Evaluation of three commercial screening tests for AIDS virus antibodies

Antigen detection for human immunodeficiency virus

The recent development of enzyme immunoassay procedures for the direct determination of human immunodeficiency virus (HIV) antigens has been of significant benefit in both clinical and research applications. The historical development of HIV antigen assays as well as their current and future applications for use in the clinical microbiology laboratory are reviewed. A detailed description of selected commercially available assays is presented, and a comparison is made of various parameters, including sensitivity, specificity, and cost. The use of the HIV antigen assay as an alternative to the reverse transcriptase assay in virus culture applications is also discussed. In addition, the diagnostic and prognostic utility of the HIV antigen assay is considered for various patient groups, including neonatal, high-risk asymptomatic, seronegative, and seropositive patient populations. The use of the HIV antigen assay as an adjunct to anti-HIV antibody testing, as well as its utility in assessing the therapeutic efficacy of antiviral drug therapy, is discussed. The biology of HIV antigen expression and modulation of anti-HIV antibody titers during infection are also discussed in terms of two possible models.

Strengths and weaknesses in methods for identifying the causative agent(s) of acquired immunodeficiency syndrome (AIDS)

Human immunodeficiency virus (HIV) is a cytoplasmic retrovirus which is transmitted via body fluids, especially through blood products and sexual contact, and is the causative agent of the acquired immunodeficiency syndrome (AIDS). Only about 5 to 10% of the patients infected with HIV contract AIDS; the great majority of infected people either develop a less aggressive condition (AIDS-related complex) or appear healthy. All persons infected with HIV may transmit the virus. In order to protect the national blood supply and to help in diagnosis, tests have been developed to identify infected persons. These include viral isolation techniques, enzyme-linked immunosorbent assay (ELISA), immunofluorescent assay (IFA), radioimmune precipitation (RIP) assay, Western blot, and, most recently, antigen identification and gene probes. Although the sensitivity and specificity among these methods varies, all are susceptible to false-positive and/or false-negative results. In order to understand the reasons for fragility in methodologies, it is necessary to appreciate several basic concepts related to the biochemistry, biology, pathophysiology, and genetic characteristics of HIV and related viruses. The purpose of this review is to present the strengths and weaknesses of each method, with emphasis on peculiar viral characteristics that lead to methodological defects or efficacies.