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HIV-1/2 Antibody Plus Antigen-Fourth Generation
Principle
This assay is an in vitro Enzyme-Linked Immunosorbent Assay (ELISA) designed for the simultaneous qualitative detection of antibodies to human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2), as well as HIV-1 p24 antigen, in human serum. A reactive result indicates the presence of HIV-1 or HIV-2 antibodies and/or p24 antigen.
HIV-1, the first identified causative agent of AIDS, is transmitted through sexual contact, exposure to infected blood or blood products, or from an infected mother to her fetus or child. The prevalence of HIV-1 antibodies is high among individuals with AIDS, AIDS-related complex (ARC), and those at increased risk. Recombinant DNA–derived antigens corresponding to HIV-1 core and envelope proteins and the HIV-2 envelope protein allow for the detection of anti–HIV-1 and/or anti–HIV-2 antibodies.
HIV-2 is similar to HIV-1 in morphology, CD4 cell tropism, interaction with the CD4 receptor, genomic structure, cytopathic effects, transmission routes, and its ability to cause AIDS.
Specimens that are initially reactive must be retested in duplicate using the original serum sample. Repeat reactivity in either or both duplicate tests (repeatable reactive) is highly predictive of HIV-1 and/or HIV-2 antibodies, particularly in individuals at increased risk for infection. However, due to the possibility of nonspecific reactivity—especially in populations with low disease prevalence (e.g., blood donors)—confirmatory testing using HIV-1 and HIV-2 Western blot or another approved supplemental assay is required to verify the presence of HIV antibodies.
Specimen Requirements
Specimen
Collection
Processing
Storage and Transport
- 2–8 °C: up to 1 week
- −20 °C or lower: for longer storage
- Avoid repeated freeze–thaw cycles
Method
Enzyme-Linked Immunosorbent Assay (ELISA).
Normal Range
Non-reactive
Turnaround Time
References
- Feorino, P.M., Jaffe, H.W., Palmer, E. et al. Transfusion-associated acquired immunodeficiency syndrome: evidence for persistent infection in blood donors. New Engl J Med 312 (20):1293-6; 1985.
- Sheehan, C. Clinical Immunology: Principl