A set of mutations [Ala-62 -> Val(A62V), V75I, F77L, F116Y, and Q151M] in the polymerase domain of reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) confers on the virus a reduced sensitivity to multiple antiretroviral dideoxynucleosides and has been seen in HIV-1 variants isolated from patients receiving combination chemotherapy with 3'-azido-3'-deoxythymidine (AZT) plus 2',3'-dideoxycytidine (ddC) or 2',3'-dideoxyinosine (ddl). The IC50 values of AZT, ddC, ddI, 2',3'-dideoxyguanosine, and 2',3'-didehydro-3'-deoxythymidine against an infectious clone constructed to include the five mutations were significantly higher than those of a wild-type infectious clone. The Ki value for AZT 5'-triphosphate determined for the virus-associated RT from a posttherapy strain was 35-fold higher than that of RT from a pretherapy strain. Detailed analysis of HIV-1 strains isolated at various times during therapy showed that the Q151M mutation developed first in vivo, at the time when the viremia level suddenly increased, followed by the F116Y and F77L mutations. All five mutations ultimately developed, and the viremia level rose even further. Analyses based on the three-dimensional structure of HIV-1 RT suggest that the positions where at least several of the five mutations occur are located in close proximity to the proposed dNTP-binding site of RT and the first nucleotide position of the single-stranded template.

From an extract of a Streptomyces culture, we identified and purified a novel compound, NP-06, which is active against human immunodeficiency virus (HIV) in vitro. Analyses indicate that NP-06 is a hydrophobic 21-mer oligopeptide, N terminally cyclized through the side chain of Asp-9, containing two intramolecular cystine linkages with a molecular weight of 2,163.4. The 50% inhibitory concentrations were 2.8 and 1.3 M when NP-06 was tested for in vitro anti-HIV-1 activity in ATH8 cells and phytohemagglutinin-activated peripheral blood mononuclear cells, respectively. NP-06 appears to block the early stage of HIV-1 infection, most likely at the stage of virus-cell fusion.We prepared ϳ9,000 different extracts from solitary colonies obtained by incubation of bacterial samples from various sources, including soil specimens collected in Japan. The methanol extract from each bacterial colony was tested for antihuman immunodeficiency virus type 1 (HIV-1) activity by using a colorimetric assay employing a tetrazolium salt (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide [MTT]) and MT4 cells (9). A crude extract of strain SKH-2344 (FERMP-14239), a Streptomyces species strain isolated from soil collected in Yamaguchi, was found to be active against HIV-1 (data not shown). The strain was then grown in culture medium and subjected to fermentation. On day 5 of fermentation, 20 liters of culture broth medium was centrifuged, and the supernatant was concentrated in vacuo to yield a paste, which was resuspended in 1 liter of methanol for 12 h. The methanol extract was then filtered and concentrated to yield a pale yellow oily specimen (fraction A). The pellet (the mycelium) was homogenized in 10 liters of methanol with agitation for 12 h, and the filtered solution was concentrated in vacuo to yield a yellow oily specimen (fraction B). Fractions A and B were combined, dissolved in water-saturated butanol, and concentrated in vacuo. The extract was column chromatographed on silica gel with ethyl acetate-methanol-water (10:5:0.25) and purified (Ͼ99%) by high-performance liquid chromatography with CH 3 CN-H 2 O-CF 3 COOH (38:62:0.1) to yield a white powder (100 mg), designated NP-06.Amino acid analysis of the NP-06 hydrolysate revealed the presence of one residue each of Ser, Ile, Leu, and Tyr; two residues each of Phe, Ala, Val, and Asp; and four residues each of Cys and Gly, although whether the two Asp residues represented Asn was to be confirmed. Thin-layer chromatography analysis of the hydrazine hydrolysate of NP-06 revealed that the C terminus was Trp. NP-06 could not be sequenced by the Edman degradation method, although the physical properties of NP-06 showed that it was a peptide. Therefore, nuclear magnetic resonance (NMR) spectroscopy was used to determine the amino acid sequence of NP-06. Inspection of the relayed signals arising from the amide resonances in a homonuclear Hartmann-Hahn spectroscopy experiment revealed the presence of 21-amino-acid spin systems. One Leu, one Ile, one Ser, two Val, two Ala,...

We determined the anti-human immunodeficiency virus type 1 (anti-HIV-1) activities of various dideoxynucleoside analogs by using phytohemagglutinin-activated peripheral blood mononuclear cells (PHA-PBMs) and resting PBMs (R-PBMs) as target cells. The comparative order of anti-HIV-1 activity in PHA-PBMs was azidothymidine (AZT) > dideoxycytidine (ddC) > dideoxythymidinene (d4T) > dideoxyinosine (ddI) and 9-(2-phosphonylmethoxyethyl)adenine (PMEA) > 2-␤-fluoro-dideoxyadenosine (F-ara-ddA), while that in R-PBMs was ddC > ddI, PMEA, and F-ara-ddA, >> AZT and d4T. A pronucleotide, bis-(S-acetylthioethanol)phosphotriester-ddAMP, which bypasses the anabolic monophosphorylation step for the intracellular delivery of ddAMP, was highly active both in PHA-PBMs and R-PBMs. These data may have basic and clinical relevance in the design of anti-HIV chemotherapy, particularly combination chemotherapy with dideoxynucleosides, and in the development of active pronucleotides.