Staphylococcus aureus Isolated from the Oral Cavity: Phage Susceptibility in Relation to Antibiotic Resistance

Nowadays, research on bacteriophage therapy and its potential use in combination with antibiotics has been gaining momentum. One hundred and ten oral Staphylococcus aureus isolates were phage-typed and their antibiotic resistance was determined by standard and molecular methods. The prevalence of MSSA and MRSA strains was 89.1% and 10.9%, respectively. Nearly all (91.8%) analyzed isolates, whether MSSA or MRSA, were susceptible to the phages used from the international set. The highest lytic activity showed phages 79 and 52 A from lytic group I. The predominant phage groups were mixed, the I+III group and a mixed group containing phages from at least three various lytic groups. S. aureus strains sensitive to phage group I were usually resistant to penicillin and susceptible to ciprofloxacin, whereas the strains typeable with group V or group V with the 95 phage were susceptible to most antibiotics. Epidemic CA-MRSA strains (SCCmecIV) of phage type 80/81 carried Panton–Valentine leucocidin genes. Considering the high sensitivity of oral S. aureus to the analyzed phages and the promising results of phage therapies reported by other authors, phage cocktails or phage-antibiotic combinations may potentially find applications in both the prevention and eradication of staphylococcal infections.

Pseudomonas Phage MD8: Genetic Mosaicism and Challenges of Taxonomic Classification of Lambdoid Bacteriophages

Pseudomonas phage MD8 is a temperate phage isolated from the freshwater lake Baikal. The organisation of the MD8 genome resembles the genomes of lambdoid bacteriophages. However, MD8 gene and protein sequences have little in common with classified representatives of lambda-like phages. Analysis of phage genomes revealed a group of other Pseudomonas phages related to phage MD8 and the genomic layout of MD8-like phages indicated extensive gene exchange involving even the most conservative proteins and leading to a high degree of genomic mosaicism. Multiple horizontal transfers and mosaicism of the genome of MD8, related phages and other λ-like phages raise questions about the principles of taxonomic classification of the representatives of this voluminous phage group. Comparison and analysis of various bioinformatic approaches applied to λ-like phage genomes demonstrated different efficiency and contradictory results in the estimation of genomic similarity and relatedness. However, we were able to make suggestions for the possible origin of the MD8 genome and the basic principles for the taxonomic classification of lambdoid phages. The group comprising 26 MD8-related phages was proposed to classify as two close genera belonging to a big family of λ-like phages.

Genomic diversity, life strategies and ecology of marine HTVC010P-type pelagiphages

SAR11 bacteria dominate ocean surface bacterioplankton communities, and play an important role in marine carbon and nutrient cycling. The biology and ecology of SAR11 are impacted by SAR11 phages (pelagiphages) that are highly diverse and abundant in the ocean. Among the currently known pelagiphages, HTVC010P represents an extremely abundant but under-studied phage group in the ocean. In this study, we have isolated seven new HTVC010P-type pelagiphages, and recovered 77 nearly full-length HTVC010P-type metagenomic viral genomes from marine metagenomes. Comparative genomic and phylogenomic analyses showed that HTVC010P-type pelagiphages display genome synteny and can be clustered into two major subgroups, with subgroup I consisting of strictly lytic phages and subgroup II mostly consisting of phages with potential lysogenic life cycles. All but one member of the subgroup II contain an integrase gene. Site-specific integration of subgroup II HTVC010P-type pelagiphage was either verified experimentally or identified by in silico genomic sequence analyses, which revealed that various SAR11 tRNA genes can serve as the integration sites of HTVC010P-type pelagiphages. Moreover, HTVC010P-type pelagiphage integration was confirmed by the detection of several Global Ocean Survey (GOS) fragments that contain hybrid phage–host integration sites. Metagenomic recruitment analysis revealed that these HTVC010P-type phages were globally distributed and most lytic subgroup I members exhibited higher relative abundance. Altogether, this study significantly expands our knowledge about the genetic diversity, life strategies and ecology of HTVC010P-type pelagiphages.

Diarrhea Duration and Performance Outcomes of Pre-Weaned Dairy Calves Supplemented with Bacteriophage

This study aimed to evaluate lytic bacteriophage supplementation in pre-weaned dairy calves over neonatal calf diarrhea and respiratory diseases occurrence, performance and biochemical parameters. Also, to determine bacterial agents causing NCD. Two hundred Holstein×Gyr crossbred female calves were divided into two groups: Control (CON, n = 100), no supplementation; and Bacteriophage (PHAGE, n = 100) bacteriophage supplementation (1 g/day) from d 3 until d 70 of life. Calves were monitored daily for respiratory disease and diarrhea, as for age at the first diarrheic episode and its duration. Fecal samples were cultured for isolation of Escherichia coli and Salmonella spp. colonies and PCR was performed to identify E. coli virulence genes and to confirm Salmonella spp. Performance outcomes were evaluated up to 80 d of age. Blood samples were collected to determine serum levels of total proteins, albumin, cholesterol, γ-glutamyl transferase and urea. PHAGE group had fewer days in diarrhea and duration of the first episode was lower, compared to CON group. Fecal samples of three animals in PHAGE and nine in CON were positive for E. coli in PCR. Thoracic perimeter tended to be higher in supplemented animals. Average daily gain mean of PHAGE was higher in the first 30 d of life, at the beginning of step-down weaning (up to 42 d) and after weaning (up to 80 d). PHAGE mean was lower for albumin and higher for urea. Therefore, phage therapy during the pre-weaned period reduced the duration of neonatal diarrhea, providing greater weight gain for calves.

Genomic Characterization and Distribution Pattern of a Novel Marine OM43 Phage

Bacteriophages have a significant impact on the structure and function of marine microbial communities. Phages of some major bacterial lineages have recently been shown to dominate the marine viral communities. However, phages that infect many important bacterial clades still remained unexplored. Members of the marine OM43 clade are methylotrophs that play important roles in C1 metabolism. OM43 phages (phages that infect the OM43 bacteria) represent an understudied viral group with only one known isolate. In this study, we describe the genomic characterization and biogeography of an OM43 phage that infects the strain HTCC2181, designated MEP301. MEP301 has a genome size of 34,774 bp. We found that MEP301 is genetically distinct from other known phage isolates and only displays significant sequence similarity with some metagenomic viral genomes (MVGs). A total of 12 MEP301-type MVGs were identified from metagenomic datasets. Comparative genomic and phylogenetic analyses revealed that MEP301-type phages can be separated into two subgroups (subgroup I and subgroup II). We also performed a metagenomic recruitment analysis to determine the relative abundance of reads mapped to these MEP301-type phages, which suggested that subgroup I MEP301-type phages are present predominantly in the cold upper waters with lower salinity. Notably, subgroup II phages have an inverse different distribution pattern, implying that they may infect hosts from a distinct OM43 subcluster. Our study has expanded the knowledge about the genomic diversity of marine OM43 phages and identified a new phage group that is widespread in the ocean.

The Assembly of Bacteriophage Functional Enzymatic Models in Association with E. coli Proteins' Profiles

Introduction: The invasion of bacteriophage on the associated host bacterium depends on their receptors' orientation that adsorb them to cell surface. During phage replication a valuable number of proteins acts as lytic enzymes for host puncher at the beginning of the infection and other for burst after lytic cycle compilation. Accordingly, the proteomic relationship among phage and bacterium proteins could easily be studied by their protein profiles analysis. Objective: To detect bacteriophages functional enzymes during lytic cycle. Methods: The isolation and identification of Escherichia coli and their parasitic T7 phage group was done using bacterial culture and common plaque assay techniques. The investigations and protein-protein interactions' assays were inveterate by proteins profile of phage and bacterium using Sodium Dodecyl Sulphate Poly Acrylamide Gel Electrophoresis (SDS-PAGE) to find out their molecular weights, where the scaled location of each mobile band was compared to the standards of identified proteins weights in the molecular ladder. Thereafter, Protein model's assembly and bands migration was done by computer analytical software. Results: Mobilization of the phage' proteins inside the Two Dimensions (2D) gel ranged between 60 and 12 kDa where a model of 4 main bands with molecular weights of (46, 35, 24 and 14 kDa) is corresponded to the host ones, where pure 9 bands with molecular weight ranged between 96-24 kDa. The computational model analysis showed common shared molecular masses of 47, 34 and 16 kDa on plot area of the phage and the bacterium. Model interpretation confirmed that proteins ranged from 47.7 to 34.3 kDa resembles 43.3% of whole phage's proteins that assembled the capsid head and the coil, while the molecular weight mass of 22.5 formed the tail's proteins. The lytic enzymes' molecular weight was ranged between 18-14 kDa according to the function of the enzyme. The study revealed that the 34 kDa band has the common shared peak between T7 phage group and associated Escherichia coli host. Conclusion: Functional models of analysed proteins during phage assembly, ensures lytic enzymes are built in the capsid head and the lysozyme in the tail, they facilitate the enzymatic decay for bacterial host. This enzymatic function is related to the lytic cycle of the bacteriophages and their phenomenon in employing the bacterial DNA in proteins manufacturing during their replication inside host.

From Orphan Phage to a Proposed New Family–The Diversity of N4-Like Viruses

Escherichia phage N4 was isolated in 1966 in Italy and has remained a genomic orphan for a long time. It encodes an extremely large virion-associated RNA polymerase unique for bacterial viruses that became characteristic for this group. In recent years, due to new and relatively inexpensive sequencing techniques the number of publicly available phage genome sequences expanded rapidly. This revealed new members of the N4-like phage group, from 33 members in 2015 to 115 N4-like viruses in 2020. Using new technologies and methods for classification, the Bacterial and Archaeal Viruses Subcommittee of the International Committee on Taxonomy of Viruses (ICTV) has moved the classification and taxonomy of bacterial viruses from mere morphological approaches to genomic and proteomic methods. The analysis of 115 N4-like genomes resulted in a huge reassessment of this group and the proposal of a new family “Schitoviridae”, including eight subfamilies and numerous new genera.

A meta-analysis and experiment assessing phage-based FMDV vaccine

Foot-and-mouth disease (FMD) is a pathological disease caused by the foot- and-mouth disease virus (FMDV), which mainly affects cloven-hoofed animals. This study was conducted to a meta-analysis and experiment on the effect of bacteriophages used in the development of FMDV vaccines. A systematic search was conducted for the collection of the protection effect for the phage-based FMDV vaccine using sensitive search strategies. The extracted data were analyzed using Rev-Man 5.4 software. This experiment used the T7 phage to express the capsid protein VP1 of the OHM-02 strain, and the recombinant VP1 phage was termed OHM-T7. Antibodies and cytokines levels were assessed after immunizing BALB/C mice with OHM-T7. The results showed that a total of 115 articles were retrieved, and 4 of them met the inclusion criteria. There was no heterogeneity with I2 = 0%, 20% or 43%. We used a fixed-effect model for meta-analysis, and the results showed a protective effect on FMDV between the phage group and control group (P<0.01) and between FMDV group and control group (P<0.01). Furthermore, when the phage group was compared to the FMDV group, there was also no significant difference (P>0.05). After successfully obtained the ohm-t7 strain and immunized the mice, it could induce high levels of IFN-γ levels in mice with little effect on IL-4 levels. OHM-T7 could be used to detect antibodies produced by mice immunized with different FMDV antigens and produce high levels of anti-FMD antibodies. In summary, these results showed the potential of phage-based FMDV vaccines in FMDV prevention.

Lactococcus Ceduovirus Phages Isolated from Industrial Dairy Plants—From Physiological to Genomic Analyses

Lactococcus Ceduovirus (formerly c2virus) bacteriophages are among the three most prevalent phage types reported in dairy environments. Phages from this group conduct a strictly lytic lifestyle and cause substantial losses during milk fermentation processes, by infecting lactococcal host starter strains. Despite their deleterious activity, there are limited research data concerning Ceduovirus phages. To advance our knowledge on this specific phage group, we sequenced and performed a comparative analysis of 10 new Lactococcus lactis Ceduovirus phages isolated from distinct dairy environments. Host range studies allowed us to distinguish the differential patterns of infection of L. lactis cells for each phage, and revealed a broad host spectrum for most of them. We showed that 40% of the studied Ceduovirus phages can infect both cremoris and lactis strains. A preference to lyse strains with the C-type cell wall polysaccharide genotype was observed. Phage whole-genome sequencing revealed an average nucleotide identity above 80%, with distinct regions of divergence mapped to several locations. The comparative approach for analyzing genomic data and the phage lytic spectrum suggested that the amino acid sequence of the orf8-encoded putative tape measure protein correlates with host range. Phylogenetic studies revealed separation of the sequenced phages into two subgroups. Finally, we identified three types of phage origin of replication regions, and showed they are able to support plasmid replication without additional phage proteins.