Identification of a small molecule HIV-1 inhibitor that targets the capsid hexamer

Modulation of HIV-1 capsid multimerization by sennoside A and sennoside B via interaction with the NTD/CTD interface in capsid hexamer

Small molecules that bind to the pocket targeted by a peptide, termed capsid assembly inhibitor (CAI), have shown antiviral effects with unique mechanisms of action. We report the discovery of two natural compounds, sennoside A (SA) and sennoside B (SB), derived from medicinal plants that bind to this pocket in the C-terminal domain of capsid (CA CTD). Both SA and SB were identified via a drug-screening campaign that utilized a time-resolved fluorescence resonance energy transfer assay. They inhibited the HIV-1 CA CTD/CAI interaction at sub-micromolar concentrations of 0.18 μM and 0.08 μM, respectively. Mutation of key residues (including Tyr 169, Leu 211, Asn 183, and Glu 187) in the CA CTD decreased their binding affinity to the CA monomer, from 1.35-fold to 4.17-fold. Furthermore, both compounds induced CA assembly in vitro and bound directly to the CA hexamer, suggesting that they interact with CA beyond the CA CTD. Molecular docking showed that both compounds were bound to the N-terminal domain (NTD)/CTD interface between adjacent protomers within the CA hexamer. SA established a hydrogen-bonding network with residues N57, V59, Q63, K70, and N74 of CA1-NTD and Q179 of CA2-CTD. SB formed hydrogen bonds with the N53, N70, and N74 residues of CA1-NTD, and the A177and Q179 residues of CA2-CTD. Both compounds, acting as glue, can bring αH4 in the NTD and αH9 in the CTD of the NTD/CTD interface close to each other. Collectively, our research indicates that SA and SB, which enhance CA assembly, could serve as novel chemical tools to identify agents that modulate HIV-1 CA assembly. These natural compounds may potentially lead to the development of new antiviral therapies with unique mechanisms of action.

Astrocytes: Role in pathogenesis and effect of commonly misused drugs in the HIV infected brain

The roles of astrocytes as reservoirs and producers of a subset of viral proteins in the HIV infected brain have been studied extensively as a key to understanding HIV-associated neurocognitive disorders (HAND). However, their comprehensive role in the context of intersecting substance use and neurocircuitry of the reward pathway and HAND has yet to be fully explained. Use of methamphetamines, cocaine, or opioids in the context of HIV infection have been shown to lead to a faster progression of HAND. Glutamatergic, dopaminergic, and GABAergic systems are implicated in the development of HAND-induced cognitive impairments. A thorough review of scientific literature exploring the variety of mechanisms in which these drugs exert their effects on the HIV brain and astrocytes has revealed marked areas of convergence in overexcitation leading to increased drug-seeking behavior, inflammation, apoptosis, and irreversible neurotoxicity. The present review investigates astrocytes, the neural pathways, and mechanisms of drug disruption that ultimately play a larger holistic role in terms of HIV progression and drug use. There are opportunities for future research, therapeutic intervention, and preventive strategies to diminish HAND in the subset population of patients with HIV and substance use disorder.

Design, synthesis, and mechanistic study of 2-piperazineone-bearing peptidomimetics as novel HIV capsid modulators

HIV-1 capsid (CA) is an attractive target for its indispensable roles in the viral life cycle. We report the design, synthesis, and mechanistic study of a novel series of 2-piperazineone peptidomimetics as HIV capsid modulators by mimicking the structure of host factors binding to CA. F-Id-3o was the most potent compound from the synthesized series, with an anti-HIV-1 EC50 value of 6.0 μM. However, this series of compounds showed a preference for HIV-2 inhibitory activity, in which Id-3o revealed an EC50 value of 2.5 μM (anti-HIV-2 potency), an improvement over PF74. Interestingly, F-Id-3o did bind HIV-1 CA monomers and hexamers with comparable affinity, unlike PF74, consequently showing antiviral activity in the early and late stages of the HIV-1 lifecycle. Molecular dynamics simulations shed light on F-Id-3o and Id-3o binding modes within the HIV-1/2 CA protein and provide a possible explanation for the increased anti-HIV-2 potency. Metabolic stability assays in human plasma and human liver microsomes indicated that although F-Id-3o has enhanced metabolic stability over PF74, further optimization is necessary. Moreover, we utilized computational prediction of drug-like properties and metabolic stability of F-Id-3o and PF74, which correlated well with experimentally derived metabolic stability, providing an efficient computational pipeline for future preselection based on metabolic stability prediction. Overall, the 2-piperazineone-bearing peptidomimetics are a promising new chemotype in the CA modulators class with considerable optimization potential.

Computer-aided drug design in seeking viral capsid modulators

Approved or licensed antiviral drugs have limited applications because of their drug resistance and severe adverse effects. By contrast, by stabilizing or destroying the viral capsid, compounds known as capsid modulators prevent viral replication by acting on new targets and, therefore, overcoming the problem of clinical drug resistance. For example. computer-aided drug design (CADD) methods, using strategies based on structures of biological targets (structure-based drug design; SBDD), such as docking, molecular dynamics (MD) simulations, and virtual screening (VS), have provided opportunities for fast and effective development of viral capsid modulators. In this review, we summarize the application of CADD in the discovery, optimization, and mechanism prediction of capsid-targeting small molecules, providing new insights into antiviral drug discovery modalities. Teaser: Computer-aided drug design will accelerate the development of viral capsid regulators, which brings new hope for the treatment of refractory viral diseases.

A Broad-Spectrum Antiviral Molecule, Protoporphyrin IX, Acts as a Moderator of HIV-1 Capsid Assembly by Targeting the Capsid Hexamer

The capsid protein (CA), an essential component of human immunodeficiency virus type 1 (HIV-1), represents an appealing target for antivirals. Small molecules targeting the CAI-binding cavity in the C-terminal domain of HIV-1 CA (CA CTD) confer potent antiviral activities. In this study, we report that a small molecule, protoporphyrin IX (PPIX), targets the HIV-1 CA by binding to this pocket. PPIX was identified via in vitro drug screening, using a homogeneous and time-resolved fluorescence-based assay. CA multimerization and a biolayer interferometry (BLI) assay showed that PPIX promoted CA multimerization and bound directly to CA. The binding model of PPIX to CA CTD revealed that PPIX forms hydrogen bonds with the L211and E212 residues in the CA CTD. Moreover, the BLI assay demonstrated that this compound preferentially binds to the CA hexamer versus the monomer. The superposition of the CAI CTD-PPIX complex and the hexameric CA structure suggests that PPIX binds to the interface formed by the NTD and the CTD between adjacent protomers in the CA hexamer via the T72 and E212 residues, serving as a glue to enhance the multimerization of CA. Taken together, our studies demonstrate that PPIX, a hexamer-targeted CA assembly enhancer, should be a new chemical probe for the discovery of modulators of the HIV-1 capsid assembly. IMPORTANCE CA and its assembled viral core play essential roles in distinct steps during HIV-1 replication, including reverse transcription, integration, nuclear entry, virus assembly, and maturation through CA-CA or CA-host factor interactions. These functions of CA are fundamental for HIV-1 pathogenesis, making it an appealing target for antiviral therapy. In the present study, we identified protoporphyrin IX (PPIX) as a candidate CA modulator that can promote CA assembly and prefers binding the CA hexamer versus the monomer. PPIX, like a glue, bound at the interfaces between CA subunits to accelerate CA multimerization. Therefore, PPIX could be used as a new lead for a CA modulator, and it holds potential research applications.

Design, Synthesis and Structure-Activity Relationships of Phenylalanine-Containing Peptidomimetics as Novel HIV-1 Capsid Binders Based on Ugi Four-Component Reaction

As a key structural protein, HIV capsid (CA) protein plays multiple roles in the HIV life cycle, and is considered a promising target for anti-HIV treatment. Based on the structural information of CA modulator PF-74 bound to HIV-1 CA hexamer, 18 novel phenylalanine derivatives were synthesized via the Ugi four-component reaction. In vitro anti-HIV activity assays showed that most compounds exhibited low-micromolar-inhibitory potency against HIV. Among them, compound I-19 exhibited the best anti-HIV-1 activity (EC50 = 2.53 ± 0.84 μM, CC50 = 107.61 ± 27.43 μM). In addition, I-14 displayed excellent HIV-2 inhibitory activity (EC50 = 2.30 ± 0.11 μM, CC50 > 189.32 μM) with relatively low cytotoxicity, being more potent than that of the approved drug nevirapine (EC50 > 15.02 μM, CC50 > 15.2 μM). Additionally, surface plasmon resonance (SPR) binding assays demonstrated direct binding to the HIV CA protein. Moreover, molecular docking and molecular dynamics simulations provided additional information on the binding mode of I-19 to HIV-1 CA. In summary, we further explored the structure—activity relationships (SARs) and selectivity of anti-HIV-1/HIV-2 of PF-74 derivatives, which is conducive to discovering efficient anti-HIV drugs.

Clade-Specific Alterations within the HIV-1 Capsid Protein with Implications for Nuclear Translocation

The HIV-1 capsid (CA) protein has emerged as an attractive therapeutic target. However, all inhibitor designs and structural analyses for this essential HIV-1 protein have focused on the clade B HIV-1 (NL4-3) variant. This study creates, overproduces, purifies, and characterizes the CA proteins from clade A1, A2, B, C, and D isolates. These new CA constructs represent novel reagents that can be used in future CA-targeted inhibitor design and to investigate CA proteins’ structural and biochemical properties from genetically diverse HIV-1 subtypes. Moreover, we used surface plasmon resonance (SPR) spectrometry and computational modeling to examine inter-clade differences in CA assembly and binding of PF-74, CPSF-6, and NUP-153. Interestingly, we found that HIV-1 CA from clade A1 does not bind to NUP-153, suggesting that the import of CA core structures through the nuclear pore complex may be altered for viruses from this clade. Overall, we have demonstrated that in silico generated models of the HIV-1 CA protein from clades other than the prototypically used clade B have utility in understanding and predicting biology and antiviral drug design and mechanism of action.

Rotten to the core: antivirals targeting the HIV-1 capsid core

The capsid core of HIV-1 is a large macromolecular assembly that surrounds the viral genome and is an essential component of the infectious virus. In addition to its multiple roles throughout the viral life cycle, the capsid interacts with multiple host factors. Owing to its indispensable nature, the HIV-1 capsid has been the target of numerous antiretrovirals, though most capsid-targeting molecules have not had clinical success until recently. Lenacapavir, a long-acting drug that targets the HIV-1 capsid, is currently undergoing phase 2/3 clinical trials, making it the most successful capsid inhibitor to-date. In this review, we detail the role of the HIV-1 capsid protein in the virus life cycle, categorize antiviral compounds based on their targeting of five sites within the HIV-1 capsid, and discuss their molecular interactions and mechanisms of action. The diverse range of inhibition mechanisms provides insight into possible new strategies for designing novel HIV-1 drugs and furthers our understanding of HIV-1 biology.

Design, synthesis, and mechanism study of dimerized phenylalanine derivatives as novel HIV-1 capsid inhibitors

HIV-1 capsid (CA) plays indispensable and multiple roles in the life cycle of HIV-1, become an attractive target in antiviral therapy. Herein, we report the design, synthesis, and mechanism study of a novel series of dimerized phenylalanine derivatives as HIV-1 capsid inhibitors using 2-piperazineone or 2,5-piperazinedione as a linker. The structure-activity relationship (SAR) indicated that dimerized phenylalanines were more potent than monomers of the same chemotype. Further, the inclusion of fluorine substituted phenylalanine and methoxyl substituted aniline was found to be beneficial for antiviral activity. From the synthesized series, Q-c4 was found to be the most potent compound with an EC₅₀ value of 0.57 μM, comparable to PF74. Interestingly, Q-c4 demonstrated a slightly higher affinity to the CA monomer than the CA hexamer, commensurate with its more significant effect in the late-stage of the HIV-1 lifecycle. Competitive SPR experiments with peptides from CPSF6 and NUP153 revealed that Q-c4 binds to the interprotomer pocket of hexameric CA as designed. Single-round infection assays showed that Q-c4 interferes with the HIV-1 life cycle in a dual-stage manner, affecting both pre-and post-integration. Stability assays in human plasma and human liver microsomes indicated that although Q-c4 has improved stability over PF74, this kind of inhibitor still requires further optimization. And the results of the online molinspiration software predicted that Q-c4 has desirable physicochemical properties but some properties still have some violation from the Lipinski rule of five. Overall, the dimerized phenylalanines are promising novel platforms for developing future HIV-1 CA inhibitors with considerable potential for optimization.

Design, synthesis, and mechanistic investigations of phenylalanine derivatives containing a benzothiazole moiety as HIV-1 capsid inhibitors with improved metabolic stability

Further clinical development of PF74, a lead compound targeting HIV-1 capsid, is impeded by low antiviral activity and inferior metabolic stability. By modifying the benzene (region I) and indole of PF74, we identified two potent compounds (7m and 7u) with significantly improved metabolic stability. Compared to PF74, 7u displayed greater metabolic stability in human liver microsomes (HLMs) with half-life (t_1/2) 109-fold that of PF74. Moreover, mechanism of action (MOA) studies demonstrated that 7m and 7u effectively mirrored the MOA of compounds that interact within the PF74 interprotomer pocket, showing direct and robust interactions with recombinant CA, and 7u displaying antiviral effects in both the early and late stages of HIV-1 replication. Furthermore, MD simulation corroborated that 7u was bound to the PF74 binding site, and the results of the online molinspiration software predicted that 7m and 7u had desirable physicochemical properties. Unexpectedly, this series of compounds exhibited better antiviral activity than PF74 against HIV-2, represented by compound 7m whose anti-HIV-2 activity was almost 5 times increased potency over PF74. Therefore, we have rationally redesigned the PF74 chemotype to inhibitors with novel structures and enhanced metabolic stability in this study. We hope that these new compounds can serve as a blueprint for developing a new generation of HIV treatment regimens.

Rapid Optimization of the Metabolic Stability of a Human Immunodeficiency Virus Type-1 Capsid Inhibitor Using a Multistep Computational Workflow

Poor metabolic stability of the human immunodeficiency virus type-1 (HIV-1) capsid (CA) inhibitor PF-74 is a major concern in its development toward clinical use. To improve on the metabolic stability, we employed a novel multistep computationally driven workflow, which facilitated the rapid design of improved PF-74 analogs in an efficient manner. Using this workflow, we designed three compounds that interact specifically with the CA interprotomer pocket, inhibit HIV-1 infection, and demonstrate enantiomeric preference. Moreover, using this workflow, we were able to increase the metabolic stability 204-fold in comparison to PF-74 in only three analog steps. These results demonstrate our ability to rapidly design CA compounds using a novel computational workflow that has improved metabolic stability over the parental compound. This workflow can be further applied to the redesign of PF-74 and other promising inhibitors with a stability shortfall.

Small-Molecule Anti-HIV-1 Agents Based on HIV-1 Capsid Proteins

The capsid of human immunodeficiency virus type 1 (HIV-1) is a shell that encloses viral RNA and is highly conserved among many strains of the virus. It forms a conical structure by assembling oligomers of capsid (CA) proteins. CA dysfunction is expected to be an important target of suppression of HIV-1 replication, and it is important to understand a new mechanism that could lead to the CA dysfunction. A drug targeting CA however, has not been developed to date. Hydrophobic interactions between two CA molecules via Trp184/Met185 in CA were recently reported to be important for stabilization of the multimeric structure of CA. In the present study, a small molecule designed by in silico screening as a dipeptide mimic of Trp184 and Met185 in the interaction site, was synthesized and its significant anti-HIV-1 activity was confirmed. Structure activity relationship (SAR) studies of its derivatives were performed and provided results that are expected to be useful in the future design and development of novel anti-HIV agents targeting CA.

Design, Synthesis, and Mechanism Study of Benzenesulfonamide-Containing Phenylalanine Derivatives as Novel HIV-1 Capsid Inhibitors with Improved Antiviral Activities

The HIV-1 CA protein has gained remarkable attention as a promising therapeutic target for the development of new antivirals, due to its pivotal roles in HIV-1 replication (structural and regulatory). Herein, we report the design and synthesis of three series of benzenesulfonamide-containing phenylalanine derivatives obtained by further structural modifications of PF-74 to aid in the discovery of more potent and drug-like HIV-1 CA inhibitors. Structure-activity relationship studies of these compounds led to the identification of new phenylalanine derivatives with a piperazinone moiety, represented by compound 11l, which exhibited anti-HIV-1_NL4-3 activity 5.78-fold better than PF-74. Interestingly, 11l also showed anti-HIV-2_ROD activity (EC₅₀ = 31 nM), with almost 120 times increased potency over PF-74. However, due to the higher significance of HIV-1 as compared to HIV-2 for the human population, this manuscript focuses on the mechanism of action of our compounds in the context of HIV-1. SPR studies on representative compounds confirmed CA as the binding target. The action stage determination assay demonstrated that these inhibitors exhibited antiviral activities with a dual-stage inhibition profile. The early-stage inhibitory activity of compound 11l was 6.25 times more potent as compared to PF-74 but appeared to work via the accelerating capsid core assembly rather than stabilization. However, the mechanism by which they exert their antiviral activity in the late stage appears to be the same as PF-74 with less infectious HIV-1 virions produced in their presence, as judged p24 content studies. MD simulations provided the key rationale for the promising antiviral potency of 11l. Additionally, 11l exhibited a modest increase in HLM and human plasma metabolic stabilities as compared to PF-74, as well as a moderately improved pharmacokinetic profile, favorable oral bioavailability, and no acute toxicity. These studies provide insights and serve as a starting point for subsequent medicinal chemistry efforts in optimizing these promising HIV inhibitors.

Recent Advances in HIV-1 Gag Inhibitor Design and Development

Acquired Immune Deficiency Syndrome (AIDS) treatment with combination antiretroviral therapy (cART) has improved the life quality of many patients since its implementation. However, resistance mutations and the accumulation of severe side effects associated with cART remain enormous challenges that need to be addressed with the continual design and redesign of anti-HIV drugs. In this review, we focus on the importance of the HIV-1 Gag polyprotein as the master coordinator of HIV-1 assembly and maturation and as an emerging drug target. Due to its multiple roles in the HIV-1 life cycle, the individual Gag domains are attractive but also challenging targets for inhibitor design. However, recent encouraging developments in targeting the Gag domains such as the capsid protein with highly potent and potentially long-acting inhibitors, as well as the exploration and successful targeting of challenging HIV-1 proteins such as the matrix protein, have demonstrated the therapeutic viability of this important protein. Such Gag-directed inhibitors have great potential for combating the AIDS pandemic and to be useful tools to dissect HIV-1 biology.

Design, synthesis and structure-activity relationships of 4-phenyl-1H-1,2,3-triazole phenylalanine derivatives as novel HIV-1 capsid inhibitors with promising antiviral activities

HIV-1 CA is involved in different stages of the viral replication cycle, performing essential roles in both early (uncoating, reverse transcription, nuclear import, integration) and late events (assembly). Recent efforts have demonstrated HIV-1 CA protein as a prospective therapeutic target for the development of new antivirals. The most extensively studied CA inhibitor, PF-3450074 (PF-74, discovered by Pfizer), that targets an inter-protomer pocket within the CA hexamer. Herein we reported the design, synthesis, and biological evaluation of a series of 4-phenyl-1H-1,2,3-triazole phenylalanine derivatives as HIV-1 CA inhibitors based on PF-74 scaffold. Most of the analogues demonstrated potent antiviral activities, among them, the anti-HIV-1 activity of 6a-9 (EC50 = 3.13 μM) is particularly prominent. The SPR binding assay of selected compounds (6a-9, 6a-10, 5b) suggested direct and effective interaction with recombinant CA proteins. The mechanism of action studies also demonstrated that 6a-9 displays the effects in both the early and late stages of HIV-1 replication. To explore the potential binding mode of the here presented analogues, 6a-9 was analyzed by MD simulation to predict its binding to the active site of HIV-1 CA monomer. In conclusion, this novel series of antivirals can serve as a starting point for the development of a new generation of HIV-1 treatment regimen and highlights the potentiality of CA as a therapeutic target.

HIV Capsid Inhibitors Beyond PF74

Human immunodeficiency virus (HIV) capsid plays important roles at multiple stages of viral replication. At the initial stages, controlled uncoating (disassembly) of the capsid ensures efficient reverse transcription of the single-stranded RNA genome, into the double-stranded DNA. Whereas at later stages, a proper assembly of capsid ensures the formation of a mature infectious virus particle. Hence, the inhibition of capsid assembly and/or disassembly has been recognized as a potential therapeutic strategy, and several capsid inhibitors have been reported. Of these, PF-3450074 (PF74) has been extensively studied. Recently reported GS-CA inhibitors (GS-CA1 and GS-6207), have shown a strong potential and appear to contain a PF74 scaffold. The location of resistance mutations and the results of structural studies further suggest that GS-CA compounds and PF74 share the same binding pocket, which is located between capsid monomers. Additionally, phenylalanine derivatives containing the PF74 scaffold show slightly enhanced capsid inhibiting activity. A comparison of capsid structures in complex with host factors and PF74, reveals the presence of common chemical entities at topologically equivalent positions. Here we present the status of capsid inhibitors that contain PF74 scaffolds and propose that the PF74 scaffold may be used to develop strong and safe capsid inhibitors.

Discovery of novel 1,4-disubstituted 1,2,3-triazole phenylalanine derivatives as HIV-1 capsid inhibitors

The HIV-1 capsid (CA) protein plays crucial roles in both early and late stages of the viral life cycle, which has intrigued researchers to target it to develop anti-HIV drugs. Accordingly, in this research, we report the design, synthesis and biological evaluation of a series of novel phenylalanine derivatives as HIV-1 CA protein inhibitors using the Cu(I)-catalyzed azide and alkyne 1,3-dipolar cycloaddition (CuAAC) reaction. Among this series of inhibitors, compound II-10c displayed a remarkable anti-HIV activity (EC₅₀ = 2.13 μM, CC₅₀ > 35.49 μM). Furthermore, surface plasmon resonance (SPR) binding assays showed that compounds II-10c and PF-74 (lead compound) have similar affinities to HIV-1 CA monomer. Further investigation showed that the weak permeability and water solubility of representative compounds were probably the important factors that restricted their cell-based activity. Preliminary structure-activity relationships (SARs) were inferred based on the activities of these compounds, and their known structure. The most promising new compound was studied with molecular dynamics simulation (MD) to determine the preferred interactions with the drug target. Finally, the activities of members of this series of inhibitors were deeply inspected to find the potential reasons for their anti-HIV-1 activity from various perspectives. This highlights the important factors required to design compounds with improved potency.

Discovery of phenylalanine derivatives as potent HIV-1 capsid inhibitors from click chemistry-based compound library

The HIV-1 capsid (CA) protein plays essential roles in both early and late stages of HIV-1 replication and is considered an important, clinically unexploited therapeutic target. As such, small drug-like molecules that inhibit this critical HIV-1 protein have become a priority for several groups. Therefore, in this study we explore small molecule targeting of the CA protein, and in particular a very attractive inter-protomer pocket. We report the design, parallel synthesis, and anti-HIV-1 activity evaluation of a series of novel phenylalanine derivatives as HIV-1 CA protein inhibitors synthesized via Cu(I)-catalyzed alkyne-azide 1,3-dipolar cycloaddition (CuAAC) reaction. We demonstrate robust inhibitory activity over a range of potencies against the HIV-1 NL_4-3 reference strain. In particular, compound 13m exhibited the greatest potency and lowest toxicity within this new series with an EC₅₀ value of 4.33 μM and CC₅₀ value of >57.74 μM (SI > 13.33). These values are very similar to the lead compound PF-74 (EC₅₀ = 5.95 μM, CC₅₀ > 70.50 μM, SI > 11.85) in our assay, despite significant structural difference. Furthermore, we demonstrate via surface plasmon resonance (SPR) binding assays that 13m interacts robustly with recombinant HIV-1 CA and exhibits antiviral activity in both the early and late stages of HIV-1 replication. Overall, the novel parallel synthesis and structure-activity relationships (SARs) identified within this study set the foundation for further rational optimization and discovery of CA-targeting compounds with improved potency.

Exploring Modifications of an HIV-1 Capsid Inhibitor: Design, Synthesis, and Mechanism of Action

Recent efforts by both academic and pharmaceutical researchers have focused on the HIV-1 capsid (CA) protein as a new therapeutic target. An interprotomer pocket within the hexamer configuration of the CA, which is also a binding site for key host dependency factors, is the target of the most widely studied CA inhibitor compound PF-3450074 (PF-74). Despite its popularity, PF-74 suffers from properties that limit its usefulness as a lead, most notably it's extremely poor metabolic stability. To minimize unfavorable qualities, we investigated bioisosteric modification of the PF-74 scaffold as a first step in redeveloping this compound. Using a field-based bioisostere identification method, coupled with biochemical and biological assessment, we have created four new compounds that inhibit HIV-1 infection and that bind to the assembled CA hexamer. Detailed mechanism of action studies indicates that the modifications alter the manner in which these new compounds affect HIV-1 capsid core stability, as compared to the parental compound. Further investigations are underway to redevelop these compounds to optimize potency and drug-like characteristics and to deeply define the mechanism of action.

Antibody-Mediated Therapy against HIV/AIDS: Where Are We Standing Now?

Acquired immunodeficiency syndrome (AIDS) cases are on the rise globally. To date, there is still no effective measure to eradicate the causative agent, human immunodeficiency virus (HIV). Highly active antiretroviral therapy (HAART) is being used in HIV/AIDS management, but it results in long-term medication and has major drawbacks such as multiple side effects, high cost, and increasing the generation rate of escape mutants. In addition, HAART does not control HIV-related complications, and hence more medications and further management are required. With this, other alternatives are urgently needed. In the past, small-molecule inhibitors have shown potent antiviral effects, and some of them are now being evaluated in clinical trials. The challenges in developing these small molecules for clinical use include the off-target effect, poor stability, and low bioavailability. On the other hand, antibody-mediated therapy has emerged as an important therapeutic modality for anti-HIV therapeutics development. Many antiviral antibodies, namely, broad neutralizing antibodies (bnAbs) against multiple strains of HIV, have shown promising effects in vitro and in animal studies; further studies are ongoing in clinical trials to evaluate their uses in clinical applications. This short review aims to discuss the current development of therapeutic antibodies against HIV and the challenges in adopting them for clinical use.