The effect of early versus delayed challenge after vaccination in controlling SHIV 89.6P infection.

We sought to determine how effectively a CD8+ T cell inducing vaccine controls SHIV-89.6P infection in rhesus macaques at a range of challenge times post-vaccination. To this end, twenty eight Mamu-A*01+ rhesus macaques were given replication incompetent human serotype 5 adenovirus vector expressing SIVmac239 gag DNA and boosted 24 weeks later.

10-Hydroxy-7,8-dihydropyrazino[1',2':1,5]pyrrolo[2,3-d]pyridazine-1,9(2H,6H)-diones: potent, orally bioavailable HIV-1 integrase strand-transfer inhibitors with activity against integrase mutants.

A series of 10-hydroxy-7,8-dihydropyrazino[1',2':1,5]pyrrolo[2,3-d]pyridazine-1,9(2H,6H)-diones was synthesized and tested for their inhibition of HIV-1 replication in cell culture. Structure-activity studies indicated that high antiviral potency against wild-type virus as well as viruses containing integrase mutations that confer resistance to three different structural classes of integrase inhibitors could be achieved by incorporation of small aliphatic groups at certain positions on the core template. An optimal compound from this study, 16, inhibits integrase strand-transfer activity with an IC(50) value of 10 nM, inhibits HIV-1 replication in cell culture with an IC(95) value of 35 nM in the presence of 50% normal human serum, and displays modest pharmacokinetic properties in rats (i.

Design and synthesis of substituted 4-oxo-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazine-2-carboxamides, novel HIV-1 integrase inhibitors.

A series of 4-oxo-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazine-2-carboxamides was synthesized and tested for their inhibition of HIV-1 integrase catalytic activity and HIV-1 replication in cells. Structure-activity studies around lead compound 5 indicated that a coplanar relationship of metal-binding heteroatoms provides optimal binding to the integrase active site. Identification of potency-enhancing substituents and adjustments in lipophilicity provided 17b which inhibits integrase-catalyzed strand transfer with an IC(50) value of 74 nM and inhibits HIV-1 replication in cell culture in the presence of 50% normal human serum with an IC(95) value of 63 nM.

8-Hydroxy-3,4-dihydropyrrolo[1,2-a]pyrazine-1(2H)-one HIV-1 integrase inhibitors.

A series of potent novel 8-hydroxy-3,4-dihydropyrrolo[1,2-a]pyrazine-1(2H)-one HIV-1 integrase inhibitors was identified. These compounds inhibited the strand transfer process of HIV-1 integrase and viral replication in cells. Compound 12 is active against replication of HIV-1 in cell culture with a CIC(95) of 0.

Dihydroxypyridopyrazine-1,6-dione HIV-1 integrase inhibitors.

A series of potent novel dihydroxypyridopyrazine-1,6-dione HIV-1 integrase inhibitors was identified. These compounds inhibited the strand transfer process of HIV-1 integrase and viral replication in cells. Compound 6 is active against replication of HIV with a CIC(95) of 0.

Synthesis of novel HIV protease inhibitors (PI) with activity against PI-resistant virus.

A series of HIV protease inhibitors with modifications on the P3 position have been designed and synthesized. These compounds exhibit excellent antiviral activity against both the wild type enzyme and PI-resistant clinical viral isolates. The synthesis and biological activity of the compounds are described.

Early depletion of proliferating B cells of germinal center in rapidly progressive simian immunodeficiency virus infection.

Lack of virus specific antibody response is commonly observed in both HIV-1-infected humans and SIV-infected monkeys with rapid disease progression. However, the mechanisms underlying this important observation still remain unclear. In a titration study of a SIVmac239 viral stock, three out of six animals with viral inoculation rapidly progressed to AIDS within 5 months.

A series of 5-aminosubstituted 4-fluorobenzyl-8-hydroxy-[1,6]naphthyridine-7-carboxamide HIV-1 integrase inhibitors.

A series of 5-amino derivatives of 8-hydroxy[1,6]-naphthyridine-7-carboxamide exhibiting sub-micromolar potency against replication of HIV-1 in cell culture was identified. One of these analogs, compound 12, displayed excellent pharmacokinetic properties when dosed orally in rats and in monkeys. This compound was demonstrated to be efficacious against replication of simian-human immunodeficiency virus (SHIV) 89.

Cytotoxic T-lymphocyte escape does not always explain the transient control of simian immunodeficiency virus SIVmac239 viremia in adenovirus-boosted and DNA-primed Mamu-A*01-positive rhesus macaques.

Adenovirus 5 (Ad5) vectors show promise as human immunodeficiency virus vaccine candidates. Indian rhesus macaques vaccinated with Ad5-gag controlled simian-human immunodeficiency virus SHIV89.6P viral replication in the absence of Env immunogens that might elicit humoral immunity.

Attenuation of simian immunodeficiency virus SIVmac239 infection by prophylactic immunization with dna and recombinant adenoviral vaccine vectors expressing Gag.

The prophylactic efficacy of DNA and replication-incompetent adenovirus serotype 5 (Ad5) vaccine vectors expressing simian immunodeficiency virus (SIV) Gag was examined in rhesus macaques using an SIVmac239 challenge. Cohorts of either Mamu-A*01(+) or Mamu-A*01(-) macaques were immunized with a DNA prime-Ad5 boost regimen; for comparison, a third cohort consisting of Mamu-A*01(+) monkeys was immunized using the Ad5 vector alone for both prime and boost. All animals, along with unvaccinated control cohorts of Mamu-A*01(+) and Mamu-A*01(-) macaques, were challenged intrarectally with SIVmac239.

Design, synthesis, and biological evaluation of monopyrrolinone-based HIV-1 protease inhibitors possessing augmented P2' side chains.

A series of monopyrrolinone-based HIV-1 protease inhibitors possessing rationally designed P2' side chains have been synthesized and evaluated for activity against wild-type HIV-1 protease. The most potent inhibitor displays subnanomolar potency in vitro for the wild-type HIV-1 protease. Additionally, the monopyrrolinone inhibitors retain potency in cellular assays against clinically significant mutant forms of the virus.

Orally bioavailable highly potent HIV protease inhibitors against PI-resistant virus.

Efforts directed to identifying potent HIV protease inhibitors (PI) have yielded a class of compounds that are not only very active against wild-type (NL4-3) HIV virus but also very potent against a panel of PI-resistant viral isolates. Chemistry and biology are described.

Vectored Gag and Env but not Tat show efficacy against simian-human immunodeficiency virus 89.6P challenge in Mamu-A*01-negative rhesus monkeys.

Simian-human immunodeficiency virus (SHIV) challenge studies in rhesus macaques were conducted to evaluate the efficacy of adenovirus-based vaccines in the context of different major histocompatibility complex class I genetic backgrounds and different vaccine compositions. Mamu-A*01 allele-negative rhesus monkeys were immunized with one of the following vaccine constructs: (i) replication-defective recombinant adenovirus type 5 (Ad5) expressing human immunodeficiency virus type 1 (HIV-1) Tat (Ad5/HIVTat); (ii) Ad5 vector expressing simian immunodeficiency virus (SIV) Gag (Ad5/SIVGag); (iii) Ad5 vector expressing the truncated HIV-1(jrfl) Env, gp140 (Ad5/gp140_jrfl); (iv) Ad5 vector expressing the SHIV-89.6P gp140 (Ad5/gp140_89.

Covalent stabilization of coiled coils of the HIV gp41 N region yields extremely potent and broad inhibitors of viral infection.

Peptides from the N-heptad repeat region of the HIV gp41 protein can inhibit viral fusion, but their potency is limited by a low tendency to form a trimeric coiled-coil. Accordingly, stabilization of N peptides by fusion with the stable coiled-coil IZ yields nanomolar inhibitors [Eckert, D. M.

A series of 5-(5,6)-dihydrouracil substituted 8-hydroxy-[1,6]naphthyridine-7-carboxylic acid 4-fluorobenzylamide inhibitors of HIV-1 integrase and viral replication in cells.

Introduction of a 5,6-dihydrouracil functionality in the 5-position of N-(4-fluorobenzyl)-8-hydroxy-[1,6]naphthyridine-7-carboxamide 1 led to a series of highly active HIV-1 integrase inhibitors. These compounds displayed low nanomolar activity in inhibiting both the strand transfer process of HIV-1 integrase and viral replication in cells. Compound 11 is a 150-fold more potent antiviral agent than 1, with a CIC(95) of 40 nM in the presence of human serum.

Potent 1,3,4-trisubstituted pyrrolidine CCR5 receptor antagonists: effects of fused heterocycles on antiviral activity and pharmacokinetic properties.

A series of 1,3,4-trisubstituted pyrrolidine CCR5 receptor antagonists containing a variety of fused heterocycles at the 4-position of the piperidine side chain has been discovered, which are orally bioavailable with potent anti-HIV activity.

Synthesis and evaluation of CCR5 antagonists containing modified 4-piperidinyl-2-phenyl-1-(phenylsulfonylamino)-butane.

Synthesis of analogs containing more rigid bicyclic piperidine replacements for the 4-benzyloxycarbonyl-(ethyl)amino-piperidine moiety of the CCR5 antagonist structure, 1, is described. Although similar binding affinity to the lead was achieved with some analogs they were overall less potent anti-HIV agents suggesting that other features besides CCR5 binding are required for good anti-viral activity.

Synthesis and biological evaluation of 5R- and 5S-methyl substituted D- and L-configuration 1,3-dioxolane nucleoside analogs.

1,3-Dioxolane and 1,3-oxathiolane nucleoside analogs play an important role in anti-viral and anti-neoplastic chemotherapy. We report here the synthesis of 2-hydroxymethyl-5-methyl-1,3-dioxolanylpurine nucleosides from 4-acetoxy-2-(benzyloxymethyl)-5-methyldioxolane. Dioxolanes of alpha-D-, beta-D-, alpha-L-, and beta-L-configuration were prepared, that included 5-methyl derivatives of both 5R and 5S configuration.

P1' oxadiazole protease inhibitors with excellent activity against native and protease inhibitor-resistant HIV-1.

HIV-1 protease inhibitors (PI's) bearing 1,3,4-oxadiazoles at the P1' position were prepared by a novel method involving the diastereoselective installation of a carboxylic acid and conversion to the P1' heterocycle. The compounds are picomolar inhibitors of native HIV-1 protease, with most of the compounds maintaining excellent antiviral activity against a panel of PI-resistant strains.

A naphthyridine carboxamide provides evidence for discordant resistance between mechanistically identical inhibitors of HIV-1 integrase.

The increasing incidence of resistance to current HIV-1 therapy underscores the need to develop antiretroviral agents with new mechanisms of action. Integrase, one of three viral enzymes essential for HIV-1 replication, presents an important yet unexploited opportunity for drug development. We describe here the identification and characterization of L-870,810, a small-molecule inhibitor of HIV-1 integrase with potent antiviral activity in cell culture and good pharmacokinetic properties.

Integrase inhibitors and cellular immunity suppress retroviral replication in rhesus macaques.

We describe the efficacy of L-870812, an inhibitor of HIV-1 and SIV integrase, in rhesus macaques infected with the simian-human immunodeficiency virus (SHIV) 89.6P. When initiated before CD4 cell depletion, L-870812 therapy mediated a sustained suppression of viremia, preserving CD4 levels and permitting the induction of virus-specific cellular immunity.

Syntheses and biological evaluation of 5-(piperidin-1-yl)-3-phenyl-pentylsulfones as CCR5 antagonists.

Cellular proliferation of HIV-1 requires the cooperative assistance of both the CCR5 and CD4 receptors. Our medicinal chemistry efforts in this area have resulted in the identification of N-alkyl piperidine sulfones as CCR5 antagonists. These compounds display potent binding and show antiviral properties in HIV-1 spread cell-based assays.

Syntheses and SAR studies of 4-(heteroarylpiperdin-1-yl-methyl)-pyrrolidin-1-yl-acetic acid antagonists of the human CCR5 chemokine receptor.

Efforts toward the exploration of the title compounds as CCR5 antagonists are disclosed. The basis for such work stems from the fact that cellular proliferation of HIV-1 requires the cooperative assistance of both CCR5 and CD4 receptors. The synthesis and SAR of pyrrolidineacetic acid derivatives as CCR5 antagonists displaying potent binding and antiviral properties in a HeLa cell-based HIV-1 infectivity assay are discussed.

Antagonists of human CCR5 receptor containing 4-(pyrazolyl)piperidine side chains. Part 3: SAR studies on the benzylpyrazole segment.

Extensive SAR studies in our benzylpyrazole series of CCR5 antagonists have shown that both lipophilic and hydrophilic substituents on the phenyl of the benzyl group increase antiviral potency. However, improvements in pharmacokinetic profiles were generally only observed with more lipophilic substitutions. 4-Biphenyl (51) performed the best in this regard.