Monitoring Anti-NS1 Antibodies in West Nile Virus-Infected and Vaccinated Horses

Table 2

Results of serological examinations in field samples from WNV infected and vaccinated horses.

Condition	Subgroup	Nº  of sera	Anti-NS1		Anti VLP		Ratio
	(by origin/ vaccine type)				(mean OD)		OD(VLP)/OD(NS1)
			OD	Posit	OD	Posit	R<4	R>4
			(mean+s.d.)	n (%)	(mean+s.d.)	n (%)	n (%)	n (%)
Field-acquired infection	A2; (France)	22	0.75±0.46	14 (63.6)	1.29±0.89	22 (100)	20 (90.9)	2 (9.1)
	A3; (Italy)	17	0.45±0.28	6 (35.3)	1.42±0.59	17 (100)	10 (58.8)	7 (41.2)
	A4; (Morocco)	24	0.69±0.29	17 (70.1)	1.52±0.66	24 (100)	21 (87.5)	3 (12.5)
	A5; (Spain)	52	0.97±0.62	40 (76.9)	2.79±1.73	52 (100)	41 (78.8)	11 (20.0)
	TOTAL (A2-A5)	115	0.72±0.41	77 (66.9)	1.75±0.97	115 (100)	92 (80.0)	23 (20.0)
Field vaccination	B2; (Equip)	26	0.29±0.29	4 (15.4)	1.16±0.52	25 (96.1)	13 (50.0)	13 (50.0)
	B3; (Proteq x1)	30	0.42±0.2	9 (30.0)	0.72±0.27	27 (90)	30 (100)	0 (0)
	B4; (Proteq x2)	75	0.23±0.28	4 (5.3)	1.75±0.57	75 (100)	14 (18.6)	61 (81.3)
	B5; (Recombitek +WNVvac)	19	0.13±0.10	0 (0)	2.08±0.33	19 (100)	0 (0)	19 (100)
	B6; (WNVvacB6)	13	0.43±0.39	5 (38.4)	2.50±0.26	13 (100)	4 (30.7)	9 (69.2)
	TOTAL (B2+B3+B4+B5+B6)	163	0.31±0.27	22 (13.4)	1.24±0.47	162 (98.7)	61 (37.4)	102 (62.6)

e. () Positives (Indirect ELISA): values above 0.5 OD units.