# Presentation: 861100

## Procleix® WNV Assay:Update

**BPAC Meeting**
**September 18, 2003**
**Jeffrey M. Linnen, Ph.D.**
**Gen-Probe Incorporated**
**San Diego, CA**

**Procleix is a registered trademark of Chiron Corporation**

## Topics

- Assay performance in the ABC/REDS Study of WNV infection in recalled plasma components from 2002.
- Update of clinical performance
- Performance of the Assay in a high prevalence region
- Future options for the Procleix WNV Assay

## ABC/REDS Study of WNV Infection in         Recalled Plasma Components from 2002

- 1,464 blinded samples from Blood Centers of the Pacific (including 5 positive controls from BBI at 10000, 1000, 300, 100, and 30 c/mL)
- Individual donor samples were initially tested with the Procleix WNV Assay (screening assay)
- Reactive samples were confirmed with the Gen-Probe Alternative TMA Assay.
- Confirmed reactive samples were tested at 1:8 and 1:16 dilutions to determine efficacy of pooled testing.

## ABC/REDS Study of WNV Infection in         Recalled Plasma Components from 2002

- 1 reactive sample identified; 5 blinded controls all detected

## ABC/REDS 2002 Recalled Plasma Study TMA Results with IgM or IgM/IgG Reactive Samples

- 13 IgM or IgM/IgG reactive samples that were NAT non-reactive were tested in 10 replicates  using the Procleix WNV Assay (screening assay)
- 2 additional NAT reactive samples were identified

## Performance of the Procleix WNV AssayABC/REDS 2002 Recalled Plasma Study

- 9/1464 initial reactive samples
- 1 confirmed as NAT reactive by repeat testing with screening assay and alternative TMA Assay (IgM and IgG positive); detected when diluted 1:8 and 1:16.
- 5 reactive samples were positive controls
- 3 samples failed to be confirmed with additional NAT testing
- Testing of blinded controls at 1:8 and 1:16 dilutions showed consistent detection at 12.5 copies/mL and detection down to less than 2 copies/mL.
- Of 13 IgM/IgG reactive samples, multiple replicate testing identified 2 additional NAT reactive samples.
- one detected in 7/10 replicates and another detected in 2/10 replicates.

## Update of Clinical Performance

- Live testing under IND started June 19; most sites started testing by July 1.
- Testing is being done at 24 sites
- Most testing is being done in pools of 16 (about 3% of donations have been tested as individual donations).
- Confirmatory testing:
- Alternative NAT Assay (Bayer Reference Lab, Berkeley,CA)
- IgM (Focus Labs, Cypress, CA)
- Additional confirmatory testing is being done with an Alternative TMA Assay (Gen-Probe)

## Update of Clinical Performance(Continued)

- Approximately _2.1 million donations_ have been tested (as 8/26/03).
- Over _400 confirmed* West Nile virus reactive donations_ have been identified (~2 per 10,000 donations).
- Confirmed reactive rates ranges:
- Low:  0% (*e.g* Central California; N = 13,604)
- High:  0.26% (Bonfils Blood Center, Denver, CO; N = 32,364)
- Confirmatory results for many initial reactive donations are still pending.

***confirmed by alternative NAT or IgM testing**

## West Nile Virus in the United States(as of September 9, 2003)

## Performance of the Procleix WNV Assay in a high prevalence region*Bonfils Blood Center (Denver, CO)

- *data as of 8/26/03

- _32, 634 total donations have been tested_ at BBC (~2,000 pools and some individual donations)
- 125 initial reactive (IR) results
- Confirmatory testing for 35 of the 125 IR results are pending (22/35 are repeat reactive)
- _86 donations have been confirmed reactive_ by alternative NAT or IgM
-  3 IR results did not confirm; 1 unconfirmed result was repeat reactive

## Procleix WNV Assay in a High Prevalence Region (continued)Bonfils Blood Center (Denver, CO)

- Specificity in pools tested: 99.85%
- results are based on repeat testing in the screening assay and alternative NAT Assay.
- Of 85 index specimens tested for IgM, 9 (10.6 %) were IgM positive.
- Based on confirmed results through 8/26/03, WNV prevalence at BBC is about _26 per 10,000 donors_.

## Options for the Procleix WNV Assay

- Option for testing in smaller pool sizes
- Software is under development for pools of 4 and 8 donations
- Preliminary feasibility has been shown on the fully automated TIGRIS system

## Acknowledgements

- This project is funded in part with federal funds from the National Heart, Lung and Blood Institute under Contract No. NHLBI-HB- 07148