In situ reprogramming of gut bacteria by oral delivery

Interactions of Bacteriophages with Animal and Human Organisms-Safety Issues in the Light of Phage Therapy

Bacteriophages are viruses infecting bacterial cells. Since there is a lack of specific receptors for bacteriophages on eukaryotic cells, these viruses were for a long time considered to be neutral to animals and humans. However, studies of recent years provided clear evidence that bacteriophages can interact with eukaryotic cells, significantly influencing the functions of tissues, organs, and systems of mammals, including humans. In this review article, we summarize and discuss recent discoveries in the field of interactions of phages with animal and human organisms. Possibilities of penetration of bacteriophages into eukaryotic cells, tissues, and organs are discussed, and evidence of the effects of phages on functions of the immune system, respiratory system, central nervous system, gastrointestinal system, urinary tract, and reproductive system are presented and discussed. Modulations of cancer cells by bacteriophages are indicated. Direct and indirect effects of virulent and temperate phages are discussed. We conclude that interactions of bacteriophages with animal and human organisms are robust, and they must be taken under consideration when using these viruses in medicine, especially in phage therapy, and in biotechnological applications.

The Many Applications of Engineered Bacteriophages-An Overview

Since their independent discovery by Frederick Twort in 1915 and Felix d’Herelle in 1917, bacteriophages have captured the attention of scientists for more than a century. They are the most abundant organisms on the planet, often outnumbering their bacterial hosts by tenfold in a given environment, and they constitute a vast reservoir of unexplored genetic information. The increased prevalence of antibiotic resistant pathogens has renewed interest in the use of naturally obtained phages to combat bacterial infections, aka phage therapy. The development of tools to modify phages, genetically or chemically, combined with their structural flexibility, cargo capacity, ease of propagation, and overall safety in humans has opened the door to a myriad of applications. This review article will introduce readers to many of the varied and ingenious ways in which researchers are modifying phages to move them well beyond their innate ability to target and kill bacteria.

New technologies for developing phage-based tools to manipulate the human microbiome

Gut bacteria play an essential role in the human body by regulating multiple functions, producing essential metabolites, protecting against pathogen invasion, and much more. Conversely, changes in their community structure are linked to several gastrointestinal (GI) and non-GI conditions. Fortunately, these bacteria are amenable to external perturbations, but we need specific tools for their safe manipulation as nonspecific changes can cause unpredicted long-term consequences. Here, we mainly discuss recent advances in cultivation-independent technologies and argue their relevance to different key steps, that is, identifying the modulation targets and developing phage-based tools to precisely modulate gut bacteria and restore a sustainable microbiome in humans. We finally suggest multiple modulating strategies for different dysbiosis-associated diseases.

Microencapsulation of Bacteriophages Using Membrane Emulsification in Different pH-Triggered Controlled Release Formulations for Oral Administration

An E.coli-specific phage was encapsulated in three different pH responsive polymer formulations using the process of membrane emulsification. Small 100 µm capsules were fabricated and shown to afford phages suitable acid protection upon exposure to pH 1.5. Selection of polymer formulations allowed controlled release of phages at pH 5.5, pH 6 and pH 7. Other aspects of phage encapsulation including factors affecting encapsulation yield, release kinetics, acid and storage stability were evaluated. The work presented here would be useful for future evaluation of new therapeutic strategies including microbiome editing approaches allowing pH-triggered release of phages and delivery of encapsulated cargo to different intestinal compartments. The size of the capsules were selected to permit ease of delivery using small bore oral gavage tubes typically used in pre-clinical studies for evaluation of drug substances using small animal vertebrate models such as in mice and rats.

Approaches for manufacture, formulation, targeted delivery and controlled release of phage-based therapeutics

A future successful bacteriophage industry requires development of robust scalable manufacturing platforms for upstream production of high phage titres and their downstream purification and concentration whilst achieving processing yields en route. Development of a broadly applicable process flow sheet employing well-characterised unit operations with knowledge of their critical process parameters is beginning to emerge. A quality-by-design approach is advocated for the development of cost-effective phage production platforms. The use of on-line and at-line process analytical tools for process monitoring, control and quality assurance are discussed. Phage biophysical characterisation tools allowing rational development of liquid formulations and dry powder forms are presented. Recent innovations in phage encapsulation methods highlight the potential innovation opportunities in this research space that could have significant impact on the future prospects of this industry.

Synthetic Biology Approaches in The Development of Engineered Therapeutic Microbes

Since the intimate relationship between microbes and human health has been uncovered, microbes have been in the spotlight as therapeutic targets for several diseases. Microbes contribute to a wide range of diseases, such as gastrointestinal disorders, diabetes and cancer. However, as host-microbiome interactions have not been fully elucidated, treatments such as probiotic administration and fecal transplantations that are used to modulate the microbial community often cause nonspecific results with serious safety concerns. As an alternative, synthetic biology can be used to rewire microbial networks such that the microbes can function as therapeutic agents. Genetic sensors can be transformed to detect biomarkers associated with disease occurrence and progression. Moreover, microbes can be reprogrammed to produce various therapeutic molecules from the host and bacterial proteins, such as cytokines, enzymes and signaling molecules, in response to a disturbed physiological state of the host. These therapeutic treatment systems are composed of several genetic parts, either identified in bacterial endogenous regulation systems or developed through synthetic design. Such genetic components are connected to form complex genetic logic circuits for sophisticated therapy. In this review, we discussed the synthetic biology strategies that can be used to construct engineered therapeutic microbes for improved microbiome-based treatment.