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Test Code LAB7471 West Nile Virus Antibody, IgG and IgM, Spinal Fluid

Additional Codes

wnc

Useful For

Aiding in diagnosis of central nervous system infection with West Nile virus

Profile Information

Test ID Reporting Name Available Separately Always Performed
WNGC West Nile Virus Ab, IgG, CSF No Yes
WNMC West Nile Virus Ab, IgM, CSF No Yes
WNVCI West Nile CSF Interpretation No Yes
Medical University of South Carolina Note:

WEST NILE IGG AND IGM AB,CSF

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)

Specimen Type

CSF


Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube: Sterile vial

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL


Medical University of South Carolina Note:

On-campus collections: Tube to 99 or deliver to University Extension Hospital Room EH318 
Send CSF in Plastic, 5-mL aliquot tube (T465), Refrigerated.
 
Off-campus collections: Send CSF in Plastic, 5-mL aliquot tube (T465). Specimen to be stored/transported at Refrigerated temp. 

Specimen Minimum Volume

0.8 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
CSF Refrigerated (preferred) 7 days
  Frozen  30 days

Reject Due To

Gross hemolysis Reject

Reference Values

IgG: Negative

IgM: Negative

 

Reference values apply to all ages.

Interpretation

Presence of specific IgM-class antibodies to West Nile virus (WNV)is consistent with the acute phase of WNV meningitis or encephalitis. In the very early stages of acute WNV infection, IgM may be detectable in cerebrospinal fluid (CSF) before it becomes detectable in serum.

 

The absence of IgM antibodies to WNV may indicate absence of disease. However, specimens collected too early in the acute phase may be negative for IgM-class antibodies to WNV. If WNV central nervous system infection is suspected, a second specimen should be collected in 1 to 2 weeks and tested.

 

The presence of IgG-class antibodies to WNV may indicate recent or past central nervous system (CNS) infection with WNV. Clinical correlation is necessary.

 

This assay is unable to distinguish between intrathecal antibody synthesis and serum antibodies introduced into the CSF at the time of lumbar puncture or from a breakdown in the blood-brain barrier. Positive results should be interpreted with other laboratory and clinical data prior to a diagnosis of CNS infection.

Method Description

IgG:

Polystyrene microwells are coated with recombinant West Nile virus (WNV) antigen. Diluted serum specimens and controls are incubated in the wells to allow specific antibody present in the specimens to react with the antigen. Nonspecific reactants are removed by washing, and peroxidase-conjugated antihuman IgG is added and reacts with specific IgG. Excess conjugate is removed by washing. Enzyme substrate and chromogen are added, and the color is allowed to develop. After adding the Stop reagent, the resultant color change is quantified by a spectrophotometric reading of optical density (OD). Specimen OD readings are compared with reference cutoff readings to determine results.(Package insert: West Nile Virus IgG DxSelect. Focus Diagnostics; 05/08/2018)

 

IgM:

Polystyrene microwells are coated with the antihuman antibody specific for IgM (mu-chain). Diluted serum specimens and controls are incubated in the wells. The IgM present in the specimen binds to the antihuman antibody (IgM specific) in the wells. Nonspecific reactants are removed by washing. WNV antigen is then added to the wells and incubated. If anti-WNV IgM is present in the specimen, the WNV antigen binds to the anti-WNV in the well. Unbound WNV antigen is then removed by washing the well. Mouse anti-flavivirus conjugated with horseradish peroxidase (HRP) is then added to the wells and incubated. If WNV antigen has been retained in the well by the anti-flavivirus in the specimen, the mouse anti-flavivirus: HRP binds to WNV antigen in the wells. Excess conjugate is removed by washing. Enzyme substrate and chromogen are added, and the color is allowed to develop. After adding the Stop reagent, the resultant color change is quantified by a spectrophotometric reading of OD that is directly proportional to the amount of antigen-specific IgM present in the specimen. Specimen OD readings are compared with reference cutoff OD readings to determine results.(Package insert: West Nile Virus IgM Capture DxSelect. Focus Diagnostics; 05/08/2018)

Day(s) Performed

Monday, Wednesday, Friday

Report Available

Same day/1 to 4 days

Specimen Retention Time

14 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

86789

86788

LOINC Code Information

Test ID Test Order Name Order LOINC Value
WNC West Nile Virus Ab, IgG and IgM,CSF 94853-9

 

Result ID Test Result Name Result LOINC Value
WNGC West Nile Virus Ab, IgG, CSF 77953-8
WNMC West Nile Virus Ab, IgM, CSF 29569-1
WNVCI West Nile CSF Interpretation 69048-7

Secondary ID

36772

Forms

If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.