TABLE 2.

IgM reactivity (expressed as S/N ratios) to COS-1 and S2 cell-expressed WNV antigens in a panel of 37 human serum specimens^a

Specimen	S/N ratio obtained by indicated assay:			Diagnosisd
	COS-1b	S2b	MDCHc
4	77.8	44.7	3.00	E
32	77.8	43.7	3.20	M/E
28	77.8	48.2	3.30	M/E
36	77.8	48.2	3.50	E
31	77.8	30.8	3.60	E
43	77.8	27.9	3.60	H
15	77.8	48.2	3.80	H
30	77.8	48.2	4.70
35	77.8	48.2	5.20
38	77.8	48.2	5.50
11	77.8	48.2	10.00	E
26	77.8	35.0	10.00	M
5	77.8	47.8	10.50	E
16	77.8	48.2	12.50	M/E
24	77.8	48.2	22.00	E
27	73.6	34.9	3.10	M/E
19	68.0	43.2	2.20	E
10	60.7	22.9	3.00
9	60.1	21.9	2.30	M
6	59.3	44.2	2.90
14	58.7	24.8	108.00
37	56.3	23.2	2.60	H
33	44.0	24.5	2.50	E
17	43.8	27.3	2.60
22	40.1	16.1	2.10	E
23	38.4	7.5	2.20	E
21	13.2	8.3	2.90	H
18	3.8	3.6	2.95
41	2.1	1.8	<2.0
25	1.8	1.4	<2.0	HR
42	1.1	1.0	<2.0
3	1.0	0.9	<2.0
40	1.0	0.9	<2.0
39	0.9	1.1	<2.0
1	0.8	0.9	<2.0
2	0.8	0.9	<2.0
34	0.8	1.0	<2.0

^aTabular data are arranged according to S/N ratios from the COS-1 assay, listed from highest to lowest.

^bThe COS-1 and S2 assay S/N ratios represent the means of duplicate determinations. Cutoff S/N ratios for the COS-1 and S2 assays were 5.0 and 4.20, respectively.

^cFor the MAC-ELISA performed at the MDCH, samples with S/N ratios of <2.0 are considered IgM negative, those with S/N ratios from 2.0 to 5.0 are equivocal, and those with S/N ratios of >5.00 are considered positive for WNV IgM. MDCH results were obtained using the WNV IgM assay, and reagents were provided by the CDC.

^dClinical diagnosis abbreviations: E, encephalitis; M, meningitis; M/E, meningo-encephalitis; H, hospitalized; HR, hospital released.