Single-stranded DNA (ssDNA) Aptamer targeting SipA protein inhibits Salmonella Enteritidis invasion of intestinal epithelial cells

Aptamers: precision tools for diagnosing and treating infectious diseases

Infectious diseases represent a significant global health challenge, with bacteria, fungi, viruses, and parasitic protozoa being significant causative agents. The shared symptoms among diseases and the emergence of new pathogen variations make diagnosis and treatment complex. Conventional diagnostic methods are laborious and intricate, underscoring the need for rapid, accurate techniques. Aptamer-based technologies offer a promising solution, as they are cost-effective, sensitive, specific, and convenient for molecular disease diagnosis. Aptamers, which are single-stranded RNA or DNA sequences, serve as nucleotide equivalents of monoclonal antibodies, displaying high specificity and affinity for target molecules. They are structurally robust, allowing for long-term storage without substantial activity loss. Aptamers find applications in diverse fields such as drug screening, material science, and environmental monitoring. In biomedicine, they are extensively studied for biomarker detection, diagnostics, imaging, and targeted therapy. This comprehensive review focuses on the utility of aptamers in managing infectious diseases, particularly in the realms of diagnostics and therapeutics.

Applications and Challenges of Bacteriostatic Aptamers in the Treatment of Common Pathogenic Bacteria Infections

The continuous evolution and spread of common pathogenic bacteria is a major challenge in diagnosis and treatment with current biotechnology and modern molecular medicine. To confront this challenge, scientists urgently need to find alternatives for traditional antimicrobial agents. Various bacteriostatic aptamers obtained through SELEX screening are one of the most promising strategies. These bacteriostatic aptamers can reduce bacterial infection by blocking bacterial toxin infiltration, inhibiting biofilm formation, preventing bacterial invasion of immune cells, interfering with essential biochemical processes, and other mechanisms. In addition, aptamers may also help enhance the function of other antibacterial materials/drugs when used in combination. This paper has reviewed the bacteriostatic aptamers in the treatment of common pathogenic bacteria infections. For this aspect, first, bacteriostatic aptamers and their screening strategies are summarized. Then, the effect of molecular tailoring and modification on the performance of the bacteriostatic aptamer is analyzed, and the antibacterial mechanism and antibacterial strategy based on aptamers are introduced. Finally, the key technical challenges and their development prospects in clinical treatment are also carefully discussed.

Aptamer-based assay for rapid detection, surveillance, and screening of pathogenic Leptospira in water samples

Leptospirosis is a potentially fatal waterborne infection caused by Leptospira interrogans, impacting both humans and animals in tropical regions. However, current diagnostic methods for detecting pathogenic Leptospira have sensitivity, cost, and time limitations. Therefore, there is a critical need for a rapid, sensitive, and cost-effective detection method. This study presents the development of an aptamer-based assay for pathogenic Leptospira detection. Aptamers targeting Leptospira were generated using the SELEX method and screened for binding affinity with major Leptospiral outer membrane proteins through in silico analysis. The aptamer with the highest binding affinity was selected for further evaluation. To enable visual detection, the aptamer was conjugated to gold nanoparticles (AuNPs), resulting in a colorimetric response in the presence of L. interrogans. The aptamer-AuNP-based colorimetric assay exhibited a detection limit of 57 CFU/mL and demonstrated high specificity and reproducibility in detecting pathogenic Leptospira in water samples. This aptamer-based assay represents a significant advancement in leptospirosis diagnostics, offering a rapid, sensitive, and cost-effective approach for detecting pathogenic Leptospira. Its potential for epidemiological applications, such as outbreak source identification and improved prevention, diagnosis, and treatment, particularly in resource-limited settings, highlights its importance in addressing the challenges associated with leptospirosis.

Research Progress on Small Molecular Inhibitors of the Type 3 Secretion System

The overuse of antibiotics has led to severe bacterial drug resistance. Blocking pathogen virulence devices is a highly effective approach to combating bacterial resistance worldwide. Type three secretion systems (T3SSs) are significant virulence factors in Gram-negative pathogens. Inhibition of these systems can effectively weaken infection whilst having no significant effect on bacterial growth. Therefore, T3SS inhibitors may be a powerful weapon against resistance in Gram-negative bacteria, and there has been increasing interest in the research and development of T3SS inhibitors. This review outlines several reported small-molecule inhibitors of the T3SS, covering those of synthetic and natural origin, including their sources, structures, and mechanisms of action.

Aptamer-based applications for cardiovascular disease

Cardiovascular disease (especially atherosclerosis) is a major cause of death worldwide, and novel diagnostic tools and treatments for this disease are urgently needed. Aptamers are single-stranded oligonucleotides that specifically recognize and bind to the targets by forming unique structures in vivo, enabling them to rival antibodies in cardiac applications. Chemically synthesized aptamers can be readily modified in a site-specific way, so they have been engineered in the diagnosis of cardiac diseases and anti-thrombosis therapeutics. Von Willebrand Factor plays a unique role in the formation of thrombus, and as an aptamer targeting molecule, has shown initial success in antithrombotic treatment. A combination of von Willebrand Factor and nucleic acid aptamers can effectively inhibit the progression of blood clots, presenting a positive diagnosis and therapeutic effect, as well as laying a novel theory and strategy to improve biocompatibility paclitaxel drug balloon or implanted stent in the future. This review summarizes aptamer-based applications in cardiovascular disease, including biomarker discovery and future management strategy. Although relevant applications are relatively new, the significant advancements achieved have demonstrated that aptamers can be promising agents to realize the integration of diagnosis and therapy in cardiac research.

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.

Nucleic acid therapeutics: a focus on the development of aptamers

INTRODUCTION

Aptamers provide exciting opportunities for the development of specific and targeted therapeutic approaches.

AREAS COVERED

In this review, the authors discuss different therapeutic options available with nucleic acids, including aptamers, focussing on similarities and differences between them. The authors concentrate on case studies with specific aptamers, which exemplify their distinct advantages. The reasons for failure, wherever available, are deliberated upon. Attempts to accelerate the in vitro selection process have been discussed. Challenges with aptamers in terms of their specificity and targeted delivery and strategies to overcome these are described. Examples of precise regulation of systemic half-life of aptamers using antidotes are discussed.

EXPERT OPINION

Despite their nontoxic nature, a variety of reasons limit the therapeutic potential of aptamers in the clinic. The analysis of adverse effects observed with the pegnivacogin/anivamersen pair has highlighted the need to screen for preexisting PEG antibodies in any clinical trial involving pegylated molecules. Surprisingly, and promisingly, the ability of nucleic acid therapeutics to breach the blood brain barrier seems achievable. The recognition of specific motifs, e.g. G-quadruplex in thrombin-binding aptamers, or a 'nucleation' zone while designing aptamer-antidote pairs, is likely to accelerate the discovery of therapeutically efficacious molecules.

Inhibition of Salmonella enteritidis biofilms by Salmonella invasion protein-targeting aptamer

The current study aimed to assess the inhibitory effect of a DNA aptamer (Apt17) which targeted Salmonella invasion proteinA (SipA). The effect of Apt17, on biofilm formation by two Salmonella enteritidis strains, was tested either separately or in combination with ampicillin at different Sub MIC concentrations. Maximum inhibitory effect equivalent to 24.34% and 26.81% was recorded when Apt17 was co-incubated with S. enteritidis TM 6 and S. enteritidis TM 68 respectively for 13 h. The inhibitory effect of Apt17 was also confirmed with Triphenyl Tetrazolium Chloride. Under Scanning Electron Microscope, the presence of Apt17 resulted in altered three dimensional structure. While the treated cells of S. enteritidis TM 6 were arranged as monolayers, the sessile aggregates of S. enteritidis TM 68 appeared thinner and exhibited less surface coverage when compared to control. Moreover, the treated cells lost their exopolysaccharide matrix. The co-incubation of Apt17 with ampicillin MIC/10 for 24 h, inhibited the biofilms of S. enteritidis TM 6 and S. enteritidis TM 68 by 12.5 and 20.9% respectively. This study demonstrated quantitative and qualitative antibiofilm effect of Apt17 against the biofilms of two Salmonella enteritidis strains. According to our knowledge, this is the first study employing an aptamer that targets SipA protein to inhibit biofilm formation in Salmonella.