Two Novel Yersinia pestis Bacteriophages with a Broad Host Range: Potential as Biocontrol Agents in Plague Natural Foci

Abstract

Bacteriophages (phages) have been successfully used as disinfectors to kill bacteria in food and the environment and have been used medically for curing human diseases. The objective of this research was to elucidate the morphological and genomic characteristics of two novel Yersinia pestis phages, vB_YpeM_ MHS112 (MHS112) and vB_YpeM_GMS130 (GMS130), belonging to the genus Gaprivervirus, subfamily Tevenvirinae, family Myoviridae. Genome sequencing showed that the sizes of MHS112 and GMS130 were 170507 and 168552 bp, respectively. A total of 303 and 292 open reading frames with 2 tRNA and 3 tRNA were predicted in MHS112 and GMS130, respectively. The phylogenetic relationships were analysed among the two novel Y. pestis phages, phages in the genus Gaprivervirus, and several T4-like phages infecting the Yersinia genus. The bacteriophage MHS112 and GMS130 exhibited a wider lytic host spectrum and exhibited comparative temperature and pH stability. Such features signify that these phages do not need to rely on Y. pestis as their host bacteria in the ecological environment, while they could be based on more massive Enterobacteriales species to propagate and form ecological barriers against Y. pestis pathogens colonised in plague foci. Such characteristics indicated that the two phages have potential as biocontrol agents for eliminating the endemics of animal plague in natural plague foci.

Phylogenetic Relationships and Evolution of the Genus Eganvirus (186-Type) Yersinia pestis Bacteriophages

“…The above filtrate was incubated with 200 µL of the EV76 strain in LB broth (OD600 ≈ 0.4) and shaken (220 rpm) at 28 • C for 24 h. Next, the phages were filtered through a 0.22 µm filter and added to 500 µL of Y. pestis EV76 culture until the liquid became clear. Single phage plaques were separated and purified by a double agar plaque assay according to the literature [13,20]. The natural plague foci included F: Rattus flavipectus, which is in Yunnan-Guangdong-Fujian provinces; E: Apodemus chevrieri-Eothenomys miletus, which is in the highlands of northwestern Yunnan Province; and *: MLG42, which belongs to the genus Felsduovirus.…”

“…A total of 114 Enterobacteriaceae strains (15 genera) were selected, including the genera Yersinia, Escherichia, Salmonella, Shigella, Cronobacter, Klebsiella, Enterobacter, Enterococcus, Cronobacter, Serratia, Proteus, Providencia, Morganella, Citrobacter, and Pantoea. A spot testing assay was used for host range analysis [13]. Briefly, 400 µL of bacterial culture liquid was added to 50 • C molten LB semisolid agar, mixed and poured into the prepared 36 grids of nutrient solid plates to make a double-layer plate.…”

“…Phages were propagated in 500 µL of LB medium supplemented with Y. pestis EV76 strain culture with shaking (220 rpm) overnight at 28 • C, and phage DNA was extracted using an ABigen corporation Lambda phage genomic DNA extraction kit (ABigen Corp., Beijing, China) according to previous methods [13]. Soapnuke (v2.0.5) was used for quality control.…”

“…Another type of Yersinia lytic phage is the T4-like phage, and T4-like phages can generally infect a broad range of hosts [44], sometimes spanning different bacterial genera [14]. T4-like Yersinia phages with a wide host spectrum are common [45], such as fD1 [46], JC221 [21], YpsP-PST (KF208315.1) [40], fPS-2 (LR215722), fPS-65 (LR215724), and fPS-90 (LR215723) [19], as well as two Gaprivervirus genus Y. pestis phages (MHS112 and GMS130) [13]. Some of these T4-like phages even appeared to reproduce much more efficiently in E. coli strains than in Y. pestis [13,46].…”

“…Bacteriophages were first explored for their ability to treat plague cases in 1925 when Dr. d'Herelle attempted to treat four bubonic plague cases using Y. pestis phage (YpsP-G) [11]. In addition, phage therapy could be a new potential strategy for treating plague infection or as a biocontrol method for eliminating the endemics of animal plague in natural plague foci [12], such as the genus Gaprivervirus Y. pestis phages with broad host range characteristics, vB_YpeM_MHS112 (OP750247) and vB_YpeM_GMS130 (OP750248) [13].…”