AEGiS-14IAC: HIV-1 p24 antigen, an inexpensive alternative viral load marker, is an independent correlate of CD4 T-cell changes in patients on successful long-term antiretroviral therapy.

14th International AIDS Conference

Barcelona, Spain - July 7-12, 2002

HIV-1 p24 antigen, an inexpensive alternative viral load marker, is an independent correlate of CD4 T-cell changes in patients on successful long-term antiretroviral therapy.

Int Conf AIDS 2002 Jul 7-12; 14:(abstract no. WeOrB1340)

Schupbach J, ni J, Tomasik Z, Bisset L, Fischer M, nthard H, Ledergerber B, Opravil M
Swiss National Center for Retroviruses, Zurich, Switzerland

BACKGROUND: Quantification of HIV-1 RNA by RT-PCR is widely used for evaluating antiretroviral therapies, but not affordable in resource-poor settings. We here assess a possible inexpensive alternative, a modified p24 antigen test, in patients receiving successful long-term antiretroviral therapy.

METHODS: HIV-1 RNA and p24, as tested by an experimental procedure involving signal-amplification-boosted ELISA of heat-denatured plasma, were prospectively measured in 329 samples from 55 patients whose HIV-1 RNA had been reduced to below 50 copies/ml and who continued to receive therapy. HIV-1 RNA in PBMC was determined retrospectively. Uni- and multivariate linear regression analysis was used to correlate CD4 counts and their changes over time with the counts or changes of other lymphocyte subsets, HIV-1 RNA, and p24.

RESULTS: During a median follow-up of 504 days, CD4 counts increased by a median of 62 cells/year. Concentrations of lymphocytes and their subsets strongly influenced the CD4 count. P24 was a significant, and among viral markers dominating, independent inverse correlate of both the CD4 count in a sample (P = .013) and its annual change in a patient (P < .0001). P24 retained similar significance even among 48 individuals whose viral RNA in plasma, apart from some transient blips, always remained below 400 copies/ml. Importantly, p24 decreased steadily in most patients (P < 0001) while a significant decrease of HIV-1 RNA in plasma or PBMC was not observed.

CONCLUSIONS: P24 antigen is a significant independent inverse correlate of the CD4 change observed in successfully treated patients. The residual virus production or occasional viral blips observed under therapy are clearly insufficient for maintaining the levels of p24 over time. P24 thus provides additional, clinically relevant information not provided by HIV-1 RNA tests alone.

Keywords: AEGIS, CD4-Positive T-Lymphocytes, CD4 Lymphocyte Count, RNA, Viral, Biological Markers, Enzyme-Linked Immunosorbent Assay, Drug Therapy, Combination, Antigens, CD4, Human, therapy, immunology, drug therapy

020707
WeOrB1340