|Values are valid only on day of printing.|
Epidemiologic data suggest that AIDS is caused by at least 2 types of HIV, HIV-1 and HIV-2. HIV-1 has been isolated from patients with AIDS and asymptomatic infected individuals. The closely related HIV-2 was first isolated from patients in West Africa in 1986, and the first case of AIDS due to HIV-2 in a patient was reported in the United States in 1988. HIV-2 appears to be endemic only in West Africa, but HIV-2 also has been identified in individuals who have lived in West Africa or had sexual relations with individuals from that region. HIV-2 infection is rare in the United States (<100 cases reported to date); most of the reported cases are from the northeastern states and involve persons from West Africa.
Both HIV-1 and HIV-2 are transmitted by sexual contact, sharing contaminated needles, exposure to infected blood or blood products, or from an infected mother to her fetus or infant. During the course of HIV-2 infection, antibodies are formed against the viral proteins p26 and gp34. Immunosuppressed patients may fail to develop these antibodies. At-risk patients with reactive results for HIV-1/-2 antigen and antibody combination assays and indeterminate or negative results for HIV-1 antibodies by supplemental testing should be investigated for the presence of HIV-2 antibodies.
Screening for and detection of HIV-2 antibodies in asymptomatic individuals
Reactive screening test results suggest the presence of HIV-2 antibodies. All repeatedly reactive serum specimens are automatically confirmed by an HIV-2 antibody confirmation assay with an additional charge.
Negative screen results indicate the absence of HIV-2 antibodies. These results should be interpreted with caution in patients who are at high risk or have symptoms or signs of HIV infection.
This test is not offered as a screening or confirmatory test for blood donor specimens.
This test is not offered for maternal/newborn HIV screening for specimens originating in New York.
All results that are reactive by HIV-2 antibody screening test and positive by confirmatory test should be verified by testing second serum specimens. Positive confirmatory HIV-2 antibody test results are required by statute in most states to be reported to the state departments of health for surveillance of communicable diseases.
False-reactive HIV-2 antibody screening test results may occur in patients with HIV-1 infection due to cross-reactivity of HIV-1 antibodies with the viral core and polymerase proteins used in the HIV-2 antibody screening tests.
Patients at risk for HIV-2 infection and suspected to have acute HIV-2 infection may have a) negative HIV-2 antibody screen results, or b) repeatedly reactive HIV-2 antibody screen results but negative or indeterminate confirmatory test results. For such patients, testing for HIV-2 DNA or RNA (FHV2Q / HIV-2 DNA/RNA Qualitative Real-Time PCR) is recommended.
Assay performance characteristics have not been established for the following types of serum specimen:
-Grossly icteric (total bilirubin level of >20 mg/dL)
-Grossly lipemic (triolein level of >3,000 mg/dL)
-Grossly hemolyzed (hemoglobin level of >500 mg/dL)
-Presence of particulate matter
See HIV Serologic Interpretive Guide in Special Instructions for further interpretive information.
1. Constantine N: HIV antibody assays May 2006. In HIV InSite Knowledge Base (online textbook). Available at: http://hivinsite.ucsf.edu/InSite?page=kb-00&doc=kb-02-02-01
2. Centers for Disease Control and Prevention and Association of Public Health Laboratories. Laboratory testing for the diagnosis of HIV infection: Updated recommendations. June 27, 2014. Available at: http://stacks.cdc.gov/view/cdc/23447
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