Comparison of non-radioactive DNA hybridization probes to detect human immunodeficiency virus nucleic acid

Simple and sensitive methods to directly detect the human immunodeficiency virus (HIV) are needed for routine use in the clinical laboratory. In this study, we compared DNA probes prepared by: (1) nick translation with biotinylated dATP; (2) direct covalent biotinylation with photobiotin; (3) direct covalent reaction with 2-acetylaminofluorene (AAF); and (4) a standard radioactive (32P) nick translation procedure. These four DNA probes were hybridized with dilutions of purified target HIV DNA blotted onto nitrocellulose strips. Hybridization was detected using a complex of strepavidin-alkaline phosphatase [for (1) and (2)], alkaline phosphatase-tagged antibodies [for (3)] and by autoradiography [for (4)]. Alkaline phosphatase was detected colorimetrically using nitroblue tetrazolium and 5-bromo-4-chloro-3-indolyl phosphate. After 1 h, AAF probes were most sensitive (amount detected less than 5 pg), followed by biotin (10 pg), photobiotinylated probes (20 pg) and the radioactive probe (10 pg). The AAF probes were then used to detect HIV DNA in infected CEM cells. We conclude that non-radioactive DNA labelling methods can be used to directly detect HIV DNA under conditions compatible with present clinical laboratory procedures.