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Recent Serologic Studies with Potential Impact on WNV Blood Screening. Wayne Hogrefe, Harry Prince Focus Technologies. Focus WNV IgG and IgM ELISA. Focus-based WNV serology technology currently used in: Reference laboratories Public health laboratories GenProbe IND study
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Recent Serologic Studies with Potential Impact on WNV Blood Screening Wayne Hogrefe, Harry Prince Focus Technologies
Focus WNV IgG and IgM ELISA • Focus-based WNV serology technology currently used in: • Reference laboratories • Public health laboratories • GenProbe IND study • Research projects for donor screening
Recent Studies using Focus IgG and IgM ELISA • Utility of the Focus Technologies WNV IgM Capture ELISA Testing CSF; Lape-Nixon, et al., AMLI 2003 • Prince and Hogrefe, CDLI 10:764, 2003 • Prevalence of West Nile Virus Infection in Frozen Donor Plasma Components Recalled from the Peak Epidemic period in 2002; Tobler, LH, et al., ASH 2003
CSF IgM Testing - Key Finding • 1188 Serum/CSF pairs tested in 2002 • Negative/Negative - 1015 (85.4%) • Positive/Negative - 43 (3.6%) • Positive/Positive - 130 (10.9%) • Negative/Positive - 0
IgM Persistence • Roehrig, et al. EID 9:376, 2003 • 7 of 12 (58%) WNV-infected encephalitis patients had detectable IgM at 500 days • Prince and Hogrefe, CDLI 10:764, 2003 • Not clinically defined patients, rather sequentially submitted samples for WNV serology in 2002 • 5/13 (46%) with detectable IgM at 60 - 111 days after first submitted sample
Prevalence of West Nile Virus Infection in Frozen Donor Plasma Components Recalled from the Peak Epidemic Period in 2002 • Collaborative study between ABC centers and the REDS Study, sponsored by NHLBI • December 2002 frozen products collected during the epidemic period from areas of high WNV activity were collected and quarantined • 1468 frozen plasma components collected between June 23, 2002 and September 28, 2002 • Sample source: IL - 53%; LA - 17%; MI - 17%; MS,OH, KY, TX, NE - 13%
WNV Antibody Profile • IgG IgMFocus ELISA # (%) • Nonreactive Nonreactive 1429 (97%) • Reactive Reactive 7 (0.48%) • Nonreactive Reactive 1 (0.07%) • Reactive Nonreactive 23 (1.57%) • Equivocal Nonreactive 8 (0.54%) • Total 1468
IgG Reactive Samples • Twenty-three IgG positive/IgM negative samples • 13 (57%) with Index values of 1.5 - 2.0 • 7 (30%) with Index values of 2.1 - 3.0 • 3 (13%) with Index values of >3.0 • Seven IgG positive/IgM positive samples • 2 (29%) with Index values of 1.5 • 1 (14%) with Index values of 2.1 - 3.0 • 4 (57%) with Index values of >3.0
PRNT and IgM Reactive Samples • IgM ELISA IgG ELISA WNV PRNT SLE PRNT • 1.14 <1.30 <10 <10 • 7.2 1.64 320 20 • 4.77 1.72 160 10 • 5.29 2.59 640 40 • 5.04 3.46 1280 20 • 4.61 3.64 320 20 • 3.83 3.69 160 20 • 4.06 3.9 640 20
GenProbe TMA and Serology • One of 1468 samples - TMA positive • Focus IgM and IgG negative, PRNT negative • The 7 Focus IgM positive samples repeat 10-fold replicate TMA testing • one sample 7/10 replicates reactive • one sample 2/10 replicates reactive