	–		18	3741 (100%)
1	MB-1	22	33			174^a (22%)	133^ab (16%)
2	MB-1	36	33			213^a (12%)	270^a (24%)	1402^a (66%)	2884^a (91%)
3	Transmune	22	22			123^a (14%)	99^ab (14%)	–	–
4	Transmune	36	22			230^a (23%)	51^ab (0%)	101^b (9%)	38^b (0%)
5	Mock	22	22		1113 (100%)	277^a (27%)	15^b (0%)	–	–
6	Mock	36	22			315^a (32%)	14^b (0%)	5^b (0%)	13^b (0%)

Note: Different superscript letters indicate significant differences between groups (P < 0.05, t-test)

Table 4. Overview of the histopathological bursal lesion scores (BLS) per group.

Group	Vaccine (in ovo)	D6948 challenge day	Number of birds	Number of birds per bursal lesion score at 10 days post-challenge
				0	1	2	3	4	5
1	MB-1	22	20	–	–	1	14	5	–
2	MB-1	36	20	–	4	7	5	4	–
3	Transmune	22	10	–	1	–	9	–	–
4	Transmune	36	10	–	–	–	–	2	8
5	Mock	22	8	–	–	–	–	3	5
6	Mock	36	10	–	–	–	–	5	5

Table 5. Bursal IBDV RT-rtPCR and Strain Differentiation/Genotyping at 5 days post-challenge with D6948 of MB-1, Transmune, or mock-vaccinated groups (10 birds per group).

Group	Vaccine (in ovo)	D6948 challenge day	RT-PCR mean Ct value	Individual Sanger sequencing	Deep sequencing (pooled sample)
					Number of contigs	Percentage
1	MB-1	22	23.2	10x MB-1	954	100% MB-1
2	MB-1	36	29.5	8x MB-1, 2x undetermined	668	100% MB-1
3	Transmune	22	24.1	9x W2512, 1x W2512/D6948	799	97% W2512, 3% D6948
4	Transmune	36	22.3	10x D6948	1392	100% D6948
5	Mock	22	19.2	10x D6948	664	100% D6948
6	Mock	36	21.1	10x D6948	1320	100% D6948