PROCLEIX® WNV Assay

Performance Characteristics - Living Donors

Clinical Specificity

The study was conducted at four blood testing laboratories using samples from donors representing geographically diverse regions of the United States. During this clinical study, testing was performed using three clinical lots of PROCLEIX® WNV Assay reagent kits (see table 1).

Table 1: Clinical Specificity of the PROCLEIX® WNV Assay in Pools anf IDS from Whole Blood Donations

Sample n Sensitivity (%) 95% CI
16-Sample Pools 16.885 99.89 99.90-99.98
IDS 43.503 99.89 99.86-99.92
Overall 60.338 99.91 99.86-99.96

n=Number of Samples
CI = Confidence Interval IDS = Individual Donor Samples

Analytical Sensitivity

An analytical sensitivity panel comprised of serially diluted WNV provided by Health Canada was used to evaluate the assay sensitivity. The WNV panel was prepared by serial dilution of heat-treated tissue culture-derived viral stock (1,000 copies/ml). Three operators tested 30 replicates of each copy level with three clinical lots using the PROCLEIX® System for a total of 90 replicates. The 95 percent confidence intervals (CI) of the reactive rates were based on the exact binomial distribution. Estimations of 50% and 95% detection rates by probit analysis are provided (see table 2).

Table 2: Detection of WNV in Health Canada Analytical Sensitivity Panel

WNV
copies/mL		 Number
reactive/tested*		 % Reactive 95% CI
Lower Upper
100 89/89 100 97 100
30 90/90 100 97 100
10 87/90 97 91 99
3 47/89 53 41 63
1 26/89 29 20 40
0 0/89 0 0** 0**

* Only valid results were included
CI = Confidence Interval
**Per NCCLS guidelines (EP5-A, page 7), numbers < 0 are recorded as 0

Probit Analysis

The predicted 50% to 95% detection rates in copies/mL were determined by probit analysis of the analytical sensitivity results. the predicted 95% detection level for WNV in this study was 8.2 copies/mL with the Health Canada Sensitivity Panel (see Table 3).

Table 3: Detection Probabilities of WNV using a Sensitivity Panel from Health Canada Reference Standard

Assay System Detection Probabilities (copies/mL)
50% (95% CI) 95% (95% CI)
PROCLEIX® System 3.4 (1.8 - 7.2) 8.2 (5.5 - 21.5)

CI = Confidence Interval

Analytical Sensitivity Using an FDA WNV Reference Panel

Performance of the assay was evaluated by testing four replicates of each copy level with clinical lots using the PROCLEIX® System for a total of 12 replicates (see Table 4).

Table 4: Detection of Lineage 1 WNV in an FDA WNV Reference Panel

Panel
I.D.		 WNV
Strain		 Copy Level
(copies/mL)		 Number of
reactive/tested		 % Reactive
1 NY99 100 12/12 100
2 NY99 10 12/12 100
3 Hu2002 0 0/12 0
4 Hu2002 50 12/12 100
5 NY99 0 0/12 0
6 NY99 1000 12/12 100
7 Hu2002 100 12/12 100
8 Hu2002 1000 12/12 100
9 Hu2002 5 12/12 100
10 NY99 5 11/12 92
11 NY99 500 12/12 100
12 Hu2002 10 12/12 100
13 NY99 50 12/12 100
14 Hu2002 500 12/12 100

Analytical Sensitivity Using a Dilutional Sensitivity Panel made from Lineage 2 WNV from Boston Biomedica (BBI)

Three operators tested 30 to 40 replicates of each copy level with three clinical lots for a total of 100 replicates (see table 5).

Table 5: Detection of Lineage 2 WNV in BBI Analytical Sensitivity Panel

WNV
copies/mL		 Number
reactive/tested*		 % Reactive 95% CI
Lower Upper
100 98/100 98 93 100
30 99/100 99 95 100
10 89/100 89 81 94
3 30/100 30 21 40
1 4/89 4 1 10
0 0/100 0 0*** 3
* Invalid reactions were not included
CI = Confidence Interval
***per NCCLS guidelines (EP5-A, page 7), numbers < 0 are recorded as 0

PROCLEIX is a trademark of Novartis Vaccines and Diagnostics, Inc.
Developed by Gen-Probe in collaboration with Chiron. Manufactured by Gen-Probe Incorporated. Distributed by Novartis Vaccines and Diagnostics.