Development of oligonucleotide-based antagonists of Ebola virus protein 24 inhibiting its interaction with karyopherin alpha 1

Strategies for the Viral Exploitation of Nuclear Pore Transport Pathways

Viruses frequently exploit the host's nucleocytoplasmic trafficking machinery to facilitate their replication and evade immune defenses. By encoding specialized proteins and other components, they strategically target host nuclear transport receptors (NTRs) and nucleoporins within the spiderweb-like inner channel of the nuclear pore complex (NPC), enabling efficient access to the host nucleus. This review explores the intricate mechanisms governing the nuclear import and export of viral components, with a focus on the interplay between viral factors and host determinants that are essential for these processes. Given the pivotal role of nucleocytoplasmic shuttling in the viral life cycle, we also examine therapeutic strategies aimed at disrupting the host's nuclear transport pathways. This includes evaluating the efficacy of pharmacological inhibitors in impairing viral replication and assessing their potential as antiviral treatments. Furthermore, we emphasize the need for continued research to develop targeted therapies that leverage vulnerabilities in nucleocytoplasmic trafficking. Emerging high-resolution techniques, such as advanced imaging and computational modeling, are transforming our understanding of the dynamic interactions between viruses and the NPC. These cutting-edge tools are driving progress in identifying novel therapeutic opportunities and uncovering deeper insights into viral pathogenesis. This review highlights the importance of these advancements in paving the way for innovative antiviral strategies.

Self-reporting photodynamic nanobody conjugate for precise and sustainable large-volume tumor treatment

Nanobodies (Nbs), the smallest antigen-binding fragments with high stability and affinity derived from the variable domain of naturally occurring heavy-chain-only antibodies in camelids, have been shown as an efficient way to improve the specificity to tumors for photodynamic therapy (PDT). Nonetheless, the rapid clearance of Nbs in vivo restricts the accumulation and retention of the photosensitizer at the tumor site causing insufficient therapeutic outcome, especially in large-volume tumors. Herein, we develop photodynamic conjugates, MNB-Pyra Nbs, through site-specific conjugation between 7D12 Nbs and type I photosensitizer MNB-Pyra (morpholine-modified nile blue structure connected to pyrazolinone) in a 1:2 ratio. The photosensitizers with long-term retention can be released at the tumor site by reactive oxygen species cleavage after illumination, accompanied with fluorescence recovery for self-reporting the occurrence of PDT. Ultimately, a single dose of MNB-Pyra Nbs demonstrate highly effective tumor suppression with high biosafety in the large-volume tumor models after three rounds of PDT. This nanobody conjugate provides a paradigm for the design of precise long-time retention photosensitizers and is expected to promote the development of PDT.

Improving synthesis and binding affinities of nucleic acid aptamers and their therapeutics and diagnostic applications

Nucleic acid aptamers have captivated the attention of analytical and medicinal scientists globally due to their several advantages as recognition molecules over conventional antibodies because of their small size, simple and inexpensive synthesis, broad target range, and high stability in varied environmental conditions. These recognition molecules can be chemically modified to make them resistant to nuclease action in blood serum, reduce rapid renel clearance, improve the target affinity and selectivity, and make them amenable to chemically conjugate with a support system that facilitates their selective applications. This review focuses on the development of efficient aptamer candidates and their application in clinical diagnosis and therapeutic applications. Significant advances have been made in aptamer-based diagnosis of infectious and non-infectious diseases. Collaterally, the progress made in therapeutic applications of aptamers is encouraging, as evident from their use in diagnosing cancer, neurodegenerative diseases, microbial infection, and in imaging. This review also updates the progress on clinical trials of many aptamer-based products of commercial interests. The key development and critical issues on the subject have been summarized in the concluding remarks.

Quercetin: A Functional Food-Flavonoid Incredibly Attenuates Emerging and Re-Emerging Viral Infections through Immunomodulatory Actions

Many of the medicinally active molecules in the flavonoid class of phytochemicals are being researched for their potential antiviral activity against various DNA and RNA viruses. Quercetin is a flavonoid that can be found in a variety of foods, including fruits and vegetables. It has been reported to be effective against a variety of viruses. This review, therefore, deciphered the mechanistic of how Quercetin works against some of the deadliest viruses, such as influenza A, Hepatitis C, Dengue type 2 and Ebola virus, which cause frequent outbreaks worldwide and result in significant morbidity and mortality in humans through epidemics or pandemics. All those have an alarming impact on both human health and the global and national economies. The review extended computing the Quercetin-contained natural recourse and its modes of action in different experimental approaches leading to antiviral actions. The gap in effective treatment emphasizes the necessity of a search for new effective antiviral compounds. Quercetin shows potential antiviral activity and inhibits it by targeting viral infections at multiple stages. The suppression of viral neuraminidase, proteases and DNA/RNA polymerases and the alteration of many viral proteins as well as their immunomodulation are the main molecular mechanisms of Quercetin's antiviral activities. Nonetheless, the huge potential of Quercetin and its extensive use is inadequately approached as a therapeutic for emerging and re-emerging viral infections. Therefore, this review enumerated the food-functioned Quercetin source, the modes of action of Quercetin for antiviral effects and made insights on the mechanism-based antiviral action of Quercetin.

Aptamers-Diagnostic and Therapeutic Solution in SARS-CoV-2

The SARS-CoV-2 virus is currently the most serious challenge to global public health. Its emergence has severely disrupted the functioning of health services and the economic and social situation worldwide. Therefore, new diagnostic and therapeutic tools are urgently needed to allow for the early detection of the SARS-CoV-2 virus and appropriate treatment, which is crucial for the effective control of the COVID-19 disease. The ideal solution seems to be the use of aptamers—short fragments of nucleic acids, DNA or RNA—that can bind selected proteins with high specificity and affinity. They can be used in methods that base the reading of the test result on fluorescence phenomena, chemiluminescence, and electrochemical changes. Exploiting the properties of aptamers will enable the introduction of rapid, sensitive, specific, and low-cost tests for the routine diagnosis of SARS-CoV-2. Aptamers are excellent candidates for the development of point-of-care diagnostic devices and are potential therapeutic tools for the treatment of COVID-19. They can effectively block coronavirus activity in multiple fields by binding viral proteins and acting as carriers of therapeutic substances. In this review, we present recent developments in the design of various types of aptasensors to detect and treat the SARS-CoV-2 infection.

Aptamer-Based Antibacterial and Antiviral Therapy against Infectious Diseases

Nucleic acid aptamers are single-stranded DNA or RNA molecules selected in vitro that can bind to a broad range of targets with high affinity and specificity. As promising alternatives to conventional anti-infective agents, aptamers have gradually revealed their potential in the combat against infectious diseases. This article provides an overview on the state-of-art of aptamer-based antibacterial and antiviral therapeutic strategies. Diverse aptamers targeting pathogen-related components or whole pathogenic cells are summarized according to the species of microorganisms. These aptamers exhibited remarkable in vitro and/or in vivo inhibitory effect for pathogenic invasion, enzymatic activities, or viral replication, even for some highly drug-resistant strains and biofilms. Aptamer-mediated drug delivery and controlled drug release strategies are also included herein. Critical technical barriers of therapeutic aptamers are briefly discussed, followed by some future perspectives for their implementation into clinical utility.

Oligonucleotide aptamers for pathogen detection and infectious disease control

During an epidemic or pandemic, the primary task is to rapidly develop precise diagnostic approaches and effective therapeutics. Oligonucleotide aptamer-based pathogen detection assays and control therapeutics are promising, as aptamers that specifically recognize and block pathogens can be quickly developed and produced through simple chemical synthesis. This work reviews common aptamer-based diagnostic techniques for communicable diseases and summarizes currently available aptamers that target various pathogens, including the SARS-CoV-2 virus. Moreover, this review discusses how oligonucleotide aptamers might be leveraged to control pathogen propagation and improve host immune system responses. This review offers a comprehensive data source to the further develop aptamer-based diagnostics and therapeutics specific for infectious diseases.

Hybrid-Type SELEX for the Selection of Artificial Nucleic Acid Aptamers Exhibiting Cell Internalization Activity

Nucleic acid aptamers have attracted considerable attention as next-generation pharmaceutical agents and delivery vehicles for small molecule drugs and therapeutic oligonucleotides. Chemical modification is an effective approach for improving the functionality of aptamers. However, the process of selecting appropriately modified aptamers is laborious because of many possible modification patterns. Here, we describe a hybrid-type systematic evolution of ligands by exponential enrichment (SELEX) approach for the generation of the artificial nucleic acid aptamers effective against human TROP2, a cell surface protein identified by drug discovery as a promising target for cancer therapy. Capillary electrophoresis SELEX was used for the pre-screening of multiple modified nucleic acid libraries and enrichment of TROP2 binding aptamers in the first step, followed by functional screening using cell-SELEX in the second step for the generation of cell-internalizing aptamers. One representative aptamer, Tac-B1, had a nanomolar-level affinity to human TROP2 and exhibited elevated capacity for internalization by cells. Because of the growing interest in the application of aptamers for drug delivery, our hybrid selection approach has great potential for the generation of functional artificial nucleic acid aptamers with ideal modification patterns in vitro.

How SARS-CoV-2 and Other Viruses Build an Invasion Route to Hijack the Host Nucleocytoplasmic Trafficking System

The host nucleocytoplasmic trafficking system is often hijacked by viruses to accomplish their replication and to suppress the host immune response. Viruses encode many factors that interact with the host nuclear transport receptors (NTRs) and the nucleoporins of the nuclear pore complex (NPC) to access the host nucleus. In this review, we discuss the viral factors and the host factors involved in the nuclear import and export of viral components. As nucleocytoplasmic shuttling is vital for the replication of many viruses, we also review several drugs that target the host nuclear transport machinery and discuss their feasibility for use in antiviral treatment.

Aptamers for Anti-Viral Therapeutics and Diagnostics

Viral infections cause a host of fatal diseases and seriously affect every form of life from bacteria to humans. Although most viral infections can receive appropriate treatment thereby limiting damage to life and livelihood with modern medicine and early diagnosis, new types of viral infections are continuously emerging that need to be properly and timely treated. As time is the most important factor in the progress of many deadly viral diseases, early detection becomes of paramount importance for effective treatment. Aptamers are small oligonucleotide molecules made by the systematic evolution of ligands by exponential enrichment (SELEX). Aptamers are characterized by being able to specifically bind to a target, much like antibodies. However, unlike antibodies, aptamers are easily synthesized, modified, and are able to target a wider range of substances, including proteins and carbohydrates. With these advantages in mind, many studies on aptamer-based viral diagnosis and treatments are currently in progress. The use of aptamers for viral diagnosis requires a system that recognizes the binding of viral molecules to aptamers in samples of blood, serum, plasma, or in virus-infected cells. From a therapeutic perspective, aptamers target viral particles or host cell receptors to prevent the interaction between the virus and host cells or target intracellular viral proteins to interrupt the life cycle of the virus within infected cells. In this paper, we review recent attempts to use aptamers for the diagnosis and treatment of various viral infections.

Discovery of cell-internalizing artificial nucleic acid aptamers for lung fibroblasts and targeted drug delivery

Lung fibroblasts play major roles in the lung repair/fibrosis process through synthesis and remodeling of extracellular matrix. Those aberrant activations and elevated proliferations are associated with several fibrotic lung diseases, such as idiopathic pulmonary fibrosis (IPF). Targeting fibroblasts is a promising approach for preventing aberrant remodeling of lung architecture and protect irreversible pulmonary fibrosis. In this study, we developed an aptamer that can target lung fibroblasts and explored its potential as a delivery vehicle of cytotoxic agents intracellularly. The aptamer was discovered from artificial nucleic acid libraries through cell-based systematic evolution of ligands by exponential enrichment (cell-SELEX). This indole-modified aptamer can bind to LL97A cells, a fibroblast cell line derived from IPF patients, with high affinity (K_d = 70 nM). It also showed affinity to other lung fibroblasts, while cross-reactivity to epithelial cells was minimal. An aptamer-monomethyl auristatin F (MMAF) conjugate was generated by hybridizing with complementary DNA linked to MMAF. The resulting aptamer-MMAF conjugate inhibited proliferation of fibroblasts but appeared non-toxic to non-targeted epithelial cells. Our results show that artificial nucleic acid aptamer may potentially be used for fibroblast-specific therapy and diagnostic applications.

Quercetin Blocks Ebola Virus Infection by Counteracting the VP24 Interferon-Inhibitory Function

Ebola virus (EBOV) is among the most devastating pathogens causing fatal hemorrhagic fever in humans. The epidemics from 2013 to 2016 resulted in more than 11,000 deaths, and another outbreak is currently ongoing. Since there is no FDA-approved drug so far to fight EBOV infection, there is an urgent need to focus on drug discovery. Considering the tight correlation between the high EBOV virulence and its ability to suppress the type I interferon (IFN-I) system, identifying molecules targeting viral protein VP24, one of the main virulence determinants blocking the IFN response, is a promising novel anti-EBOV therapy approach. Hence, in the effort to find novel EBOV inhibitors, a screening of a small set of flavonoids was performed; it showed that quercetin and wogonin can suppress the VP24 effect on IFN-I signaling inhibition. The mechanism of action of the most active compound, quercetin, showing a half-maximal inhibitory concentration (IC₅₀) of 7.4 μM, was characterized to significantly restore the IFN-I signaling cascade, blocked by VP24, by directly interfering with the VP24 binding to karyopherin-α and thus restoring P-STAT1 nuclear transport and IFN gene transcription. Quercetin significantly blocked viral infection, specifically targeting EBOV VP24 anti-IFN-I function. Overall, quercetin is the first identified inhibitor of the EBOV VP24 anti-IFN function, representing a molecule interacting with a viral binding site that is very promising for further drug development aiming to block EBOV infection at the early steps.

Insights into Ebola Virus VP35 and VP24 Interferon Inhibitory Functions and their Initial Exploitation as Drug Targets

Upon viral infection, the interferon (IFN) system triggers potent antiviral mechanisms limiting viral growth and spread. Hence, to sustain their infection, viruses evolved efficient counteracting strategies to evade IFN control. Ebola virus (EBOV), member of the family Filoviridae, is one of the most virulent and deadly pathogen ever faced by humans. The etiological agent of the Ebola Virus Disease (EVD), EBOV can be undoubtedly considered the perfect example of a powerful inhibitor of the host organism immune response activation. Particularly, the efficacious suppression of the IFN cascade contributes to disease progression and severity. Among the EBOVencoded proteins, the Viral Proteins 35 (VP35) and 24 (VP24) are responsible for the EBOV extreme virulence, representing the core of such inhibitory function through which EBOV determines its very effective shield to the cellular immune defenses. VP35 inhibits the activation of the cascade leading to IFN production, while VP24 inhibits the activation of the IFN-stimulated genes. A number of studies demonstrated that both VP35 and VP24 is validated target for drug development. Insights into the structural characteristics of VP35 and VP24 domains revealed crucial pockets exploitable for drug development. Considered the lack of therapy for EVD, restoring the immune activation is a promising approach for drug development. In the present review, we summarize the importance of VP35 and VP24 proteins in counteracting the host IFN cellular response and discuss their potential as druggable viral targets as a promising approach toward attenuation of EBOV virulence.