Phages bearing affinity peptides to severe acute respiratory syndromes-associated coronavirus differentiate this virus from other viruses

Bacteriophages: Status quo and emerging trends toward one health approach

The alarming rise in antimicrobial resistance (AMR) among the drug-resistant pathogens has been attributed to the ESKAPEE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, Enterobacter sp., and Escherichia coli). Recently, these AMR microbes have become difficult to treat, as they have rendered the existing therapeutics ineffective. Thus, there is an urgent need for effective alternatives to lessen or eliminate the current infections and limit the spread of emerging diseases under the "One Health" framework. Bacteriophages (phages) are naturally occurring biological resources with extraordinary potential for biomedical, agriculture/food safety, environmental protection, and energy production. Specific unique properties of phages, such as their bactericidal activity, host specificity, potency, and biocompatibility, make them desirable candidates in therapeutics. The recent biotechnological advancement has broadened the repertoire of phage applications in nanoscience, material science, physical chemistry, and soft-matter research. Herein, we present a comprehensive review, coupling the substantial aspects of phages with their applicability status and emerging opportunities in several interdependent areas under one health concept. Consolidating the recent state-of-the-art studies that integrate human, animal, plant, and environment health, the following points have been highlighted: (i) The biomedical and pharmacological advantages of phages and their antimicrobial derivatives with particular emphasis on in-vivo and clinical studies. (ii) The remarkable potential of phages to be altered, improved, and applied for drug delivery, biosensors, biomedical imaging, tissue engineering, energy, and catalysis. (iii) Resurgence of phages in biocontrol of plant, food, and animal-borne pathogens. (iv) Commercialization of phage-based products, current challenges, and perspectives.

Phage Display Technique as a Tool for Diagnosis and Antibody Selection for Coronaviruses

Phage display is one of the important and effective molecular biology techniques and has remained indispensable for research community since its discovery in the year 1985. As a large number of nucleotide fragments may be cloned into the phage genome, a phage library may harbour millions or sometimes billions of unique and distinctive displayed peptide ligands. The ligand–receptor interactions forming the basis of phage display have been well utilized in epitope mapping and antigen presentation on the surface of bacteriophages for screening novel vaccine candidates by using affinity selection-based strategy called biopanning. This versatile technique has been modified tremendously over last three decades, leading to generation of different platforms for combinatorial peptide display. The translation of new diagnostic tools thus developed has been used in situations arising due to pathogenic microbes, including bacteria and deadly viruses, such as Zika, Ebola, Hendra, Nipah, Hanta, MERS and SARS. In the current situation of pandemic of Coronavirus disease (COVID-19), a search for neutralizing antibodies is motivating the researchers to find therapeutic candidates against novel SARS-CoV-2. As phage display is an important technique for antibody selection, this review presents a concise summary of the very recent applications of phage display technique with a special reference to progress in diagnostics and therapeutics for coronavirus diseases. Hopefully, this technique can complement studies on host–pathogen interactions and assist novel strategies of drug discovery for coronaviruses.

Viral Related Tools against SARS-CoV-2

At the end of 2019, a new disease appeared and spread all over the world, the COVID-19, produced by the coronavirus SARS-CoV-2. As a consequence of this worldwide health crisis, the scientific community began to redirect their knowledge and resources to fight against it. Here we summarize the recent research on viruses employed as therapy and diagnostic of COVID-19: (i) viral-vector vaccines both in clinical trials and pre-clinical phases; (ii) the use of bacteriophages to find antibodies specific to this virus and some studies of how to use the bacteriophages themselves as a treatment against viral diseases; and finally, (iii) the use of CRISPR-Cas technology both to obtain a fast precise diagnose of the patient and also the possible use of this technology as a cure.

Regulation of Osteoblast Differentiation by Affinity Peptides of TGF-β1 Identified via Phage Display Technology

Transforming growth factor β1 (TGF-β1) plays a dual role in bone formation. In addition to promoting early differentiation of osteogenesis, it may also lead to uncontrolled extracellular matrix synthesis, inhibition of bone mineralization in the late stage, and aberrant bone remodeling. In this work, affinity peptides of TGF-β1 (Tβms) were identified from a phage display library to modify the TGF-β1 signal transduction. Tβms with more order and compact structures tended to have a higher affinity to TGF-β1 but maintained a greater immunoreactivity of TGF-β1. Tβms promoted the early osteoblast proliferation and had a negligible effect on the osteoblast differentiation. In synergy with exogenous TGF-β1, Tβms reduced the alkaline phosphatase (ALP) mRNA expression but significantly improved the expression of osteocalcin (OCN), along with impaired phosphorylation of Smad2/3. Moreover, osteoblasts showed an overall increase in ALP activity and Ca deposition than the blank control. These results demonstrated that Tβms could weaken the inhibition of TGF-β1 on osteogenic differentiation in the late stage. Depending on the impact features of Tβms on TGF-β1 response, these peptides may help to modify the implant surfaces to optimize the bone remodeling of interface, and be of interest in design of multidomain peptides.

Biopanning of polypeptides binding to bovine ephemeral fever virus G1 protein from phage display peptide library

Background

The bovine ephemeral fever virus (BEFV) glycoprotein neutralization site 1 (also referred as G₁ protein), is a critical protein responsible for virus infectivity and eliciting immune-protection, however, binding peptides of BEFV G₁ protein are still unclear. Thus, the aim of the present study was to screen specific polypeptides, which bind BEFV G₁ protein with high-affinity and inhibit BEFV replication.

Methods

The purified BEFV G₁ was coated and then reacted with the M13-based Ph.D.-7 phage random display library. The peptides for target binding were automated sequenced after four rounds of enrichment biopanning. The amino acid sequences of polypeptide displayed on positive clones were deduced and the affinity of positive polypeptides with BEFV G₁ was assayed by ELISA. Then the roles of specific G₁-binding peptides in the context of BEFV infection were analyzed.

Results

The results showed that 27 specific peptide ligands displaying 11 different amino acid sequences were obtained, and the T18 and T25 clone had a higher affinity to G₁ protein than the other clones. Then their antiviral roles of two phage clones (T25 and T18) showed that both phage polypeptide T25 and T18 exerted inhibition on BEFV replication compared to control group. Moreover, synthetic peptide based on T18 (HSIRYDF) and T25 (YSLRSDY) alone or combined use on BEFV replication showed that the synthetic peptides could effectively inhibit the formation of cytopathic plaque and significantly inhibit BEFV RNA replication in a dose-dependent manner.

Conclusion

Two antiviral peptide ligands binding to bovine ephemeral fever virus G₁ protein from phage display peptide library were identified, which may provide a potential research tool for diagnostic reagents and novel antiviral agents.

Electronic supplementary material

The online version of this article (10.1186/s12917-017-1315-x) contains supplementary material, which is available to authorized users.

Characterization and utility of phages bearing peptides with affinity to porcine reproductive and respiratory syndrome virus nsp7 protein

High-affinity peptides to porcine reproductive and respiratory syndrome virus (PRRSV) nonstructural protein (nsp) 7 were identified using phage-display technology. Five 12-amino-acid peptide sequences were identified after six rounds of biopanning. A putative CD##WC motif was found in two different consensus peptides borne by phages 4 and 5. The peptides borne by phages 4, 5, and 6 were synthesized for subsequent experiments, according to the results of the binding assays. Immunofluorescence assay revealed that all these peptides recognized nsp7 in PRRSV-infected cells. Furthermore, the peptides demonstrated antiviral activities, with peptides 5 and 6 showing effective inhibition. Early peptide stimulation was associated with strong antiviral activity, and the inhibitory effects of the peptides were dose-dependent at 36 and 48 h post-infection. Peptide 5 was selected to detect the intracellular localization of nsp7 by confocal microscopy. This peptide had a similar effect to anti-nsp7 monoclonal antibody on nsp7. These results suggest that high-affinity peptides to PRRSV nsp7 could mimic the potential of nsp7 antibody as a diagnostic reagent for virus detection. Moreover, the peptides selected in this study represented a potentially effective antiviral candidate to inhibit PRRSV.