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Updated: Aug 8, 2026
Conformational Evaluation of HIV-1 Trimeric Envelope Glycoproteins Using a Cell-based ELISA Assay
Published on: September 14, 2014
Combination assay detecting both human immunodeficiency virus (HIV) p24 antigen and anti-HIV antibodies opens a
David Speers1, Peter Phillips, John Dyer
1Division of Clinical Microbiology and Infectious Diseases, The Western Australian Centre for Pathology and Medical Research (PathCentre), Hospital Avenue, Nedlands, Western Australia 6009, Australia. david.speers@health.wa.gov.au
Insights
Fourth-generation human immunodeficiency virus (HIV) tests detect both HIV antibodies and p24 antigen. A rare decline in p24 antigen created a second diagnostic window, impacting HIV detection timelines.
Area of Science:
- Virology
- Immunology
- Diagnostic Assay Development
Background:
- Fourth-generation immunoassays for human immunodeficiency virus (HIV) screening integrate HIV antibody and p24 antigen detection.
- This dual-antigen and antibody approach aims to shorten the window period between HIV infection and laboratory diagnosis.
Observation:
- A case of HIV seroconversion revealed a secondary diagnostic window with a fourth-generation assay.
- This occurred due to a transient decline in detectable HIV p24 antigen levels before HIV antibodies became apparent.
Findings:
- A dedicated HIV p24 antigen test successfully detected the antigen during this secondary window.
- HIV proviral DNA was also concurrently detected, confirming active viral presence.
- This phenomenon, though potentially rare, has been documented with other fourth-generation HIV assays.
Implications:
- The findings challenge the established diagnostic window periods for some fourth-generation HIV immunoassays.
- Healthcare providers should be aware of this potential for delayed diagnosis.
- Further research is needed to understand the frequency and clinical significance of this p24 antigen decline.
Abstract:
Fourth-generation human immunodeficiency virus (HIV) screening immunoassays reduce the diagnostic window between infection and diagnosis by the inclusion of HIV p24 antigen detection together with HIV antibody detection in the same test. We compared third- and fourth-generation HIV immunoassays and a dedicated HIV p24 antigen test for detection of a case of HIV seroconversion. This demonstrated a second diagnostic window using the fourth-generation assay due to a decline of HIV p24 antigen prior to the detection of HIV antibody. However, HIV p24 antigen was detected in the same sample by the dedicated HIV p24 antigen test, as was HIV proviral DNA. Although it is likely to be rare, this phenomenon has also been reported for other fourth-generation HIV immunoassays and has implications for the reported diagnostic windows of these assays.
