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Test Code LAB867 West Nile Virus Antibody, IgG and IgM, Serum

Useful For

Laboratory diagnosis of infection with West Nile virus in serum specimens

Profile Information

Test ID Reporting Name Available Separately Always Performed
WNGS West Nile Virus Ab, IgG, S No Yes
WNMS West Nile Virus Ab, IgM, S No Yes
WNVSI West Nile Serum Interpretation No Yes

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)

Reporting Name

West Nile Virus Ab, IgG and IgM, S

Specimen Type

Serum


Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.5 mL


Specimen Minimum Volume

0.4 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 14 days
  Frozen  14 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject
Heat Inactivated specimen Reject

Reference Values

IgG: negative

IgM: negative

Reference values apply to all ages

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: Flavivirus [West Nile] ELISA IgG. Focus Technologies;10/16/2012)

 

IgM:

Polystyrene microwells are coated with the antihuman antibody specific for IgM (u-chain). Diluted serum specimens and controls are incubated in the wells, and 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 antiflavivirus conjugated with horseradish peroxidase (HRP) is then added to the wells and incubated. If WNV antigen has been retained in the well by the antiflavivirus in the specimen, the mouse antiflavivirus: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: Flavivirus [West Nile] IgM Capture ELISA. Focus Technologies; 06/01/2015)

Day(s) Performed

Monday, Wednesday, Friday

Seattle Children's Hospital Note:

TAT: 3 - 6 days

Report Available

Same day/1 to 4 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

IgG-86789

IgM-86788

LOINC Code Information

Test ID Test Order Name Order LOINC Value
WNS West Nile Virus Ab, IgG and IgM, S 94854-7

 

Result ID Test Result Name Result LOINC Value
WNGS West Nile Virus Ab, IgG, S 29566-7
WNMS West Nile Virus Ab, IgM, S 29567-5
WNVSI West Nile Serum Interpretation 69048-7

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

Forms

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

Testing Algorithm

The following algorithms are available in Special Instructions:

-Meningitis/Encephalitis Panel Algorithm

-Mosquito-borne Disease Laboratory Testing