Comparison of eight commercial test kits for detecting anti-HIV antibodies in saliva specimens

For the evaluation of several commercial anti-HIV-antibody test kits for saliva screening saliva was collected from 100 HIV-seropositive and 100 HIV-seronegative clients of the Thai Red Cross Anonymous Clinic in Bangkok Thailand by having clients spit into clean containers. The saliva specimens were coded randomly and frozen in aliquots for simultaneous testing for anti-HIV antibodies using 3 enzyme-linked immunosorbent assay (ELISA)-based and 5 rapid/simple commercial anti-HIV test kits. Cut-off optical densities (OD) for ELISA-based tests were set at means plus 2 s.d. of the 100 HIV-seronegative saliva samples. The results of the rapid/simple tests were read in the same way as blood or serum testing. Of the 3 ELISA-based tests Genelavia HIV-1/HIV-2 and Abbott-HIV-1/HIV-2 EIA were 100% as sensitive as serum testing; the Abbott test was 99% specific compared to the 96% specificity of the Genelavia test. The sensitivity of the DB-ELISA HIV-1 test was only 89% and its specificity was 94%. The GPA HIV-1 gave nonspecific agglutination even when seronegative saliva was diluted 1:64 whereas SimpliRed HIV-1 and HIV-SPOT HIV-1/HIV-2 gave negative reactions with saliva from all seropositive individuals. However the Abbott Testpack HIV-1/HIV-2 rapid test and Recombigen HIV-1/HIV-2 RTD were 100% sensitive and specific. For the same dilutions of HIV-positive paired serum and saliva the OD readings of the saliva were always about half those of the serum. Thus the results reported depend upon the dilutions of saliva used in the assay. For DB ELISA HIV-1 and Genelavia HIV- 1/HIV-2 the dilutions were 1:P2. For Abbott HIV-1/HIV-2 EIA the saliva was diluted to 3:1; other dilutions of saliva were not tested. The discrepancy in the performance of the rapid/simple tests may be occasioned by nonspecific agglutination by substances in saliva caused by the test device itself. These preliminary results indicate that saliva can be reliably used for HIV screening.