[When 2'-O-methylation throws a wrench in HIV-1 reverse transcriptase]. / La 2'-O-méthylation : un grain de sable dans les rouages de la transcriptase inverse du VIH-1.

HIV-1 polymerase, commonly known as HIV reverse transcriptase (RT), catalyzes the critical reaction of reverse transcription by synthesizing a double-stranded DNA copy of the viral genomic RNA. During the replication cycle, this synthesized DNA is integrated into the host genome. This entire process is essential for viral replication and is targeted by several antiviral drugs. Numerous studies in biochemistry and structural biology have led to a good understanding of HIV-1 RT functions. However, the discovery of epitranscriptomic marks, such as 2'-O-methylations, on the HIV-1 RNA genome raise the questions about RT's ability to copy RNAs decorated with these biochemical modifications. This review focuses on the importance of RT in the viral cycle, its structure and function and the impact of 2'-O-methylations on its activity and replication regulation, particularly in quiescent cells.

Discovery of 2,4,6-trisubstituted pyrimidine derivatives as novel potent HIV-1 NNRTIs by exploiting the tolerant region II of the NNIBP.

The rapid emergence of drug resistance severely reduces the clinical response of human immunodeficiency virus-1 (HIV-1) to non-nucleoside reverse transcriptase inhibitors (NNRTIs). Herein, a series of 2,4,6-trisubstituted pyrimidine derivatives was designed and synthesized, with the aim to identify novel anti-HIV-1 agents with improved drug resistance profiles. The antiviral activity results demonstrated that all compounds showed excellent potency to wild-type (WT) HIV-1 strain (EC50 = 3.61-15.5 nM). Moreover, 13c was proved to be the most potent inhibitor against the whole tested viral panel, with EC50 ranging from 4.68 to 229 nM. In addition, 13c yielded moderate HIV-1 RT inhibition with IC50 value of 0.231 µM, which demonstrated it was a classical NNRTI. Molecular docking was further conducted to illustrate its binding mode with HIV-1 RT. These encouraging results indicated that 13c can be used as a lead compound for further study.

Discovery of potent HIV-1 NNRTIs by CuAAC click-chemistry-based miniaturized synthesis, rapid screening and structure optimization.

In addressing the urgent need for novel HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) to combat drug resistance, we employed CuAAC click chemistry to construct a diverse 312-member diarylpyrimidine (DAPY) derivative library. This rapid synthesis approach facilitated the identification of A6N36, demonstrating exceptional HIV-1 RT inhibitory activity. Moreover, it was demonstrated with EC50 values of 1.8-8.7 nM for mutant strains L100I, K103 N, Y181C, and E138K, being equipotent or superior to that of ETR. However, A6N36's efficacy was compromised against specific resistant strains (Y188L, F227L + V106A and RES056), highlighting a need for further optimization. Through scaffold hopping, we optimized this lead to develop 10c, which exhibited broad-spectrum activity with EC50 values ranging from 3.2 to 57.5 nM and superior water solubility. Molecular docking underscored the key interactions of 10c within the NNIBP. Our findings present 10c as a promising NNRTI lead, illustrating the power of click chemistry and rational design in combatting HIV-1 resistance.

Discovery of Novel Amino Acids (Analogues)-Substituted Thiophene[3,2-d]pyrimidine Derivatives as Potent HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitors: Design, Synthesis, and Biological Evaluation.

Inspired by our previous work on the modification of diarylpyrimidine-typed non-nucleoside reverse transcriptase inhibitors (NNRTIs) and the reported crystallographic studies, a series of novel amino acids (analogues)-substituted thiophene[3,2-d]pyrimidine derivatives were designed and synthesized by targeting the solvent-exposed region of the NNRTI-binding pocket. The biological evaluation results showed that compound 5k was the most active inhibitor, exhibiting moderate-to-excellent potency against HIV-1 wild-type (WT) and a panel of NNRTI-resistant strains, with EC50 values ranging from 0.042 µM to 7.530 µM. Of special note, 5k exhibited the most potent activity against single-mutant strains (K103N and E138K), with EC50 values of 0.031 µM and 0.094 µM, being about 4.3-fold superior to EFV (EC50 = 0.132 µM) and 1.9-fold superior to NVP (EC50 = 0.181 µM), respectively. In addition, 5k demonstrated lower cytotoxicity (CC50 = 27.9 µM) and higher selectivity index values. The HIV-1 reverse transcriptase (RT) inhibition assay was further performed to confirm their binding target. Moreover, preliminary structure-activity relationships (SARs) and molecular docking studies were also discussed in order to provide valuable insights for further structural optimizations. In summary, 5k turned out to be a promising NNRTI lead compound for further investigations of treatments for HIV-1 infections.

Deviated binding of anti-HBV nucleoside analog E-CFCP-TP to the reverse transcriptase active site attenuates the effect of drug-resistant mutations.

While certain human hepatitis B virus-targeting nucleoside analogs (NAs) serve as crucial anti-HBV drugs, HBV yet remains to be a major global health threat. E-CFCP is a 4'-modified and fluoromethylenated NA that exhibits potent antiviral activity against both wild-type and drug-resistant HBVs but less potent against human immunodeficiency virus type-1 (HIV-1). Here, we show that HIV-1 with HBV-associated amino acid substitutions introduced into the RT's dNTP-binding site (N-site) is highly susceptible to E-CFCP. We determined the X-ray structures of HBV-associated HIV-1 RT mutants complexed with DNA:E-CFCP-triphosphate (E-CFCP-TP). The structures revealed that exocyclic fluoromethylene pushes the Met184 sidechain backward, and the resultant enlarged hydrophobic pocket accommodates both the fluoromethylene and 4'-cyano moiety of E-CFCP. Structural comparison with the DNA:dGTP/entecavir-triphosphate complex also indicated that the cyclopentene moiety of the bound E-CFCP-TP is slightly skewed and deviated. This positioning partly corresponds to that of the bound dNTP observed in the HIV-1 RT mutant with drug-resistant mutations F160M/M184V, resulting in the attenuation of the structural effects of F160M/M184V substitutions. These results expand our knowledge of the interactions between NAs and the RT N-site and should help further design antiviral NAs against both HIV-1 and HBV.

May I Help You with Your Coat? HIV-1 Capsid Uncoating and Reverse Transcription.

The human immunodeficiency virus type 1 (HIV-1) capsid is a protein core formed by multiple copies of the viral capsid (CA) protein. Inside the capsid, HIV-1 harbours all the viral components required for replication, including the genomic RNA and viral enzymes reverse transcriptase (RT) and integrase (IN). Upon infection, the RT transforms the genomic RNA into a double-stranded DNA molecule that is subsequently integrated into the host chromosome by IN. For this to happen, the viral capsid must open and release the viral DNA, in a process known as uncoating. Capsid plays a key role during the initial stages of HIV-1 replication; therefore, its stability is intimately related to infection efficiency, and untimely uncoating results in reverse transcription defects. How and where uncoating takes place and its relationship with reverse transcription is not fully understood, but the recent development of novel biochemical and cellular approaches has provided unprecedented detail on these processes. In this review, we present the latest findings on the intricate link between capsid stability, reverse transcription and uncoating, the different models proposed over the years for capsid uncoating, and the role played by other cellular factors on these processes.

Efficacy of first-line ART regimens based on tenofovir in HIV-infected patients with pre-existing A62V mutation in reverse transcriptase.

INTRODUCTION: The amino acid substitution A62V in reverse transcriptase was identified as a mutation correlated with virologic failure in patients on first-line therapy including tenofovir (TDF) and tenofovir alafenamide (TAF). A62V is a typically polymorphic mutation in HIV-1 sub-subtype A6, which is the most widespread virus variant in Russia. MATERIALS AND METHODS: The European EuResist (EIDB) database was queried to form two equivalent groups of patients: group 1 ‒ patients with A62V at baseline treated with TDF or TAF on the first-line therapy, group 2 ‒ patients without A62V at baseline treated with TDF or TAF on the first-line therapy. Each group included 23 patients. RESULTS: There was no statistical difference between the two groups in virologic efficacy in 4, 12, and 24 weeks after the start of antiretroviral therapy (ART) and in the frequency of virologic failures. CONCLUSION: This study has some limitations, and the exact role of A62V in the efficacy of the first-line ART based on tenofovir deserves further investigation.

Structure-based design, synthesis, and biological characterization of indolylarylsulfone derivatives as novel human immunodeficiency virus type 1 inhibitors with potent antiviral activities and favorable drug-like profiles.

In the current antiretroviral landscape, continuous efforts are still needed to search for novel chemotypes of human immunodeficiency virus type 1 (HIV-1) inhibitors with improved drug resistance profiles and favorable drug-like properties. Herein, we report the design, synthesis, biological characterization, and druggability evaluation of a class of non-nucleoside reverse transcriptase inhibitors. Guided by the available crystallographic information, a series of novel indolylarylsulfone derivatives were rationally discovered via the substituent decorating strategy to fully explore the chemical space of the entrance channel. Among them, compound 11h bearing the cyano-substituted benzyl moiety proved to be the most effective inhibitor against HIV-1 wild-type and mutant strains (EC50 = 0.0039-0.338 µM), being far more potent than or comparable to etravirine and doravirine. Besides, 11h did not exhibit cytotoxicity at the maximum test concentration. Meanwhile, the binding target of 11h was further confirmed to be reverse transcriptase (IC50 = 0.055 µM). Preliminary structure-activity relationship were discussed to guide further optimization work. Molecular docking and dynamics simulation studies were investigated in detail to rationalize the biological evaluation results. Further drug-likeness assessment indicated that 11h possessed excellent physicochemical properties. Moreover, no apparent hERG blockade liability and cytochrome P450 inhibition were observed for 11h. Notably, 11h was characterized by favorable in vitro metabolic stability with moderate clearance rates and long half-lives in human plasma and liver microsomes. Overall, 11h holds great promise as an ideal Anti-HIV-1 lead compound due to its potent antiviral efficacy, low toxicity, and favorable drug-like profiles.

TAR RNA selective targeting ruthenium(II) complexes as HIV-1 reverse transcriptase inhibitors: On exploring structure-activity relationships of multiple positions.

HIV-1 reverse transcriptase (RT) inhibitors play a crucial role in the treatment of HIV by preventing the activity of the enzyme responsible for the replication of the virus. The HIV-1 Tat protein binds to transactivation response (TAR) RNA and recruits host factors to stimulate HIV-1 transcription. We have created a small library consisting of 4 × 6 polypyridyl Ru(II) complexes that selectively bind to TAR RNA, with targeting groups specific to HIV-1 TAR RNA. The molecule design was conducted by introducing hydroxyl or methoxy groups into an established potent TAR binder. The potential TAR binding ability was analysis from nature charge population and electrostatic potential by quantum chemistry calculations. Key modifications were found to be R1 and R3 groups. The most potent and selective TAR RNA binder was a3 with R1 = OH, R2 = H and R3 = Me. Through molecular recognition of hydrogen bonds and electrostatic attraction, they were able to firmly and selectively bind HIV-1 TAR RNA. Furthermore, they efficiently obstructed the contact between TAR RNA and Tat protein, and inhibited the reverse transcription activity of HIV-1 RT. The polypyridyl Ru(II) complexes were chemical and photo-stable, and sensitive and selective spectroscopic responses to TAR RNA. They exhibited little toxicity towards normal cells. Hence, this study might offer significant drug design approaches for researching AIDS and other illnesses associated with RT, including HCV, EBOV, and SARS-CoV-2. Moreover, it could contribute to fundamental research on the interactions of inorganic transition metal complexes with biomolecules.

Discovery of Benzisothiazolone Derivatives as Bifunctional Inhibitors of HIV-1 Reverse Transcriptase DNA Polymerase and Ribonuclease H Activities.

The ribonuclease H (RNase H) active site of HIV-1 reverse transcriptase (RT) is the only viral enzyme not targeted by approved antiretroviral drugs. Using a fluorescence-based in vitro assay, we screened 65,239 compounds at a final concentration of 10 µM to identify inhibitors of RT RNase H activity. We identified 41 compounds that exhibited 50% inhibitory concentration (i.e., IC50) values < 1.0 µM. Two of these compounds, 2-(4-methyl-3-(piperidin-1-ylsulfonyl)phenyl)benzo[d]isothiazol-3(2H)-one (1) and ethyl 2-(2-(3-oxobenzo[d]isothiazol-2(3H)-yl)thiazol-4-yl)acetate (2), which both share the same benzisothiazolone pharmacophore, demonstrate robust antiviral activity (50% effective concentrations of 1.68 ± 0.94 µM and 2.68 ± 0.54, respectively) in the absence of cellular toxicity. A limited structure-activity relationship analysis identified two additional benzisothiazolone analogs, 2-methylbenzo[d]isothiazol-3(2H)-one (3) and N,N-diethyl-3-(3-oxobenzo[d]isothiazol-2(3H)-yl)benzenesulfonamide (4), which also resulted in the inhibition of RT RNase H activity and virus replication. Compounds 1, 2 and 4, but not 3, inhibited the DNA polymerase activity of RT (IC50 values~1 to 6 µM). In conclusion, benzisothiazolone derivatives represent a new class of multifunctional RT inhibitors that warrants further assessment for the treatment of HIV-1 infection.

2'-ß-Methylselenyl nucleos(t)ide analogs as reverse transcriptase inhibitors against diverse HIV mutants.

Nucleoside reverse transcriptase inhibitors (NRTIs) have been extensively studied as drugs targeting HIV RT. However, the practice or use of approved NRTIs lacking the 3'-hydroxy group often promotes frequent HIV mutations and generates drug-resistance. Here, we describe a novel NRTI with 2'-ß-methylselenyl modification. We found that this modification inhibited the DNA elongation reaction by HIV-1 RT despite having a 3'-hydroxy group. Moreover, the conformation of this nucleoside analog is controlled at C3'-endo, a conformation that resists excision from the elongating DNA by HIV RT. Accordingly, the designed analogs exhibited activity against both wild-type HIV and multidrug-resistant HIV mutants.

Structure-based discovery of novel piperidine-biphenyl-DAPY derivatives as non-nucleoside reverse transcriptase inhibitors featuring improved potency, safety, and selectivity: From piperazine-biphenyl-DAPYs to piperidine-biphenyl-DAPYs.

Starting from our previously reported nonnucleoside reverse transcriptase inhibitor (NNRTI, 3), continuous efforts were made to enhance its potency and safety through a structure-based drug design strategy. This led to the discovery of a series of novel piperidine-biphenyl-diarylpyrimidines (DAPYs). Compound 10p, the most active compound in this series, exhibited an EC50 value of 6 nM against wide-type HIV-1 strain, which was approximately 560-fold more potent than the initial compound 3 (EC50 = 3.36 µM). Furthermore, significant improvements were observed in cytotoxicity and selectivity (CC50 > 202.17 µM, SI > 33144) compared to compound 3 (CC50 = 14.84 µM, SI = 4). Additionally, compound 10p demonstrated increased inhibitory activity against clinically mutant virus strains (EC50 = 7-63 nM). Further toxicity evaluation revealed that compound 10p exhibited minimal CYP enzyme and hERG inhibition. Importantly, single-dose acute toxicity testing did not result in any fatalities or noticeable pathological damage in mice. Therefore, compound 10p can be regarded as a lead candidate for guiding further development of biphenyl-diarylpyrimidine NNRTIs with favorable druggability for HIV therapy.

No antagonism or cross-resistance and a high barrier to the emergence of resistance in vitro for the combination of islatravir and lenacapavir.

Islatravir (ISL) is a deoxyadenosine analog that inhibits HIV-1 reverse transcription by multiple mechanisms. Lenacapavir (LEN) is a novel capsid inhibitor that inhibits HIV-1 at multiple stages throughout the viral life cycle. ISL and LEN are being investigated as once-weekly combination oral therapy for the treatment of HIV-1. Here, we characterized ISL and LEN in vitro to assess combinatorial antiviral activity, cytotoxicity, and the potential for interactions between the two compounds. Bliss analysis revealed ISL with LEN demonstrated additive inhibition of HIV-1 replication, with no evidence of antagonism across the range of concentrations tested. ISL exhibited potent antiviral activity against variants encoding known LEN resistance-associated mutations (RAMs) with or without the presence of M184V, an ISL RAM in reverse transcriptase (RT) . Static resistance selection experiments were conducted with ISL and LEN alone and in combination, initiating with either wild-type virus or virus containing the M184I RAM in RT to further assess their barrier to the emergence of resistance. The combination of ISL with LEN more effectively suppressed viral breakthrough at lower multiples of the compounds' IC50 (half-maximal inhibitory concentration) values and fewer mutations emerged with the combination compared to either compound on its own. The known pathways for development of resistance with ISL and LEN were not altered, and no novel single mutations emerged that substantially reduced susceptibility to either compound. The lack of antagonism and cross-resistance between ISL and LEN support the ongoing evaluation of the combination for treatment of HIV-1.

Interplay between protease and reverse transcriptase dimerization in a model HIV-1 polyprotein.

The Gag-Pol polyprotein in human immunodeficiency virus type I (HIV-1) encodes enzymes that are essential for virus replication: protease (PR), reverse transcriptase (RT), and integrase (IN). The mature forms of PR, RT and IN are homodimer, heterodimer and tetramer, respectively. The precise mechanism underlying the formation of dimer or tetramer is not yet understood. Here, to gain insight into the dimerization of PR and RT in the precursor, we prepared a model precursor, PR-RT, incorporating an inactivating mutation at the PR active site, D25A, and including two residues in the p6* region, fused to a SUMO-tag, at the N-terminus of the PR region. We also prepared two mutants of PR-RT containing a dimer dissociation mutation either in the PR region, PR(T26A)-RT, or in the RT region, PR-RT(W401A). Size exclusion chromatography showed both monomer and dimer fractions in PR-RT and PR(T26A)-RT, but only monomer in PR-RT(W401A). SEC experiments of PR-RT in the presence of protease inhibitor, darunavir, significantly enhanced the dimerization. Additionally, SEC results suggest an estimated PR-RT dimer dissociation constant that is higher than that of the mature RT heterodimer, p66/p51, but slightly lower than the premature RT homodimer, p66/p66. Reverse transcriptase assays and RT maturation assays were performed as tools to assess the effects of the PR dimer-interface on these functions. Our results consistently indicate that the RT dimer-interface plays a crucial role in the dimerization in PR-RT, whereas the PR dimer-interface has a lesser role.

From Intercalation to External Binding: Ru(II) Complexes with a Spiro Ligand for TAR RNA Selective Binding and HIV-1 Reverse Transcriptase Inhibition.

As a typical RNA virus, the genetic information on HIV-1 is entirely stored in RNA. The reverse transcription activity of HIV-1 reverse transcriptase (RT) plays a crucial role in the replication and transmission of the virus. Non-nucleoside RT inhibitors (NNRTIs) block the function of RT by binding to the RNA binding site on RT, with very few targeting viral RNA. In this study, by transforming planar conjugated ligands into a spiro structure, we convert classical Ru(II) DNA intercalators into a nonintercalator. This enables selective binding to HIV-1 transactivation response (TAR) RNA on the outer side of nucleic acids through dual interactions involving hydrogen bonds and electrostatic attraction, effectively inhibiting HIV-1 RT and serving as a selective fluorescence probe for TAR RNA.

DORAVIR: a French national survey of people with HIV-1 treated with an antiretroviral regimen including doravirine.

BACKGROUND: Doravirine is the latest NNRTI to be approved for the treatment of HIV-1 and has a different resistance profile from first-generation NNRTIs. Our aim was to investigate the virological efficacy of antiretroviral treatment including doravirine in people living with HIV-1 (PLWHIV), the factors associated with virological failure (VF) and those associated with the emergence of reverse transcriptase (RT) mutations in the case of VF. METHODS: A retrospective national survey of PLWHIV who were either naive or experienced on antiretroviral treatment including doravirine was conducted. VF was defined as two consecutive plasma viral loads (VLs) of ≥50 copies/mL or one VL of ≥200 copies/mL. Genotypic resistance tests were interpreted using the Stanford (v9.4.1) and ANRS (v33) algorithms. RESULTS: Of the 589 PLWHIV treated with a doravirine-containing regimen, 8.5% were naive and 91.5% had prior antiretroviral experience; 56.9% were infected with HIV-1 B subtype. Overall, 88.3% and 85.1% of participants were virologically controlled at Month (M)3 and M6 of doravirine treatment, respectively. In multivariable analysis, CRF02_AG subtype, higher zenith plasma HIV-1 RNA VL, doravirine initiation in the context of failure and baseline V179D mutation presence were associated with VF. Among 88 PLWHIV who experienced virological failure at M6, 15.9% had a median of 2 (IQR 1-3) HIV RT mutations. In multivariable analysis, the only factor associated with the occurrence of mutations was a genotypic sensitivity score that was not fully sensitive. CONCLUSIONS: This study is one of the largest to characterize the virological efficacy of doravirine-containing regimens in clinical practice and to identify factors associated with VF or emergence of resistance mutations that should be considered in clinical management.

Performance of the Applied Biosystems HIV-1 Genotyping Kit with Integrase.

HIV genotyping is used to assess HIV susceptibility to antiretroviral drugs. The Applied Biosystems HIV-1 Genotyping Kit with Integrase (AB kit, Thermo Fisher Scientific) detects resistance-associated mutations (RAMs) in HIV protease (PR), reverse transcriptase (RT), and integrase (IN). We compared results from the AB kit with results obtained previously with the ViroSeq HIV-1 Genotyping System. DNA amplicons from the AB kit were also analyzed using next-generation sequencing (NGS). HIV RNA was extracted using the MagNA Pure 24 instrument (Roche Diagnostics; 96 plasma samples, HIV subtype B, viral load range: 530-737,741 copies/mL). FASTA files were generated from AB kit data using Exatype (Hyrax Biosciences). DNA amplicons from the AB kit were also analyzed by NGS using the Nextera XT kit (Illumina). Drug resistance was predicted using the Stanford HIV Drug Resistance Database. The mean genetic distance for sequences from ViroSeq and the AB kit was 0.02% for PR/RT and 0.04% for IN; 103 major RAMs were detected by both methods. Four additional major RAMs were detected by the AB kit only. These four major RAMs were also detected by NGS (detected in 18.1%-38.2% of NGS reads). NGS detected 27 major RAMs that were not detected with either of the Sanger sequencing-based kits. All major RAMs detected with ViroSeq were detected with the AB kit; additional RAMs were detected with the AB kit only. DNA amplicons from the AB kit can be used for NGS for more sensitive detection of RAMs.

The RT M184V resistance mutation clearance in the reservoir is mainly related to CD4 nadir and viral load zenith independently of therapeutic regimen type.

OBJECTIVES: Resistance associated mutations (RAMs) are archived in the HIV reservoir and can re-emerge with an inappropriate ART use limiting treatment options. However, recent studies, using ultra-deep sequencing (UDS), showed a decrease of quasispecies harbouring RAMs, suggesting that recycling some antiretrovirals could be considered. The aim of this study was to characterize, in HIV treated PLWHIV, the M184V mutation decrease kinetics in proviral DNA and associated factors of M184V mutation clearance over time. METHODS: UDS was performed on HIV-DNA from blood cells at different time points to quantify the percentage of M184V positive quasispecies. The sequence reads were analysed with a minimum coverage set at 50 and an ambiguity filter at 5% or 2%. RESULTS: At 2.5 years after the first time point, the M184V lost was observed in 50% of PLWHIV. Moreover, univariate analyses highlight that a higher nadir CD4 count and a lower zenith HIV1 RNA viral load were correlated with a faster clearance of the mutation. In multivariate analysis, a higher zenith was negatively associated with the M184V clearance at the 5% threshold. Interestingly, lamivudine/emtricitabine presence in the ART therapy regiment during the 5 years was not associated with the persistence of the M184V. CONCLUSIONS: Our study provides new information concerning the clearance speed of M184V mutation over time in PLWHIV with fully suppressed viremia, opens the discussion about the duration needed to consider a lamivudine/emtricitabine recycling and reinforces the association of the nadir and zenith values with the M184V mutation clearance.

Comparison of feline and human immunodeficiency virus reverse transcriptase enzymes through chemical screening and computational analysis.

Feline immunodeficiency virus (FIV) is a common infection found in domesticated and wild cats worldwide. Despite the wealth of therapeutic understanding of the disease in humans, considerably less information exists regarding the treatment of the disease in felines. Current treatment relies on drugs developed for the related human immunodeficiency virus (HIV) and includes compounds of the popular non-nucleotide reverse transcriptase (NNRTI) class. This is despite FIV-RT being only 67% similar to HIV-1 RT at the enzyme level, increasing to 88% for the allosteric pocket targeted by NNRTIs. The goal of this project was to try to quantify how well the more extensive pharmacological knowledge available for human disease translates to felines. To this end we screened known NNRTIs and 10 diverse pyrimidine analogs identified virtually. We use this chemo-centric probe approach to (a) assess the similarity between the two related RT targets based on the observed experimental inhibition values, (b) try to identify more potent inhibitors at FIV, and (c) gain a better appreciation of the structure-activity relationships (SAR). We found the correlation between IC50s at the two targets to be strong (r2 = 0.87) and identified compound 1 as the most potent inhibitor of FIV with IC50 of 0.030 µM ± 0.009. This compared to FIV IC50 values of 0.22 ± 0.17 µM, 0.040 ± 0.010 µM and >160 µM for known anti HIV-1 RT drugs Efavirenz, Rilpivirine, and Nevirapine, respectively. This knowledge, along with an understanding of the structural origin that give rise to any differences could improve the way HIV drugs are repurposed for FIV.

Structure-guided design of novel biphenyl-quinazoline derivatives as potent non-nucleoside reverse transcriptase inhibitors featuring improved anti-resistance, selectivity, and solubility.

In pursuit of enhancing the anti-resistance efficacy and solubility of our previously identified NNRTI 1, a series of biphenyl-quinazoline derivatives were synthesized employing a structure-based drug design strategy. Noteworthy advancements in anti-resistance efficacy were discerned among some of these analogs, prominently exemplified by compound 7ag, which exhibited a remarkable 1.37 to 602.41-fold increase in potency against mutant strains (Y181C, L100I, Y188L, F227L + V106A, and K103N + Y181C) in comparison to compound 1. Compound 7ag also demonstrated comparable anti-HIV activity against both WT HIV and K103N, albeit with a marginal reduction in activity against E138K. Of significance, this analog showed augmented selectivity index (SI > 5368) relative to compound 1 (SI > 37764), Nevirapine (SI > 158), Efavirenz (SI > 269), and Etravirine (SI > 1519). Moreover, it displayed a significant enhancement in water solubility, surpassing that of compound 1, Etravirine, and Rilpivirine. To elucidate the underlying molecular mechanisms, molecular docking studies were undertaken to probe the critical interactions between 7ag and both WT and mutant strains of HIV-1 RT. These findings furnish invaluable insights driving further advancements in the development of DAPYs for HIV therapy.