Persistence of antibodies to West Nile virus nonstructural protein 5.
BACKGROUND
Because IgM antibody against West Nile virus (WNV) pre-membrane/envelope (preM/E) recombinant protein may persist for more than 1 year, an assay distinguishing recent from past WNV infection would be useful. Published findings for a single patient suggest that the presence of antibody against WNV nonstructural protein 5 (NS5) indicates recent infection.


OBJECTIVE
To compare the persistence of WNV NS5 antibodies and preM/E IgM using plasma samples from blood donors who were viremic at the time of donation.


METHODS
Follow-up plasma samples from 35 viremic donors were tested for WNV NS5 antibodies using a microsphere immunoassay, and compared to WNV preM/E IgM antibodies determined on the same samples using an enzyme-linked immunosorbent assay (ELISA).


RESULTS
At 90+/-14 days of follow-up, 20/26 donors (77%) were positive for NS5 antibodies; 6/25 (24%) were positive at 180+/-27 days, and 3/23 (13%) were positive at 365+/-55 days. The comparable values for preM/E IgM antibodies were 77%, 32% and 17%, respectively.


CONCLUSIONS
Persistence of WNV NS5 antibody in plasma is similar to that of preM/E IgM antibody. WNV NS5 antibody cannot be used to distinguish recent from past WNV infection.
Prince
Harry E
HE
Focus Diagnostics, 5785 Corporate Avenue, Cypress, CA 90630, USA. hprince@focusdx.com
Lapé-Nixon
Mary
M
Yeh
Cindy
C
Tobler
Leslie H
LH
Busch
Michael P
MP
D000914:Antibodies, Viral / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D008863:Microspheres; D013997:Time Factors; D014759:Viral Envelope Proteins / Q000276:immunology; D017361:Viral Nonstructural Proteins / Q000276:immunology*; D014901:West Nile Fever / Q000276:immunology*; D014902:West Nile virus / Q000276:immunology*
D000914:Antibodies, Viral; D007075:Immunoglobulin M; C096041:NS5 protein, flavivirus; D014759:Viral Envelope Proteins; D017361:Viral Nonstructural Proteins; C074932:prM protein, Flavivirus