Table 3. nAb titres by serum neutralizing tests (SNTs), clinical reaction indexes (CRIs) and the percentage of protection.

Group	Animal number	SNT titres (day) against BTV1, BTV6 or BTV8a						CRIb	% protectionc
		21 (0 dpc)			42 (21 dpc)
		BTV1	BTV6	BTV8	BTV1	BTV6	BTV8
BTVac-1	4905	80	15	15	10	20	20	0	100
	4906	120	<10	15	30	10	20	0	100
	4907	640	15	20	960	20	80	1	87.5
	4908	3840	10	480	160	30	640	1	87.5
	Mean ± SE							0.5±0.29	93.8±3.6
BTVac-6d	4901	<10	640	80	<10	160	40	0	100
	4902	10	640	320	<10	80	120	1	87.5
	4903	20	160	<10	<10	160	40	0	100
	4904	10	320	40	<10	40	40	1	87.5
	Mean ± SE							0.5±0.29	93.8±3.6
BTVac-8	4909	<10	<10	480	<10	20	80	3	62.5
	4910	<10	<10	480	<10	10	480	2	75
	4911	<10	<10	640	15	20	320	0	100
	4912	<10	10	2560	<10	30	2560	0	100
	Mean ± SE							1.25±0.75	84.4±9.4
CombiVace	4913	1280	15	160	1280	640	480	2	75
	4914	20	<10	960	320	10	1280	3	62.5
	4915	20	15	640	480	320	160	2	75
	4916	30	<10	5120	480	<10	1280	0	100
	Mean ± SE							1.75±0.63	78.1±7.9
control	4917	<10	<10	<10	<10	15	1280	6	NA
	4918	10	10	15	160	10	3840	9	NA
	4919	<10	<10	<10	<10	<10	2560	5	NA
	4920	<10	<10	<10	<10	<10	960	12	NA
	Mean ± SE							8.0±1.58

a. The respective serum neutralization titres were determined against 30–300 TCID₅₀ of the indicated BTVs and expressed as the dilution of serum giving a 50% neutralisation endpoint.

b. The clinical reaction index (CRI) was determined according to Huismans et al [24]. See also materials and methods.

c. The percentage of protection was determined as 100-RR, in which RR is the CRI of each sheep expressed as a percentage of that of the average control.

d. BTVac-6 was previously named rgBTV6 [17].

e. CombiVac is a combination of BTVac-1, BTVac-6, BTVac-8.