HIV-1 Integrase Inhibitors Research Articles

Drug Resistance to HIV-1 Integrase Inhibitors Among Treatment-Naive Patients in Beijing, China.

IntroductionIntegrase strand transfer inhibitors (INSTIs) are important drugs that are currently used as the first line treatment for HIV-1 patients. The aim of this study was to characterize HIV-1 INSTI mutations among ART-naive patients in Beijing from 2019–2021.Methods865 ART-naive patients were enrolled in this study between January 2019 and June 2021 in Beijing. The amplification of the entire pol gene containing the reverse transcriptase, protease and integrase regions was performed using a validated In-house SBS method. HIV-1 subtypes and circulating recombinant forms (CRFs) were determined using the COMET online tool (http://comet.retrovirology.lu). Stanford HIV-1 drug resistance database (HIVdb version 8.9) was used to analyze the mutations.Results865 HIV-1 pol sequences were successfully amplified and sequenced. Among them, no major INSTI-related mutations were identified, but 12 polymorphic accessory mutations were found. Two patients have E138A and G163R mutations respectively and both could cause low-level resistance to RAL and EVG. Furthermore, one patient having S230R mutation resulted in low-level resistance to RAL, EVG, DTG and BIC.ConclusionThe prevalence of INSTIs mutations remains low, which demonstrated that INSTIs have good applicability currently in our city. Nevertheless, it is very important to monitor the INSTI-related mutations in Beijing.

Novel RNase H Inhibitors Blocking RNA-directed Strand Displacement DNA Synthesis by HIV-1 Reverse Transcriptase

In retroviruses, strand displacement DNA-dependent DNA polymerization catalyzed by the viral reverse transcriptase (RT) is required to synthesize double-stranded proviral DNA. In addition, strand displacement during RNA-dependent DNA synthesis is critical to generate high-quality cDNA for use in molecular biology and biotechnology. In this work, we show that the loss of RNase H activity due to inactivating mutations in HIV-1 RT (e.g. D443N or E478Q) has no significant effect on strand displacement while copying DNA templates, but has a large impact on DNA polymerization in reactions carried out with RNA templates. Similar effects were observed with β-thujaplicinol and other RNase H active site inhibitors, including compounds with dual activity (i.e., characterized also as inhibitors of HIV-1 integrase and/or the RT DNA polymerase). Among them, dual inhibitors of HIV-1 RT DNA polymerase/RNase H activities, containing a 7-hydroxy-6-nitro-2H-chromen-2-one pharmacophore were found to be very potent and effective strand displacement inhibitors in RNA-dependent DNA polymerization reactions. These findings might be helpful in the development of transcriptomics technologies to obtain more uniform read coverages when copying long RNAs and for the construction of more representative libraries avoiding biases towards 5′ and 3′ ends, while providing valuable information for the development of novel antiretroviral agents.

RP-HPLC separation of interconvertible rotamers of a 5-tetrahydroisoquinolin-6-yl-pyridin-3-yl acetic acid derivative and confirmation by VT NMR and DFT study

Due to emergence of drug resistance and drug tolerability, there is urgent need for discovery of new chemical entity for the treatment of HIV infection. As a part of in-house small molecule drug discovery program for HIV infection, sodium-2-(tert-butoxy)− 2-(5-(2-(2-chloro-6-methylbenzyl)− 1,2,3,4-tetrahydroisoquinolin-6-yl)− 4-(4,4-dimethylpiperidin-1-yl)− 2,6-dimethylpyridin-3-yl) acetate (SCMTDDA) was prepared as an intermediate for the synthesis of an API, designed as a HIV-1 integrase inhibitor. Initially, the final compound was isolated as a mixture of rotamers. In the current study, we have developed a simple and efficient achiral, reversed phase (RP) HPLC method to separate the interconvertible rotamers of SCMTDDA. The effect of several parameters, including stationary phase, buffer, modifiers and column temperature, were optimized for the chromatographic separation and it was observed that best separation was achieved on a SunFire C18 column using TFA/acetonitrile (ACN) - methanol (MeOH) (1:1 v/v) as the mobile phase at 10 0C. The chromatographic observations were complemented with variable-temperature NMR and energy barrier calculations using density functional theory (DFT).

Piroxicam Analogs: Design, Synthesis, Docking Study and Biological Evaluation as Promising Anti-HIV-1 Agents.

In this study, we describe the synthesis, docking study and biological evaluation of 1,2-benzothiazines 1,1-dioxide derivatives. Taking the well-known drug, Piroxicam as a lead compound, we designed and synthesized two series of 1,2-benzothiazines 1,1-dioxide derivatives to assay their ability in inhibition of HIV-1 replication in cell culture. Most of the new compounds were active in the cell-based anti-HIV-1 assay with EC50 < 50 μM. Among them, compound 7g was found to be the most active molecule.Docking study using 3OYA pdb code on the most active molecule 7g with EC50 values of 10 μM showed a similar binding mode to the HIV integrase inhibitors. Since all the compounds showed no remarkable cytotoxicity (CC50> 500 μM), the designed scaffold is promising structure for the development of new anti-HIV-1 agents.

Two-Metal Ion-Dependent Enzymes as Potential Antiviral Targets in Human Herpesviruses.

ABSTRACTThe majority of drug discovery efforts against herpesviruses have focused on nucleoside analogs that target viral DNA polymerases, agents that are associated with dose-limiting toxicity and/or a narrow spectrum of activity. We are pursuing a strategy based on targeting two-metal ion-dependent (TMID) viral enzymes. This family of enzymes consists of structurally related proteins that share common active sites containing conserved carboxylates predicted to coordinate divalent cations essential for catalysis. Compounds that target TMID enzymes, such as HIV integrase and influenza endoribonuclease, have been successfully developed for clinical use. HIV integrase inhibitors have been reported to inhibit replication of herpes simplex virus (HSV) and other herpesviruses; however, the molecular targets of their antiviral activities have not been identified. We employed a candidate-based approach utilizing several two-metal-directed chemotypes and the potential viral TMID enzymatic targets in an effort to correlate target-based activity with antiviral potency. The panel of compounds tested included integrase inhibitors, the anti-influenza agent baloxavir, three natural products previously shown to exhibit anti-HSV activity, and two 8-hydroxyquinolines (8-HQs), AK-157 and AK-166, from our in-house program. The integrase inhibitors exhibited weak overall anti-HSV-1 activity, while the 8-HQs were shown to inhibit both HSV-1 and cytomegalovirus (CMV). Target-based analysis demonstrated that none of the antiviral compounds acted by inhibiting ICP8, contradicting previous reports. On the other hand, baloxavir inhibited the proofreading exonuclease of HSV polymerase, while AK-157 and AK-166 inhibited the alkaline exonuclease UL12. In addition, AK-157 also inhibited the catalytic activity of the HSV polymerase, which provides an opportunity to potentially develop dual-targeting agents against herpesviruses.

Antiviral Activity and Resistance Profile of the Novel HIV-1 Non-Catalytic Site Integrase Inhibitor JTP-0157602.

HIV-1 integrase (IN) is an essential enzyme for viral replication. Non-catalytic site integrase inhibitors (NCINIs) are allosteric HIV-1 IN inhibitors and a potential new class of antiretrovirals. In this report, we identified a novel NCINI, JTP-0157602, with an original scaffold. JTP-0157602 exhibited potent antiviral activity against HIV-1 and showed a serum-shifted 90% effective concentration (EC90) of 138 nM, which is comparable to those of the FDA-approved IN strand transfer inhibitors (INSTIs). This compound was fully potent against a wide range of recombinant viruses with IN polymorphisms, including amino acids 124/125, a hot spot of IN polymorphisms. In addition, JTP-0157602 retained potent antiviral activity against a broad panel of recombinant viruses with INSTI-related resistance mutations, including multiple substitutions that emerged in clinical studies of INSTIs. Resistance selection experiments of JTP-0157602 led to the emergence of A128T and T174I mutations, which are located at the lens epithelium-derived growth factor/p75 binding pocket of IN. JTP-0157602 inhibited HIV-1 replication mainly during the late phase of the replication cycle, and HIV-1 virions produced by reactivation from HIV-1 latently infected Jurkat cells in the presence of JTP-0157602 were noninfectious. These results suggest that JTP-0157602 and analog compounds can be used to treat HIV-1 infectious diseases. IMPORTANCE Non-catalytic site integrase inhibitors (NCINIs) are allosteric HIV-1 integrase (IN) inhibitors that bind to the lens epithelium-derived growth factor (LEDGF)/p75 binding pocket of IN. NCINIs are expected to be a new class of anti-HIV-1 agents. In this study, we present a novel NCINI, JTP-0157602, which has potent activity against a broad range of HIV-1 strains with IN polymorphisms. Furthermore, JTP-0157602 shows strong antiviral activity against IN strand transfer inhibitor-resistant mutations, suggesting that JTP-0157602 and its analogs are potential agents for treating HIV-1 infections. Structural modeling indicated that JTP-0157602 binds to the LEDGF/p75 binding pocket of IN, and the results of in vitro resistance induction revealed the JTP-0157602 resistance mechanism of HIV-1. These data shed light on developing novel NCINIs that exhibit potent activity against HIV-1 with broad IN polymorphisms and multidrug-resistant HIV-1 variants.

Characterization of the SARS-CoV-2 ExoN (nsp14ExoN-nsp10) complex: implications for its role in viral genome stability and inhibitor identification.

The SARS-CoV-2 coronavirus is the causal agent of the current global pandemic. SARS-CoV-2 belongs to an order, Nidovirales, with very large RNA genomes. It is proposed that the fidelity of coronavirus (CoV) genome replication is aided by an RNA nuclease complex, comprising the non-structural proteins 14 and 10 (nsp14–nsp10), an attractive target for antiviral inhibition. Our results validate reports that the SARS-CoV-2 nsp14–nsp10 complex has RNase activity. Detailed functional characterization reveals nsp14–nsp10 is a versatile nuclease capable of digesting a wide variety of RNA structures, including those with a blocked 3′-terminus. Consistent with a role in maintaining viral genome integrity during replication, we find that nsp14–nsp10 activity is enhanced by the viral RNA-dependent RNA polymerase complex (RdRp) consisting of nsp12–nsp7–nsp8 (nsp12–7–8) and demonstrate that this stimulation is mediated by nsp8. We propose that the role of nsp14–nsp10 in maintaining replication fidelity goes beyond classical proofreading by purging the nascent replicating RNA strand of a range of potentially replication-terminating aberrations. Using our developed assays, we identify drug and drug-like molecules that inhibit nsp14–nsp10, including the known SARS-CoV-2 major protease (Mpro) inhibitor ebselen and the HIV integrase inhibitor raltegravir, revealing the potential for multifunctional inhibitors in COVID-19 treatment.

Repurposing FDA-approved drugs as HIV-1 integrase inhibitors: an in silico investigation

The Human Immunodeficiency Virus (HIV) infection is a global pandemic that has claimed 33 million lives to-date. One of the most efficacious treatments for naïve or pretreated HIV patients is the HIV integrase strand transfer inhibitors (INSTIs). However, given that HIV treatment is life-long, the emergence of HIV strains resistant to INSTIs is an imminent challenge. In this work, we showed two best regression QSAR models that were constructed using a boosted Random Forest algorithm (r2 = 0.998, q2 10CV = 0.721, q2 external_test = 0.754) and a boosted K* algorithm (r2 = 0.987, q2 10CV = 0.721, q2 external_test = 0.758) to predict the pIC50 values of INSTIs. Subsequently, the regression QSAR models were deployed against the Drugbank database for drug repositioning. The top-ranked compounds were further evaluated for their target engagement activity using molecular docking studies and accelerated Molecular Dynamics simulation. Lastly, their potential as INSTIs were also evaluated from our literature search. Our study offers the first example of a large-scale regression QSAR modelling effort for discovering highly active INSTIs to combat HIV infection. Communicated by Ramaswamy H. Sarma

Designing potential HIV-1 integrase inhibitors: An In silico approach

Human immunodeficiency virus is a spectrum of conditions caused by infection with the human immunodeficiency virus. In 2019, about 38 million people worldwide were living with HIV and 690,000 deaths had occurred in that year. To date, for the treatment of HIV-1 disease, many compounds have been synthesized and some of them was approved by FDA. However, the use of these drugs has been limited due to reasons such as resistance caused by the misuse of drugs and bad side effects. We describe herein designing 48 novel compounds as a potential inhibitor of HIV-1 integrase through in silico studies such as molecular docking, target analysis, toxicity prediction and ADME prediction. The online web-based platform, SwissADME, also predicts these molecules solubility, pharmacodynamics property and target accuracy.

Dolutegravir as First- or Second-Line Treatment for HIV-1 Infection in Children

BackgroundChildren with human immunodeficiency virus type 1 (HIV-1) infection have limited options for effective antiretroviral treatment (ART).MethodsWe conducted an open-label, randomized, noninferiority trial comparing three-drug ART based on the HIV integrase inhibitor dolutegravir with standard care (non–dolutegravir-based ART) in children and adolescents starting first- or second-line ART. The primary end point was the proportion of participants with virologic or clinical treatment failure by 96 weeks, as estimated by the Kaplan–Meier method. Safety was assessed.ResultsFrom September 2016 through June 2018, a total of 707 children and adolescents who weighed at least 14 kg were randomly assigned to receive dolutegravir-based ART (350 participants) or standard care (357). The median age was 12.2 years (range, 2.9 to 18.0), the median weight was 30.7 kg (range, 14.0 to 85.0), and 49% of the participants were girls. By design, 311 participants (44%) started first-line ART (with 92% of those in the standard-care group receiving efavirenz-based ART), and 396 (56%) started second-line ART (with 98% of those in the standard-care group receiving boosted protease inhibitor–based ART). The median follow-up was 142 weeks. By 96 weeks, 47 participants in the dolutegravir group and 75 in the standard-care group had treatment failure (estimated probability, 0.14 vs. 0.22; difference, –0.08; 95% confidence interval, −0.14 to −0.03; P=0.004). Treatment effects were similar with first- and second-line therapies (P=0.16 for heterogeneity). A total of 35 participants in the dolutegravir group and 40 in the standard-care group had at least one serious adverse event (P=0.53), and 73 and 86, respectively, had at least one adverse event of grade 3 or higher (P=0.24). At least one ART-modifying adverse event occurred in 5 participants in the dolutegravir group and in 17 in the standard-care group (P=0.01).ConclusionsIn this trial involving children and adolescents with HIV-1 infection who were starting first- or second-line treatment, dolutegravir-based ART was superior to standard care. (Funded by ViiV Healthcare; ODYSSEY ClinicalTrials.gov number, NCT02259127; EUDRACT number, 2014-002632-14; and ISRCTN number, ISRCTN91737921.)

Novel 2-(Diphenylmethylidene) Malonic Acid Derivatives as Anti-HIV Agents: Molecular Modeling, Synthesis and Biological Evaluation.

HIV, the virus that causes AIDS (acquired immunodeficiency syndrome), is one of the world's most severe health and development challenges. In this study, a novel series of 2-(diphenyl methylidene) malonic acid derivatives were designed as triple inhibitors of HIV reverse transcriptase, integrase, and protease. Docking models revealed that the target compounds have appropriate affinities to the active sites of the three HIV key enzymes. The synthesized malonic acid analogs were evaluated for their activities against the HIV virus (NL4-3) in HeLa cells cultures. Among them, compound 3 was the most potent anti-HIV agent with 55.20% inhibition at 10 μM and an EC50 of 8.4 μM. Interestingly, all the synthesized compounds do not show significant cytotoxicity at a concentration of 10 μM. As a result, these compounds may serve as worthy hits for the development of novel anti-HIV-agents.

Quantum Mechanical-Based Stability Evaluation of Crystal Structures for HIV-Targeted Drug Cabotegravir.

The long-acting parenteral formulation of the HIV integrase inhibitor cabotegravir (GSK744) is currently being developed to prevent HIV infections, benefiting from infrequent dosing and high efficacy. The crystal structure can affect the bioavailability and efficacy of cabotegravir. However, the stability determination of crystal structures of GSK744 have remained a challenge. Here, we introduced an ab initio protocol to determine the stability of the crystal structures of pharmaceutical molecules, which were obtained from crystal structure prediction process starting from the molecular diagram. Using GSK744 as a case study, the ab initio predicted that Gibbs free energy provides reliable further refinement of the predicted crystal structures and presents its capability for becoming a crystal stability determination approach in the future. The proposed work can assist in the comprehensive screening of pharmaceutical design and can provide structural predictions and stability evaluation for pharmaceutical crystals.

Identification of Influenza PAN Endonuclease Inhibitors via 3D-QSAR Modeling and Docking-Based Virtual Screening

Structural and biochemical studies elucidate that PAN may contribute to the host protein shutdown observed during influenza A infection. Thus, inhibition of the endonuclease activity of viral RdRP is an attractive approach for novel antiviral therapy. In order to envisage structurally diverse novel compounds with better efficacy as PAN endonuclease inhibitors, a ligand-based-pharmacophore model was developed using 3D-QSAR pharmacophore generation (HypoGen algorithm) methodology in Discovery Studio. As the training set, 25 compounds were taken to generate a significant pharmacophore model. The selected pharmacophore Hypo1 was further validated by 12 compounds in the test set and was used as a query model for further screening of 1916 compounds containing 71 HIV-1 integrase inhibitors, 37 antibacterial inhibitors, 131 antiviral inhibitors and other 1677 approved drugs by the FDA. Then, six compounds (Hit01–Hit06) with estimated activity values less than 10 μM were subjected to ADMET study and toxicity assessment. Only one potential inhibitory ‘hit’ molecule (Hit01, raltegravir’s derivative) was further scrutinized by molecular docking analysis on the active site of PAN endonuclease (PDB ID: 6E6W). Hit01 was utilized for designing novel potential PAN endonuclease inhibitors through lead optimization, and then compounds were screened by pharmacophore Hypo1 and docking studies. Six raltegravir’s derivatives with significant estimated activity values and docking scores were obtained. Further, these results certainly do not confirm or indicate the seven compounds (Hit01, Hit07, Hit08, Hit09, Hit10, Hit11 and Hit12) have antiviral activity, and extensive wet-laboratory experimentation is needed to transmute these compounds into clinical drugs.

HIV-1 drug resistance in adults and adolescents on protease inhibitor-based antiretroviral therapy in KwaZulu-Natal Province, South Africa

In low-middle-income countries, increasing levels of HIV drug resistance (HIVDR) on second-line protease inhibitor (PI)-based regimens are a cause for concern given the limited drug options for third-line antiretroviral therapy (ART). We conducted a retrospective analysis of routine HIV-1 genotyping laboratory data from KwaZulu-Natal, South Africa, to describe the frequency and patterns of HIVDR mutations and their consequent impact on standardised third-line regimens. This was a cross-sectional analysis of all HIV-1 genotypic resistance tests conducted by the National Health Laboratory Service in KwaZulu-Natal (January 2015 to December 2016) for adults and adolescents (age ≥10 years) on second-line PI-based ART with virological failure. We assigned a third-line regimen to each record based on a national treatment algorithm and calculated the genotypic susceptibility score (GSS) for that regimen. Of 348 samples analysed, 287 (82.5%) had at least one drug resistance mutation (DRM) and 114 (32.8%) had at least one major PI DRM. Major PI resistance was associated with longer duration on second-line ART (aOR per 6-months=1.11, 95% CI 1.04-1.19) and older age (aOR=1.03, 95% CI 1.01-1.05). Of 112 patients requiring third-line ART, 12 (10.7%) had a GSS of <2 for the algorithm-assigned third-line regimen. One-third of people failing second-line ART had significant PI DRMs. A subgroup of these individuals had extensive HIVDR, where the predicted activity of third-line ART was suboptimal, highlighting the need for continuous evaluation of outcomes on third-line regimens and close monitoring for emergent HIV-1 integrase inhibitor resistance.

No developmental toxicity observed with dolutegravir in rat whole embryo culture.

An in vitro rat whole embryo culture study investigated whether direct exposure to dolutegravir (TivicayTM ) during the critical period for neural tube development would result in abnormal development. Dolutegravir (DTG), and HIV integrase inhibitor, was administered at 0 (vehicle), 5.3 μg/mL and 9.3 μg/mL on Gestation Day (GD) 9 through 11 (approximate 40 hour exposure period) along with positive (Valproic Acid) and negative (Penicillin G) controls. The DTG concentrations tested were selected based on clinical exposure at the maximum human recommended dose and maximum feasible concentration that could be formulated under the experimental conditions. Approximately 6% of DTG present in the culture media was absorbed into the embryos, demonstrating embryonic exposure at a similar level to that observed in a rat DTG placental transfer study. There was no effect in either the DTG or Penicillin G groups on visceral yolk sac size/morphology, embryo size, somite number and embryo morphology at any concentration tested. Valproic Acid, by contrast, produced statistically significant decreases in visceral yolk sac size, embryo size and somite number along with defects in visceral yolk sac and embryonic morphology, including neural tube defects (NTDs), in all embryos. DTG at the maximum human recommended dose administered to rats in a whole embryo culture assay did not produce any abnormal effects, while the positive control Valproic Acid produced abnormal effects, including neural tube defects.

A highly potent and safe pyrrolopyridine-based allosteric HIV-1 integrase inhibitor targeting host LEDGF/p75-integrase interaction site.

Allosteric integrase inhibitors (ALLINIs) are a class of experimental anti-HIV agents that target the noncatalytic sites of the viral integrase (IN) and interfere with the IN-viral RNA interaction during viral maturation. Here, we report a highly potent and safe pyrrolopyridine-based ALLINI, STP0404, displaying picomolar IC50 in human PBMCs with a >24,000 therapeutic index against HIV-1. X-ray structural and biochemical analyses revealed that STP0404 binds to the host LEDGF/p75 protein binding pocket of the IN dimer, which induces aberrant IN oligomerization and blocks the IN-RNA interaction. Consequently, STP0404 inhibits proper localization of HIV-1 RNA genomes in viral particles during viral maturation. Y99H and A128T mutations at the LEDGF/p75 binding pocket render resistance to STP0404. Extensive in vivo pharmacological and toxicity investigations demonstrate that STP0404 harbors outstanding therapeutic and safety properties. Overall, STP0404 is a potent and first-in-class ALLINI that targets LEDGF/p75 binding site and has advanced to a human trial.

Molecular Basis for Two Stereoselective Diels-Alderases that Produce Decalin Skeletons*.

Enzymes catalyzing [4+2] cycloaddition have attracted increasing attention because of their key roles in natural product biosynthesis. Here, we solved the X‐ray crystal structures of a pair of decalin synthases, Fsa2 and Phm7, that catalyze intramolecular [4+2] cycloadditions to form enantiomeric decalin scaffolds during biosynthesis of the HIV‐1 integrase inhibitor equisetin and its stereochemical opposite, phomasetin. Computational modeling, using molecular dynamics simulations as well as quantum chemical calculations, demonstrates that the reactions proceed through synergetic conformational constraints assuring transition state‐like substrates folds and their stabilization by specific protein‐substrate interactions. Site‐directed mutagenesis experiments verified the binding models. Intriguingly, the flexibility of bound substrates is largely different in two enzymes, suggesting the distinctive mechanism of dynamics regulation behind these stereoselective reactions. The proposed reaction mechanism herein deepens the basic understanding how these enzymes work but also provides a guiding principle to create artificial enzymes.

Prevalence of resistance mutations associated with integrase inhibitors in therapy-naive HIV-positive patients in Hungary.

Widespread introduction of HIV integrase inhibitors into clinical care may result in appearance of drug resistance mutations affecting treatment outcome. The aim of our study was to monitor the resistance patterns of integrase inhibitors beside protease and reverse transcriptase inhibitors in newly diagnosed therapy-naive HIV-positive patients in Hungary between 2017 and 2019.Genotype-based resistance testing of HIV integrase, protease and reverse transcriptase was performed by amplification and Sanger population sequencing from plasma samples. Drug resistance mutations were identified by the algorithm of Stanford HIV Drug Resistance Database.Potentially transmitted, non-polymorphic integrase major mutation was detected in 1 out of 249 samples, while accessory mutations were observed in further 31 patients (12.4%). The overall prevalence of transmitted drug resistance (TDR) mutations related to protease and reverse transcriptase inhibitors was 5.8% (10/173) between the end of 2017 and 2019. Nucleoside reverse transcriptase inhibitor associated resistance mutations were the most frequent indicators of TDR (6/173; 3.5%), followed by resistance mutations associated with protease (3/173; 1.7%) and non-nucleoside reverse transcriptase inhibitors (2/173, 1.2%).The first detection of integrase major mutation and the changing patterns of other resistance mutations in Hungarian untreated HIV-positive population indicate the necessity of continuous molecular surveillance of Hungarian HIV epidemic.

Crystal Structures of Fsa2 and Phm7 Catalyzing [4 + 2] Cycloaddition Reactions with Reverse Stereoselectivities in Equisetin and Phomasetin Biosynthesis.

Fsa2 and Phm7 are a unique pair of pericyclases catalyzing [4 + 2] cycloaddition reactions with reverse stereoselectivities in the biosynthesis of equisetin and phomasetin, both of which are potent HIV-1 integrase inhibitors. We here solve the crystal structures of Fsa2 and Phm7, both of which possess unusual “two-β barrel” folds. Different residues are evident between the active sites of Fsa2 and Phm7, and modeling experiments provide key structural information determining the reverse stereoselectivities. These results provide a better understanding of how natural pericyclases control the catalytic stereoselectivities and benefit the protein engineering in future.

Communicable and noncommunicable liver disease in HIV

The aim of this study was to highlight the profound changes in the cause in chronic liver disease in HIV-infected individuals. Hepatitis C virus (HCV) has been transformed into a curable viral infection by highly effective treatments. This has resulted in elimination of chronic hepatitis C in HIV-coinfected individuals at least in resource-rich settings. Hepatitis B virus (HBV) has become a chronic infection, which is easily controlled by long-term therapy with HBV polymerase inhibitors. As a result, nonalcoholic steatohepatitis (NASH) has gained clinical importance. The obesity epidemic in the general population has also included people with HIV and weight gain has been associated with some newer antiretroviral drugs, such as HIV integrase inhibitors and tenofovir alafenamide fumarate. Medical treatment for obesity is a focus of intense research efforts, but currently, the only convincing therapeutic option in morbidly obese patients is bariatric surgery, which can also improve liver outcomes. The wider use of this approach has included HIV-infected individuals allowing to assess at least the safety aspects of bariatric surgery in this special population. The shift from communicable to noncommunicable liver disease is changing the clinical practice in HIV-infected individuals. Research activities are focusing more on treatment of NASH and obesity, although a curative therapy for HBV infection would have a great clinical impact.