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HelpTest Code RBPG Rubella Antibodies, IgG, Serum
Reporting Name
Rubella Ab, IgG, SUseful For
Determining immune status to the rubella virus
Method Name
Multiplex Flow Immunoassay (MFI)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Instructions: Plastic vial
Specimen Volume: 0.5 Ml
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
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
Vaccinated: positive (≥1.0 AI)
Unvaccinated: negative (≤0.7 AI)
Reference values apply to all ages.
Day(s) Performed
Monday through Saturday
CPT Code Information
86762
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| RBPG | Rubella Ab, IgG, S | 5334-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| RBG | Rubella Ab, IgG, S | 40667-8 |
| DEXG2 | Rubella IgG Antibody Index | 5334-8 |
Clinical Information
Rubella (German or 3-day measles) is a member of the Togavirus family and humans remain the only natural host for this virus. Transmission is typically through inhalation of infectious aerosolized respiratory droplets and the incubation period following exposure can range from 12 to 23 days.(1) Infection is generally mild, self-limited, and characterized by a maculopapular rash beginning on the face and spreading to the trunk and extremities, fever, malaise, and lymphadenopathy.(2)
Primary in utero rubella infections can lead to severe sequelae for the fetus, particularly if infection occurs within the first 4 months of gestation. Congenital rubella syndrome is often associated with hearing loss and cardiovascular, and ocular defects.(3)
The United States 2-dose measles, mumps, rubella vaccination program, which calls for vaccination of all children, leads to seroconversion in 95% of children following the first dose.(1) A total of 4 cases of rubella were reported to the Centers for Disease Control and Prevention in 2011 without any cases of congenital rubella syndrome.(4) Due to the success of the national vaccination program, rubella is no longer considered endemic in the United States (www.cdc.gov/rubella). However, immunity may wane with age as approximately 80% to 90% of adults will show serologic evidence of immunity to rubella.
Interpretation
The reported AI value is for reference only. This is a qualitative test and the numeric value of the AI is not indicative of the amount of antibody present. AI values above the manufacturer recommended cutoff for this assay indicate that specific antibodies were detected, suggesting prior exposure or vaccination.
Positive: Antibody index (AI) value of 1.0 or higher
-The presence of detectable IgG-class antibodies indicates immunity to the rubella virus through prior immunization or exposure. Individuals testing positive are considered immune to rubella infection.
Equivocal: AI value 0.8-0.9
Submit an additional sample for testing in 10 to 14 days to demonstrate IgG seroconversion if recently vaccinated or if otherwise clinically indicated.
Negative: AI value of 0.7 or lower
The absence of detectable IgG-class antibodies suggests the lack of a specific immune response to immunization or no prior exposure to the rubella virus.
Cautions
IgG-class antibodies to rubella virus may be present in serum specimens from individuals who have received blood products within the past several months, but who have not been immunized or experienced past infection with this virus.
Serum samples drawn early during acute phase of infection may be negative for IgG-class antibodies to this virus.
The presence of anti-rubella-IgG antibodies does not exclude the possibility of a recent or ongoing infection. Testing for IgM-class antibodies to rubella should be performed at a state health laboratory or at the Centers for Disease Control and Prevention if the clinical presentation is suggestive of acute rubella infection.
Method Description
The BioPlex 2200 Rubella IgG assay uses multiplex flow immunoassay technology. Briefly, serum samples are mixed and incubated at 37° C with sample diluent and dyed beads coated with rubella antigen. After a wash cycle, anti-human IgG antibody conjugated to phycoerythrin (PE) is added to the mixture and incubated at 37° C. Excess conjugate is removed in another wash cycle and the beads are resuspended in wash buffer. The bead mixture then passes through a detector which identifies the bead based on dye fluorescence and determines the amount of antibody captured by the antigen based on the fluorescence of the attached PE. Raw data is calculated in relative fluorescence intensity.
Three additional dyed beads, an internal standard bead, a serum verification bead, and a reagent blank bead are present in each reaction mixture to verify detector response, the addition of serum to the reaction vessel and the absence of significant nonspecific binding in serum.(Package insert: BioPlex 2200 System MMRV IgG. Bio-Rad Laboratories; 02/2019)