The use of phages as antibacterial agents is limited by their generally narrow host range. The aim of this study was to make a T4-like phage, WG01, obtain the host range of another T4-like phage, QL01, by replacing its host determinant gene region with that of QL01. This process triggered a direct expansion of the WG01 host range. The offspring of WG01 obtained the host ranges of both QL01 and WG01, as well as the ability to infect eight additional host bacteria in comparison to the wildtype strains. WQD had the widest host range; therefore, the corresponding QD fragments could be used for constructing a homologous sequence library. Moreover, after a sequencing analysis of gene37, we identified two different mechanisms responsible for the expanded host range: 1) the first generation of WG01 formed chimeras without mutations; and 2) the second generation of WG01 mutants formed from the chimeras. The expansion of the host range indicated that regions other than the C-terminal region may indirectly change the receptor specificity by altering the supportive capacity of the binding site. Additionally, we also found that the subsequent generations acquired a novel means of expanding the host range through acquiring a wider temperature range for lysis by exchanging gene37. The method developed in this work offers a quick way to change or expand the host range of a phage. Future clinical applications for screening phages against a given clinical isolate could be achieved after acquiring more suitable homologous sequences. T4-like phages have been established as safe in numerous phage therapy applications. The primary drawbacks to the use of phages as therapeutic agents include their highly specific host range. Thus, changing or expanding the host range of T4-like phages is beneficial for selecting phages for phage therapy. In this study, the host range of one T4-like phage WG01 was expanded using genetic manipulation. The WG01 derivatives acquired a novel means of expanding their host range through acquiring a wider temperature range for lysis. A region was located that had the potential to be used as a sequence region for homologous sequence recombination.
Avian pathogenic Escherichia coli (APEC) causes colibacillosis in poultry, resulting in severe economic losses worldwide. Coliphages represent alternative antibacterial substitutes based on high lytic efficiency and few side-effects. However, the complete genome sequences information of APEC phages are limited, and knowledge of undesired genes and the narrow host range restrict their applications. In this study, we isolated a virulent phage QL01, with a relatively broad lytic spectrum (41 of 78 APEC strains). Transmission electron micrography showed it belonged to the family Myoviridae with an elongated head and a contractile tail. Whole genome sequencing revealed a linear double-stranded DNA (170,527 kb; GC content, 39.6%) with 275 possible ORFs. Comparative genome analysis revealed high homology between QL01 and other T4-like phages. However, it also showed some unique features, for example, ORF142 and ORF143, which encode IP9 and IP8, respectively, and may counteract host resistance only exist in a few T4-like phages such as IME08 and vB_EcoM_VR5. Furthermore, phage therapy in artificially infected ducks showed a 26.67% decrease in mortality compared with the untreated group. Our study indicates the potential antibacterial function of phage QL01 against APEC infections and highlights unique molecular features underlying the relatively broad host range.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.