Human Immunodeficiency Virus

This chapter focuses on the various technologies that are currently available from commercial companies for the diagnosis and monitoring of human immunodeficiency virus (HIV) infections, and it is not meant to duplicate more extensive reviews of HIV. Infection with HIV type 1 (HIV-1) results in the induction of a humoral antibody response specific to viral proteins, with the production of immunoglobulin A (IgA), IgM, and IgG. The majority of the automated immunoassay analyzers provide walk-away simplicity to perform assays from sample processing through interpretation of results. The major advantage of Western blot assays over enzyme immunoassays (EIAs) is that the specific interaction of antibody and antigen can be directly visualized. Immunofluorescence assay (IFA) is a very useful and inexpensive alternative to performing Western blot assays for confirmation of HIVspecific antibody responses. The Fluorognost HIV-1 IFA is based on the specific binding of HIV-1 antibodies in a specimen to HIV-1 antigens expressed on the surfaces of immortalized human T- cells fixed to glass slides. Specific antibody-antigen complexes are then detected using an anti-human antibody conjugated with fluorescein isothiocyanate. The development of molecular assays to quantitate the levels of HIV RNA in infected patients has provided one of the most valuable tools to assess the progression of HIV disease, monitor the impact of antiviral therapy, predict treatment failure and the emergence of drug-resistant viruses, and facilitate our understanding of the natural history and pathogenesis of this virus.