Serological studies of West Nile virus in a liver transplant population.
BACKGROUND
Solid organ transplant populations are at increased risk for serious clinical manifestations of West Nile virus (WNV) infection.


OBJECTIVE
To monitor liver transplant recipients during the 2003 WNV season in Manitoba and to identify incidence, clinical presentation and serology.


METHODS
Serial blood specimens were obtained from adult patients followed at the liver transplant outpatient clinic between May 2003 and October 2003. Studies for WNV infection included immunoglobulin (Ig) G and IgM enzyme immunoassay (EIA), hemagglutination inhibition (HI), plaque reduction neutralization test and reverse transcriptase-polymerase chain reaction.


RESULTS
None of the 79 patients had clinical presentations suggestive of WNV infection. On testing of the final serum specimen obtained, 14 patients (18%) had positive IgG anti-WNV by EIA and six patients (7%) had indeterminate IgG anti-WNV by EIA, although all were negative by IgM EIA. Four (20%) of the EIA-positive samples were reactive by HI, but all of these were negative by WNV plaque reduction neutralization test; this is consistent with the presence of non-West Nile flavivirus antibody in these sera. Blood specimens obtained throughout the season from EIA- and HI-positive individuals were uniformly negative for WNV-RNA by reverse transcriptasepolymerase chain reaction. Age, sex, hematology and biochemistry findings, hepatitis B or C virus status, immunosuppressive regimen (cyclosporin or tacrolimus) and pretransplant diagnosis of liver disease were similar for EIA-positive and EIA-negative patients. For the 10 patients with a positive IgG EIA maintained on cyclosporin, the cyclosporin level was 129.1+/-28.6 microg/L compared with 85.6+/-36.7 microg/L in 26 patients who were EIA-negative (P=0.002).


CONCLUSIONS
False-positive IgG EIA serology for WNV was common in this cohort of liver transplant recipients, and was associated with elevated serum cyclosporin levels.
Nicolle
L E
LE
Departments of Internal Medicine, University of Manitoba;
Gutkin
A
A
Smart
G
G
Dawood
M
M
Drebot
M
M
Van Caeseele
P
P
Giulivi
A
A
Minuk
Gy
G