With the recent rise in interest in using lytic bacteriophages as therapeutic agents, there is an urgent requirement to understand their fundamental biology to enable the engineering of their genomes. Current methods of phage engineering rely on homologous recombination, followed by a system of selection to identify recombinant phages. For bacteriophage T7, the host genes cmk or trxA have been used as a selection mechanism along with both type I and II CRISPR systems to select against wild-type phage and enrich for the desired mutant. Here, we systematically compare all three systems; we show that the use of marker-based selection is the most efficient method and we use this to generate multiple T7 tail fibre mutants. Furthermore, we found the type II CRISPR-Cas system is easier to use and generally more efficient than a type I system in the engineering of phage T7. These results provide a foundation for the future, more efficient engineering of bacteriophage T7.

Phages or bacteriophages, viruses that infect and replicate inside bacteria, are the most abundant microorganisms on earth. The realization that antibiotic resistance poses a substantial risk to the world's health and global economy is revitalizing phage therapy as a potential solution. The increasing ease by which phage genomes can be modified, owing to the influx of new technologies, has led to an expansion of their natural capabilities, and a reduced dependence on phage isolation from environmental sources. This review will discuss the way synthetic biology has accelerated the construction of genetically modified phages and will describe the wide range of their applications. It will further provide insight into the societal and economic benefits that derive from the use of recombinant phages in various sectors, from health to biodetection, biocontrol and the food industry.

Tel.: +44 (0)116 252 5743With the recent rise in interest in using lytic bacteriophages as therapeutic agents, there is an urgent requirement to understand their fundamental biology to enable the engineering of their genomes. Current methods of phage engineering rely on homologous recombination, followed by a system of selection to identify recombinant phages. For bacteriophage T7, the host genes cmk or trx have been used as a selection mechanism along with both type I and II CRISPR systems to select against wild-type phage and enrich for the desired mutant. Here we systematically compare all three systems; we show that the use of marker-based selection is the most efficient method and we use this to generate multiple T7 tail fiber mutants. Furthermore, we found the type II CRISPR-Cas system is easier to use and generally more efficient than a type I system in the engineering of phage T7. These results provide a foundation for the future, more efficient engineering of bacteriophage T7.

Sodium and water perturbations, manifesting as hyponatraemia and hypernatraemia, are common in patients who had an acute stroke, and are associated with worse outcomes and increased mortality. Other non-stroke-related causes of sodium and water perturbations in these patients include underlying comorbidities and concomitant medications. Additionally, hospitalised patients who had an acute stroke may receive excessive intravenous hypotonic solutions, have poor fluid intake due to impaired neurocognition and consciousness, may develop sepsis or are administered drugs (eg, mannitol); factors that can further alter serum sodium levels. Sodium and water perturbations can also be exacerbated by the development of endocrine consequences after an acute stroke, including secondary adrenal insufficiency, syndrome of inappropriate antidiuretic hormone secretion and diabetes insipidus. Recently, COVID-19 infection has been reported to increase the risk of development of sodium and water perturbations that may further worsen the outcomes of patients who had an acute stroke. Because there are currently no accepted consensus guidelines on the management of sodium and water perturbations in patients who had an acute stroke, we conducted a systematic review of the literature published in English and in peer-reviewed journals between January 2000 and December 2020, according to PRISMA guidelines, to assess on the current knowledge and clinical practices of this condition. In this review, we discuss the signs and symptoms of hyponatraemia and hypernatraemia, the pathogenesis of hyponatraemia and hypernatraemia, their clinical relevance, and we provide our recommendations for effective treatment strategies for the neurologist in the management of sodium and water perturbations in commonly encountered aetiologies of patients who had an acute stroke.