Immunization with M2e-displaying T7 bacteriophage nanoparticles protects against influenza A virus challenge

Expression and purification of an NP-hoc fusion protein: Utilizing influenza a nucleoprotein and phage T4 hoc protein

Influenza poses a substantial health risk, with infants and the elderly being particularly susceptible to its grave impacts. The primary challenge lies in its rapid genetic evolution, leading to the emergence of new Influenza A strains annually. These changes involve punctual mutations predominantly affecting the two main glycoproteins: Hemagglutinin (HA) and Neuraminidase (NA). Our existing vaccines target these proteins, providing short-term protection, but fall short when unexpected pandemics strike. Delving deeper into Influenza's genetic makeup, we spotlight the nucleoprotein (NP) - a key player in the transcription, replication, and packaging of RNA. An intriguing characteristic of the NP is that it is highly conserved across all Influenza A variants, potentially paving the way for a more versatile and broadly protective vaccine. We designed and synthesized a novel NP-Hoc fusion protein combining Influenza A nucleoprotein and T4 phage Hoc, cloned using Gibson assembly in E. coli, and purified via ion affinity chromatography. Simultaneously, we explore the T4 coat protein Hoc, typically regarded as inconsequential in controlled viral replication. Yet, it possesses a unique ability: it can link with another protein, showcasing it on the T4 phage coat. Fusing these concepts, our study designs, expresses, and purifies a novel fusion protein named NP-Hoc. We propose this protein as the basis for a new generation of vaccines, engineered to guard broadly against Influenza A. The excitement lies not just in the immediate application, but the promise this holds for future pandemic resilience, with NP-Hoc marking a significant leap in adaptive, broad-spectrum influenza prevention.

Evaluation of immunogenicity and protective efficacy of bacteriophage conjugated haemagglutinin based subunit vaccine against equine influenza virus in a murine model

Equine influenza (EI) is a highly contagious acute respiratory disease of equines caused by the H3N8 subtype of Influenza A virus i.e. equine influenza virus (EIV). Vaccination is an important and effective tool for the control of EI in equines. Most of the commercial influenza vaccines are produced in embryonated hen's eggs which has several inherent disadvantages. Hence, subunit vaccine based on recombinant haemagglutinin (HA) antigen, being the most important envelope glycoprotein has been extensively exploited for generating protective immune responses, against influenza A and B viruses. We hypothesized that novel vaccine formulation using baculovirus expressed recombinant HA1 (rHA1) protein coupled with bacteriophage will generate strong protective immune response against EIV. In the present study, the recombinant HA1 protein was produced in insect cells using recombinant baculovirus having cloned HA gene of EIV (Florida clade 2 sublineage) and the purified rHA1 was chemically coupled with bacteriophage using a crosslinker to produce rHA1-phage vaccine candidate. The protective efficacy of vaccine preparations of rHA1-phage conjugate and only rHA1 proteins were evaluated in mouse model through assessing serology, cytokine profiling, clinical signs, gross and histopathological changes, immunohistochemistry, and virus quantification. Immunization of vaccine preparations have stimulated moderate antibody response (ELISA titres-5760 ± 640 and 11,520 ± 1280 for rHA1 and rHA1-phage, respectively at 42 dpi) and elicited strong interferon (IFN)-γ expression levels after three immunizations of vaccine candidates. The immunized BALB/c mice were protected against challenge with wild EIV and resulted in reduced clinical signs and body weight loss, reduced pathological changes, decreased EIV antigen distribution, and restricted EIV replication in lungs and nasopharynx. In conclusion, the immune responses with moderate antibody titer and significantly higher cytokine responses generated by the rHA1-phage vaccine preparation without any adjuvant could be a novel vaccine candidate for quick vaccine preparation through further trials of vaccine in the natural host.

New role of bacteriophages in medical oncology

Targeted treatment of cancer is one of the most paramount approaches in cancer treatment. Despite significant advances in cancer diagnosis and treatment methods, there are still significant limitations and disadvantages in the field, including high costs, toxicity, and unwanted damage to healthy cells. The phage display technique is an innovative method for designing carriers containing exogenic peptides with cancer diagnostic and therapeutic properties. Bacteriophages possess unique properties making them effective in cancer treatment. These characteristics include the small size enabling them to penetrate vessels; having no pathogenicity to mammals; easy manipulation of their genetic information and surface proteins to introduce vaccines and drugs to cancer tissues; lower cost of large-scale production; and greater stimulation of the immune system. Bacteriophages will certainly play a more effective role in the future of medical oncology; however, studies are in the early stages of conception and require more extensive research. We aimed in this review to provide some related examples and bring insights into the potential of phages as targeted vectors for use in cancer diagnosis and treatment, especially regarding their capability in gene and drug delivery to cancer target cells, determination of tumor markers, and vaccine design to stimulate anticancer immunity.

SpyTag/SpyCatcher display of influenza M2e peptide on norovirus-like particle provides stronger immunization than direct genetic fusion

Introduction

Virus-like particles (VLPs) are similar in size and shape to their respective viruses, but free of viral genetic material. This makes VLP-based vaccines incapable of causing infection, but still effective in mounting immune responses. Noro-VLPs consist of 180 copies of the VP1 capsid protein. The particle tolerates C-terminal fusion partners, and VP1 fused with a C-terminal SpyTag self-assembles into a VLP with SpyTag protruding from its surface, enabling conjugation of antigens via SpyCatcher.

Methods

To compare SpyCatcher-mediated coupling and direct peptide fusion in experimental vaccination, we genetically fused the ectodomain of influenza matrix-2 protein (M2e) directly on the C-terminus of norovirus VP1 capsid protein. VLPs decorated with SpyCatcher-M2e and VLPs with direct M2 efusion were used to immunize mice.

Results and discussion

We found that direct genetic fusion of M2e on noro-VLP raised few M2e antibodies in the mouse model, presumably because the short linker positions the peptide between the protruding domains of noro-VLP, limiting its accessibility. On the other hand, adding aluminum hydroxide adjuvant to the previously described SpyCatcher-M2e-decorated noro-VLP vaccine gave a strong response against M2e. Surprisingly, simple SpyCatcher-fused M2e without VLP display also functioned as a potent immunogen, which suggests that the commonly used protein linker SpyCatcher-SpyTag may serve a second role as an activator of the immune system in vaccine preparations. Based on the measured anti-M2e antibodies and cellular responses, both SpyCatcher-M2e as well as M2e presented on the noro-VLP via SpyTag/Catcher show potential for the development of universal influenza vaccines.

Phage engineering and phage-assisted CRISPR-Cas delivery to combat multidrug-resistant pathogens

Antibiotic resistance ranks among the top threats to humanity. Due to the frequent use of antibiotics, society is facing a high prevalence of multidrug resistant pathogens, which have managed to evolve mechanisms that help them evade the last line of therapeutics. An alternative to antibiotics could involve the use of bacteriophages (phages), which are the natural predators of bacterial cells. In earlier times, phages were implemented as therapeutic agents for a century but were mainly replaced with antibiotics, and considering the menace of antimicrobial resistance, it might again become of interest due to the increasing threat of antibiotic resistance among pathogens. The current understanding of phage biology and clustered regularly interspaced short palindromic repeats (CRISPR) assisted phage genome engineering techniques have facilitated to generate phage variants with unique therapeutic values. In this review, we briefly explain strategies to engineer bacteriophages. Next, we highlight the literature supporting CRISPR-Cas9-assisted phage engineering for effective and more specific targeting of bacterial pathogens. Lastly, we discuss techniques that either help to increase the fitness, specificity, or lytic ability of bacteriophages to control an infection.

Use of Nanomaterials for Diagnosis and Treatment: The Advancement of Next-Generation Antiviral Therapy

Globally, viral illness propagation is the leading cause of morbidity and death, causing wreaking havoc on socioeconomic development and health care systems. The rise of infected individuals has outpaced the existing critical care facilities. Early and sophisticated methods are desperately required in this respect to halt the spread of the infection. Therefore, early detection of infectious agents and an early treatment approach may help minimize viral outbreaks. Conventional point-of-care diagnostic techniques such as computed tomography scan, quantitative real time polymerase chain reaction (qRT-PCR), X-ray, and immunoassay are still deemed valuable. However, the labor demanding, low sensitivity, and complex infrastructure needed for these methods preclude their use in distant areas. Nanotechnology has emerged as a potentially transformative technology due to its promise as an effective theranostic platform for diagnosing and treating viral infection, circumventing the limits of traditional techniques. Their unique physical and chemical characteristics make nanoparticles (NPs) advantageous for drug delivery platforms due to their size, encapsulation efficiency, improved bioavailability, effectiveness, immunogenicity, and antiviral response. This study discusses the recent research on nanotechnology-based treatments designed to combat new viruses.

Protein Cages: From Fundamentals to Advanced Applications

Proteins that self-assemble into polyhedral shell-like structures are useful molecular containers both in nature and in the laboratory. Here we review efforts to repurpose diverse protein cages, including viral capsids, ferritins, bacterial microcompartments, and designed capsules, as vaccines, drug delivery vehicles, targeted imaging agents, nanoreactors, templates for controlled materials synthesis, building blocks for higher-order architectures, and more. A deep understanding of the principles underlying the construction, function, and evolution of natural systems has been key to tailoring selective cargo encapsulation and interactions with both biological systems and synthetic materials through protein engineering and directed evolution. The ability to adapt and design increasingly sophisticated capsid structures and functions stands to benefit the fields of catalysis, materials science, and medicine.

A single-shot vaccine approach for the universal influenza A vaccine candidate M2e

Although the need for a universal influenza vaccine has long been recognized, only a handful of candidates have been identified so far, with even fewer advancing in the clinical pipeline. The 24–amino acid ectodomain of M2 protein (M2e) has been developed over the past two decades. However, M2e-based vaccine candidates have shortcomings, including the need for several administrations and the lack of sustained antibody titers over time. We report here a vaccine targeting strategy that has the potential to confer sustained and strong protection upon a single shot of a small amount of M2e antigen. The current COVID-19 pandemic has highlighted the importance of developing versatile, powerful platforms for the rapid deployment of vaccines against any incoming threat.

Influenza, commonly referred to as “flu,” is a major global public health concern and a huge economic burden to societies. Current influenza vaccines need to be updated annually to match circulating strains, resulting in low take-up rates and poor coverage due to inaccurate prediction. Broadly protective universal flu vaccines that do not need to be updated annually have therefore been pursued. The highly conserved 24–amino acid ectodomain of M2 protein (M2e) is a leading candidate, but its poor immunogenicity has been a major roadblock in its clinical development. Here, we report a targeting strategy that shuttles M2e to a specific dendritic cell subset (cDC1) by engineering a recombinant anti-Clec9A monoclonal antibody fused at each of its heavy chains with three copies of M2e. Single administration in mice of 2 µg of the Clec9A–M2e construct triggered an exceptionally sustained anti-M2e antibody response and resulted in a strong anamnestic protective response upon influenza challenge. Furthermore, and importantly, Clec9A–M2e immunization significantly boosted preexisting anti-M2e titers from prior flu exposure. Thus, the Clec9A-targeting strategy allows antigen and dose sparing, addressing the shortcomings of current M2e vaccine candidates. As the cDC1 subset exists in humans, translation to humans is an exciting and realistic avenue.

Phage T7 as a Potential Platform for Vaccine Development

Bacteriophages have been explored for their uses in vaccine development, due to the ease of propagation while displaying epitopes in high density. Bacteriophage T7 has been demonstrated to be useful in the production of potential vaccine candidates for various diseases, including influenza A, foot-and mouth disease (FMD), and cancers. In this chapter, we described the use of phage T7 to display potential foot-and-mouth disease virus (FMDV) epitope, from cloning to expression, purification, and immunization in a mouse model.

The bacteriophage decides own tracks: When they are with or against the bacteria

Bacteriophages, bacteria-infecting viruses, are considered by many researchers a promising solution for antimicrobial resistance. On the other hand, some phages have shown contribution to bacterial resistance phenomenon by transducing antimicrobial resistance genes to their bacterial hosts. Contradictory consequences of infections are correlated to different phage lifecycles. Out of four known lifecycles, lysogenic and lytic pathways have been riddles since the uncontrolled conversion between them could negatively affect the intended use of phages. However, phages still can be engineered for applications against bacterial and viral infections to ensure high efficiency. This review highlights two main aspects: (1) the different lifecycles as well as the different factors that affect lytic-lysogenic switch are discussed, including the intracellular and molecular factors control this decision. In addition, different models which describe the effect of phages on the ecosystem are compared, besides the approaches to study the switch. (2) An overview on the contribution of the phage in the evolution of the bacteria, instead of eating them, as a consequence of different mode of actions. As well, how phage display has helped in restricting phage cheating and how it could open new gates for immunization and pandemics control will be tacked.

Bacteriophage T4 Vaccine Platform for Next-Generation Influenza Vaccine Development

Developing influenza vaccines that protect against a broad range of viruses is a global health priority. Several conserved viral proteins or domains have been identified as promising targets for such vaccine development. However, none of the targets is sufficiently immunogenic to elicit complete protection, and vaccine platforms that can enhance immunogenicity and deliver multiple antigens are desperately needed. Here, we report proof-of-concept studies for the development of next-generation influenza vaccines using the bacteriophage T4 virus-like particle (VLP) platform. Using the extracellular domain of influenza matrix protein 2 (M2e) as a readout, we demonstrate that up to ~1,281 M2e molecules can be assembled on a 120 x 86 nanometer phage capsid to generate M2e-T4 VLPs. These M2e-decorated nanoparticles, without any adjuvant, are highly immunogenic, stimulate robust humoral as well as cellular immune responses, and conferred complete protection against lethal influenza virus challenge. Potentially, additional conserved antigens could be incorporated into the M2e-T4 VLPs and mass-produced in E. coli in a short amount of time to deal with an emerging influenza pandemic.

Intranasal administration of immunogenic poly-epitope from influenza H1N1 and H3N2 viruses adjuvanted with chitin and chitosan microparticles in BALB/c mice

OBJECTIVES

Prevalence of influenza virus, creates the need to achieve an efficient vaccine against it. We examined whether the predicted antigenic epitopes of HA, NP, and M2 proteins of the influenza H1N1 and H3N2 viruses accompanied by chitin and chitosan biopolymers might be relevant to the induction of effective proper mucosal responses.

MATERIALS AND METHODS

The construct was prepared using B and T cell predicted epitopes of HA, NP, and M2 proteins from the influenza H1N1 and H3N2 viruses by considering haplotype "d" as a dominant allele in the BALB/c mice. Intranasal immunization with purified LPS free recombinant protein together with chitin and chitosan microparticles as adjuvants was administered at an interval of 2 weeks in thirty-five BALB/c female mice which were divided into seven groups. Ten days after the last immunization, humoral and cellular immune responses were examined.

RESULTS

Elevated systemic IgG2a, IgA, and mucosal IgA revealed a humoral response to the construct. An increase in the number of IFN-γ-producing cells in re-stimulation of splenocytes in the culture medium by poly-tope as well as rise in the concentrations of IL-6, IL-17, and TNF-α along with the regulatory response of IL-10, presented the capacity of the designed protein to provoke significant immune responses. The neutralization test ultimately confirmed the high efficacy of the protein in inhibiting the virus.

CONCLUSION

The results support the fact that immunogenic poly-tope protein in the presence of chitin and chitosan microparticles as mucosal adjuvants is able to induce humoral and cell-mediated responses in BALB/c mice.

Bacteriophages as Potential Tools for Use in Antimicrobial Therapy and Vaccine Development

The constantly growing number of people suffering from bacterial, viral, or fungal infections, parasitic diseases, and cancers prompts the search for innovative methods of disease prevention and treatment, especially based on vaccines and targeted therapy. An additional problem is the global threat to humanity resulting from the increasing resistance of bacteria to commonly used antibiotics. Conventional vaccines based on bacteria or viruses are common and are generally effective in preventing and controlling various infectious diseases in humans. However, there are problems with the stability of these vaccines, their transport, targeted delivery, safe use, and side effects. In this context, experimental phage therapy based on viruses replicating in bacterial cells currently offers a chance for a breakthrough in the treatment of bacterial infections. Phages are not infectious and pathogenic to eukaryotic cells and do not cause diseases in human body. Furthermore, bacterial viruses are sufficient immuno-stimulators with potential adjuvant abilities, easy to transport, and store. They can also be produced on a large scale with cost reduction. In recent years, they have also provided an ideal platform for the design and production of phage-based vaccines to induce protective host immune responses. The most promising in this group are phage-displayed vaccines, allowing for the display of immunogenic peptides or proteins on the phage surfaces, or phage DNA vaccines responsible for expression of target genes (encoding protective antigens) incorporated into the phage genome. Phage vaccines inducing the production of specific antibodies may in the future protect us against infectious diseases and constitute an effective immune tool to fight cancer. Moreover, personalized phage therapy can represent the greatest medical achievement that saves lives. This review demonstrates the latest advances and developments in the use of phage vaccines to prevent human infectious diseases; phage-based therapy, including clinical trials; and personalized treatment adapted to the patient's needs and the type of bacterial infection. It highlights the advantages and disadvantages of experimental phage therapy and, at the same time, indicates its great potential in the treatment of various diseases, especially those resistant to commonly used antibiotics. All the analyses performed look at the rich history and development of phage therapy over the past 100 years.

Broad cross protection by recombinant live attenuated influenza H3N2 seasonal virus expressing conserved M2 extracellular domain in a chimeric hemagglutinin

Hemagglutinin (HA)-based current vaccines provide suboptimum cross protection. Influenza A virus contains an ion channel protein M2 conserved extracellular domain (M2e), a target for developing universal vaccines. Here we generated reassortant influenza virus rgH3N2 4xM2e virus (HA and NA from A/Switzerland/9715293/2013/(H3N2)) expressing chimeric 4xM2e-HA fusion proteins with 4xM2e epitopes inserted into the H3 HA N-terminus. Recombinant rgH3N2 4xM2e virus was found to retain equivalent growth kinetics as rgH3N2 in egg substrates. Intranasal single inoculation of mice with live rgH3N2 4xM2e virus was effective in priming the induction of M2e specific IgG antibody responses in mucosal and systemic sites as well as T cell responses. The rgH3N2 4xM2e primed mice were protected against a broad range of different influenza A virus subtypes including H1N1, H3N2, H5N1, H7N9, and H9N2. The findings support a new approach to improve the efficacy of current vaccine platforms by recombinant influenza virus inducing immunity to HA and cross protective M2e antigens.

Engineered Nanoparticle Applications for Recombinant Influenza Vaccines

Influenza viruses cause seasonal epidemics and represent a pandemic risk. With current vaccine methods struggling to protect populations against emerging strains, there is a demand for a next-generation flu vaccine capable of providing broad protection. Recombinant biotechnology, combined with nanomedicine techniques, could address this demand by increasing immunogenicity and directing immune responses toward conserved antigenic targets on the virus. Various nanoparticle candidates have been tested for use in vaccines, including virus-like particles, protein and carbohydrate nanoconstructs, antigen-carrying lipid particles, and synthetic and inorganic particles modified for antigen presentation. These methods have yielded some promising results, including protection in animal models against antigenically distinct influenza strains, production of antibodies with broad reactivity, and activation of potent T cell responses. Based on the evidence of current research, it is feasible that the next generation of influenza vaccines will combine recombinant antigens with nanoparticle carriers.

Filamentous anti-influenza agents wrapping around viruses

Owing to the emerging resistance to current anti-influenza therapies, strategies for blocking virus-cell interaction with agents that mimic interactions with host cell receptors are garnering interest. In this context, a multivalent presentation of sialyl groups on various types of scaffold materials such as dendrimers, liposomes, nanoparticles, and natural/synthetic polymers has been investigated for the inhibition of influenza A virus infection. However, the development of versatile antiviral agents based on monodisperse scaffolds capable of precise molecular design remains challenging. Whether an anisotropically extended filamentous nanostructure can serve as an effective scaffold for maximum inhibition of viral cell attachment has not been investigated. In this study, the preparation of a series of sialyllactose-conjugated filamentous bacteriophages (SLPhages), with controlled loading levels, ligand valencies, and two types of sialyllactose (α2,3' and α2,6'), is demonstrated. With optimal ligand loading and valency, SLPhages showed inhibitory activity (in vitro) against influenza A viruses at concentrations of tens of picomolar. This remarkable inhibition is due to the strong interaction between the SLPhage and the virus; this interaction is adequately potent to compensate for the cost of the bending and wrapping of the SLPhage around the influenza virus. Our study may open new avenues for the development of filamentous anti-viral agents, in which virus-wrapping or aggregation is the primary feature responsible for the blocking of cell entry.

The Next Generation of Influenza Vaccines: Towards a Universal Solution

Influenza viruses remain a constant burden in humans, causing millions of infections and hundreds of thousands of deaths each year. Current influenza virus vaccine modalities primarily induce antibodies directed towards the highly variable head domain of the hemagglutinin protein on the virus surface. Such antibodies are often strain-specific, meaning limited cross-protection against divergent influenza viruses is induced, resulting in poor vaccine efficacy. To attempt to counteract this, yearly influenza vaccination with updated formulations containing antigens from more recently circulating viruses is required. This is an expensive and time-consuming exercise, and the constant arms race between host immunity and virus evolution presents an ongoing challenge for effective vaccine development. Furthermore, there exists the constant pandemic threat of highly pathogenic avian influenza viruses with high fatality rates (~30–50%) or the emergence of new, pathogenic reassortants. Current vaccines would likely offer little to no protection from such viruses in the event of an epidemic or pandemic. This highlights the urgent need for improved influenza virus vaccines capable of providing long-lasting, robust protection from both seasonal influenza virus infections as well as potential pandemic threats. In this narrative review, we examine the next generation of influenza virus vaccines for human use and the steps being taken to achieve universal protection.

Bacteriophage-Based Vaccines: A Potent Approach for Antigen Delivery

Vaccines are considered one of the most important bioproducts in medicine. Since the development of the smallpox vaccine in 1796, several types of vaccines for many diseases have been created. However, some vaccines have shown limitations as high cost and low immune responses. In that regard, bacteriophages have been proposed as an attractive alternative for the development of more cost-effective vaccines. Phage-displayed vaccines consists in the expression of antigens on the phage surface. This approach takes advantage of inherent properties of these particles such as their adjuvant capacity, economic production and high stability, among others. To date, three types of phage-based vaccines have been developed: phage-displayed, phage DNA and hybrid phage-DNA vaccines. Typically, phage display technology has been used for the identification of new and protective epitopes, mimotopes and antigens. In this context, phage particles represent a versatile, effective and promising alternative for the development of more effective vaccine delivery systems which should be highly exploited in the future. This review describes current advances in the development of bacteriophage-based vaccines, with special attention to vaccine delivery strategies. Moreover, the immunological aspects of phage-based vaccines, as well as the applications of phage display for vaccine development, are explored. Finally, important challenges and the future of phage-bases vaccines are discussed.

Self-Assembled Nanoparticles: Exciting Platforms for Vaccination

Vaccination is successfully advanced to control several fatal diseases and improve human life expectancy. However, additional innovations are required in this field because there are no effective vaccines to prevent some infectious diseases. The shift from the attenuated or inactivated pathogens to safer but less immunogenic protein or peptide antigens has led to a search for effective antigen delivery carriers that can function as both antigen vehicles and intrinsic adjuvants. Among these carriers, self-assembled nanoparticles (SANPs) have shown great potential to be the best representative. For the nanoscale and multiple presentation of antigens, with accurate control over size, geometry, and functionality, these nanoparticles are assembled spontaneously and mimic pathogens, resulting in enhanced antigen presentation and increased cellular and humoral immunity responses. In addition, they may be applied through needle-free routes due to their adhesive ability, which gives them a great future in vaccination applications. This review provides an overview of various SANPs and their applications in prophylactic vaccines.

Cross protection by inactivated recombinant influenza viruses containing chimeric hemagglutinin conjugates with a conserved neuraminidase or M2 ectodomain epitope

Influenza virus neuraminidase (NA) contains a universally conserved epitope (NAe, NA_222-230). However, no studies have reported vaccines targeting this NA conserved epitope and inducing antibodies recognizing NAe. The extracellular domain of M2 (M2e) is considered as an attractive target for a universal influenza vaccine. We generated recombinant influenza H1N1 viruses expressing conserved epitopes in hemagglutinin (HA) molecules: NAe (NAe-HA) or M2e (M2e-HA) within the HA head domain. Inactivated recombinant NAe-HA and M2e-HA viruses were more effective in inducing IgG antibodies specific for an inserted conserved epitope than live recombinant virus. Recombinant inactivated M2e-HA virus vaccination induced cross protection against H3N2 virus with less weight loss compared to NAe-HA and was more effective in inducing humoral and cellular M2e immune responses. This study provides insight into developing recombinant influenza virus vaccines compatible with current platforms to induce antibody responses to conserved poorly immunogenic epitopes.

Tetramerizing tGCN4 domain facilitates production of Influenza A H1N1 M2e higher order soluble oligomers that show enhanced immunogenicity in vivo

One strategy for the development of a next generation influenza vaccine centers upon using conserved domains of the virus to induce broader and long-lasting immune responses. The production of artificial proteins by mimicking native-like structures has shown to be a promising approach for vaccine design against diverse enveloped viruses. The amino terminus of influenza A virus matrix 2 ectodomain (M2e) is highly conserved among influenza subtypes, and previous studies have shown M2e-based vaccines are strongly immunogenic, making it an attractive target for further exploration. We hypothesized that stabilizing M2e protein in the mammalian system might influence the immunogenicity of M2e with the added advantage to robustly produce the large scale of proteins with native-like fold and hence can act as an efficient vaccine candidate. In this study, we created an engineered construct in which the amino terminus of M2e is linked to the tetramerizing domain tGCN4, expressed the construct in a mammalian system, and tested for immunogenicity in BALB/c mice. We have also constructed a stand-alone M2e construct (without tGCN4) and compared the protein expressed in mammalian cells and in Escherichia coli using in vitro and in vivo methods. The mammalian-expressed protein was found to be more stable, more antigenic than the E. coli protein, and form higher-order oligomers. In an intramuscular protein priming and boosting regimen in mice, these proteins induced high titers of antibodies and elicited a mixed Th1/Th2 response. These results highlight the mammalian-expressed M2e soluble proteins as a promising vaccine development platform.

Phage Display-Based Nanotechnology Applications in Cancer Immunotherapy

Phage display is a nanotechnology with limitless potential, first developed in 1985 and still awaiting to reach its peak. Awarded in 2018 with the Nobel Prize for Chemistry, the method allows the isolation of high-affinity ligands for diverse substrates, ranging from recombinant proteins to cells, organs, even whole organisms. Personalized therapeutic approaches, particularly in oncology, depend on the identification of new, unique, and functional targets that phage display, through its various declinations, can certainly provide. A fast-evolving branch in cancer research, immunotherapy is now experiencing a second youth after being overlooked for years; indeed, many reports support the concept of immunotherapy as the only non-surgical cure for cancer, at least in some settings. In this review, we describe literature reports on the application of peptide phage display to cancer immunotherapy. In particular, we discuss three main outcomes of this procedure: (i) phage display-derived peptides that mimic cancer antigens (mimotopes) and (ii) antigen-carrying phage particles, both as prophylactic and/or therapeutic vaccines, and (iii) phage display-derived peptides as small-molecule effectors of immune cell functions. Preclinical studies demonstrate the efficacy and vast potential of these nanosized tools, and their clinical application is on the way.

Phage display as a tool for vaccine and immunotherapy development

Bacteriophages, or phages, are viruses that specifically infect bacteria and coopt the cellular machinery to create more phage proteins, eventually resulting in the release of new phage particles. Phages are heavily utilized in bioengineering for applications ranging from tissue engineering scaffolds to immune signal delivery. Of specific interest to vaccines and immunotherapies, phages have demonstrated an ability to activate both the innate and adaptive immune systems. The genome of these viral particles can be harnessed for DNA vaccination, or the surface proteins can be exploited for antigen display. More specifically, genes that encode an antigen of interest can be spliced into the phage genome, allowing antigenic proteins or peptides to be displayed by fusion to phage capsid proteins. Phages therefore present antigens to immune cells in a highly ordered and repetitive manner. This review discusses the use of phage with adjuvanting activity as antigen delivery vehicles for vaccination against infectious disease and cancer.

Nanoparticles in influenza subunit vaccine development: Immunogenicity enhancement

The threat of novel influenza infections has sparked research efforts to develop subunit vaccines that can induce a more broadly protective immunity by targeting selected regions of the virus. In general, subunit vaccines are safer but may be less immunogenic than whole cell inactivated or live attenuated vaccines. Hence, novel adjuvants that boost immunogenicity are increasingly needed as we move toward the era of modern vaccines. In addition, targeting, delivery, and display of the selected antigens on the surface of professional antigen-presenting cells are also important in vaccine design and development. The use of nanosized particles can be one of the strategies to enhance immunogenicity as they can be efficiently recognized by antigen-presenting cells. They can act as both immunopotentiators and delivery system for the selected antigens. This review will discuss on the applications, advantages, limitations, and types of nanoparticles (NPs) used in the preparation of influenza subunit vaccine candidates to enhance humoral and cellular immune responses.

M2e-based universal influenza vaccines: a historical overview and new approaches to development

The influenza A virus was isolated for the first time in 1931, and the first attempts to develop a vaccine against the virus began soon afterwards. In addition to causing seasonal epidemics, influenza viruses can cause pandemics at random intervals, which are very hard to predict. Vaccination is the most effective way of preventing the spread of influenza infection. However, seasonal vaccination is ineffective against pandemic influenza viruses because of antigenic differences, and it takes approximately six months from isolation of a new virus to develop an effective vaccine. One of the possible ways to fight the emergence of pandemics may be by using a new type of vaccine, with a long and broad spectrum of action. The extracellular domain of the M2 protein (M2e) of influenza A virus is a conservative region, and an attractive target for a universal influenza vaccine. This review gives a historical overview of the study of M2 protein, and summarizes the latest developments in the preparation of M2e-based universal influenza vaccines.

The Quest for a Truly Universal Influenza Vaccine

There is an unmet public health need for a universal influenza vaccine (UIV) to provide broad and durable protection from influenza virus infections. The identification of broadly protective antibodies and cross-reactive T cells directed to influenza viral targets present a promising prospect for the development of a UIV. Multiple targets for cross-protection have been identified in the stalk and head of hemagglutinin (HA) to develop a UIV. Recently, neuraminidase (NA) has received significant attention as a critical component for increasing the breadth of protection. The HA stalk-based approaches have shown promising results of broader protection in animal studies, and their feasibility in humans are being evaluated in clinical trials. Mucosal immune responses and cross-reactive T cell immunity across influenza A and B viruses intrinsic to live attenuated influenza vaccine (LAIV) have emerged as essential features to be incorporated into a UIV. Complementing the weakness of the stand-alone approaches, prime-boost vaccination combining HA stalk, and LAIV is under clinical evaluation, with the aim to increase the efficacy and broaden the spectrum of protection. Preexisting immunity in humans established by prior exposure to influenza viruses may affect the hierarchy and magnitude of immune responses elicited by an influenza vaccine, limiting the interpretation of preclinical data based on naive animals, necessitating human challenge studies. A consensus is yet to be achieved on the spectrum of protection, efficacy, target population, and duration of protection to define a “universal” vaccine. This review discusses the recent advancements in the development of UIVs, rationales behind cross-protection and vaccine designs, and challenges faced in obtaining balanced protection potency, a wide spectrum of protection, and safety relevant to UIVs.

An Inactivated Influenza Virus Vaccine Approach to Targeting the Conserved Hemagglutinin Stalk and M2e Domains

Universal influenza virus vaccine candidates that focus on the conserved hemagglutinin (HA) stalk domain and the extracellular domain of the matrix protein 2 (M2e) have been developed to increase the breadth of protection against multiple strains. In this study, we report a novel inactivated influenza virus vaccine approach that combines these two strategies. We inserted a human consensus M2e epitope into the immunodominant antigenic site (Ca2 site) of three different chimeric HAs (cHAs). Sequential immunization with inactivated viruses containing these modified cHAs substantially enhanced M2e antibody responses while simultaneously boosting stalk antibody responses. The combination of additional M2e antibodies with HA stalk antibodies resulted in superior antibody-mediated protection in mice against challenge viruses expressing homologous or heterosubtypic hemagglutinin and neuraminidase compared to vaccination strategies that targeted the HA stalk or M2e epitopes in isolation.

An Influenza A Vaccine Based on the Extracellular Domain of Matrix 2 Protein Protects BALB/C Mice Against H1N1 and H3N2

Current seasonal influenza A virus (IAV) vaccines are strain-specific and require annual reconstitution to accommodate the viral mutations. Mismatches between the vaccines and circulating strains often lead to high morbidity. Hence, development of a universal influenza A vaccine targeting all IAV strains is urgently needed. In the present study, the protective efficacy and immune responses induced by the extracellular domain of Matrix 2 protein (M2e) displayed on the virus-like particles of Macrobrachium rosenbergii nodavirus (NvC-M2ex3) were investigated in BALB/c mice. NvC-M2ex3 was demonstrated to be highly immunogenic even in the absence of adjuvants. Higher anti-M2e antibody titers corresponded well with increased survival, reduced immunopathology, and morbidity of the infected BALB/c mice. The mice immunized with NvC-M2ex3 exhibited lower H1N1 and H3N2 virus replication in the respiratory tract and the vaccine activated the production of different antiviral cytokines when they were challenged with H1N1 and H3N2. Collectively, these results suggest that NvC-M2ex3 could be a potential universal influenza A vaccine.

Immunological properties of the SLLTEVET epitope of Influenza A virus in multiple display on filamentous M13 phage

Small peptides require large carriers to stimulate the humoral immune system. The filamentous phages, such as M13, have been proposed as vectors for expressing and carrying these peptides on their capsid surface. M2e 2-9 (SLLTEVET) residues of the transmembrane protein M2 of Influenza A virus are conserved and considered as a suitable target for immunization against a wide range of Influenza A virus strains. Here, M2e (2-9) sequence of Influenza A virus was fused to the N-terminus of the major coat protein gpVIII of M13 phage and was used to immunize broiler chickens. The results showed that the SLLTEVET peptide on the surface of M13 phage was expressed, the hybrid phage was immunogenic and produced specific antibodies against M2e (2-9) in broiler chickens.

The dawn of phage therapy

Bacteriophages or phages, being the most abundant entities on earth, represent a potential solution to a diverse range of problems. Phages are successful antibacterial agents whose use in therapeutics was hindered by the discovery of antibiotics. Eventually, because of the development and spread of antibiotic resistance among most bacterial species, interest in phage as therapeutic entities has returned, because their noninfectious nature to humans should make them safe for human nanomedicine. This review highlights the most recent advances and progress in phage therapy and bacterial hosts against which phage research is currently being conducted with respect to food, human, and marine pathogens. Bacterial immunity against phages and tactics of phage revenge to defeat bacterial defense systems are also summarized. We have also discussed approved phage-based products (whole phage-based products and phage proteins) and shed light on their influence on the eukaryotic host with respect to host safety and induction of immune response against phage preparations. Moreover, creation of phages with desirable qualities and their uses in cancer treatment, vaccine production, and other therapies are also reviewed to bring together evidence from the scientific literature about the potentials and possible utility of phage and phage encoded proteins in the field of therapeutics and industrial biotechnology.

Phage-based vaccines

Bacteriophages, or more colloquially as phages, are viruses that possess the ability to infect and replicate with bacterial cells. They are assembled from two major types of biomolecules, the nucleic acids and the proteins, with the latter forming a capsid and the former being encapsulated. In the eukaryotic hosts, phages are inert particulate antigens and cannot trigger pathogenesis. In recent years, many studies have been explored about using phages as nanomedicine platforms for developing vaccines due to their unique biological characteristics. The whole phage particles can be used for vaccine design in the form of phage-displayed vaccines or phage DNA vaccines. Phage-displayed vaccines are the phages with peptide or protein antigens genetically displayed on their surfaces as well as those with antigens chemically conjugated or biologically bound on their surfaces. The phages can then deliver the immunogenic peptides or proteins to the target cells or tissues. Phage DNA vaccines are the eukaryotic promoter-driven vaccine genes inserted in the phage genomes, which are carried by phages to the target cells to generate antigens. The antigens, either as the immunogenic peptides or proteins displayed on the phages, or as the products expressed from the vaccine genes, can serve as vaccines to elicit immune responses for disease prevention and treatment. Both phage-displayed vaccines and phage DNA vaccines promise a brilliant future for developing vaccines. This review presents the recent advancements in the field of phage-based vaccines and their applications in both the prevention and treatment of various diseases. It also discusses the challenges and perspectives in moving this field forwards.

Bacteriophage T4 nanoparticles for vaccine delivery against infectious diseases

Subunit vaccines containing one or more target antigens from pathogenic organisms represent safer alternatives to whole pathogen vaccines. However, the antigens by themselves are not sufficiently immunogenic and require additives known as adjuvants to enhance immunogenicity and protective efficacy. Assembly of the antigens into virus-like nanoparticles (VLPs) is a better approach as it allows presentation of the epitopes in a more native context. The repetitive, symmetrical, and high density display of antigens on the VLPs mimic pathogen-associated molecular patterns seen on bacteria and viruses. The antigens, thus, might be better presented to stimulate host's innate as well as adaptive immune systems thereby eliciting both humoral and cellular immune responses. Bacteriophages such as phage T4 provide excellent platforms to generate the nanoparticle vaccines. The T4 capsid containing two non-essential outer proteins Soc and Hoc allow high density array of antigen epitopes in the form of peptides, domains, full-length proteins, or even multi-subunit complexes. Co-delivery of DNAs, targeting molecules, and/or molecular adjuvants provides additional advantages. Recent studies demonstrate that the phage T4 VLPs are highly immunogenic, do not need an adjuvant, and provide complete protection against bacterial and viral pathogens. Thus, phage T4 could potentially be developed as a "universal" VLP platform to design future multivalent vaccines against complex and emerging pathogens.

Lambda bacteriophage nanoparticles displaying GP2, a HER2/neu derived peptide, induce prophylactic and therapeutic activities against TUBO tumor model in mice

Generating a protective and long-lasting immune response is the primary goal in the expanding field of immunotherapeutic research. In current study we designed an immunogenic bacteriophage- based vaccine to induce a cytotoxic T lymphocyte activity against a mice tumor model over-expressing HER2/neu. Bacteriophage λ displaying a HER2/neu derived peptide GP2 was constructed and used as an anti-cancer vaccine in a BALB/c mouse xenograft tumor model. The results of our study indicated that phage nanoparticles displaying GP2 as a fused peptide to the gpD phage capsid protein induced a robust CTL response. Furthermore, the chimeric phage nanoparticles protected mice against HER2/neu-positive tumor challenge in both prophylactic and therapeutic settings. In conclusion, we propose that λ phage nanoparticles decorated with GP2 peptide merit further investigation for the development of peptide-based vaccines against HER2/neu overexpressing tumors.

A Perspective on Nanoparticle Universal Influenza Vaccines

Annually recurring seasonal influenza causes massive economic loss and poses severe threats to public health worldwide. The current seasonal influenza vaccines are the most effective means of preventing influenza infections but possess major weaknesses. Seasonal influenza vaccines require annual updating of the vaccine strains. However, it is an unreachable task to accurately predict the future circulating strains. Vaccines with mismatched strains dramatically compromise the vaccine efficacy. In addition, the seasonal influenza vaccines are ineffective against an unpredictable pandemic. A universal influenza vaccine would overcome these weaknesses of the seasonal vaccines and abolish the threat of influenza pandemics. One approach under investigation is to design influenza vaccine immunogens based on conserved, type-specific amino acid sequences and conformational epitopes, rather than strain-specific. Such vaccines can elicit broadly reactive humoral and cellular immunity. Universal influenza vaccine development has intensively employed nanotechnology because the structural and morphological properties of nanoparticles dramatically improve vaccine immunogenicity and the induced immunity duration. Layered protein nanoparticles can decrease off-target immune responses, fine-tune antigen recognition and processing, and facilitate comprehensive immune response induction. Herein, we review the designs of effective nanoparticle universal influenza vaccines, the recent discoveries of specific nanoparticle features that contribute to immunogenicity enhancement, and recent progress in clinical trials.

Immunogenicity and antitumor activity of the superlytic λF7 phage nanoparticles displaying a HER2/neu-derived peptide AE37 in a tumor model of BALB/c mice

Phage display technique has been increasingly researched for vaccine design and delivery strategies in recent years. In this study, the AE37 (Ii-Key/HER-2/neu 776-790) peptide derived from HER2 (human epidermal growth factor receptor protein) was used as a fused peptide to the lambda phage (λF7) coat protein gpD, and the phage nanoparticles were used to induce antitumor immunogenicity in a TUBO model of breast cancer in mice. Mice were immunized with the AE37 peptide displaying phage, λF7 (gpD::AE37) every 2-week intervals over 6-weeks, then the generated immune responses were evaluated. An induction of CTL immune response by the λF7 (gpD::AE37) construct compared to the control λF7 and buffer groups was observed in vitro. Moreover, in the in vivo studies, the vaccine candidate showed promising prophylactic and therapeutic effects against the HER2 overexpressing cancer in BALB/c mice.

Advances in the T7 phage display system (Review)

The present review describes the advantages and updated applications of the T7 phage display system in bioscience and medical science. Current phage display systems are based on various bacteriophage vectors, including M13, T7, T4 and f1. Of these, the M13 phage display is the most frequently used, however, the present review highlights the advantages of the T7 system. As a phage display platform, M13 contains single‑stranded DNA, while the T7 phage consists of double‑stranded DNA, which exhibits increased stability and is less prone to mutation during replication. Additional characteristics of the T7 phage include the following: The T7 phage does not depend on a protein secretion pathway in the lytic cycle; expressed peptides and proteins are usually located on the C‑terminal region of capsid protein gp10B, which avoids problems associated with steric hindrance; and T7 phage particles exhibit high stability under various extreme conditions, including high temperature and low pH, which facilitates effective high‑throughput affinity elutriation. Recent applications of the T7 phage display system have been instrumental in uncovering mechanisms of molecular interaction, particularly in the fields of antigen discovery, vaccine development, protein interaction, and cancer diagnosis and treatment.

Development of a novel dual-domain nanoparticle antigen construct for universal influenza vaccine

A highly effective antigen construct for presenting conserved antigen domains is essential to the development of a universal influenza vaccine. We have developed a novel dual-domain nanoparticle fusion protein (DDNFP) which allows independent presentation of two conserved domains. The conserved domains used were from two separate viral surface proteins, M2e of M2 and fusion peptide (FP) or long alpha helix (CD) of HA2. The carrier is a novel nanoparticle protein - the dodecameric DNA binding protein from starved cells (Dps) of bacteria or archaea. Dps was found to be uniquely capable of simultaneous fusion and surface presentation at both N- and C-termini while retaining the ability to form nanoparticles. Thus, DDNFPs with M2e and FP or CD fused at N- and C-termini of Dps from E. coli (EcDps) or other bacteria were first constructed based on the H1 subtype sequences along with corresponding single-domain nanoparticle fusion proteins (SDNFPs). They were expressed at high levels in bacteria and found to form nanoparticles of the expected size (∼9 nm). They were stable against treatment at high temperatures. The DDNFPs (M2e-EcDps-FP and M2e-EcDps-CD) induced strong antibody responses against individual antigen domains and provided full protection against lethal challenge with PR8 virus (H1N1). Importantly, the protection by DDNFPs was synergistically enhanced as compared to SDNFPs. The M2e-EcDps-CD provided an even stronger protection than M2e-EcDps-FP and therefore appeared to be the superior construct. Together, with novel domain combination, enhanced protection and ease of production, this M2e/CD DDNFP could potentially be a highly effective antigen construct for the universal influenza vaccine.

Immunogenicity and efficacy of replication-competent recombinant influenza virus carrying multimeric M2 extracellular domains in a chimeric hemagglutinin conjugate

Current influenza vaccines provide hemagglutinin (HA) strain-specific protection. To improve cross protection, we engineered replication-competent influenza A virus to express tandem repeats of heterologous M2 extracellular (M2e) domains in a chimeric HA. M2e epitopes conjugated to HA glycoproteins (M2e4x-HA) were found to be expressed on the surfaces of a replicable influenza virus as examined by electron microscopy. The recombinant influenza virus containing M2e4x-HA was moderately attenuated but superior to the parental virus in inducing M2e specific antibodies without compromising HA immunogenicity. Recombinant influenza virus immune mice showed better cross protection than parental virus immune mice. Immune sera from the mice with inoculation of live recombinant influenza virus expressing M2e4x-HA were effective in conferring protection against H1, H3, and H5 subtype influenza viruses. This study indicates that recombinant influenza virus expressing conserved protective epitopes in an HA chimeric form can provide a new approach for improving the efficacy of influenza vaccines.

Advances in the study of nodavirus

Nodaviruses are small bipartite RNA viruses which belong to the family of Nodaviridae. They are categorized into alpha-nodavirus, which infects insects, and beta-nodavirus, which infects fishes. Another distinct group of nodavirus infects shrimps and prawns, which has been proposed to be categorized as gamma-nodavirus. Our current review focuses mainly on recent studies performed on nodaviruses. Nodavirus can be transmitted vertically and horizontally. Recent outbreaks have been reported in China, Indonesia, Singapore and India, affecting the aquaculture industry. It also decreased mullet stock in the Caspian Sea. Histopathology and transmission electron microscopy (TEM) are used to examine the presence of nodaviruses in infected fishes and prawns. For classification, virus isolation followed by nucleotide sequencing are required. In contrast to partial sequence identification, profiling the whole transcriptome using next generation sequencing (NGS) offers a more comprehensive comparison and characterization of the virus. For rapid diagnosis of nodavirus, assays targeting the viral RNA based on reverse-transcription PCR (RT-PCR) such as microfluidic chips, reverse-transcription loop-mediated isothermal amplification (RT-LAMP) and RT-LAMP coupled with lateral flow dipstick (RT-LAMP-LFD) have been developed. Besides viral RNA detections, diagnosis based on immunological assays such as enzyme-linked immunosorbent assay (ELISA), immunodot and Western blotting have also been reported. In addition, immune responses of fish and prawn are also discussed. Overall, in fish, innate immunity, cellular type I interferon immunity and humoral immunity cooperatively prevent nodavirus infections, whereas prawns and shrimps adopt different immune mechanisms against nodavirus infections, through upregulation of superoxide anion, prophenoloxidase, superoxide dismutase (SOD), crustin, peroxinectin, anti-lipopolysaccharides and heat shock proteins (HSP). Potential vaccines for fishes and prawns based on inactivated viruses, recombinant proteins or DNA, either delivered through injection, oral feeding or immersion, are also discussed in detail. Lastly, a comprehensive review on nodavirus virus-like particles (VLPs) is presented. In recent years, studies on prawn nodavirus are mainly focused on Macrobrachium rosenbergii nodavirus (MrNV). Recombinant MrNV VLPs have been produced in prokaryotic and eukaryotic expression systems. Their roles as a nucleic acid delivery vehicle, a platform for vaccine development, a molecular tool for mechanism study and in solving the structures of MrNV are intensively discussed.

Immunogenicity of T7 bacteriophage nanoparticles displaying G-H loop of foot-and-mouth disease virus (FMDV)

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals that causes severe economic losses worldwide. The G-H loop of the FMDV VP1 structural protein is the major neutralizing antigenic site. However, a fully protective G-H loop peptide vaccine requires the addition of promiscuous Th sites from a source outside VP1. Thus, we demonstrated the potential of T7 bacteriophage based nanoparticles displaying a genetically fused G-H loop peptide (T7-GH) as a FMDV vaccine candidate. Recombinant T7-GH phage was constructed by inserting the G-H loop coding region into the T7 Select 415-1b vector. Purified T7-GH phage nanoparticles were analyzed by SDS-PAGE, Western blot and Dot-ELISA. Pigs seronegative for FMDV exposure were immunized with T7-GH nanoparticles along with the adjuvant Montanide ISA206, and two commercially available FMDV vaccines (InactVac and PepVac). Humoral and cellular immune responses, as well as protection against virulent homologous virus challenge were assessed following single dose immunization. Pigs immunized T7-GH developed comparable anti-VP1 antibody titers to PepVac, although lower LPBE titers than was induced by InactVac. Antigen specific lymphocyte proliferation was detected in T7-GH group similar to that of PepVac group, however, weaker than InactVac group. Pigs immunized with T7-GH developed a neutralizing antibody response stronger than PepVac, but weaker than InactVac. Furthermore, 80% (4/5) of T7-GH immunized pigs were protected from challenge with virulent homologous virus. These findings demonstrate that the T7-GH phage nanoparticles were effective in eliciting antigen specific immune responses in pigs, highlighting the value of such an approach in the research and development of FMDV vaccines.

Bacteriophages and Their Immunological Applications against Infectious Threats

Bacteriophage therapy dates back almost a century, but the discovery of antibiotics led to a rapid decline in the interests and investments within this field of research. Recently, the novel threat of multidrug-resistant bacteria highlighted the alarming drop in research and development of new antibiotics: 16 molecules were discovered during 1983–87, 10 new therapeutics during the nineties, and only 5 between 2003 and 2007. Phages are therefore being reconsidered as alternative therapeutics. Phage display technique has proved to be extremely promising for the identification of effective antibodies directed against pathogens, as well as for vaccine development. At the same time, conventional phage therapy uses lytic bacteriophages for treatment of infections and recent clinical trials have shown great potential. Moreover, several other approaches have been developed in vitro and in vivo using phage-derived proteins as antibacterial agents. Finally, their use has also been widely considered for public health surveillance, as biosensor phages can be used to detect food and water contaminations and prevent bacterial epidemics. These novel approaches strongly promote the idea that phages and their proteins can be exploited as an effective weapon in the near future, especially in a world which is on the brink of a “postantibiotic era.”

Supplementation of inactivated influenza vaccine with norovirus P particle-M2e chimeric vaccine enhances protection against heterologous virus challenge in chickens

The current inactivated influenza vaccines provide satisfactory protection against homologous viruses but limited cross-protection against antigenically divergent strains. Consequently, there is a need to develop more broadly protective vaccines. The highly conserved extracellular domain of the matrix protein 2 (M2e) has shown promising results as one of the components of a universal influenza vaccine in different animal models. As an approach to overcome the limited, strain specific, protective efficacy of inactivated influenza vaccine (IIV), a combination of recombinant M2e expressed on the surface of norovirus P particle (M2eP) and IIV was tested in chickens. Co-immunization of birds with both vaccines did not affect the production of M2e-specific IgG antibodies compared to the group vaccinated with M2eP alone. However, the co-immunized birds developed significantly higher pre-challenge hemagglutination inhibition antibody titers against the homologous IIV antigen and heterologous challenge virus. These combined vaccine groups also had cross reactive antibody responses against different viruses (H5, H6, and H7 subtypes) compared to the IIV alone vaccinated group. Upon intranasal challenge with homologous and heterologous viruses, the combined vaccine groups showed greater reduction in viral shedding in tracheal swabs compared to those groups receiving IIV alone. Moreover, M2eP antisera from vaccinated birds were able to bind to the native M2 expressed on the surface of whole virus particles and infected cells, and inhibit virus replication in vitro. Our results support the potential benefit of supplementing IIV with M2eP, to expand the vaccine cross protective efficacy.

A dual purpose universal influenza vaccine candidate confers protective immunity against anthrax

Preventive influenza vaccines must be reformulated annually because of antigen shift and drift of circulating influenza viral strains. However, seasonal vaccines do not always match the circulating strains, and there is the ever-present threat that avian influenza viruses may adapt to humans. Hence, a universal influenza vaccine is needed to provide protective immunity against a broad range of influenza viruses. We designed an influenza antigen consisting of three tandem M2e repeats plus HA2, in combination with a detoxified anthrax oedema toxin delivery system (EFn plus PA) to enhance immune responses. The EFn-3×M2e-HA2 plus PA vaccine formulation elicited robust, antigen-specific, IgG responses; and was protective against heterologous influenza viral challenge when intranasally delivered to mice three times. Moreover, use of the detoxified anthrax toxin system as an adjuvant had the additional benefit of generating protective immunity against anthrax. Hence, this novel vaccine strategy could potentially address two major emerging public health and biodefence threats.

Genetically modified bacteriophages in applied microbiology

Bacteriophages represent a simple viral model of basic research with many possibilities for practical application. Due to their ability to infect and kill bacteria, their potential in the treatment of bacterial infection has been examined since their discovery. With advances in molecular biology and gene engineering, the phage application spectrum has been expanded to various medical and biotechnological fields. The construction of bacteriophages with an extended host range or longer viability in the mammalian bloodstream enhances their potential as an alternative to conventional antibiotic treatment. Insertion of active depolymerase genes to their genomes can enforce the biofilm disposal. They can also be engineered to transfer various compounds to the eukaryotic organisms and the bacterial culture, applicable for the vaccine, drug or gene delivery. Phage recombinant lytic enzymes can be applied as enzybiotics in medicine as well as in biotechnology for pathogen detection or programmed cell death in bacterial expression strains. Besides, modified bacteriophages with high specificity can be applied as bioprobes in detection tools to estimate the presence of pathogens in food industry, or utilized in the control of food-borne pathogens as part of the constructed phage-based biosorbents.