Insights into the Novel Therapeutics and Vaccines against Herpes Simplex Virus

Herpes simplex virus (HSV) is a great concern of the global health community due to its linked infection of inconspicuous nature and resultant serious medical consequences. Seropositive patients may develop ocular disease or genital herpes as characteristic infectious outcomes. Moreover, the infectious nature of HSV is so complex that the available therapeutic options have been modified in certain ways to cure it. However, no permanent and highly effective cure has been discovered. This review generates insights into the available prophylactic and therapeutic interventions against HSV. A methodological research approach is used for study design and data complication. Only the latest data from publications are acquired to shed light on updated therapeutic approaches. These studies indicate that the current antiviral therapeutics can suppress the symptoms and control viral transmission up to a certain level, but cannot eradicate the natural HSV infection and latency outcomes. Most trials that have entered the clinical phase are made part of this review to understand what is new within the field. Some vaccination approaches are also discussed. Moreover, some novel therapeutic options that are currently in research annals are given due consideration for future development. The data can enable the scientific community to direct their efforts to fill the gaps that remain unfilled in terms of therapies for HSV. The need is to integrate scientific efforts to produce a proper cure against HSV to control the virus spread, resistance, and mutation in future disease management.

DNA-Immobilized Fluorescent Polystyrene Nanoparticles as Probes with Tunable Detection Limits

DNA-immobilized nanoparticle probes show high target specificity; thus, they are employed in various bioengineering and biomedicine applications. When the nanoparticles employed are dye-loaded polymer particles, the resulting probes have the additional benefit of biocompatibility and versatile surface properties. In this study, we construct DNA-immobilized fluorescent polystyrene (PS) nanoparticles through controlled surface reactions. PS nanoparticles with surface carboxyl groups are utilized, and amine-functionalized dye molecules and capture DNAs are covalently immobilized via a one-pot reaction. We show that the surface chemistry employed allows for quantitative control over the number of fluorescent dyes and DNA strands immobilized on the PS nanoparticle surfaces. The nanoparticles thus prepared are then used for DNA detection. The off state of the nanoprobe is achieved by hybridizing quencher-functionalized DNAs (Q-DNAs) to the capture DNAs immobilized on nanoparticle surfaces. Target-DNAs (T-DNAs) are detected by the displacement of the prehybridized Q-DNAs. The nanoprobes show successful detection of T-DNAs with high sequence specificity and long-term stability. They also show excellent detection sensitivity, and the detection limit can be tuned by adjusting the capture DNA-to-dye ratio.

Amplification-free, sequence-specific 16S rRNA detection at 1 aM

A nucleic acid amplification-free, optics-free platform has been demonstrated for sequence-specific detection of Escherichia coli (E. coli) 16S rRNA at 1 aM (10-18 M) against a 106-fold (1 pM) background of Pseudomonas putida (P. putida) RNA. This work was driven by the need for simple, rapid, and low cost means for species-specific bacterial detection at low concentration. Our simple, conductometric sensing device functioned by detecting blockage of a nanopore fabricated in a sub-micron-thick glass membrane. Upon sequence-specific binding of target 16S rRNA, otherwise charge-neutral, PNA oligonucleotide probe-polystyrene bead conjugates become electrophoretically mobile and are driven to the glass nanopore of lesser diameter, which is blocked, thereby generating a large, sustained and readily observable step decrease in ionic current. No false positive signals were observed with P. putida RNA when this device was configured to detect E. coli 16S rRNA. Also, when a universal PNA probe complementary to the 16S rRNA of both E. coli and P. putida was conjugated to beads, a positive response to rRNA of both bacterial species was observed. Finally, the device readily detected E. coli at 10 CFU mL-1 in a 1 mL sample, also against a million-fold background of viable P. putida. These results suggest that this new device may serve as the basis for small, portable, low power, and low-cost systems for rapid detection of specific bacterial species in clinical samples, food, and water.

Single-Molecule Counting of Point Mutations by Transient DNA Binding

High-confidence detection of point mutations is important for disease diagnosis and clinical practice. Hybridization probes are extensively used, but are hindered by their poor single-nucleotide selectivity. Shortening the length of DNA hybridization probes weakens the stability of the probe-target duplex, leading to transient binding between complementary sequences. The kinetics of probe-target binding events are highly dependent on the number of complementary base pairs. Here, we present a single-molecule assay for point mutation detection based on transient DNA binding and use of total internal reflection fluorescence microscopy. Statistical analysis of single-molecule kinetics enabled us to effectively discriminate between wild type DNA sequences and single-nucleotide variants at the single-molecule level. A higher single-nucleotide discrimination is achieved than in our previous work by optimizing the assay conditions, which is guided by statistical modeling of kinetics with a gamma distribution. The KRAS c.34 A mutation can be clearly differentiated from the wild type sequence (KRAS c.34 G) at a relative abundance as low as 0.01% mutant to WT. To demonstrate the feasibility of this method for analysis of clinically relevant biological samples, we used this technology to detect mutations in single-stranded DNA generated from asymmetric RT-PCR of mRNA from two cancer cell lines.

Role of metal and metal oxide nanoparticles as diagnostic and therapeutic tools for highly prevalent viral infections

Nanotechnology is increasingly playing important roles in various fields including virology. The emerging use of metal or metal oxide nanoparticles in virus targeting formulations shows the promise of improved diagnostic or therapeutic ability of the agents while uniquely enhancing the prospects of targeted drug delivery. Although a number of nanoparticles varying in composition, size, shape, and surface properties have been approved for human use, the candidates being tested or approved for clinical diagnosis and treatment of viral infections are relatively less in number. Challenges remain in this domain due to a lack of essential knowledge regarding the in vivo comportment of nanoparticles during viral infections. This review provides a broad overview of recent advances in diagnostic, prophylactic and therapeutic applications of metal and metal oxide nanoparticles in human immunodeficiency virus, hepatitis virus, influenza virus and herpes virus infections. Types of nanoparticles commonly used and their broad applications have been explained in this review.

A single-bead telomere sensor based on fluorescence resonance energy transfer

We present a 200 nm in-diameter single-bead sensor for the detection of single, unlabeled DNA molecules in solution using fluorescence resonance energy transfer technology. DNA-bound Alexa 488 and Crimson 625 loaded on commercial beads served as the donor and acceptor, respectively. Binding of the target DNA to the single bead sensor induces G-quadruplex stretching, resulting in a decrease in fluorescence energy transfer. G-rich telomere sequences formed a G-quadruplex structure in the presence of ZnTCPP, as demonstrated by the detection of two strong donor and acceptor signals. The sensitivity of the sensor was 1 fM. Under optimized conditions using a polydimethylsiloxane microfluidic device, we measured the number of sensor beads by direct counting. By controlling the flow rate via the probe volume, one sensing experiment can be completed in 5 minutes. Based on these results, we propose a new parameter-dependability (RS)-as a quantitative measure to judge the quality of a bio-sensor. This parameter is based on the ratio of the sensor and sensing sample fluorescence signals. This parameter can range from 0.1 to 100, where a value of 10 represents an optimized bio-sensor.

Sequence-specific DNA detection at 10 fM by electromechanical signal transduction

Target DNA fragments at 10 fM concentration (approximately 6 × 10(5) molecules) were detected against a DNA background simulating the noncomplementary genomic DNA present in real samples using a simple, PCR-free, optics-free approach based on electromechanical signal transduction. The development of a rapid, sensitive, and cost-effective nucleic acid detection platform is highly desired for a range of diverse applications. We previously described a potentially low-cost device for sequence-specific nucleic acid detection based on conductance change measurement of a pore blocked by electrophoretically mobilized bead-(peptide nucleic acid probe) conjugates upon hybridization with target nucleic acid. Here, we demonstrate the operation of our device with longer DNA targets, and we describe the resulting improvement in the limit of detection (LOD). We investigated the detection of DNA oligomers of 110, 235, 419, and 1613 nucleotides at 1 pM to 1 fM and found that the LOD decreased as DNA length increased, with 419 and 1613 nucleotide oligomers detectable down to 10 fM. In addition, no false positive responses were obtained with noncomplementary, control DNA fragments of similar length. The 1613-base DNA oligomer is similar in size to 16S rRNA, which suggests that our device may be useful for detection of pathogenic bacteria at clinically relevant concentrations based on recognition of species-specific 16S rRNA sequences.

Application of microfluidics in waterborne pathogen monitoring: a review

A review of the recent advances in microfluidics based systems for the monitoring of waterborne pathogens is provided in this article. Emphasis has been made on existing, commercial and state-of-the-art systems and research activities in laboratories worldwide. The review separates sample processing systems and monitoring systems, highlighting the slow progress made in automated sample processing for monitoring of pathogens in waterworks and in the field. Future potential directions of research are also highlighted in the conclusions.

Fabricating a cycloolefin polymer immunoassay platform with a dual-function polymer brush via a surface-initiated photoiniferter-mediated polymerization strategy

The development of technologies for a biomedical detection platform is critical to meet the global challenges of various disease diagnoses. In this study, an inert cycloolefin polymer (COP) support was modified with two-layer polymer brushes possessing dual functions, i.e., a low fouling poly[poly(ethylene glycol) methacrylate] [p(PEGMA)] bottom layer and a poly(acrylic acid) (PAA) upper layer for antibody loading, via a surface-initiated photoiniferter-mediated polymerization strategy for fluorescence-based immunoassay. It was demonstrated through a confocal laser scanner that, for the as-prepared COP-g-PEG-b-PAA-IgG supports, nonspecific protein adsorption was suppressed, and the resistance to nonspecific protein interference on antigen recognition was significantly improved, relative to the COP-g-PAA-IgG references. This strategy for surface modification of a polymeric platform is also applicable to the fabrication of other biosensors.

A paramagnetic-reporter two-particle system for amplification-free detection of DNA in serum

Quantitative nucleic acid detection is used extensively in the management of many pathogenic infections, where viral or bacterial nucleic acid copy number relates directly to disease prognosis. Temperature-cycle or isothermal amplification formats offer excellent performance, but their requirement for purified nucleic acid and accurate temperature control increases costs and renders their migration to resource-limited environments problematic. In contrast, amplification-free nucleic acid assays could allow simplified system design, resulting in reduced costs. In this study, we report a amplification-free herpes simplex virus (HSV) assay where oligoethylene glycol methacrylate (OEGMA) grafted ssDNA capture-probes on paramagnetic nanoparticles are coupled with reporter-probe-modified fluorescent nanoparticles in a target-dependent manner. Following assay and reagent optimization, a sub-pM (25 amol) limit of detection could be achieved in buffer and also in neat, undiluted serum, representing a 160-fold improvement over that achieved using convention detection with a fluorescence plate reader. Equivalent performance in serum and buffer offers the opportunity for simplified diagnostic device design for resource-limited environments.

Zeptomole detection of DNA nanoparticles by single-molecule fluorescence with magnetic field-directed localization

Single-molecule fluorescence methods offer the promise of ultrasensitive detection of biomolecules, but the passive immobilization methods commonly employed require analyte concentrations in the picomolar range. Here, we demonstrate that superparamagnetic Fe(3)O(4) nanoparticles (NPs) can be used with an external magnetic field as a simple strategy to enhance the immobilization efficiency and thereby decrease the detection limit. Inorganic NPs functionalized with streptavidin were bound to biotinylated single-stranded DNA oligonucleotides, which were in turn annealed to complementary oligonucleotides labeled with a Cy3 fluorescent dye. Using an external magnetic field, the superparamagnetic nanoparticles were localized to a specific region within the flow chamber surface. From the single-molecule fluorescence time traces, single-step photobleaching indicated that the surface-immobilized NPs were primarily bound with a single Cy3-labeled oligonucleotide. This strategy gave a concentration detection limit for the Cy3-labeled oligonucleotide of 100aM, 3000-fold lower than that from an analogous strategy with passive immobilization. With a sample volume of 25μl, this method achieved a mole detection limit of approximately 2.5zmol (∼1500 molecules). Together, the results support that idea that single-molecule fluorescence methods could be used for biological applications such as detection and measurements of nucleic acids from biological or clinical samples without polymerase chain reaction amplification.

Oligonucleotide and polymer functionalized nanoparticles for amplification-free detection of DNA

Sensitive and quantitative nucleic acid testing from complex biological samples is now an important component of clinical diagnostics. Whereas nucleic acid amplification represents the gold standard, its utility in resource-limited and point-of-care settings can be problematic due to assay interferants, assay time, engineering constraints, and costs associated with both wetware and hardware. In contrast, amplification-free nucleic acid testing can circumvent these limitations by enabling direct target hybridization within complex sample matrices. In this work, we grew random copolymer brushes from the surface of silica-coated magnetic nanoparticles using azide-modified and hydroxyl oligo ethylene glycol methacrylate (OEGMA) monomers. The azide-functionalized polymer brush was first conjugated, via copper-catalyzed azide/alkyne cycloaddition (CuAAC), with herpes simplex virus (HSV)-specific oligonucleotides and then with alkyne-substituted polyethylene glycol to eliminate all residual azide groups. Our methodology enabled control over brush thickness and probe density and enabled multiple consecutive coupling reactions on the particle grafted brush. Brush- and probe-modified particles were then combined in a 20 min hybridization with fluorescent polystyrene nanoparticles modified with HSV-specific reporter probes. Following magnetic capture and washing, the particles were analyzed with an aggregate fluorescence measurement, which yielded a limit of detection of 6 pM in buffer and 60 pM in 50% fetal bovine serum. Adoption of brush- and probe-modified particles into a particle counting assay will result in the development of diagnostic assays with significant improvements in sensitivity.