HIV-1 Promoter Activity Research Articles

Functional Analysis of KAP1/TRIM28 Requirements for HIV-1 Transcription Activation.

HIV-1 latency maintenance and reactivation are regulated by several viral and host factors. One such factor is Krüppel-associated box (KRAB)-associated protein 1 (KAP1: also named TRIM28 or TIF1β). While initial studies have revealed KAP1 to be a positive regulator of latency reversal in transformed and primary CD4+ T cells, subsequent studies have proposed KAP1 to be a repressor required for latency maintenance. Given this discrepancy, in this study, we re-examine KAP1 transcription regulatory functions using a chemical genetics strategy to acutely deplete KAP1 expression to avoid the accumulation of indirect effects. Notably, KAP1 acute loss partially decreased HIV-1 promoter activity in response to activating signals, a function that can be restored upon complementation with exogenous KAP1, thus revealing that KAP1-mediated activation is on target. By combining comprehensive KAP1 domain deletion and mutagenesis in a cell-based reporter assay, we genetically defined the RING finger domain and an Intrinsically Disordered Region as key activating features. Together, our study solidifies the notion that KAP1 activates HIV-1 transcription by exploiting its multi-domain protein arrangement via previously unknown domains and functions.

HIV-2 inhibits HIV-1 gene expression via two independent mechanisms during cellular co-infection.

Twenty-five years after the first report that HIV-2 infection can reduce HIV-1-associated pathogenesis in dual-infected patients, the mechanisms are still not well understood. We explored these mechanisms in cell culture and showed first that these viruses can co-infect individual cells. Under specific conditions, HIV-2 inhibits HIV-1 through two distinct mechanisms, a broad-spectrum interferon response and an HIV-1-specific inhibition conferred by the HIV-2 TAR. The former could play a prominent role in dually infected individuals, whereas the latter targets HIV-1 promoter activity through competition for HIV-1 Tat binding when the same target cell is dually infected. That mechanism suppresses HIV-1 transcription by stalling RNA polymerase II complexes at the promoter through a minimal inhibitory region within the HIV-2 TAR. This work delineates the sequence of appearance and the modus operandi of each mechanism.

Sulforaphane prevents the reactivation of HIV-1 by suppressing NFκB signaling

Despite more than 20 years of combination antiretroviral therapy (cART), complete eradication of HIV remains a daunting task. While cART has been very effective in limiting new cycles of infection and keeping viral load below detectable levels with partial restoration of immune functions, it cannot provide a cure. Evidently, the interruption of cART leads to a quick rebound of the viral load within a few weeks. These consistent observations have revealed HIV ability to persist as an undetectable latent reservoir in a variety of tissues that remain insensitive to antiretroviral therapies. The ‘Block-and-Lock’ approach to drive latent cells into deep latency has emerged as a viable strategy to achieve a functional cure. It entails the development of latency-promoting agents with anti-HIV functions. Recent reports have suggested sulforaphane (SFN), an inducer of NRF-2 (nuclear erythroid 2-related factor 2)-mediated antioxidative signaling, to possess anti-HIV properties by restricting HIV replication at the early stages. However, the effect of SFN on the expression of integrated provirus remains unexplored. We have hypothesized that SFN may promote latency and prevent reactivation. Our results indicate that SFN can render latently infected monocytes and CD4+ T cells resistant to reactivation. SFN treatments antagonized the effects of known latency reactivating agents, tumor necrosis pactor (TNF-α), and phorbol 12-myristate 13-acetate (PMA), and caused a significant reduction in HIV transcription, viral RNA copies, and p24 levels. Furthermore, this block of reactivation was found to be mediated by SFN-induced NRF-2 signaling that specifically decreased the activation of NFκB signaling and thus restricted the HIV-1 promoter (5′LTR) activity. Overall, our study provides compelling evidence to highlight the latency-promoting potential of SFN which could be used in the ‘Block-and-Lock’ approach to achieve an HIV cure.

Integration site-dependent HIV-1 promoter activity shapes host chromatin conformation.

HIV-1 integration introduces ectopic transcription factor binding sites into host chromatin. We postulate that the integrated provirus serves as an ectopic enhancer that recruits additional transcription factors to the integration locus, increases chromatin accessibility, changes 3D chromatin interactions, and enhances both retroviral and host gene expression. We used four well-characterized HIV-1-infected cell line clones having unique integration sites and low to high levels of HIV-1 expression. Using single-cell DOGMA-seq, which captured the heterogeneity of HIV-1 expression and host chromatin accessibility, we found that HIV-1 transcription correlated with HIV-1 accessibility and host chromatin accessibility. HIV-1 integration increased local host chromatin accessibility within an ∼5- to 30-kb distance. CRISPRa- and CRISPRi-mediated HIV-1 promoter activation and inhibition confirmed integration site-dependent HIV-1-driven changes of host chromatin accessibility. HIV-1 did not drive chromatin confirmation changes at the genomic level (by Hi-C) or the enhancer connectome (by H3K27ac HiChIP). Using 4C-seq to interrogate HIV-1-chromatin interactions, we found that HIV-1 interacted with host chromatin ∼100-300 kb from the integration site. By identifying chromatin regions having both increased transcription factor activity (by ATAC-seq) and HIV-1-chromatin interaction (by 4C-seq), we identified enrichment of ETS, RUNT, and ZNF-family transcription factor binding that may mediate HIV-1-host chromatin interactions. Our study has found that HIV-1 promoter activity increases host chromatin accessibility, and HIV-1 interacted with host chromatin within the existing chromatin boundaries in an integration site-dependent manner.

Transcriptome analysis of CD4+ T cells from HIV-infected individuals receiving ART with LLV revealed novel transcription factors regulating HIV-1 promoter activity

Some HIV-infected individuals receiving ART develop low-level viremia (LLV), with a plasma viral load of 50–1000 copies/mL. Persistent low-level viremia is associated with subsequent virologic failure. The peripheral blood CD4+ T cell pool is a source of LLV. However, the intrinsic characteristics of CD4+ T cells in LLV which may contribute to low-level viremia are largely unknown. We analyzed the transcriptome profiling of peripheral blood CD4+ T cells from healthy controls (HC) and HIV-infected patients receiving ART with either virologic suppression (VS) or LLV. To identify pathways potentially responding to increasing viral loads from HC to VS and to LLV, KEGG pathways of differentially expressed genes (DEGs) were acquired by comparing VS with HC (VS-HC group) and LLV with VS (LLV-VS group), and overlapped pathways were analyzed. Characterization of DEGs in key overlapping pathways showed that CD4+ T cells in LLV expressed higher levels of Th1 signature transcription factors (TBX21), toll-like receptors (TLR-4, -6, -7 and -8), anti-HIV entry chemokines (CCL3 and CCL4), and anti-IL-1β factors (ILRN and IL1R2) compared to VS. Our results also indicated activation of the NF-κB and TNF signaling pathways that could promote HIV-1 transcription. Finally, we evaluated the effects of 4 and 17 transcription factors that were upregulated in the VS-HC and LLV-VS groups, respectively, on HIV-1 promoter activity. Functional studies revealed that CXXC5 significantly increased, while SOX5 markedly suppressed HIV-1 transcription. In summary, we found that CD4+ T cells in LLV displayed a distinct mRNA profiling compared to that in VS, which promoted HIV-1 replication and reactivation of viral latency and may eventually contribute to virologic failure in patients with persistent LLV. CXXC5 and SOX5 may serve as targets for the development of latency-reversing agents.

Opposing roles of CLK SR kinases in controlling HIV-1 gene expression and latency

BackgroundThe generation of over 69 spliced HIV-1 mRNAs from one primary transcript by alternative RNA splicing emphasizes the central role that RNA processing plays in HIV-1 replication. Control is mediated in part through the action of host SR proteins whose activity is regulated by multiple SR kinases (CLK1-4, SRPKs).MethodsBoth shRNA depletion and small molecule inhibitors of host SR kinases were used in T cell lines and primary cells to evaluate the role of these factors in the regulation of HIV-1 gene expression. Effects on virus expression were assessed using western blotting, RT-qPCR, and immunofluorescence.ResultsThe studies demonstrate that SR kinases play distinct roles; depletion of CLK1 enhanced HIV-1 gene expression, reduction of CLK2 or SRPK1 suppressed it, whereas CLK3 depletion had a modest impact. The opposing effects of CLK1 vs. CLK2 depletion were due to action at distinct steps; reduction of CLK1 increased HIV-1 promoter activity while depletion of CLK2 affected steps after transcript initiation. Reduced CLK1 expression also enhanced the response to several latency reversing agents, in part, by increasing the frequency of responding cells, consistent with a role in regulating provirus latency. To determine whether small molecule modulation of SR kinase function could be used to control HIV-1 replication, we screened a GSK library of protein kinase inhibitors (PKIS) and identified several pyrazolo[1,5-b] pyridazine derivatives that suppress HIV-1 gene expression/replication with an EC50 ~ 50 nM. The compounds suppressed HIV-1 protein and viral RNA accumulation with minimal impact on cell viability, inhibiting CLK1 and CLK2 but not CLK3 function, thereby selectively altering the abundance of individual CLK and SR proteins in cells.ConclusionsThese findings demonstrate the unique roles played by individual SR kinases in regulating HIV-1 gene expression, validating the targeting of these functions to either enhance latency reversal, essential for “Kick-and-Kill” strategies, or to silence HIV protein expression for “Block-and-Lock” strategies.

The Clonal Expansion Dynamics of the HIV-1 Reservoir: Mechanisms of Integration Site-Dependent Proliferation and HIV-1 Persistence.

More than 50% of the HIV-1 latent reservoir is maintained by clonal expansion. The clonally expanded HIV-1-infected cells can contribute to persistent nonsuppressible low-level viremia and viral rebound. HIV-1 integration site and proviral genome landscape profiling reveals the clonal expansion dynamics of HIV-1-infected cells. In individuals under long-term suppressive antiretroviral therapy (ART), HIV-1 integration sites are enriched in specific locations in certain cancer-related genes in the same orientation as the host transcription unit. Single-cell transcriptome analysis revealed that HIV-1 drives aberrant cancer-related gene expression through HIV-1-to-host RNA splicing. Furthermore, the HIV-1 promoter dominates over the host gene promoter and drives high levels of cancer-related gene expression. When HIV-1 integrates into cancer-related genes and causes gain of function of oncogenes or loss of function of tumor suppressor genes, HIV-1 insertional mutagenesis drives the proliferation of HIV-1-infected cells and may cause cancer in rare cases. HIV-1-driven aberrant cancer-related gene expression at the integration site can be suppressed by CRISPR-mediated inhibition of the HIV-1 promoter or by HIV-1 suppressing agents. Given that ART does not suppress HIV-1 promoter activity, therapeutic agents that suppress HIV-1 transcription and halt the clonal expansion of HIV-1-infected cells should be explored to block the clonal expansion of the HIV-1 latent reservoir.

HIV-1 promoter is gradually silenced when integrated into BACH2 in Jurkat T-cells.

BackgroundThe persistence of the latent HIV-1 reservoir is a major obstacle to curing HIV-1 infection. HIV-1 integrates into the cellular genome and some targeted genomic loci are frequently detected in clonally expanded latently HIV-1 infected cells, for instance, the gene BTB domain and CNC homology 2 (BACH2).MethodsWe investigated HIV-1 promoter activity after integration into specific sites in BACH2 in Jurkat T-cells. The HIV-1-based vector LTatCL[M] contains two fluorophores: (1) Cerulean, which reports the activity of the HIV-1 promoter and (2) mCherry driven by a constitutive promotor and flanked by genetic insulators. This vector was inserted into introns 2 and 5 of BACH2 of Jurkat T-cells via CRISPR/Cas9 technology in the same and convergent transcriptional orientation of BACH2, and into the genomic safe harbour AAVS1. Single cell clones representing active (Cerulean+/mCherry+) and inactive (Cerulean–/mCherry+) HIV-1 promoters were characterised.ResultsUpon targeted integration of the 5.3 kb vector LTatCL[M] into BACH2, the HIV-1 promoter was gradually silenced as reflected by the decrease in Cerulean expression over a period of 162 days. Silenced HIV-1 promoters could be reactivated by TNF-α and Romidepsin. This observation was independent of the targeted intron and the transcriptional orientation. BACH2 mRNA and protein expression was not impaired by mono-allelic integration of LTatCL[M].ConclusionSuccessful targeted integration of the HIV-1-based vector LTatCL[M] allows longitudinal analyses of HIV-1 promoter activity.

G-quadruplex ligands targeting telomeres do not inhibit HIV promoter activity and cooperate with latency reversing agents in killing latently infected cells

ABSTRACT Altered telomere maintenance mechanism (TMM) is linked to increased DNA damage at telomeres and telomere uncapping. We previously showed that HIV-1 latent cells have altered TMM and are susceptible to ligands that target G-quadruplexes (G4) at telomeres. Susceptibility of latent cells to telomere targeting could potentially be used to support approaches to eradicate HIV reservoirs. However, G4 ligands also target G-quadruplexes in promoters blocking gene transcription. Since HIV promoter sequence can form G-quadruplexes, we investigated whether G4 ligands interfere with HIV-1 promoter activity and virus reactivation from latency, and whether telomere targeting could be combined with latency reversing agents (LRAs) to promote elimination of HIV reservoirs. Our results indicate that Sp1 binding region in HIV-1 promoter can adopt G4 structures in duplex DNA, and that in vitro binding of Sp1 to G-quadruplex is blocked by G4 ligand, suggesting that agents targeting telomeres interfere with virus reactivation. However, our studies show that G4 agents do not affect HIV-1 promoter activity in cell culture, and do not interfere with latency reversal. Importantly, primary memory CD4 + T cells infected with latent HIV-1 are more susceptible to combined treatment with LRAs and G4 ligands, indicating that drugs targeting TMM may enhance killing of HIV reservoirs. Using a cell-based DNA repair assay, we also found that HIV-1 infected cells have reduced efficiency of DNA mismatch repair (MMR), and base excision repair (BER), suggesting that altered TMM in latently infected cells could be associated with accumulation of DNA damage at telomeres and changes in telomeric caps.

PIWIL4 Maintains HIV-1 Latency by Enforcing Epigenetically Suppressive Modifications on the 5' Long Terminal Repeat.

Although substantial progress has been made in depicting the molecular pathogenesis of human immunodeficiency virus type 1 (HIV-1) infection, the comprehensive mechanism of HIV-1 latency and the most promising therapeutic strategies to effectively reactivate the HIV-1 latent reservoir to achieve a functional cure for AIDS remain to be systematically illuminated. Here, we demonstrated that piwi (P element-induced Wimpy)-like RNA-mediated gene silencing 4 (PIWIL4) played an important role in suppressing HIV-1 transcription and contributed to the latency state in HIV-1-infected cells through its recruitment of various suppressive factors, including heterochromatin protein 1α/β/γ, SETDB1, and HDAC4. The knockdown of PIWIL4 enhanced HIV-1 transcription and reversed HIV-1 latency in both HIV-1 latently infected Jurkat T cells and primary CD4+ T lymphocytes and resting CD4+ T lymphocytes from HIV-1-infected individuals on suppressive combined antiretroviral therapy (cART). Furthermore, in the absence of PIWIL4, HIV-1 latently infected Jurkat T cells were more sensitive to reactivation with vorinostat (suberoylanilide hydroxamic acid, or SAHA), JQ1, or prostratin. These findings indicated that PIWIL4 promotes HIV-1 latency by imposing repressive marks at the HIV-1 5' long terminal repeat. Thus, the manipulation of PIWIL4 could be a novel strategy for developing promising latency-reversing agents (LRAs).IMPORTANCE HIV-1 latency is systematically modulated by host factors and viral proteins. During this process, the suppression of HIV-1 transcription plays an essential role in promoting HIV-1 latency. In this study, we found that PIWIL4 repressed HIV-1 promoter activity and maintained HIV-1 latency. In particular, we report that PIWIL4 can regulate gene expression through its association with the suppressive activity of HDAC4. Therefore, we have identified a new function for PIWIL4: it is not only a suppressor of endogenous retrotransposons but also plays an important role in inhibiting transcription and leading to latent infection of HIV-1, a well-known exogenous retrovirus. Our results also indicate a novel therapeutic target to reactivate the HIV-1 latent reservoir.

CAMP Signaling Enhances HIV-1 Long Terminal Repeat (LTR)-directed Transcription and Viral Replication in Bone Marrow Progenitor Cells.

CD34+ hematopoietic progenitor cells have been shown to be susceptible to HIV-1 infection, possibly due to a low-level expression of CXCR4, a coreceptor for HIV-1 entry. Given these observations, we have explored the impact of forskolin on cell surface expression of CXCR4 in a cell line model (TF-1). The elevation of intracellular cyclic adenosine monophosphate (cAMP) by forskolin through adenylyl cyclase (AC) resulted in transcriptional upregulation of CXCR4 with a concomitant increase in replication of the CXCR4-utilizing HIV-1 strain IIIB. Transient expression analyses also demonstrated an increase in CXCR4-, CCR5-, and CXCR4-/CCR5-utilizing HIV-1 (LAI, YU2, and 89.6, respectively) promoter activity. Studies also implicated the protein kinase A (PKA) pathway and the downstream transcription factor CREB-1 in interfacing with cAMP response elements located in the CXCR4 and viral promoter. These observations suggest that the cAMP signaling pathway may serve as a regulator of CXCR4 levels and concomitantly of HIV-1 replication in bone marrow (BM) progenitor cells.

HIV-1 Tat Recruits HDM2 E3 Ligase To Target IRF-1 for Ubiquitination and Proteasomal Degradation.

ABSTRACTIn addition to its ability to regulate HIV-1 promoter activation, the viral transactivator Tat also functions as a determinant of pathogenesis and disease progression by directly and indirectly modulating the host anti-HIV response, largely through the capacity of Tat to interact with and modulate the activities of multiple host proteins. We previously demonstrated that Tat modulated both viral and host transcriptional machinery by interacting with the cellular transcription factor interferon regulatory factor 1 (IRF-1). In the present study, we investigated the mechanistic basis and functional significance of Tat−IRF-1 interaction and demonstrate that Tat dramatically decreased IRF-1 protein stability. To accomplish this, Tat exploited the cellular HDM2 (human double minute 2 protein) ubiquitin ligase to accelerate IRF-1 proteasome-mediated degradation, resulting in a quenching of IRF-1 transcriptional activity during HIV-1 infection. These data identify IRF-1 as a new target of Tat-induced modulation of the cellular protein machinery and reveal a new strategy developed by HIV-1 to evade host immune responses.

LGIT In Vitro Latency Model in Primary and T Cell Lines to Test HIV-1 Reactivation Compounds.

Persistent latent HIV-1 reservoirs pose a major barrier for combinatorial antiretroviral therapy (cART) to achieve eradication of the virus. A variety of mechanisms likely contribute to HIV-1 persistence, including establishment of post-integration latency in resting CD4+ T-lymphocytes, the proliferation of these latently infected cells, and the induced or spontaneous reactivation of latent virus. To elucidate the mechanisms of latency and to investigate therapeutic strategies for reactivating and purging the latent reservoir, investigators have developed in vitro models of HIV-1 latency using primary CD4+ T-lymphocytes and CD4+ T-cell lines. Several types of in vitro latency models range from replication-competent to single-round, replication-deficient viruses exhibiting different degrees of viral genomic deletion. Working under the hypothesis that HIV-1 post-integration latency is directly linked to HIV-1 promoter activity, which can be obscured by additional proteins expressed during replication, we focus here on the creation of latently infected primary human T-cells and cell lines through the single-round, replication deficient HIV-1 LGIT model. In this model the long terminal repeat (LTR) of the HIV-1 virus drives a cassette of GFP-IRES-Tat that allows testing of reactivating components and initiates a positive feedback loop through Tat expression.

The oral commensal, Streptococcus gordonii, synergizes with Tat protein to induce HIV-1 promoter activation in monocytes/macrophages

Trans-activator of transcription (Tat) is an HIV-1 protein essential for viral replication. Oral periodontopathogens (e.g. Fusobacterium nucleatum) enhance HIV-1LTR promoter activation in monocytes/macrophages in absence of Tat; however, some oral commensals fail to trigger this response. We sought to determine the effect of Tat on HIV-1LTR promoter activation induced by the representative oral commensal Streptococcus gordonii in monocytes/macrophages. S. gordonii enhanced HIV-1LTR reactivation in THP89GFP (Tat +), but not in BF24 (Tat −) cells. Interestingly, S. gordonii, but not Streptococcus sanguinis enhanced HIV-1LTR activation in the presence of recombinant Tat in BF24 cells. This response correlated with IL-8 but not TNFα or IL-6 production, and was abrogated by the NFκB inhibitor BAY 11–7082. Kinetics of NFκB-RelA activation did not explain the S. gordonii-induced HIV-1LTR activation in presence of Tat. These results suggest that S. gordonii-induced HIV-1 reactivation in monocytes/macrophages is Tat-dependent and appears to involve NFκB activation.

Histone deacetylase inhibition allows latent HIV-1 promoter activity by inducing histone modification in latently infected cells

Histone deacetylase inhibition allows latent HIV-1 promoter activity by inducing histone modification in latently infected cells

Supernatants from oral epithelial cells and gingival fibroblasts modulate Human Immunodeficiency Virus type 1 promoter activation induced by periodontopathogens in monocytes/macrophages

Bacterial and host cell products during coinfections of Human Immunodeficiency Virus type 1-positive (HIV-1(+)) patients regulate HIV-1 recrudescence in latently infected cells (e.g. T cells, monocytes/macrophages), impacting highly active antiretroviral therapy (HAART) failure and progression of acquired immunodeficiency syndrome. A high frequency of oral opportunistic infections (e.g. periodontitis) in HIV-1(+) patients has been demonstrated; however, their potential to impact HIV-1 exacerbation is unclear. We sought to determine the ability of supernatants derived from oral epithelial cells (OKF4) and human gingival fibroblasts (Gin-4) challenged with periodontal pathogens, to modulate the HIV-1 promoter activation in monocytes/macrophages. BF24 monocytes/macrophages transfected with the HIV-1 promoter driving the expression of chloramphenicol acetyltransferase (CAT) were stimulated with Porphyromonas gingivalis, Fusobacterium nucleatum, or Treponema denticola in the presence of supernatants from OKF4 or Gin4 cells either unstimulated or previously pulsed with bacteria. CAT levels were determined by enzyme-linked immunosorbent assay and cytokine production was evaluated by Luminex beadlyte assays. OKF4 and Gin4 supernatants enhanced HIV-1 promoter activation particularly related to F. nucleatum challenge. An additive effect was observed in HIV-1 promoter activation when monocytes/macrophages were simultaneously stimulated with gingival cell supernatants and bacterial extracts. OKF4 cells produced higher levels of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukins -6 and -8 in response to F. nucleatum and P. gingivalis. Preincubation of OKF4 supernatants with anti-GM-CSF reduced the additive effect in periodontopathogen-induced HIV-1 promoter activation. These results suggest that soluble mediators produced by gingival resident cells in response to periodontopathogens could contribute to HIV-1 promoter activation in monocytes/macrophages, albeit this effect is most notable following direct stimulation of the cells with oral gram-negative bacteria.

Multi-Functional Anti-HIV Agents Based on Amino Acid Sequences Present in Serpin C-Terminal Peptides

The observation that proteinases located at the surface of HIV-1 target cells were involved in viral infection led to the discovery of the anti-HIV-1 properties of serpin A1(α1-proteinase inhibitor, α1-antitrypsin). Antiviral activity could be explained by the capacity of serpin A1 to prevent binding of the HIV envelope glycoprotein to proteinases associated with host cell membranes. Surprisingly, serpin A1 inhibited as well HIV-1 replication and promoter activity. A1- C36, the C-terminal peptide produced after serpin-proteinase complex formation [A1(359-394)] is probably responsible for this intracellular anti-HIV activity because the synthetic, truncated 26-residue peptide A1-C26 [A1(369-394)] , comprising the complete β-hairpin structure of A1-C36, strongly inhibited HIV-1 expression in infected cells. The major receptor involved in internalization of A1-C36 and many serpin-proteinase complexes is CD91, a protein highly expressed in HIV-1-infected true non-progressors. CD91 also internalizes the antiviral defensins, structurally similar to A1-C26. A1- C26 contains a putative internalization signal pentapeptide FVFLM [A1(372-376)]. Synthetic peptides based on this sequence go to the nucleus few minutes after cell membrane interaction. VIRIP (serpin A1(353-372), virus-inhibitory peptide) is a serpin A1 fragment isolated from hemofiltrates of patients with chronic kidney failure. VIRIP does not have the complete internalization sequence and does not affect HIV-1 promoter activity but effectively blocks HIV-1 entry by binding to the fusion peptide of gp41, a crucial component of the HIV envelope glycoprotein complex. C-terminal peptides derived from serpins B9 (anti-granzyme B) and C1 (antithrombin III) were not as active as A1-C26. However, other C-terminal peptides of the more than 500 members of the serpin superfamily could be potential anti-infective agents. Keywords: Protegrin, gelatinases, MMP-2, MMP-9, oncostatin M, TGBβ, interleukin-6

Reciprocal transactivation between HIV-1 and other human viruses

A variety of rare clinical syndromes are seen with strikingly increased prevalence in HIV-1-infected individuals, many with underlying viral etiologies. The emergence of these diseases in AIDS reflects a reduction in the ability of the immune system to mount an adequate defense against viruses in general due to the damage inflicted to the immune system by HIV-1 infection. However, in many cases, it has been found that HIV-1 can enhance the level of expression and hence the life cycle of other viruses independently of immunosuppression through specific interactions with the viruses. This can occur either directly by HIV-1 proteins such as Tat enhancing the activity of heterologous viral promoters, and/or indirectly by HIV-1 inducing the expression of cytokines and activation of their downstream signaling that eventually promotes the multiplication of the other virus. In a reciprocal manner, the effects of other viruses can enhance the pathogenicity of HIV-1 infection in individuals with AIDS through stimulation of the HIV-1 promoter activity and genome expression. The purpose of this review is to examine the cross-interactions between these viruses and HIV-1.

Anti-Tat and anti-HIV activities of trimers of n-alkylglycines

Transcription of human immunodeficiency virus (HIV-1) is activated by viral Tat protein which regulates HIV–LTR transcription and elongation. In the present report, the evaluation of the anti-Tat activity of a combinatorial library composed of 5120 N-trialkylglycines is reported. The antiviral activity was studied through luciferase-based assays targeting the HIV-1 promoter activation induced by the HIV-1 Tat protein. We identified five peptoids with specific anti-HIV-1 Tat activity; none of these peptoids affected the binding of HIV-1 Tat protein to the viral TAR RNA. Using a recombinant-virus assay in which luciferase activity correlates with the rate of HIV-1 transcription we have detected that one of the five selected peptoids, NC37-37-15C, is a potent inhibitor of HIV-1–LTR transcription in both primary T lymphocytes and transformed cell lines. The inhibitory effect of NC37-37-15C, which is additive with azidothymidine (AZT), correlates with its ability to inhibit CTD phosphorylation and shows a suitable profile for development of novel anti-HIV-1 drugs. Likewise, the structural simplicity of N-alkylglycine oligomers makes these peptidomimetics amenable to structural manipulation, thus facilitating the optimisation of lead molecules for drug-like properties.

Anti‐HIV Activity of Some Synthetic Lignanolides and Intermediates.

AbstractFor Abstract see ChemInform Abstract in Full Text.