HIV-1/-2 Antibody Confirmation Without Immunofluorescence Assay, Serum
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Confirmatory detection of HIV-1 and/or HIV-2 antibodies in patients with reactive antibody screen or rapid HIV antibody results
Reflex Tests Lists test(s) that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial test(s)
|Test ID||Reporting Name||Available Separately||Always Performed|
|HIV2||HIV-2 Ab Eval, S||Yes||No|
|HIV2L||HIV-2 Ab Confirmation, S||Yes||No|
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
This HIV-1/-2 antibody confirmatory evaluation begins with HIV-1 antibody by Western blot (WB) assay. If WB is negative, indeterminate or unreadable, then HIV-2 antibody evaluation is performed at an additional charge. If HIV-2 antibody evaluation is reactive, then HIV-2 antibody confirmation testing will be added at an additional charge.
The following algorithms are available in Special Instructions:
-HIV Serologic Interpretive Guide
-HIV Testing Algorithm (excludes HIV rapid testing)
-HIV Rapid Serologic Testing Follow-up Algorithm
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
HIV-1/-2 Ab Confirmation w/o IFA, S
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Collection Container/Tube: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1.6 mL
Collection Instructions: Spin down and remove serum from clot within 24 hours.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Mild OK; Gross OK
Mild OK; Gross OK
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Serum SST||Frozen (preferred)|
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
AIDS is caused by at least 2 known types of HIV. HIV type 1 (HIV-1) was isolated from patients with AIDS, AIDS-related complex, and asymptomatic infected individuals at high risk for AIDS. The virus is transmitted by sexual contact, exposure to infected blood or blood products, or from an infected mother to her fetus or infant. HIV type 2 (HIV-2) was isolated from patients in West Africa in 1986. It appears to be endemic only in West Africa and it also has been identified in individuals who had sexual relations with individuals from that geographic region. HIV-2 is similar to HIV-1 in viral morphology, overall genomic structure, and its ability to cause AIDS.
Antibodies against HIV-1 and HIV-2 are usually not detectable until 6 to 12 weeks following exposure and are almost always detectable by 12 months. They may fall into undetectable levels in the terminal stage of AIDS. Routine serologic screening of patients at risk for HIV-1 or HIV-2 infection usually begins with a HIV-1/-2 antibody screening test, which may be performed by various FDA-approved assays, including rapid HIV antibody tests, EIA, and chemiluminescent immunoassay (CIA) methods.
In testing algorithms that begin with EIA or CIA methods, confirmatory HIV antibody tests should only be ordered for patients who are found to be reactive by routine HIV-1/-2 antibody screening tests or by rapid HIV antibody tests. However, for testing algorithms that begin with rapid HIV antibody tests, confirmatory antibody testing should be performed regardless of the result of the EIA or CIA tests. Individuals at risk for HIV infection may have negative HIV antibody screening test results by EIA or CIA with indeterminate Western blot results (especially during early stage of infection). Such individuals may be erroneously interpreted to not have HIV infection, despite having reactive rapid HIV antibody test results.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
See HIV Serologic Interpretive Guide in Special Instructions for further interpretive information.
If this test is ordered as a follow-up test on a patient with a reactive rapid HIV antibody test result, Centers for Disease Control and Prevention (CDC) recommends supplemental testing with Western blot, even if routine antibody screening result is negative.
An HIV-1 antibody Western blot (WB) result is interpreted as positive when at least 2 of the 3 following bands are present: p24, gp41, and gp120/160. A positive HIV-1 antibody WB result following a reactive HIV-1/-2 antibody screening test, or rapid HIV antibody test, indicates infection with HIV-1, but it does not indicate the stage of disease. In many states, positive confirmatory HIV antibody test results are required to be reported to the state department of health.
A negative HIV-1 antibody WB result with either a reactive HIV-1/-2 antibody screening test or a reactive rapid HIV antibody test, in the absence of signs, symptoms, or risk factors for HIV infection, probably indicates a false-positive screening test or rapid test. However, a negative HIV-1 WB does not exclude the possibility of early HIV-1 or HIV-2 infection. If the HIV-1 antibody WB test result is negative, the HIV-2 antibody test by EIA will be performed automatically (at an additional charge).
Indeterminate WB patterns can be found in up to 15% of persons without evidence of HIV infection. If the HIV-1 antibody WB test result is indeterminate, the HIV-2 antibody test by EIA will be performed automatically (at an additional charge). Individuals at risk for HIV infections should undergo nucleic acid testing if acute HIV infection is suspected or repeat HIV serologic testing in 2 to 4 weeks. If no additional WB bands develop during that time, the patient is considered not to be infected with HIV-1.
An unreadable HIV-1 antibody WB result indicates the presence of smear or blotches obscuring proper reading of the WB strip. Such findings indicate probable nonspecific binding of antibodies in the patient's serum to the strip. For specimens with such unreadable WB results, HIV-2 antibody test by EIA will be performed automatically (at additional charges).
The following algorithms are available in Special Instructions:
-HIV Serologic Screening Algorithm (excludes HIV rapid testing)
-HIV Rapid Serology Follow-up Algorithm
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
The US Association of Public Health Laboratories recommends verification of all positive confirmatory test results prior to the clinical diagnosis of HIV infection. A second serum specimen should be obtained from the patient and submitted for repeat testing to verify all positive confirmatory test results.
Although a positive HIV-1 antibody WB result indicates HIV-1 infection, a diagnosis of AIDS can only be made based on the case definition of AIDS established by the CDC.
High-risk individuals with reactive rapid HIV antibody tests, but negative routine HIV-1/-2 antibody screening tests and indeterminate or negative HIV-1 antibody WB results should be retested in 2 to 4 weeks. Repeat testing may be done by a combination of HIV-1 antibody WB with either rapid HIV antibody or routine HIV-1/-2 antibody screening test.
Positive HIV antibody WB results in infants of < or =18 months of age and born to HIV-infected mothers may indicate passive transfer of maternal HIV antibodies. Serologic tests (screening or confirmatory) cannot distinguish between active neonatal HIV infection and passive transfer of maternal HIV antibodies in infants during the postnatal period (up to 18 months). Diagnosis of HIV infection in newborns and infants should be made by virologic tests such as detection of HIV RNA (HIVQU / HIV-1 RNA Quantification, Plasma) or HIV proviral DNA (PHIV / HIV-1 Proviral DNA Qualitative Detection by PCR, Blood).
This test should be ordered only on sera that are reactive by FDA-licensed HIV-1/-2 screening EIA or rapid HIV antibody tests.
Although hemolyzed serum specimens are acceptable for testing, this assay is not FDA-approved for testing cadaveric specimens.
Assay performance characteristics have not been established for:
-Those that contain particulate matter
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Constantine N: HIV antibody assays, May 2006. In HIV InSite Knowledge Base (online textbook). Available from URL: http://hivinsite.ucsf.edu/InSite?page=kb-00&doc=kb-02-02-01
2. Centers for Disease Control and Prevention: Revised recommendations for HIV testing of adults, adolescents, and pregnant women in health-care settings. MMWR Recomm Rep 2006;55:1-17
3. Hariri S, McKenna MT: Epidemiology of human immunodeficiency virus in the United States. Clin Microbiol Rev 2007;20:478-488
4. Owen SM, Yang C, Spira T, et al: Alternative algorithms for human immunodeficiency virus infection diagnosis using tests that are licensed in the United States. J Clin Microbiol 2008;46:1588-1595
Method Description Describes how the test is performed and provides a method-specific reference
Samples are diluted and applied to the nitrocellulose strip containing specific protein bands derived from purified, inactivated HIV-1 strain lymphadenopathy associated virus grown in the CEM cell line. If specific HIV-1 antibodies are present, they bind to these proteins resolved on the strip. Unbound sample is removed by washing. The phosphatase-labeled conjugate is then added to the strip and allowed to incubate. The conjugate attaches to antibody already bound to viral proteins on the strip. Excess conjugate is removed by washing. Color development reagent is then added to the strip. Reaction sites, where enzyme-labeled antibody is bound, are identified by dark bands. The position and intensity of the bands are compared to reference strips developed using positive control sera. All specimens yielding indeterminate or unreadable results are retested, and results are reported based on the best 2 out of 3 replicate testing.(Package insert: GS HIV-1 Western blot. Bio-Rad Laboratories, Redmond, WA)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; Varies
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Stored serum 7 days
Performing Laboratory Location The location of the laboratory that performs the test
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
86689 x 2-HIV-1 and HIV-2 (if appropriate)
86702-HIV-2 antibody evaluation (if appropriate)
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
|Result ID||Reporting Name||LOINC Code|
|32554||HIV-1 Ab Confirm Western Blot NF, S||13499-9|