Integrase Strand Transfer Inhibitors (INSTIs) are currently used as the most effective therapy in the treatment of human immunodeficiency virus (HIV) infections. Raltegravir (RAL) and Elvitegravir (EVG), the first generation of INSTIs used successfully in clinical treatment, are susceptible to the emergence of viral resistance and have a high rate of cross-resistance. To counteract these resistant mutants, second-generation INSTI drugs have been developed: Dolutegravir (DTG), Cabotegravir (CAB), and Bictegravir (BIC). However, HIV is also able to develop resistance mechanisms against the second-generation of INSTIs. This review describes the mode of action of INSTIs and then summarizes and evaluates some typical resistance mutations, such as substitution and insertion mutations. The role of unintegrated viral DNA is also discussed as a new pathway involved in conferring resistance to INSTIs. This allows us to have a more detailed understanding of HIV resistance to these inhibitors, which may contribute to the development of new INSTIs in the future.

There is a strong demand for new and efficient antiviral compounds. A series of 2-hydroxy-1,4-naphthoquinone Mannich bases were screened for their HIV-1-RNase H inhibitory activity. An HIV-1-RNase H assay was used to study the RNase H inhibition by the test compounds. Docking of active derivatives into the active site of the enzyme was carried out. Compounds 1e and 2k showed distinctly higher HIV-1-RNase H inhibitory activity (IC₅₀ = 2.8–3.1 µM) than the known inhibitors RDS1759 and compound 13. The binding mode and possible interactions of 1e and 2k with the HIV-1-RNase H active site were determined using molecular docking, which led to the identification of salient and concealed pharmacophoric features of these molecules. The docking analysis revealed that there are significant differences in the binding mode of these compounds within the active site of the target enzyme. A selection of HIV-1-RNase H-inhibitory Mannich bases was tested for antiviral activity against HIV-1, and compound 2k showed the highest activity at low toxicity to host cells. The lawsone Mannich bases 1e and 2k also underwent a preliminary screening for activity against SARS-CoV-2, and compound 1e was found to inhibit SARS-CoV-2 replication (IC₅₀ = 11.2 µM).

Curcumin derivatives (curcuminoids) exhibit considerable antiparasitic and antiviral activities. In this study, EF24-like bis-2-fluorobenzylidene piperidone derivatives were synthesized and evaluated for antiprotozoal activity and inhibition of the human immunodeficiency virus (HIV)-1 reverse transcriptase (RT)-associated RNase H (HIV-1 RNase H). A series of bis-arylidene piperidones and tetrahydro(thio)pyranones bearing halogen or nitro substituents were tested against Leishmania major (promastigotes and amastigotes) and Toxoplasma gondii. L. major promastigotes were the most sensitive parasitic model, with several compounds exhibiting low-nanomolar IC₅₀ values, while ortho- or para-halogenated analogues demonstrated submicromolar activity against T. gondii. Among them, 3,4-dichlorophenyl (HPip-DC) and 4-bromophenyl (HPip-4Br) derivatives showed potent activity against L. major and HIV-1 RNase H. The entropy-uncorrected MM-GBSA effective binding energy estimates were −33.41, −9.29, −8.37, and −4.27 kcal/mol for the predicted L. major squalene monooxygenase–HPip-DC, bovine cytochrome bc₁–DiFiD (2,4-difluorophenyl derivative), RNase H–HPip-4NO (4-nitrophenyl derivative), and RNase H–HPip-DC complexes, respectively. During 300 ns simulations, the ligands remained associated with their binding pockets. The Arg557 residue was crucial for HPip-4NO-mediated RNase H inhibition while the inhibitory activity of HPip-DC was much less dependent on this amino acid. These findings identify EF24-like curcuminoids with potent in vitro antiprotozoal activity and biochemical inhibition of HIV-1 RNase H. Antiviral activity was observed but confounded by host cell toxicity.

Caractéristiques de nouvelles mutations dans le gene de l'intégrase et dans le 3'PPT du virus de l'Immunodéficience Humaine dans le mécanisme de résistance: Le VIH-1, membre de la famille des Retroviridae, est l'agent étiologique du SIDA — l'une des pandémies les plus dévastatrices et persistantes de l'histoire contemporaine. Malgré les avancées majeures dans la thérapie antirétrovirale (TAR), les traitements actuels reposent principalement sur les inhibiteurs de l'intégrase (INSTIs), ciblant spécifiquement l'étape d'intégration du génome viral. Toutefois, l'émergence de variants du VIH-1 résistants aux INSTIs constitue un défi urgent pour les stratégies de santé publique. Ce travail de recherche développe et valide une méthode innovante de quantification de l'ADN intégré du VIH-1, en affinant la technique classique Alu-PCR. Cette nouvelle approche combine des amorces Alu biotinylées, une séparation magnétique via des billes M280 recouvertes de streptavidine, et un traitement enzymatique ciblant l'ADN simple brin par les exonucléases RecJf et ExoVII. Ce protocole améliore significativement la spécificité en éliminant les signaux non spécifiques provenant de l'ADN viral non intégré, réduisant les faux positifs de plus de 2,5 log₁₀, et détecte l'ADN intégré dans 10 % des échantillons cliniques auparavant classés comme négatifs par la méthode traditionnelle. Au-delà de l'innovation méthodologique, ce travail met en évidence deux mécanismes atypiques de résistance aux INSTIs. Le premier concerne des mutations d'insertion dans le gène codant pour l'intégrase, introduisant des acides aminés supplémentaires qui abolissent totalement l'activité enzymatique, rendant le virus insensible aux traitements ciblant l'intégrase via une perte fonctionnelle de la cible moléculaire. Le second mécanisme repose sur des mutations au niveau du segment polypurine 3′ (3′PPT), une séquence ARN conservée essentielle à la synthèse de l'ADN brin positif pendant la transcription inverse. Ces mutations perturbent le rôle initiateur du 3′PPT, bloquant l'intégration du génome viral, mais favorisent la formation d'ADN viral circulaire non intégré (cercles 1-LTR). Les expériences démontrent que les souches mutantes du VIH-1 portant des altérations du 3′PPT ne forment pas de provirus intégré, mais continuent néanmoins à exprimer des protéines virales (Tat, GFP) à partir de l'ADN circulaire. Certaines de ces souches peuvent même se répliquer et produire des particules virales infectieuses sans passage par l'intégration, révélant un nouveau mode de réplication indépendant de l'intégration. Notamment, la formation de ces cercles 1-LTR a lieu dans le cytoplasme, contrairement aux souches de type sauvage qui les produisent dans le noyau, suggérant une stratégie adaptative permettant au virus de contourner l'action des INSTIs. En somme, cette étude contribue à améliorer les outils de quantification du VIH intégré tout en révélant des mécanismes de résistance non conventionnels. Elle remet en question le dogme selon lequel l'intégration est indispensable à la réplication productive du VIH-1, et souligne la nécessité de surveiller de manière plus large les mutations non classiques dans le cadre du traitement moderne du VIH.

Objectives: This study aimed to gain a better understanding of the role of insertional mutations in the integrase (IN)-coding sequence of 13 HIV-1-infected people. Results: Here, we present the first documentation of amino acid insertion in the IN-coding sequence of HIV-1-infected people at positions 168, 253, 255 and 260. The consequences of these mutations in terms of viral replication and resistance to INSTIs were analysed using virological and biochemical assays and 3D modelling. Analysis of viral genomes by quantitative PCR demonstrated that insertional mutations reduce reverse transcription efficiency and had different impacts on viral integration. Taken together, we showed that mutants were delayed in their replication. Virological assays using two potent strand-transfer inhibitors (INSTIs), raltegravir and dolutegravir, demonstrated that no resistance to INSTIs was observed. Conclusions: Our study has revealed that the mutations observed in people living with HIV-1 do not confer resistance to anti-integrase compounds but are detrimental to viral replication.