What laboratory tests are used for HIV-2 (Human Immunodeficiency Virus type 2) diagnosis?

From the Guidelines

HIV-2 Diagnosis Laboratory Tests

HIV-2 diagnosis is typically performed using a combination of laboratory tests, including enzyme-linked immunosorbent assay (ELISA) and Western blot 1.

• Initially, a combination of HIV-1 and HIV-2 antibody tests should be used to screen for the presence of antibodies against both viruses.
• If the initial result is positive, a type-specific confirmatory test should be performed to determine whether the infection is due to HIV-1 or HIV-2 1.
• The tests should be performed on serum or plasma samples.
• Additionally, nucleic acid testing (NAT) such as polymerase chain reaction (PCR) can be used for early detection and confirmation of HIV-2 infection.
• It is essential to use FDA-approved or CE-marked kits for these tests 1.
• A positive result should be confirmed with a second test, and a medical professional should interpret the results and provide guidance on further management and treatment.
• If the HIV-1 Western blot result is negative or indeterminate, an HIV-2 EIA should be performed to determine the presence of HIV-2 antibodies 1.
• If the HIV-2 EIA is positive, an HIV-2 supplemental test such as Western blot or immunofluorescence assay should be performed to confirm the diagnosis 1.

From the Research

Laboratory Tests for HIV-2 Diagnosis

The following laboratory tests are used for HIV-2 diagnosis:

• Enzyme-linked immunosorbent assay (ELISA) 2, 3, 4, 5
• Western blot assay 2, 3, 4, 5
• Synthetic peptide enzyme-linked immunosorbent assay (SPE) 3
• Virus-specific whole-virus enzyme-linked immunosorbent assay (WVE) 3
• Rapid mixed antigen tests (RMATs) 3
• Automated ELISA, such as Enzymun-Test Anti HIV-1 + 2 5

Test Characteristics

These tests have the following characteristics:

• ELISA: sensitivity > 98% and specificity > 98% 2, but may have false-positive and false-negative results 2, 4
• Western blot: used as a confirmatory test, but may not be optimally effective and has limitations 2, 4
• SPE: allows for more specific distinction between HIV-1 and HIV-2 infections than Western blot 3
• Automated ELISA: provides reliable selective HIV-1 and HIV-2 antibody detection at a lower cost than Western blot tests 5

Test Strategies

The following test strategies are recommended:

• Using WVE or RMATs as a screening test, followed by SPE as a supplemental test, can provide results with high sensitivity and specificity 3
• A mixed antigen screening test followed by SPE seems to be an efficient testing strategy for diagnosing HIV-1 and HIV-2 infections 3