Cell-free multi-omics analysis reveals potential biomarkers in gastrointestinal cancer patients' blood.

During cancer progression, tumorigenic and immune signals are spread through circulating molecules, such as cell-free DNA (cfDNA) and cell-free RNA (cfRNA) in the blood. So far, they have not been comprehensively investigated in gastrointestinal cancers. Here, we profile 4 categories of cell-free omics data from patients with colorectal cancer and patients with stomach adenocarcinoma and then assay 15 types of genomic, epigenomic, and transcriptomic variations. We find that multi-omics data are more appropriate for detection of cancer genes compared with single-omics data. In particular, cfRNAs are more sensitive and informative than cfDNAs in terms of detection rate, enriched functional pathways, etc. Moreover, we identify several peripheral immune signatures that are suppressed in patients with cancer. Specifically, we establish a γδ-T cell score and a cancer-associated-fibroblast (CAF) score, providing insights into clinical statuses like cancer stage and survival. Overall, we reveal a cell-free multi-molecular landscape that is useful for blood monitoring in personalized cancer treatment.

Identification of novel cell-free RNAs in maternal plasma as preterm biomarkers in combination with placental RNA profiles.

BACKGROUND: Preterm birth (PTB) is the main driver of newborn deaths. The identification of pregnancies at risk of PTB remains challenging, as the incomplete understanding of molecular mechanisms associated with PTB. Although several transcriptome studies have been done on the placenta and plasma from PTB women, a comprehensive description of the RNA profiles from plasma and placenta associated with PTB remains lacking. METHODS: Candidate markers with consistent trends in the placenta and plasma were identified by implementing differential expression analysis using placental tissue and maternal plasma RNA-seq datasets, and then validated by RT-qPCR in an independent cohort. In combination with bioinformatics analysis tools, we set up two protein-protein interaction networks of the significant PTB-related modules. The support vector machine (SVM) model was used to verify the prediction potential of cell free RNAs (cfRNAs) in plasma for PTB and late PTB. RESULTS: We identified 15 genes with consistent regulatory trends in placenta and plasma of PTB while the full term birth (FTB) acts as a control. Subsequently, we verified seven cfRNAs in an independent cohort by RT-qPCR in maternal plasma. The cfRNA ARHGEF28 showed consistence in the experimental validation and performed excellently in prediction of PTB in the model. The AUC achieved 0.990 for whole PTB and 0.986 for late PTB. CONCLUSIONS: In a comparison of PTB versus FTB, the combined investigation of placental and plasma RNA profiles has shown a further understanding of the mechanism of PTB. Then, the cfRNA identified has the capacity of predicting whole PTB and late PTB.

Cell-free RNA for the liquid biopsy of gastrointestinal cancer.

Gastrointestinal (GI) cancer includes many cancer types, such as esophageal, liver, gastric, pancreatic, and colorectal cancer. As the cornerstone of personalized medicine for GI cancer, liquid biopsy based on noninvasive biomarkers provides promising opportunities for early diagnosis and dynamic treatment management. Recently, a growing number of studies have demonstrated the potential of cell-free RNA (cfRNA) as a new type of noninvasive biomarker in body fluids, such as blood, saliva, and urine. Meanwhile, transcriptomes based on high-throughput RNA detection technologies keep discovering new cfRNA biomarkers. In this review, we introduce the origins and applications of cfRNA, describe its detection and qualification methods in liquid biopsy, and summarize a comprehensive list of cfRNA biomarkers in different GI cancer types. Moreover, we also discuss perspective studies of cfRNA to overcome its current limitations in clinical applications. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Cancer type classification using plasma cell-free RNAs derived from human and microbes.

The utility of cell-free nucleic acids in monitoring cancer has been recognized by both scientists and clinicians. In addition to human transcripts, a fraction of cell-free nucleic acids in human plasma were proven to be derived from microbes and reported to have relevance to cancer. To obtain a better understanding of plasma cell-free RNAs (cfRNAs) in cancer patients, we profiled cfRNAs in ~300 plasma samples of 5 cancer types (colorectal cancer, stomach cancer, liver cancer, lung cancer, and esophageal cancer) and healthy donors (HDs) with RNA-seq. Microbe-derived cfRNAs were consistently detected by different computational methods when potential contaminations were carefully filtered. Clinically relevant signals were identified from human and microbial reads, and enriched Kyoto Encyclopedia of Genes and Genomes pathways of downregulated human genes and higher prevalence torque teno viruses both suggest that a fraction of cancer patients were immunosuppressed. Our data support the diagnostic value of human and microbe-derived plasma cfRNAs for cancer detection, as an area under the ROC curve of approximately 0.9 for distinguishing cancer patients from HDs was achieved. Moreover, human and microbial cfRNAs both have cancer type specificity, and combining two types of features could distinguish tumors of five different primary locations with an average recall of 60.4%. Compared to using human features alone, adding microbial features improved the average recall by approximately 8%. In summary, this work provides evidence for the clinical relevance of human and microbe-derived plasma cfRNAs and their potential utilities in cancer detection as well as the determination of tumor sites.

Optimizing factors for the efficient expression and purification of spao and lamb from Salmonella typhi

We optimized the expression and purification of outer membrane proteins SpaO and LamB from Salmonella typhi. We investigated various factors in the expression and purification processes, including the use of isopropyl ß-d-1 thiogalactopyranoside (IPTG), imidazole, and urea. First, PCR amplification was carried out on SpaO and LamB genes. The genes were then cloned in pTZ57R/T, and then expressed in pET28a vector and transformed into Escherichia coli BL21 (DE3). Gene insertion was confirmed by enzymatic digestion with NdeI and XhoI. Inclusion bodies expressing recombinant SpaO and LamB were induced with 200 and 400 µL 0.5 mM IPTG, respectively. The formed protein inclusion bodies were then isolated from the pellet and solubilized in IB buffer containing 8 M urea for SpaO and 6 M urea for LamB. Proteins were refolded by dialysis in 3M urea. Purified proteins with nickel-nitrilotriacetic acid affinity chromatography and eluted with buffer containing 250 mM imidazole for SpaO and 150 mM imidazole for LamB. The protein expression profiles were analyzed by SDS-PAGE, which identified the 33 and 49 kDa bands corresponding to rSpaO and rLamB. Western blotting Purification was carried out by nickel affinity resin with 250 mM and 150 mM imidazole for rSpaO and rLamB and refolded through stepwise dialysis with anti-His tag antibodies confirmed their expression. These optimized methods can be used to generate recombinant proteins for the development of future vaccines.

Identification and Evaluation of Recombinant Outer Membrane Proteins as Vaccine Candidates Against Klebsiella pneumoniae.

Klebsiella pneumoniae found in the normal flora of the human oral and intestinal tract mainly causes hospital-acquired infections but can also cause community-acquired infections. To date, most clinical trials of vaccines against K. pneumoniae have ended in failure. Furthermore, no single conserved protein has been identified as an antigen candidate to accelerate vaccine development. In this study, we identified five outer membrane proteins of K. pneumoniae, namely, Kpn_Omp001, Kpn_Omp002, Kpn_Omp003, Kpn_Omp004, and Kpn_Omp005, by using reliable second-generation proteomics and bioinformatics. Mice vaccinated with these five KOMPs elicited significantly higher antigen-specific IgG, IgG1, and IgG2a. However, only Kpn_Omp001, Kpn_Omp002, and Kpn_Omp005 were able to induce a protective immune response with two K. pneumoniae infection models. These protective effects were accompanied by the involvement of different immune responses induced by KOMPs, which included KOMPs-specific IFN-γ-, IL4-, and IL17A-mediated immune responses. These findings indicate that Kpn_Omp001, Kpn_Omp002, and Kpn_Omp005 are three potential Th1, Th2, and Th17 candidate antigens, which could be developed into multivalent and serotype-independent vaccines against K. pneumoniae infection.

Integrative analysis of long extracellular RNAs reveals a detection panel of noncoding RNAs for liver cancer.

Rationale: Long extracellular RNAs (exRNAs) in plasma can be profiled by new sequencing technologies, even with low abundance. However, cancer-related exRNAs and their variations remain understudied. Methods: We investigated different variations (i.e. differential expression, alternative splicing, alternative polyadenylation, and differential editing) in diverse long exRNA species (e.g. long noncoding RNAs and circular RNAs) using 79 plasma exosomal RNA-seq (exoRNA-seq) datasets of multiple cancer types. We then integrated 53 exoRNA-seq datasets and 65 self-profiled cell-free RNA-seq (cfRNA-seq) datasets to identify recurrent variations in liver cancer patients. We further combined TCGA tissue RNA-seq datasets and validated biomarker candidates by RT-qPCR in an individual cohort of more than 100 plasma samples. Finally, we used machine learning models to identify a signature of 3 noncoding RNAs for the detection of liver cancer. Results: We found that different types of RNA variations identified from exoRNA-seq data were enriched in pathways related to tumorigenesis and metastasis, immune, and metabolism, suggesting that cancer signals can be detected from long exRNAs. Subsequently, we identified more than 100 recurrent variations in plasma from liver cancer patients by integrating exoRNA-seq and cfRNA-seq datasets. From these datasets, 5 significantly up-regulated long exRNAs were confirmed by TCGA data and validated by RT-qPCR in an independent cohort. When using machine learning models to combine two of these validated circular and structured RNAs (SNORD3B-1, circ-0080695) with a miRNA (miR-122) as a panel to classify liver cancer patients from healthy donors, the average AUROC of the cross-validation was 89.4%. The selected 3-RNA panel successfully detected 79.2% AFP-negative samples and 77.1% early-stage liver cancer samples in the testing and validation sets. Conclusions: Our study revealed that different types of RNA variations related to cancer can be detected in plasma and identified a 3-RNA detection panel for liver cancer, especially for AFP-negative and early-stage patients.

Genomic and proteomic portrait of a novel mycobacteriophage SWU2 isolated from China.

Phage therapy, especially combination with antibiotics, was revitalized to control the antibiotics resistance. Mycobacteriophage, the phage of mycobacterium with the most notorious Mycobacterium tuberculosis (M. tuberculosis), was intensively explored. A novel mycobacteriophage SWU2 was isolated from a soil sample collected at Nanchang city, Jiangxi province, China, by using Mycolicibacterium smegmatis (M. smegmatis) mc2 155 as the host. Phage morphology and biology were characterized. Phage structure proteins were analyzed by LC-MS/MS. The putative functions of phage proteins and multi-genome comparison were performed with bioinformatics. The transmission electron microscopy result indicated that this phage belongs to Siphoviridae of Caudovirales. Plaques of SWU2 appeared clear but small. In a one-step growth test, we demonstrated that SWU2 had a latent period of 30 min and a logarithmic phase of 120 min. Among the 76 predicted Open Reading Frames (ORFs), 9 ORFs were identified as phage structure proteins of SWU2. The assembled phage genome size is 50,013 bp, with 62.7% of G + C content. SWU2 genome sequence shares 88% identity with Mycobacterium phages HINdeR and Timshel, differing in substitutions, insertions and deletions in SWU2. Phylogenetic tree revealed that SWU2 is grouped into A7 sub-cluster. There are several substitutions, insertions and deletions in SWU2 genome in comparison with close cousin phages HINdeR and Timshel. The new phage adds another dimension of abundance to the mycobacteriophages.

Screening of Polyvalent Phage-Resistant Escherichia coli Strains Based on Phage Receptor Analysis.

Bacteria-based biotechnology processes are constantly under threat from bacteriophage infection, with phage contamination being a non-neglectable problem for microbial fermentation. The essence of this problem is the complex co-evolutionary relationship between phages and bacteria. The development of phage control strategies requires further knowledge about phage-host interactions, while the widespread use of Escherichia coli strain BL21 (DE3) in biotechnological processes makes the study of phage receptors in this strain particularly important. Here, eight phages infecting E. coli BL21 (DE3) via different receptors were isolated and subsequently identified as members of the genera T4virus, Js98virus, Felix01virus, T1virus, and Rtpvirus. Phage receptors were identified by whole-genome sequencing of phage-resistant E. coli strains and sequence comparison with wild-type BL21 (DE3). Results showed that the receptors for the isolated phages, designated vB_EcoS_IME18, vB_EcoS_IME253, vB_EcoM_IME281, vB_EcoM_IME338, vB_EcoM_IME339, vB_EcoM_IME340, vB_EcoM_IME341, and vB_EcoS_IME347 were FhuA, FepA, OmpF, lipopolysaccharide, Tsx, OmpA, FadL, and YncD, respectively. A polyvalent phage-resistant BL21 (DE3)-derived strain, designated PR8, was then identified by screening with a phage cocktail consisting of the eight phages. Strain PR8 is resistant to 23 of 32 tested phages including Myoviridae and Siphoviridae phages. Strains BL21 (DE3) and PR8 showed similar expression levels of enhanced green fluorescent protein. Thus, PR8 may be used as a phage resistant strain for fermentation processes. The findings of this study contribute significantly to our knowledge of phage-host interactions and may help prevent phage contamination in fermentation.

Identification of a lytic Pseudomonas aeruginosa phage depolymerase and its anti-biofilm effect and bactericidal contribution to serum.

Pseudomonas aeruginosa (P. aeruginosa) infection has imposed a great threat to patients with cystic fibrosis. With the emergence of multidrug-resistant P. aeruginosa, developing an alternative anti-microbial strategy is indispensable and more urgent than ever. In this study, a lytic P. aeruginosa phage was isolated from the sewage of a hospital, and one protein was predicted as the depolymerase-like protein by genomic sequence analysis, it includes two catalytic regions, the Pectate lyase_3 super family and Glycosyl hydrolase_28 super family. Further analysis demonstrated that recombinant depolymerase-like protein degraded P. aeruginosa exopolysaccharide and enhanced bactericidal activity mediated by serum in vitro. Additionally, this protein disrupted host bacterial biofilms. All of these results showed that the phage-derived depolymerase-like protein has the potential to be developed into an anti-microbial agent that targets P. aeruginosa.

Genomic and biological characterization of the Vibrio alginolyticus-infecting "Podoviridae" bacteriophage, vB_ValP_IME271.

As an opportunist pathogen, Vibrio alginolyticus (V. alginolyticus), causes disease in marine animals. Bacterial contamination of seafood is not uncommon, and phage therapy is considered a safe way to decontaminate such foods to control the emergence of vibriosis. Here, we report on the isolation of a new, virulent phage called vB_ValP_IME271 (designated phage IME271), which infects V. alginolyticus and was isolated from seawater. Phage IME271 displayed good pH (7-9) and temperature tolerance (< 40 °C) and had a broad host range against Vibrio isolates, including 7 strains of V. alginolyticus and11 strains of V. parahaemolyticus. The IME271 genome was sequenced and annotated, the results of which showed that this phage is a Podoviridae family member with a genome length of 50,345 base pairs. The complete genome is double-stranded DNA with a G+C content of 41.4%. Encoded within the genome are 67 putative proteins, of which only 22 coding sequences have known functions, and no tRNAs are present. The BLASTn results for IME271 showed that it only shares similarity with the Vibrio phage VPp1 (sequence identity score of 96% over 87% of the genome) whose host is V. parahaemolyticus. Comparative analysis showed that IME271 and VPp1 share a similar genomic structure, and the structural proteins are highly similar (> 95% similarity score). In summary, our work identified a new lytic Podoviridae bacteriophage, which is infective to V. alginolyticus and V. parahaemolyticus. This bacteriophage could potentially be used to control V. alginolyticus and V. parahaemolyticus infections in marine animals.

Characterization and genome analysis of novel phage vB_EfaP_IME195 infecting Enterococcus faecalis.

Enterococcus faecalis is one of the main bacteria in the human and animal intestine but is also classed as an opportunistic pathogen. During normal growth, E. faecalis produces natural antibiotics and is conducive to human health. As ectopic parasites, E. faecalis is capable of causing infective endocarditis, neonatal sepsis, bloodstream infections, bacteremia, and intraabdominal infections. With the incidence of antibiotic resistance reaching crisis point, it is imperative to find alternative treatments for multidrug-resistant infections. Using phage for pathogen control is a promising treatment option to combat bacterial resistance. In this study, a lytic phage, designated vB_EfaP_IME195, was isolated from hospital sewage using a clinical multidrug-resistant Enterococcus faecalis strain as an indicator. The one-step growth curve with the optimal multiplicity of infection of (MOI) 0.01 revealed a latent period of ~ 30 min and a burst size of ~ 120 plaque-forming units (pfu) per cell. Transmission electron microscopy showed that the phage belongs to the family Podoviridae. Phage vB_EfaP_IME195 has a linear, double-stranded DNA genome of 18,607 bp with a G + C content of 33% and 27 coding sequences (GenBank accession no. KT932700). Run-off sequencing experiments showed that the phage has a unique 59-bp inverted repeat sequences at the terminal ends. BLASTn analysis revealed that vB_EfaP_IME195 shares 92% identity (93% genome coverage) with unpublished E. faecalis phage Idefix. This study reported a novel E. faecalis phage with unique genome termini containing inverted repeats. The isolation and characterization of this novel lytic E. faecalis phage provides the basis for the development of new therapeutic agents like phage cocktails for multidrug-resistant E. faecalis infection, and its unique genomic feature would also provide valuable knowledge and insight for further phage genome analysis.

Isolation and characterization of a novel phage Xoo-sp2 that infects Xanthomonas oryzae pv. oryzae.

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a serious bacterial disease in rice-growing regions worldwide. Phage therapy has been proposed as a potential measure to treat bacterial infections. In this study, a novel phage, Xoo-sp2, which infects Xoo was isolated from soil. The characteristics of Xoo-sp2, including the morphology, one-step growth curve and host range, were analysed. The genome of phage Xoo-sp2 was sequenced and annotated. The results demonstrated that Xoo-sp2 is a siphovirus and has a broad lytic spectrum, infecting 9 out of 10 representative Xoo strains. Genome analysis showed that the Xoo-sp2 genome consists of a linear double-stranded DNA molecule of length 60 370 bp. Annotation of the whole genome indicated that Xoo-sp2 encodes 79 putative open reading frames (ORFs). Comparative genomics analysis of Xoo-sp2 showed that it shares significant similarity only with Pseudomonas and Stenotrophomonas phages (with maximum identity reaching 80 % along 69 % of the genome), and thus represents a novel Xanthomonas phage. Xoo-sp2 significantly inhibited Xoo growth in liquid culture. An experiment with potted plants indicated that Xoo-sp2 could efficiently control BLB in living rice. In summary, our work characterized a novel Xanthomonas phage and demonstrated its potential as a prophylactic agent in the control of BLB in rice.

Fatal swine acute diarrhoea syndrome caused by an HKU2-related coronavirus of bat origin.

Cross-species transmission of viruses from wildlife animal reservoirs poses a marked threat to human and animal health 1 . Bats have been recognized as one of the most important reservoirs for emerging viruses and the transmission of a coronavirus that originated in bats to humans via intermediate hosts was responsible for the high-impact emerging zoonosis, severe acute respiratory syndrome (SARS) 2-10 . Here we provide virological, epidemiological, evolutionary and experimental evidence that a novel HKU2-related bat coronavirus, swine acute diarrhoea syndrome coronavirus (SADS-CoV), is the aetiological agent that was responsible for a large-scale outbreak of fatal disease in pigs in China that has caused the death of 24,693 piglets across four farms. Notably, the outbreak began in Guangdong province in the vicinity of the origin of the SARS pandemic. Furthermore, we identified SADS-related CoVs with 96-98% sequence identity in 9.8% (58 out of 591) of anal swabs collected from bats in Guangdong province during 2013-2016, predominantly in horseshoe bats (Rhinolophus spp.) that are known reservoirs of SARS-related CoVs. We found that there were striking similarities between the SADS and SARS outbreaks in geographical, temporal, ecological and aetiological settings. This study highlights the importance of identifying coronavirus diversity and distribution in bats to mitigate future outbreaks that could threaten livestock, public health and economic growth.

Investigation on Mosquito-Borne Viruses at Lancang River and Nu River Watersheds in Southwestern China.

During 2007 and 2010, an extensive entomological survey was performed to assess the distribution of mosquitoes and mosquito-borne arboviruses at Lancang River and Nu River watersheds in southwestern China. A total of 20,450 mosquitoes consisting 20 species was trapped and submitted 261 pools according to species and location. Culex tritaeniorhynchus and Anopheles sinensis were the most abundant species. Eighty-seven isolates representing 11 virus species in 8 genera were obtained from 6 mosquito species. The new isolates were identified as Getah virus (GETV), Japanese encephalitis virus (JEV), Yunnan Culex-related flavivirus (YNCxFV), Yunnan Aedes-related flavivirus (YNAeFV), Banna virus (BAV), Yunnan orbivirus (YUOV), Banna orbivirus (BAOV), Yunnan totivirus (YNToV), Nam Dinh virus (NDiV), Menghai rhabdovirus (MRV), and Anopheles minimus iridovirus (AMIV). These viruses included confirmed or potential pathogen of human disease, such as JEV, BAV, and NDiV, and several novel or reassortant arboviruses, such as YNAeFV, MRV, AMIV, and BAOV. GETV, JEV, YNCxFV, and NDiV were widely prevalent in the whole basin of the two rivers. The findings contribute to our understanding of the diversity and wide distribution of mosquito-borne arboviruses in the area, and are helpful to explore pathogenic evidence for fevers and viral encephalitis of unknown etiology.

Complete genome sequence of a novel, virulent Ahjdlikevirus bacteriophage that infects Enterococcus faecium.

A novel virulent bacteriophage named vB_EfaP_IME199 that specifically infects Enterococcus faecium was isolated and characterized. Its optimal multiplicity of infection was 0.01, and it had a 30 minute outbreak period. High-throughput sequencing revealed that the phage has a dsDNA genome of 18,838 bp with 22 open reading frames. The genome has very low homology to all other bacteriophage sequences in the GenBank database. Run-off sequencing experiments confirmed that vB_EfaP_IME199 has short inverted terminal repeats. Phylogenetic analysis indicated that vB_EfaP_IME199 can be taxonomically classified as a new member of the genus Ahjdlikevirus of family Podoviridae.

Complete Genome Sequence of a Novel Multidrug-Resistant Klebsiella pneumoniae Phage, vB_Kpn_IME260.

Klebsiella pneumoniae is the most common clinically important opportunistic bacterial pathogen and its infection is often iatrogenic. Its drug resistance poses a grave threat to public health. The genomic data reported here comprise an important resource for research on phage therapy in the control of drug-resistant bacteria.

Characterization and complete genome sequence analysis of a novel virulent Siphoviridae phage against Staphylococcus aureus isolated from bovine mastitis in Xinjiang, China.

Bovine mastitis is one of the most costly diseases in dairy cows worldwide. It can be caused by over 150 different microorganisms, where Staphylococcus aureus is the most frequently isolated and a major pathogen responsible for heavy economic losses in dairy industry. Although antibiotic therapy is most widely used, alternative treatments are necessary due to the increasing antibiotic resistance. Using phage for pathogen control is a promising tool in the fight against antibiotic resistance. Mainly using high-throughput sequencing, bioinformatics and our proposed phage termini identification method, we have isolated and characterized a novel virulent phage, designated as vB_SauS_IMEP5, from manure collected from dairy farms in Shihezi, Xinjiang, China, for use as a biocontrol agent against Staphylococcus aureus infections. Its latent period was about 30 min and its burst size was approximately 272PFU/cell. Phage vB_SauS_IMEP5 survives in a wide pH range between 3 and 12. A treatment at 70 °C for 20 min can inactive the phage. Morphological analysis of vB_SauS_IMEP5 revealed that phage vB_SauS_IMEP5 morphologically resembles phages in the family Siphoviridae. Among our tested multiplicity of infections (MOIs), the optimal multiplicity of infection (MOI) of this phage was determined to be 0.001, suggesting that phage vB_SauS_IMEP5 has high bacteriolytic potential and good efficiency for reducing bacterial growth. The complete genome of IME-P5 is a 44,677-bp, linear, double-stranded DNA, with a G+C content of 34.26%, containing 69 putative ORFs. The termini of genome were determined with next-generation sequencing data using our previously proposed termini identification method, which suggests that this phage has non-redundant termini with 9nt 3' protruding cohesive ends. The genomic and proteomic characteristics of IMEP5 demonstrate that this phage does not belong to any of the previously recognized Siphoviridae Staphylococcus phage groups, suggesting the creation of a new lineage, thus adding to the knowledge on the diversity of Staphylococcus phages. An N-acetylmuramoyl-L-alanine amidase gene and several conserved genes were predicted, while no virulence or antibiotic resistance genes were identified. This study isolated and characterized a novel S. aureus phage vB_SauS_IMEP5, and our findings suggest that this phage may be potentially utilized as a therapeutic or prophylactic candidate against S.aureus infections.

First complete genome sequence of a virulent bacteriophage infecting the opportunistic pathogen Serratia rubidaea.

A Serratia rubidaea phage, vB_Sru IME250, was isolated from hospital sewage. The morphology suggested that phage vB_Sru IME250 should be classified as a member of the family Myoviridae. High-throughput sequencing revealed that the phage genome has 154,938 nucleotides and consists of 193 coding DNA sequences, 90 of which have putative functions. The genome of vB_Sru IME250 is a linear, double-stranded DNA with an average GC content of 40.04%. The phage has a relatively high similarity to Klebsiella phage 0507-KN2-1, with a genome coverage of 84%.