Objective:To compare heat denaturation and acidification as immune complex dissociation (ICD) methods in adult HIV-1 infection and to increase the sensitivity by a signal-amplification-boosted HIV-1 p24 antigen enzyme-linked immunosorbent assay (ELISA).
Design:Prospective and retrospective blinded study of paired serum and plasma samples from 245 patients (112 of class A, 66 of B, 67 of C of the Centers for Disease Control and Prevention 1993 classification).
Methods:Plasma and sera were prospectively tested for antigen by ELISA using native, acidified, or heat-denatured material. Retrospective tests included batch analysis of heat-denatured samples for antigen by the signal-amplification-boosted ELISA and for viral RNA.
Results:With serum, native antigen was reactive in 26.5%. Acidification increased the rate to 53.1% (P ≤ 0.0001), but was inefficient at a CD4 + count ≥ 500 × 106/l. Heat denaturation further elevated the rate to 67.8% (P ≤ 0.0007) and the use of plasma to 78.0% (P ≤ 0.008). The boosted ELISA, performed with plasma samples diluted 1:6, which eliminated the problem of heat-induced sample coagulation, was confirmed positive in 89.5% of serum and 97.8% of plasma samples. RNA was detected in 95.7%.
Conclusion:Heat-mediated ICD combined with a signal-amplification-boosted ELISA detects HIV-1 expression as sensitively as a polymerase chain reaction kit for viral RNA, but at only a fraction of the cost. The procedure uses a 50 μl plasma sample and should be fully automatable.
From the Swiss National Centre for Retroviruses, University of Zurich and the *Division of Infectious Diseases, Department of Medicine, Zurich University Hospital, Zurich, Switzerland.
Sponsorship: Supported by the Swiss Federal Office of Public Health and Swiss National Science Foundation. Antigen test kits for the prospective part of this study were provided free of charge by Du Pont de Nemours GmbH, Bad Homburg, Germany.
Requests for reprints to: Dr Jörg Schüpbach, Swiss National Centre for Retroviruses, University of Zürich, Gloriastrasse 30, CH-8028 Zürich, Switzerland.
Date of receipt: 31 January 1996; revised: 24 April 1996; accepted: 6 June 1996.
© Lippincott-Raven Publishers.