Therapy efficacy can be monitored by a sensitive and precise yet inexpensive HIV p24 antigen assay

Measurement of plasma RNA has become widely used for the management of HIV infected patients. The high costs have limited its use to 2-3 times per year or after the onset of clinical symptoms. Although the aggressive combined therapy has induced a sustained reduction of the HIV viremia to undetectable levels, an increasing high percentage of patients are experiencing treatment failure. Since a surprisingly high number of antiretroviral drugs are available and more will be soon, the monitoring of treated patients should be done more frequently. We suggest that the new “3Plus” format of the p24 antigen assay, which is comparable to viral RNA with respect to sensitivity and specificity, should be used to frequent monitoring antiretroviral treatment. During the past few years significant progress has been made: 1) interferen-ce by antibodies has been eliminated by boiling diluted samples for 5 minutes; 2) the sensitivity has reached the ~70 fg/reaction with the use of a signal amplification (ELAST) step; and 3) the kinetic reading of the colorimetric signal, assisted by the Quanti-Kin software, guarantees a dynamic range of 102-107 fg/ml. Recently the American Medical Association and the International AIDS Society (15:9, 2000) have positively reviewed and published these studies from Schüpbach and our group. The antiretroviral treatment monitoring of 23 adult patients and in 25 children in Switzerland and 110 patients in Italy provided convincing evidences that this simple, inexpensive and easily automatable p24 procedure is a suitable tool for patients management. We believe that further studies are warranted and we invite others to join us in this task.