Identification and characterization of UK-201844, a novel inhibitor that interferes with human immunodeficiency virus type 1 gp160 processing.

More than 10(6) compounds were evaluated in a human immunodeficiency virus type 1 (HIV-1) high-throughput antiviral screen, resulting in the identification of a novel HIV-1 inhibitor (UK-201844). UK-201844 exhibited antiviral activity against HIV-1 NL4-3 in MT-2 and PM1 cells, with 50% effective concentrations of 1.3 and 2.7 microM, respectively, but did not exhibit measurable antiviral activity against the closely related HIV-1 IIIB laboratory strain. UK-201844 specifically inhibited the production of infectious virions packaged with an HIV-1 envelope (Env), but not HIV virions packaged with a heterologous Env (i.e., the vesicular stomatitis virus glycoprotein), suggesting that the compound targets HIV-1 Env late in infection. Subsequent antiviral assays using HIV-1 NL4-3/IIIB chimeric viruses showed that HIV-1 Env sequences were critical determinants of UK-201844 susceptibility. Consistent with this, in vitro resistant-virus studies revealed that amino acid substitutions in HIV-1 Env are sufficient to confer resistance to UK-201844. Western analysis of HIV Env proteins expressed in transfected cells or in isolated virions showed that UK-201844 inhibited HIV-1 gp160 processing, resulting in the production of virions with nonfunctional Env glycoproteins. Our results demonstrate that UK-201844 represents the prototype for a unique HIV-1 inhibitor class that directly or indirectly interferes with HIV-1 gp160 processing.

Substituted acrylophenones and related mannich bases as possible spermicides and inhibitors of HIV envelope glycoprotein-CD4 interaction.

Several appropriately substituted 4-(dialkylamino-alkyl)-substituted-styryl-alkyl ketones or acetophenones were prepared and subjected to the Mannich reaction to yield compounds that would incorporate both alpha,beta-unsaturated keto groups and a substituted aminomethyl function with or without another olefinic moiety at position 4. The spermicidal activity of the prepared compounds was evaluated. Several compounds 2d, 4a and 4e were found to possess spermicidal activity at 0.005% concentration, while compounds 2a, 2c, 2f, 3a and 4b were active at 0.01% concentration. Compounds 2a, 2c, 3a, 4a and 4e also inhibited the interaction between recombinant HIV Env and CD4. Out of these, compound 2c was found to be most active.

An anti-HIV peptide construct derived from the cleavage region of the Env precursor acts on Env fusogenicity through the presence of a functional cleavage sequence.

A 22-amino-acid-long multibranched peptide construct (CLV) derived from the cleavage region (KIEPLGVAPTKAKRR*VVQREKR*) of the human immunodeficiency virus (HIV) type-1 envelope precursor inhibits HIV infection (Virology, 1996, 223, 406-408). We attempted to characterize its activity for Env expressed via a recombinant vaccinia virus (rVV): gp 160 cleavage was delayed, but not impaired, in the presence of CLV (10 microM), whereas neither Env production nor Env membrane expression was significantly altered. Through the synthesis of analogs, we concluded that the presence of a cleavage sequence was required for inhibition of syncytium formation by CLV in rVV-infected CD(4+) cell cultures: indeed, a single amino acid residue substitution (R* > S) in the cleavage sites presented by CLV abolished its activity. Other analogs allowed us to further determine the region of CLV which mediates its activity. The ability of a radiolabeled CLV analog to enter cells was also shown. Although, these data strongly suggest that CLV acts on Env fusogenicity at least partially through interference with gp160 processing.

Characterization of siamycin I, a human immunodeficiency virus fusion inhibitor.

The human immunodeficiency virus (HIV) fusion inhibitor siamycin I, a 21-residue tricyclic peptide, was identified from a Streptomyces culture by using a cell fusion assay involving cocultivation of HeLa-CD4+ cells and monkey kidney (BSC-1) cells expressing the HIV envelope gp160. Siamycin I is effective against acute HIV type 1 (HIV-1) and HIV-2 infections, with 50% effective doses ranging from 0.05 to 5.7 microM, and the concentration resulting in a 50% decrease in cell viability in the absence of viral infection is 150 microM in CEM-SS cells. Siamycin I inhibits fusion between C8166 cells and CEM-SS cells chronically infected with HIV (50% effective dose of 0.08 microM) but has no effect on Sendai virus-induced fusion or murine myoblast fusion. Siamycin I does not inhibit gp120 binding to CD4 in either gp120- or CD4-based capture enzyme-linked immunosorbent assays. Inhibition of HIV-induced fusion by this compound is reversible, suggesting that siamycin I binds noncovalently. An HIV-1 resistant variant was selected by in vitro passage of virus in the presence of increasing concentrations of siamycin I. Drug susceptibility studies on a chimeric virus containing the envelope gene from the siamycin I-resistant variant indicate that resistance maps to the gp160 gene. Envelope-deficient HIV complemented with gp160 from siamycin I-resistant HIV also displayed a resistant phenotype upon infection of HeLa-CD4-LTR-beta-gal cells. A comparison of the DNA sequences of the envelope genes from the resistant and parent viruses revealed a total of six amino acid changes. Together these results indicate that siamycin I interacts with the HIV envelope protein.