RESUMEN
In an era of antibiotic therapy crisis caused by spreading antimicrobial resistance, and when recurrent urinary tract infections constitute a serious social and medical problem, the isolation and complex characterization of phages with a potential therapeutic application represents a promising solution. It is an inevitable, and even a necessary direction in the development of current phage research. In this paper, we present two newly isolated myoviruses that show lytic activity against multidrug-resistant clinical isolates of Enterobacter spp. (E. cloacae, E. hormaechei, and E. kobei), the genomes of which belong to a poorly represented phage group. Both phages were classified as part of the Tevenvirinae subfamily (Entb_43 was recognized as Karamvirus and Entb_45 as Kanagawavirus). Phage lytic spectra ranging from 40 to 60% were obtained. The most effective phage-to-bacteria ratios (MOI = 0.01 and MOI = 0.001) for both the phage amplification and their lytic activity against planktonic bacteria were also estimated. Complete adsorption to host cells were obtained after about 20 min for Entb_43 and 10 min for Entb_45. The phage lysates retained their initial titers even during six months of storage at both -70 °C and 4 °C, whereas storage at 37 °C caused a complete loss in their activity. We showed that phages retained their activity after incubation with solutions of silver and copper nanoparticles, which may indicate possible synergistic antibacterial activity. Moreover, a significant reduction in phage titers was observed after incubation with a disinfectant containing octenidinum dihydrochloridum and phenoxyethanol, as well as with 70% ethanol. The observed maintenance of phage activity during incubation in a urine sample, along with other described properties, may suggest a therapeutic potential of phages at the infection site after intravesical administration.
Asunto(s)
Bacteriófagos , Infecciones Urinarias , Antibacterianos/farmacología , Bacteriófagos/genética , Enterobacter , Humanos , Myoviridae/genéticaRESUMEN
[This corrects the article DOI: 10.3389/fmicb.2021.632686.].
RESUMEN
The Tevenvirinae viruses are some of the most common viruses on Earth. Representatives of this subfamily have long been used in the molecular biology studies as model organisms - since the emergence of the discipline. Tevenvirinae are promising agents for phage therapy in animals and humans, since their representatives have only lytic life cycle and many of their host bacteria are pathogens. As confirmed experimentally, some Tevenvirinae have non-canonical DNA bases. Non-canonical bases can play an essential role in the diversification of closely related viruses. The article performs a comparative and evolutionary analysis of Tevenvirinae genomes and components of Tevenvirinae genomes. A comparative analysis of these genomes and the genes associated with the synthesis of non-canonical bases allows us to conclude that non-canonical bases have a major influence on the divergence of Tevenvirinae viruses within the same habitats. Supposedly, Tevenvirinae developed a strategy for changing HGT frequency in individual populations, which was based on the accumulation of proteins for the synthesis of non-canonical bases and proteins that used those bases as substrates. Owing to this strategy, ancestors of Tevenvirinae with the highest frequency of HGT acquired genes that allowed them to exist in a certain niche, and ancestors with the lowest HGT frequency preserved the most adaptive of those genes. Given the origin and characteristics of genes associated with the synthesis of non-canonical bases in Tevenvirinae, one can assume that other phages may have similar strategies. The article demonstrates the dependence of genomic diversity of closely related Tevenvirinae on non-canonical bases.
RESUMEN
Resistance to carbapenems in Enterobacteriaceae, including Klebsiella pneumoniae, represents a major clinical problem given the lack of effective alternative antibiotics. Bacteriophages could provide a valuable tool to control the dissemination of antibiotic resistant isolates, for the decolonization of colonized individuals and for treatment purposes. In this work, we have characterized a lytic bacteriophage, named vB_Kpn_F48, specific for K. pneumoniae isolates belonging to clonal group 101. Phage vB_Kpn_F48 was classified as a member of Myoviridae, order Caudovirales, on the basis of transmission electron microscopy analysis. Physiological characterization demonstrated that vB_Kpn_F48 showed a narrow host range, a short latent period, a low burst size and it is highly stable to both temperature and pH variations. High throughput sequencing and bioinformatics analysis revealed that the phage is characterized by a 171 Kb dsDNA genome that lacks genes undesirable for a therapeutic perspective such integrases, antibiotic resistance genes and toxin encoding genes. Phylogenetic analysis suggests that vB_Kpn_F48 is a T4-like bacteriophage which belongs to a novel genus within the Tevenvirinae subfamily, which we tentatively named "F48virus". Considering the narrow host range, the genomic features and overall physiological parameters phage vB_Kpn_F48 could be a promising candidate to be used alone or in cocktails for phage therapy applications.
Asunto(s)
Bacteriólisis , Bacteriófagos/crecimiento & desarrollo , Bacteriófagos/aislamiento & purificación , Klebsiella pneumoniae/virología , Myoviridae/crecimiento & desarrollo , Myoviridae/aislamiento & purificación , Bacteriófagos/clasificación , Bacteriófagos/genética , Biología Computacional , Secuenciación de Nucleótidos de Alto Rendimiento , Especificidad del Huésped , Concentración de Iones de Hidrógeno , Microscopía Electrónica de Transmisión , Myoviridae/clasificación , Myoviridae/genética , Filogenia , Homología de Secuencia , Temperatura , Virión/ultraestructuraRESUMEN
The mechanisms by which bacteriophage T4 converts the metabolism of its E. coli host to one dedicated to progeny phage production was the subject of decades of intense research in many labs from the 1950s through the 1980s. Presently, a wide range of phages are starting to be used therapeutically and in many other applications, and also the range of phage sequence data available is skyrocketing. It is thus important to re-explore the extensive available data about the intricacies of the T4 infection process as summarized here, expand it to looking much more broadly at other genera of phages, and explore phage infections using newly-available modern techniques and a range of appropriate environmental conditions.