Targeted small interfering RNA-immunoliposomes as a promising therapeutic agent against highly pathogenic Avian Influenza A (H5N1) virus infection

Leveraging immunoliposomes as nanocarriers against SARS-CoV-2 and its emerging variants

The global COVID-19 pandemic arising from SARS-CoV-2 has impacted many lives, gaining interest worldwide ever since it was first identified in December 2019. Till 2023, 752 million cumulative cases and 6.8 million deaths were documented globally. COVID-19 has been rapidly evolving, affecting virus transmissibility and properties and contributing to increased disease severity. The Omicron is the most circulating variant of concern. Although success in its treatment has indicated progress in tackling the virus, limitations in delivering the current antiviral agents in battling emerging variants remain remarkable. With the latest advancements in nanotechnology for controlling infectious diseases, liposomes have the potential to counteract SARS-CoV-2 because of their ability to employ different targeting strategies, incorporating monoclonal antibodies for the active and passive targeting of infected patients. This review will present a concise summary of the possible strategies for utilizing immunoliposomes to improve current treatment against the occurrence of SARS-CoV-2 and its variants.

Functionalized lipid-based drug delivery nanosystems for the treatment of human infectious diseases

Infectious diseases are still public health problems. Microorganisms such as fungi, bacteria, viruses, and parasites are the main causing agents related to these diseases. In this context, the search for new effective strategies in prevention and/or treatment is considered essential, since current drugs often have side effects or end up, causing microbial resistance, making it a serious health problem. As an alternative to these limitations, nanotechnology has been widely used. The use of lipid-based drug delivery nanosystems (DDNs) has some advantages, such as biocompatibility, low toxicity, controlled release, the ability to carry both hydrophilic and lipophilic drugs, in addition to be easel scalable. Besides, as an improvement, studies involving the conjugation of signalling molecules on the surfaces of these nanocarriers can allow the target of certain tissues or cells. Thus, this review summarizes the performance of functionalized lipid-based DDNs for the treatment of infectious diseases caused by viruses, including SARS-CoV-2, bacteria, fungi, and parasites.

Improving siRNA design targeting nucleoprotein gene as antiviral against the Indonesian H5N1 virus

Background

Small interfering RNA technology has been considered a prospective alternative antiviral treatment using gene silencing against influenza viruses with high mutations rates. On the other hand, there are no reports on its effectiveness against the highly pathogenic avian influenza H5N1 virus isolated from Indonesia.

Objectives

The main objective of this study was to improve the siRNA design based on the nucleoprotein gene (siRNA-NP) for the Indonesian H5N1 virus.

Methods

The effectiveness of these siRNA-NPs (NP672, NP1433, and NP1469) was analyzed in vitro in Marbin-Darby canine kidney cells.

Results

The siRNA-NP672 caused the largest decrease in viral production and gene expression at 24, 48, and 72 h post-infection compared to the other siRNA-NPs. Moreover, three serial passages of the H5N1 virus in the presence of siRNA-NP672 did not induce any mutations within the nucleoprotein gene.

Conclusions

These findings suggest that siRNA-NP672 can provide better protection against the Indonesian strain of the H5N1 virus.

Brief on Recent Application of Liposomal Vaccines for Lower Respiratory Tract Viral Infections: From Influenza to COVID-19 Vaccines

Vaccination is the most effective means of preventing infectious diseases and saving lives. Modern biotechnology largely enabled vaccine development. In the meantime, recent advances in pharmaceutical technology have resulted in the emergence of nanoparticles that are extensively investigated as promising miniaturized drug delivery systems. Scientists are particularly interested in liposomes as an important carrier for vaccine development. Wide acceptability of liposomes lies in their flexibility and versatility. Due to their unique vesicular structure with alternating aqueous and lipid compartments, liposomes can enclose both hydrophilic and lipophilic compounds, including antigens. Liposome composition can be tailored to obtain the desired immune response and adjuvant characteristics. During the current pandemic of COVID-19, many liposome-based vaccines have been developed with great success. This review covers a liposome-based vaccine designed particularly to combat viral infection of the lower respiratory tract (LRT), i.e., infection of the lung, specifically in the lower airways. Viruses such as influenza, respiratory syncytial virus (RSV), severe acute respiratory syndrome (SARS-CoV-1 and SARS-CoV-2) are common causes of LRT infections, hence this review mainly focuses on this category of viruses.

Effective Inhibition of Newly Emerged A/H7N9 Virus with Oligonucleotides Targeted to Conserved Regions of the Virus Genome

Newly emerged highly pathogenic A/H7N9 viruses with pandemic potential are effectively transmitted from birds to humans and require the development of novel antiviral drugs. For the first time, we studied the in vitro and in vivo antiviral activity against A/H7N9 of oligodeoxyribonucleotides (ODNs), which were delivered into the cells in the proposed TiO₂-based nanocomposites (TiO₂∼ODN). The highest inhibition of A/H7N9 in vitro (∼400-fold) and efficient, sequence-specific, and dose-dependent protection (up to 100%) of A/H7N9-infected mice was revealed when ODN was targeted to the conserved terminal 3'-noncoding region of viral (-)RNA. After the treatment with ODN, the virus titer values in the lungs of mice decreased by several orders of magnitude. The TiO₂∼ODN nanocomposite did not show toxicity in mice under the treatment conditions. The proposed approach for effective inhibition of the A/H7N9 can be tested against other viruses, for example, new emerging influenza viruses and coronaviruses with pandemic potential.

Nanomedicine based approaches for combating viral infections

Millions of people die each year from viral infections across the globe. There is an urgent need to overcome the existing gap and pitfalls of the current antiviral therapy which include increased dose and dosing frequency, bioavailability challenges, non-specificity, incidences of resistance and so on. These stumbling blocks could be effectively managed by the advent of nanomedicine. Current review emphasizes over an enhanced understanding of how different lipid, polymer and elemental based nanoformulations could be potentially and precisely used to bridle the said drawbacks in antiviral therapy. The dawn of nanotechnology meeting vaccine delivery, role of RNAi therapeutics in antiviral treatment regimen, various regulatory concerns towards clinical translation of nanomedicine along with current trends and implications including unexplored research avenues for advancing the current drug delivery have been discussed in detail.

Matrix Metalloproteinase 2 Knockdown Suppresses the Proliferation of HepG2 and Huh7 Cells and Enhances the Cisplatin Effect

Background

This study evaluated the functions of matrix metalloproteinase 2 (MMP2) in hepatocellular carcinoma (HCC) cells and assessed the effects of MMP2 on HCC cell sensitivity to cisplatin.

Methodology

HepG2 and Huh7 cells were cultured. A pre-experiment was performed to explore the optimal transduction conditions of the MMP2-siRNA lentivirus (si-MMP2). Quantitative real-time PCR and western blot assays were performed to measure the expression levels of MMP2 in HepG2 and Huh7 cells. An MTT assay was used to evaluate cell proliferation, and flow cytometry analysis was applied to examine cell apoptosis. A Transwell assay was carried out to assess cell invasion.

Results

The optimal virus:cell ratio was 100 multiplicity of infection (MOI) for both cells, and the optimal transduction times for HepG2 and Huh7 cells were 48 h and 72 h, respectively. MMP2 knockdown significantly decreased the mRNA and protein levels of MMP2 in both cell lines (P<0.01). MMP2 knockdown significantly decreased the proliferation and increased the apoptosis of HepG2 and Huh7 cells (P<0.01). Co-treatment with si-MMP2 and cisplatin significantly increased the sensitivity of HepG2 and Huh7 cells to cisplatin (P<0.01).

Conclusion

MMP2 may act as an oncogene and may be a potential therapeutic target in HCC.

Immunoliposomes: A review on functionalization strategies and targets for drug delivery

Nanoparticles, especially liposomes, have gained prominence in the field of drug delivery for the treatment of human diseases, particularly cancer; they provide several advantages, including controlled drug release, protection of the drug against degradation, improved pharmacokinetics, long circulation, and passive targeting to tumors and inflammatory sites due to the enhanced permeability and retention effect. The functionalization of liposomes with monoclonal antibodies or antibody fragments to generate immunoliposomes has emerged as a promising strategy for targeted delivery to and uptake by cells overexpressing the antigens to these antibodies, with a consequent reduction in side effects. In this review, we address functionalization strategies for the non-covalent and covalent attachment of monoclonal antibodies and their fragments to liposomal surfaces. The main reaction occurs between the sulfhydryl groups of thiolated antibodies and maleimide-containing liposomes. Furthermore, we explore the main targeting possibilities with these ligands for the treatment of a variety of pathologies, including HER2- and EGFR-positive cancers, inflammatory and cardiovascular diseases, infectious diseases, and autoimmune and neurodegenerative diseases, which have not previously been reviewed together. Overall, many studies have shown selective delivery of immunoliposomes to target cells, with promising in vivo results, particularly for cancer treatment. Although clinical trials have been conducted, immunoliposomes have not yet received clinical approval. However, immunoliposomes are promising formulations that are expected to become available for therapeutic use after clinical trials prove their safety and efficacy, and after scaling issues are resolved.

Delivery of RNAi Therapeutics to the Airways-From Bench to Bedside

RNA interference (RNAi) is a potent and specific post-transcriptional gene silencing process. Since its discovery, tremendous efforts have been made to translate RNAi technology into therapeutic applications for the treatment of different human diseases including respiratory diseases, by manipulating the expression of disease-associated gene(s). Similar to other nucleic acid-based therapeutics, the major hurdle of RNAi therapy is delivery. Pulmonary delivery is a promising approach of delivering RNAi therapeutics directly to the airways for treating local conditions and minimizing systemic side effects. It is a non-invasive route of administration that is generally well accepted by patients. However, pulmonary drug delivery is a challenge as the lungs pose a series of anatomical, physiological and immunological barriers to drug delivery. Understanding these barriers is essential for the development an effective RNA delivery system. In this review, the different barriers to pulmonary drug delivery are introduced. The potential of RNAi molecules as new class of therapeutics, and the latest preclinical and clinical studies of using RNAi therapeutics in different respiratory conditions are discussed in details. We hope this review can provide some useful insights for moving inhaled RNAi therapeutics from bench to bedside.

Targeting the pseudorabies virus DNA polymerase processivity factor UL42 by RNA interference efficiently inhibits viral replication

RNA interference (RNAi) is a conserved gene-silencing mechanism in which small interfering RNAs (siRNAs) induce the sequence-specific degradation of homologous RNAs. It has been shown to be a novel and effective antiviral therapy against a wide range of viruses. The pseudorabies virus (PRV) processivity factor UL42 can enhance the catalytic activity of the DNA polymerase and is essential for viral replication, thus it may represent a potential drug target of antiviral therapy against PRV infection. Here, we synthesized three siRNAs (siR-386, siR-517, and siR-849) directed against UL42 and determined their antiviral activities in cell culture. We first examined the kinetics of UL42 expression and found it was expressed with early kinetics during PRV replication. We verified that siR-386, siR-517, and siR-849 efficiently inhibited UL42 expression in an in vitro transfection system, thereby validating their inhibitory effects. Furthermore, we confirmed that these three siRNAs induced potent inhibitory effects on UL42 expression after PRV infection, comparable to the positive control siRNA, siR-1046, directed against the PRV DNA polymerase, the UL30 gene product, which is essential for virus replication. In addition, PRV replication was markedly reduced upon downregulation of UL42 expression. These results indicate that UL42-targeted RNAi efficiently inhibits target gene expression and impairs viral replication. This study provides a new clue for the design of an intervention strategy against herpesviruses by targeting their processivity factors.

Adding Functions to Biomaterial Surfaces through Protein Incorporation

The concept of biomaterials has evolved from one of inert mechanical supports with a long-term, biologically inactive role in the body into complex matrices that exhibit selective cell binding, promote proliferation and matrix production, and may ultimately become replaced by newly generated tissues in vivo. Functionalization of material surfaces with biomolecules is critical to their ability to evade immunorecognition, interact productively with surrounding tissues and extracellular matrix, and avoid bacterial colonization. Antibody molecules and their derived fragments are commonly immobilized on materials to mediate coating with specific cell types in fields such as stent endothelialization and drug delivery. The incorporation of growth factors into biomaterials has found application in promoting and accelerating bone formation in osteogenerative and related applications. Peptides and extracellular matrix proteins can impart biomolecule- and cell-specificities to materials while antimicrobial peptides have found roles in preventing biofilm formation on devices and implants. In this progress report, we detail developments in the use of diverse proteins and peptides to modify the surfaces of hard biomaterials in vivo and in vitro. Chemical approaches to immobilizing active biomolecules are presented, as well as platform technologies for isolation or generation of natural or synthetic molecules suitable for biomaterial functionalization.

Use of single chain antibody derivatives for targeted drug delivery

Single chain antibodies (scFvs), which contain only the variable domains of full-length antibodies, are relatively small molecules that can be used for selective drug delivery. In this review, we display how scFv antibodies help improve the specificity and efficiency of drugs. Small interfering RNA (siRNA) delivery using scFv-drug fusion peptides, siRNA delivery using scFv-conjugated nanoparticles, targeted delivery using scFv-viral peptide- fusion proteins, use of scFv in fusion with cell penetrating peptides for effective targeted drug delivery, scFv-mediated targeted delivery of inorganic nanoparticles, scFv-mediated increase of tumor killing activity of granulocytes, use of scFv for tumor imaging, site-directed conjugation of scFv molecules to drug carrier systems, use of scFv to relieve pain, use of scFv for increasing drug loading efficiency are among the topics that are discussed here.

Inhibiting avian influenza virus shedding using a novel RNAi antiviral vector technology: proof of concept in an avian cell model

Influenza A viruses pose significant health and economic threats to humans and animals. Outbreaks of avian influenza virus (AIV) are a liability to the poultry industry and increase the risk for transmission to humans. There are limitations to using the AIV vaccine in poultry, creating barriers to controlling outbreaks and a need for alternative effective control measures. Application of RNA interference (RNAi) techniques hold potential; however, the delivery of RNAi-mediating agents is a well-known obstacle to harnessing its clinical application. We introduce a novel antiviral approach using bacterial vectors that target avian mucosal epithelial cells and deliver (small interfering RNA) siRNAs against two AIV genes, nucleoprotein (NP) and polymerase acidic protein (PA). Using a red fluorescent reporter, we first demonstrated vector delivery and intracellular expression in avian epithelial cells. Subsequently, we demonstrated significant reductions in AIV shedding when applying these anti-AIV vectors prophylactically. These antiviral vectors provided up to a 10,000-fold reduction in viral titers shed, demonstrating in vitro proof-of-concept for using these novel anti-AIV vectors to inhibit AIV shedding. Our results indicate this siRNA vector technology could represent a scalable and clinically applicable antiviral technology for avian and human influenza and a prototype for RNAi-based vectors against other viruses.

High antiviral effect of TiO2·PL-DNA nanocomposites targeted to conservative regions of (-)RNA and (+)RNA of influenza A virus in cell culture

Background: The development of new antiviral drugs based on nucleic acids is under scrutiny. An important problem in this aspect is to find the most vulnerable conservative regions in the viral genome as targets for the action of these agents. Another challenge is the development of an efficient system for their delivery into cells. To solve this problem, we proposed a TiO₂·PL-DNA nanocomposite consisting of titanium dioxide nanoparticles and polylysine (PL)-containing oligonucleotides. Results: The TiO₂·PL-DNA nanocomposites bearing the DNA fragments targeted to different conservative regions of (-)RNA and (+)RNA of segment 5 of influenza A virus (IAV) were studied for their antiviral activity in MDCK cells infected with the H1N1, H5N1, and H3N2 virus subtypes. Within the negative strand of each of the studied strains, the efficiency of DNA fragments increased in the direction of its 3'-end. Thus, the DNA fragment aimed at the 3'-noncoding region of (-)RNA was the most efficient and inhibited the reproduction of different IAV subtypes by 3-4 orders of magnitude. Although to a lesser extent, the DNA fragments targeted at the AUG region of (+)RNA and the corresponding region of (-)RNA were also active. For all studied viral subtypes, the nanocomposites bearing the DNA fragments targeted to (-)RNA appeared to be more efficient than those containing fragments aimed at the corresponding (+)RNA regions. Conclusion: The proposed TiO₂·PL-DNA nanocomposites can be successfully used for highly efficient and site-specific inhibition of influenza A virus of different subtypes. Some patterns of localization of the most vulnerable regions in IAV segment 5 for the action of DNA-based drugs were found. The (-)RNA strand of IAV segment 5 appeared to be more sensitive as compared to (+)RNA.

Design and Generation of Humanized Single-chain Fv Derived from Mouse Hybridoma for Potential Targeting Application

Single-chain variable antibody fragments (scFvs) are attractive candidates for targeted immunotherapy in several human diseases. In this study, a concise humanization strategy combined with an optimized production method for humanizing scFvs was successfully employed. Two antibody clones, one directed against the hemagglutinin of H5N1 influenza virus, the other against EpCAM, a cancer biomarker, were used to demonstrate the validity of the method. Heavy chain (VH) and light chain (VL) variable regions of immunoglobulin genes from mouse hybridoma cells were sequenced and subjected to the construction of mouse scFv 3-D structure. Based on in silico modeling, the humanized version of the scFv was designed via complementarity-determining region (CDR) grafting with the retention of mouse framework region (FR) residues identified by primary sequence analysis. Root-mean-square deviation (RMSD) value between mouse and humanized scFv structures was calculated to evaluate the preservation of CDR conformation. Mouse and humanized scFv genes were then constructed and expressed in Escherichia coli. Using this method, we successfully generated humanized scFvs that retained the targeting activity of their respective mouse scFv counterparts. In addition, the humanized scFvs were engineered with a C-terminal cysteine residue (hscFv-C) for site-directed conjugation for use in future targeting applications. The hscFv-C expression was extensively optimized to improve protein production yield. The protocol yielded a 20-fold increase in production of hscFv-Cs in E. coli periplasm. The strategy described in this study may be applicable in the humanization of other antibodies derived from mouse hybridoma.

Achieving successful delivery of oligonucleotides--From physico-chemical characterization to in vivo evaluation

RNA interference is one of the most promising fields in modern medicine to treat several diseases, ranging from cancer to cardiac diseases, passing through viral infections and metabolic pathologies. Since the discovery of the potential therapeutic properties of non-self oligonucleotides, it was clear that it is important to develop delivery systems that are able to increase plasma stability and bestow membrane-crossing abilities to the oligonucleotides in order to reach their cytoplasmic targets. Polymer therapeutics, among other systems, are widely investigated as delivery systems for therapeutic agents, such as oligonucleotides. Physico-chemical characterization of the supramolecular polyplexes obtained upon charge interaction or covalent conjugation between the polymeric carrier and the oligonucleotides is critical. Appropriate characterization is fundamental in order to predict and understand the in vivo silencing efficacy and to avoid undesired side effects and toxicity profile. Shedding light on the physico-chemical and in vitro requirements of a polyplex leads to an efficient in vivo delivery system for RNAi therapeutics. In this review, we will present the most common techniques for characterization of obtained polymer/oligonucleotide polyplexes and an up-to-date state of the art in vivo preclinical and clinical studies. This is the first review to deal with the difficulties in appropriate characterization of small interfering RNA (siRNA) or microRNA (miRNA) polyplexes and conjugates which limit the clinical translation of this promising technology.

Gene silencing: a therapeutic approach to combat influenza virus infections

ABSTRACT 

Selective gene silencing technologies such as RNA interference (RNAi) and nucleic acid enzymes have shown therapeutic potential for treating viral infections. Influenza virus is one of the major public health concerns around the world and its management is challenging due to a rapid increase in antiviral resistance. Influenza vaccine also has its limitations due to the emergence of new strains that may escape the immunity developed by the previous year's vaccine. Antiviral drugs are the primary mode of prevention and control against a pandemic and there is an urgency to develop novel antiviral strategies against influenza virus. In this review, we discuss the potential utility of several gene silencing mechanisms and their prophylactic and therapeutic potential against the influenza virus.

Active targeted drug delivery for microbes using nano-carriers

Although vaccines and antibiotics could kill or inhibit microbes, many infectious diseases remain difficult to treat because of acquired resistance and adverse side effects. Nano-carriers-based technology has made significant progress for a long time and is introducing a new paradigm in drug delivery. However, it still has some challenges like lack of specificity toward targeting the infectious site. Nanocarriers utilized targeting ligands on their surface called 'active target' provide the promising way to solve the problems like accelerating drug delivery to infectious areas and preventing toxicity or side-effects. In this mini review, we demonstrate the recent studies using the active targeted strategy to kill or inhibit microbes. The four common nano-carriers (e.g. liposomes, nanoparticles, dendrimers and carbon nanotubes) delivering encapsulated drugs are introduced.

Stealth anti-CD4 conjugated immunoliposomes with dual antiretroviral drugs--modern Trojan horses to combat HIV

Highly active antiretroviral therapy (HAART) is the currently employed therapeutic intervention against AIDS where a drug combination is used to reduce the viral load. The present work envisages the development of a stealth anti-CD4 conjugated immunoliposomes containing two anti-retroviral drugs (nevirapine and saquinavir) that can selectively home into HIV infected cells through the CD4 receptor. The nanocarrier was characterized using transmission electron microscopy, FTIR, differential scanning calorimetry, particle size and zeta potential. The cell uptake was also evaluated qualitatively using confocal microscopy and quantitatively by flow cytometry. The drug to lipid composition was optimized for maximum encapsulation of the two drugs. Both drugs were found to localize in different regions of the liposome. The release of the reverse transcriptase inhibitor was dominant during the early phases of the release while in the later phases, the protease inhibitor is the major constituent released. The drugs delivered via anti-CD4 conjugated immunoliposomes inhibited viral proliferation at a significantly lower concentration as compared to free drugs. In vitro studies of nevirapine to saquinavir combination at a ratio of 6.2:5 and a concentration as low as 5 ng/mL efficiently blocked viral proliferation suggesting that co-delivery of anti-retroviral drugs holds a greater promise for efficient management of HIV-1 infection.

Lipid nanoparticles as carriers for RNAi against viral infections: current status and future perspectives

The efforts made to develop RNAi-based therapies have led to productive research in the field of infections in humans, such as hepatitis C virus (HCV), hepatitis B virus (HBV), human immunodeficiency virus (HIV), human cytomegalovirus (HCMV), herpetic keratitis, human papillomavirus, or influenza virus. Naked RNAi molecules are rapidly digested by nucleases in the serum, and due to their negative surface charge, entry into the cell cytoplasm is also hampered, which makes necessary the use of delivery systems to exploit the full potential of RNAi therapeutics. Lipid nanoparticles (LNP) represent one of the most widely used delivery systems for in vivo application of RNAi due to their relative safety and simplicity of production, joint with the enhanced payload and protection of encapsulated RNAs. Moreover, LNP may be functionalized to reach target cells, and they may be used to combine RNAi molecules with conventional drug substances to reduce resistance or improve efficiency. This review features the current application of LNP in RNAi mediated therapy against viral infections and aims to explore possible future lines of action in this field.