HIV-1 reverse transcriptase inhibiting antibody titer in serum: relation to disease progression and to core-antibody...

A new assay for detecting inhibition of reverse transcriptase activity (the RT-i REA) was developed. This assay was standardized for screening serum samples for reverse transcriptase inhibiting antibodies (RT-iAb). High specificity (100%) and sensitivity (greater than 98%) were achieved with samples from HIV-negative individuals and HIV-infected individuals. The RT-i REA was also used in a study of the titers of RT-iAb in serum samples obtained from 33 HIV-infected homosexual men. The results confirmed the relation between decreasing RT-iAb levels and progression to late stages of the disease. Furthermore, a falling RT-iAb titer was observed in 14 of 15 individuals experiencing periods of severe clinical symptoms attributed to HIV-activity. In 7 of the patients the decline in RT-iAb titer began prior to severe clinical symptoms. The fall in RT-iAb titer also correlated with a reduction in core Ab level. The core Ab level has previously been reported to be a disease progression marker with considerable prognostic value. However, whereas all patients were positive for RT-iAb, 8 of the 33 patients did not have detectable core Ab. The use of RT-iAb titer as a marker of disease progression is discussed.