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HIV-1/HIV-2 Plus O EIA

Test Code: 30816

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Clinical Utility

The GS HIV-1/HIV-2 PLUS O EIA is an enzyme immunoassay utilizing recombinant proteins and synthetic peptides for the detection of antibodies to HIV-1 (Groups M and O) and/or HIV-2 in human serum and plasma. It is indicated as a screening test for specimens from individual human donors, including donors of whole blood, blood components, and source plasma and from other living donors. It is also intended for use in testing plasma and serum specimens to screen organ donors when specimens are obtained while the donor's heart is still beating. In addition, it is intended as an aid in the diagnosis of infection with HIV-1 and/or HIV-2. The assay is not intended for use on cord blood specimens.

About HIV

The acquired immunodeficiency syndrome (AIDS) is caused by viruses transmitted by sexual contact, exposure to blood (including sharing contaminated needles and syringes) or certain blood products, or transmitted from an infected mother to her fetus or child during the perinatal period.1 Additionally, transmission of these viruses can occur through tissue transplantation.2 Human Immunodeficiency Virus Type 1 (HIV-1) has been isolated from patients with AIDS and AIDS-related complex (ARC).3-5 HIV-1 was thought to be the sole causative agent of these syndromes until 1986, when a second type of Human Immunodeficiency Virus (Human Immunodeficiency Virus Type 2 or HIV-2) was isolated and also reported to cause AIDS.6-7 Since the initial discovery, hundreds of cases of HIV-2 infection have been documented worldwide, including cases of AIDS related to HIV-2.8 In the United States, there have been more than 80 cases of infection with HIV-2 reported, including three potential blood donors.

Any specimen that reacts in an initial test (is initially reactive) with the GS HIV-1/HIV-2 PLUS O EIA must be retested in duplicate with the GS HIV-1/HIV-2 PLUS O EIA. Initially reactive specimens that are reactive in either one or both duplicates from the repeat testing are referred to as repeatedly reactive. Repeatedly reactive specimens may contain antibodies to either HIV-1 or HIV-2. Therefore, additional, more specific or supplemental tests for antibodies to both HIV-1 and HIV-2, such as Western blot or immunofluorescence, must be performed to verify the presence of antibodies to HIV-1 or HIV-2. Recommendations for appropriate use of additional tests may be issued periodically by the United States Public Health Service.

Procedure

The GS HIV-1/HIV-2 PLUS O EIA is an enzyme immunoassay based on the principle of the direct antibody sandwich technique. Microwell strip plates (the solid phase) are coated with purified antigens; gp160 and p24 recombinant proteins derived from HIV-1; a peptide representing the immunodominant region of the HIV-2 transmembrane glycoprotein, gp36; and a synthetic polypeptide mimicking as artificial (i.e., encoded by no existing virus) HIV-1 Group O specific epitope.

Samples and controls are added to the wells along with Specimen Diluent. The Specimen Diluent contains a dye that changes color from purple to blue when combined with a sample or control. The wells are incubated and then washed. The next step is the addition of a color Conjugate Solution (green), which contains peroxidase-conjugated antigens (peptides mimicking various immunodominant epitopes of the HIV-1 and HIV-2 transmembrane glycoproteins, and a P24 recombinant protein). The wells are then incubated. If HIV-1 and/or HIV-2 antibody is present, it will bind to the antigen coated on the well and to the peroxidase-conjugated antigens in the conjugate. The antigen-antibody-antigen complexes remain bound to the well during the subsequent wash step, which will remove any unbound materials. Working TMB Solution is added to the plate and allowed to incubate. A blue or blue-green color develops in proportion to the amount of HIV antibody present in the sample. Color development is stopped by the addition of an acid, which changes the blue-green color to yellow. The optical absorbance of specimens and controls is determined spectrophotometrically at a wavelength of 450 nm. Test performed by VRL Eurofins, 6933 S. Revere Parkway, Centennial, CO 80112. This test has been cleared or approved for diagnostic use by the U.S. Food and Drug Administration. See package insert for more information.

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