Despite a high current standard of care in antiretroviral therapy for HIV, multidrug-resistant strains continue to emerge, underscoring the need for additional novel mechanism inhibitors that will offer expanded therapeutic options in the clinic. We report a new class of small molecule antiretroviral compounds that directly target HIV-1 capsid (CA) via a novel mechanism of action. The compounds exhibit potent antiviral activity against HIV-1 laboratory strains, clinical isolates, and HIV-2, and inhibit both early and late events in the viral replication cycle. We present mechanistic studies indicating that these early and late activities result from the compound affecting viral uncoating and assembly, respectively. We show that amino acid substitutions in the N-terminal domain of HIV-1 CA are sufficient to confer resistance to this class of compounds, identifying CA as the target in infected cells. A high-resolution co-crystal structure of the compound bound to HIV-1 CA reveals a novel binding pocket in the N-terminal domain of the protein. Our data demonstrate that broad-spectrum antiviral activity can be achieved by targeting this new binding site and reveal HIV CA as a tractable drug target for HIV therapy.

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IntroductionA major pathophysiologic mechanism in sepsis is impaired host immunity which results in failure to eradicate invading pathogens and increased susceptibility to secondary infections. Although many immunosuppressive mechanisms exist, increased expression of the inhibitory receptor programmed cell death 1 (PD-1) and its ligand (PD-L1) are thought to play key roles. The newly recognized phenomenon of T cell exhaustion is mediated in part by PD-1 effects on T cells. This study tested the ability of anti-PD-1 and anti-PD-L1 antibodies to prevent apoptosis and improve lymphocyte function in septic patients.MethodsBlood was obtained from 43 septic and 15 non-septic critically-ill patients. Effects of anti-PD-1, anti-PD-L1, or isotype-control antibody on lymphocyte apoptosis and interferon gamma (IFN-γ) and interleukin-2 (IL-2) production were quantitated by flow cytometry.ResultsLymphocytes from septic patients produced decreased IFN-γ and IL-2 and had increased CD8 T cell expression of PD-1 and decreased PD-L1 expression compared to non-septic patients (P<0.05). Monocytes from septic patients had increased PD-L1 and decreased HLA-DR expression compared to non-septic patients (P<0.01). CD8 T cell expression of PD-1 increased over time in ICU as PD-L1, IFN-γ, and IL2 decreased. In addition, donors with the highest CD8 PD-1 expression together with the lowest CD8 PD-L1 expression also had lower levels of HLA-DR expression in monocytes, and an increased rate of secondary infections, suggestive of a more immune exhausted phenotype. Treatment of cells from septic patients with anti-PD-1 or anti-PD-L1 antibody decreased apoptosis and increased IFN-γ and IL-2 production in septic patients; (P<0.01). The percentage of CD4 T cells that were PD-1 positive correlated with the degree of cellular apoptosis (P<0.01).ConclusionsIn vitro blockade of the PD-1:PD-L1 pathway decreases apoptosis and improves immune cell function in septic patients. The current results together with multiple positive studies of anti-PD-1 and anti-PD-L1 in animal models of bacterial and fungal infections and the relative safety profile of anti-PD-1/anti-PD-L1 in human oncology trials to date strongly support the initiation of clinical trials testing these antibodies in sepsis, a disorder with a high mortality.

Indole derivative 1 interferes with the interaction of the HIV surface protein gp120 with the host cell receptor CD4. The 4-fluoro derivative 2 exhibited markedly enhanced potency and was bioavailable in the rat, dog, and cynomolgus monkey when administered orally as a solution formulation. However, aqueous suspensions of 2 were poorly bioavailable, indicative of dissolution-limited absorption. The 7-azaindole derivative 3, BMS-378806, exhibited improved pharmaceutical properties while retaining the HIV-1 inhibitory profile of 2.

The potent C-terminal activation domain of the RelA(p65) subunit of the cellular transcription factor NF-KB is shown to contain several discrete acidic activation modules. These short, -11-amino-acid modules were able to give rise to only a low level of transcription activation when fused to the GAL4 DNA-binding domain as monomers. However, dimers and higher-order multimers activated the transcription of minimal promoter elements as effectively as the full-length RelA or VP16 activation domain. Therefore, this 11-aminoacid ReIA-derived acidic module appears to contain all of the sequence information required to fully activate a target promoter element as long as it is presented in a form that permits functional synergy. Critical primary sequence requirements for acidic activation module function included a core phenylalanine residue and flanking bulky hydrophobic residues. Overall negative charge was necessary but not sufficient for function. While dimeric forms of the 11-amino-acid acidic activation module bound to either TFIIB or TATA-binding protein efficiently in vitro, a similarly charged peptide lacking the core phenylalanine residue failed to interact.Overall, these data demonstrate that the biological activity of the RelA activation domain is dependent on acidic activator sequences that are closely comparable to those detected in the activation domain of the viral VP16 regulatory protein. We hypothesize that the ability of these acidic activators to specifically interact with multiple components of the transcription initiation complex likely underlies the dramatic functional synergy exhibited by this class of activation domains in vivo.